Presentation on theme: "University of Jordan Faculty of Agriculture Department of horticulture and crop science Protected Agriculture(0641322) Dr. AZMI ABU-RAYYAN."— Presentation transcript:
University of Jordan Faculty of Agriculture Department of horticulture and crop science Protected Agriculture(0641322) Dr. AZMI ABU-RAYYAN
Introduction It is the intensive cultivation of vegetables crops under protective structures (GH, PH, low tunnels, hot beds ----- mulch) having many objectives: 1- High quality and quantity. 2- Off season production. 3- Elongation of growing season (early and or delay). 4- Higher profit as consequence. This is possible, since we are able to manage: 1.Providing the protective plants with proper Env. Conditions (Temp. ↓or↑, R.H.↑or↓, light intensity ↓or↑ and CO 2 ↓or↑). 2.Providing the plants with proper Nutritional requirements. 3.Providing the plants with well prepared soil, free from diseases, using resistant CSV's or free from diseases, or using sterilized growing media or fertilizer solution in soil less cultivation.
This sector is differing from open field system in techniques to be applied but with similar basics. Points of differences are: 1.Production cost is much more → more Efficient use of land (vertical extend and increase plant population as much as possible.) → increase production → increase profit. But in the same time much more risks (diseases, pollination problem fertilizers shortage as a result of monoculture and intensive cultivation system, heating and cooling problem, ventilation, light intensity. 2.These risks, make the sector under continuous check using developed equipment that enable resolving any problems in relatively short time as the presence of irrigation system, fertilization one, heating, cooling ventilation as well as presence of professionals to control pests problem effectively. 3.All these are costing factors which need a real capital to be employed and experienced farmers which are able to face and resolve any sudden problems in the field or in the market.
4-In any time and as a result of high cost of production → farmers are ready to use any further idea to increase their profits or to save their crops from any sudden problem. This leads in many cases to unwise utilization of the factors (to increase production or to overcome the problem) leading to possibility of very high pollution than in case of open field cultivation. 5-To certain extent, you can control time of production according to the market demand. (Degree day). 6-Keeping continuous quality of the product for long period of season. This standard quality is deeply related to the level of production factors effectuated and type of protective structures and their efficiency in controlling the variations in environmental condition including covering materials.
So, all these points lead to off season production and increase the production as a result of intensive cultivation and elongating the growing cycle → higher profits (if marketing is programmed in well manner, otherwise the opposite will occur. Also protective structures are highly need for isolation and breading programs, production of valuable plants as flowers and indoor plants (that characterized by high profits) and as nurseries and for hardening purposes. More than 400,000ha is the area utilized for production under protective conditions in the Mediterranean region 2.5% of that is covered with glass, 17.5% as plastic houses, 50% is covered with mulch and 23% is covered with low tunnels. USA, Japan, Holland, France, Spain, Italy, Belgium, Germany and Grand Britain are first countries in world in this sector. Low tunnels, in addition to their function as nurseries and for hardening purposes. Also can be utilized for watermelon and muskmelon and strawberry cultivation. To anticipate melon production by being covered at early growth stages. They are proper for farmers of low budget and can realize a good profit if managed well.
Tomato, Strawberry, Pepper, Cucumber, Squash (Hybrid), Eggplant, Lettuce, Melon and Beans are the main vegetables to be cultivated under protection showing two production periods: early: April-June and late in Autumn except for lettuce that could be produced mainly from January- March (Esbjerg for summer). This not valid for J.V.: early (autumn) from November to February and late (spring) from March to May or June. Also the activity of nurseries (for vegetable seedling production, flowers, indoor plants) is much related to the planting time of plants in permanent field (open or protective). They are well prepared, control of R.H, heating, parasite----- etc.). In Jordan: protection of vegetables had started in J.V. at 1968 with 2 Plastic Houses in Dir- Alla station. One was planted with various cucumber cvs while the other with tomato hybrid cvs.
J.V. is a very big natural G.H in which you can produce summer vegetables in winter time without heating but under protective structures. But there are some limits that decrease the production, the quality or some times eliminate the production totally as: - low temp. during clean sky nights → heat inversion. -low temp. during the 40days (22/12-2/2). for improving the quantity and quality of the protected vegetables there should be the use of protective structures and the covering sheets (pH, GH and tunnels). By protection, tomato production had increased from 1.5 ton/donum in open → 10 ton/donum of P.H. and 1ton/donum in open → 8ton/donumP.H. for cucumber. In 1980’s, protection techniques had spreaded to hilly land for (1) having early production in hilly are and (2) extending it into autumn producing in months of off production in J.V.
(July, August, September and October). (3) cost of pest control in J.V. (4) severe depletion of input resources. % of protected area Tot. vegetables Tot. protected Don. pH Don. tunnel Year 418038537951978 8%313243250506911181391994 5.7%429309245018596159051995 11.3%271483307019503211951996 634%2370%460% of ↑
The % of protective is low because of: 1.No need to protect all vegetables as roots, tubers. 2.Protection is highly costed. 3.Low income of major part of farmers. also increase production → decrease profit since exporting to the outer markets is limited → diversification
Means of Protection From non favorable condition The non favorable conditions which affect negatively the quantity and quality or cause death of plants are: frost, minimum temp. or below, max: temp. or above, winds (cold, hot, sandy----), high, low light intensity, hail and others. The means of protection were developed from simple to highly sophisticated and complete automatic GH’s. they are: 1.Selection of protective place and using the proper method of cultivation, (in between mountains or in southern side of the mountain or south-Eastside to gain earlier warming condition and anticipate the spring planting time. Also making bed with slope towards south. Planting your plants in west or north side of the furrow to be directly exposed to sun shine.
2-Protecting the planted area by fences (hedges) (as like 2-3 lines of corn, sunflower, cactus, roses) against animals, winds, thieves and sand. These fences can be sufficient especially for vegetables of bus by growth (not vertical) where no need to do wind breaks to avoid loss of certain part of your land by shading and very low cost of wind breaks construction. 3-Wind breaks: if there is a sever wind, and sandy conditions they are build to filtrate the prevail wind (perpendicularly) as like 1)- living plants (pines, casuarinas ----) in a one or 2 lines (alternative) according to wind severity (1.5-2m between plants × 2-3m between lines) leaving about 8-10m in south or east sixes without planting since wind break will induce shading later on. *Characters of plants to be used are: 1) Ever green 2) of high growth rate into the upright and laterally. 3) Hard wood to tolerate wind force 4) not to be a source of pests infections.
2) Sterns of semi woody plants to be fixed in soil or built as not as those corn, sugar can ----- leaving space between each strip and other, so as to filtrate the strong wind and absorbing it’s force 3) nets of plastic strips to decrease the wind velocity and not to block (since blocking creates forces behind the nets which can destroy both the break and crop). So they are filtrating about 50% of wind speed. Can be established with more than one line. Should be treated against negative effect of U.V. light so as to elongate their life up to 5 years. They have advantages of non competing your crop on water or nutrient elements and not to be as a host for pests. 4) Caps of plants: that protect from winds and sands and can anticipate the production by rising temp.
little bit more than non covered and so non severe frost is overcome. They are of inverted V over cucumber against wind, hot tent over melons during low temp. where ventilation is done by cutting certain part 3-5cm from the side opposite to prevailed strong wind and this cut is very high as plant grown and very high in size up to be removed as the plant becomes in touch with the inner side of the cover. Ventilation is important to get rid of RH% and hardening well established plant. Disadvantages: exposing to decrease temp. after increase temp. can harmful the plants since during high temp we will have soft, sensitive plants to cool conditions. 5- Spraying the plant by mist water when temp. is around freezing level to release energy (80 cal/gm of water) when frozen which can to certain extent protect plants especially if the sprayed water is heated. It is practically applied for farm of citrus..
6- Spraying the plants with foam (as Agri-foam (commercial name) of Gelatin protein and stabilizer material for the foam and spreading one at the night of expected frost. It has been proved to be efficient in protected melon by very high temp. 12c > non treated since treated have been isolated from atmosphere and energy released from soil will be conserved for plants. Done by having source pf compress air to pass through a sponge surface that covered with foam material → small air foams which will be covered with membrane of the foam material which will an in volume up to cover plant. 7- Smoking over plant during frost nights → Radiahrns Air mixing to mix the upper warm with lower cold air in calm conditions. 8- The use beds are cold or hot for production of seedling early in season when low temp. is dominating. These beds should established near farm serves as water and over a well drained soil and protected by wall of farm building or behind wind break and well exposed to sunshine. It is firmed from bed (soil or sand or mix), over which frames of wood or cement are established with 45- 60cm for northern side × 22.5-45 for southern side as height × cover frame (cloth, glass or plastic of 180cm × 90cm exactly as dimension of base bed.
Methods of Heating in hot beds: a)Non fermented manures × straw with 2 : 1 ratio that prepared 10- 14 days before being used as covered a pile that moistened and mix each 3 days to have uniform decomposition. Then spreading at the bed base to 30-90cm height according to the time needed to have heating (where 30-45cm gives heating up to 3-4 weeks while 60-90cm give heat up to 3 months). The base of bed should be well drained to draw down the excess moisture which if remain will block the fermentation and heat evolve. Normally, it is distributed: 12.5cm manure then pressed uniformly then another one up to final height distributing the top a layer of soil of 5-15cm for having uniform heat distribution and avoiding hot spots that may burn plants or seeds. Warm moistened manure shows > rate of decomposition than the cold moistened one.
b)Hot air: released heat of wood, methane or fuel burning is carried and pump ed as hot air to end of pipes established in the bed. c)Hot water: hot water is distributed from burning point into various bed points through pipes that established at the base and in both sides of the bed, pipes volume and eff. Of heater and prop sloping of bed an show better heating efficiency. d)Electricity: the electrical resistance which isolated by covered with lead, is distributed on soil surface and soil and along the inner side of the bed. Automatic means can be established for ventilation, irrigation < 50g mists → uniform distribution. In case of cold bed, there is no heating source. So main source of energy gaining inside it is the conserved solar radiation which related to type of cover, ventilation is important during sunny day at the morning up to afternoon not later so as to avoid sever drop in temp. during night. *They are used for: 1)ear by production of seedlings especially in areas of not sever winter. 2)hardening of seedling that produced under heated structure.
In addition to ventilation process which prevents RH% ↑. The irrigation is done also during the morning so as to be dried out before evening (avoid risks of RH and avoid drop down of temp. as a result of water evaporation) and avoid burning spots of leaves by direct sun. 9- Low plastic tunnels: can be used for 1- seedlings production during low temp. of December and January. Can be consider as a beds or basins of 90cm × 3-4m. that seeded, irrigated then the tunnel is built over them by using galvanized wines each 1m (4-5mm as Ө ventilation done after 3weeks of seeding if temp. is low. By lifting the opposite side to prevailed wind during the day and close during night up to 10-12day before transplanting where lifting the cover completely is done. Irrigation is just at seeding time and if temp. increase another time can be done. 2- protecting plants of crops during early stages so as to have early production than open since frost risk can be avoided and reflected radiations from soil are maintained under the tunnel and protection from winds, rainfall ----- How to build the tunnel ??? after preparation.
Which can be from galvanized wires of 4-5mm Ө × 2m length or from galvanized tubes of ½ as Ө × 3m length which immersed a 1.5m space in the soil. Or could be from reinforced metallic wire of 8-10mm in Ө × 3.65m that can make an arc of 2m width as like the galvanized tubes. While the galvanized wire can make an arc 1m in width. P.E is the covering sheet of 50-80 micron and not more since it is costed and used and used for only one growing season or tow while height ranged from 45-80cm.
As the bed base increase, then thickness of the covering sheet is ↑↑ but within the range of 50-80m. and also sheet width TypeThickness m Sheet width (cm) Tunnel H. (cm) Tunnel base(cm) P.E38-50130-1504540-50 P.E38-50180-2005580-90 P.E50-8020055120-130 P.E8025055140-160 P.E8033080180-220
Tunnel Length should not exceed 30m to facilitate ventilation and improving pollination process (as a result of air shaking) for those that need pollens. >70% of what reflected will be lost oury tunnel this % is decrease at presence of water vapor film at the inner side of plastic sheet when it is of P. Ethylene, the normal type to be used for tunnels. Small tunnels for seedlings production and early protection while bigly ones → for protecting plant even at well developed stage. Fiber glass, corrugated type can be used for protecting vegetables of home garden, which can be used for many times and clean easily but dimensions of tunnel should be exactly prepared with fiber glass. Perforated plastic sheets, can be used so as to have efficient ventilation and elimination risks related to excess R H% in tunnel but this should not be highly perforated so as not to loose efficient of heating
10- Floating Covers: sheets of poly propylene that weighed 14gm/m2. as specific weight. So they are light so as to be spreaded directly over plants without inducing any damage and leaved free in order not to block plant growth allowing 80% of light tmns. 11- Shading against strong sunlight: can be done by: -covering fruit with straw as like melons against suns cold or most of tomato plants. This method low drastically % of light to reach. -- production of vegetables under palm plants which protect vegetables from high temp., wind and direct sun shine in hot areas as Albasre. -- using plastic nets: that spreaded over frames (as those of normal tunnels). Of black or green color which transmit certain % of light according to netting intensity, the preferred is what allow to 50-60% of light transmittance so as to have 4000-5000lux of light intensity, They are treated against U.V. damage, so can remain for 3-4 years in a good state.
-using of Jute sheets in nurseries to protect the tender plants during very high temp. condition or for those that considered shade loving plants. -spraying of time solution over plastic or glass covers for one or 2 times to have good shading level, stick material can be mixed with solution but washing of it later during cold condition become more difficult. (washing by spraying with 5% oxalic acid). -clay solution to be sprayed over the covers during very high temp. season to elongate growth and productive life of crop but ↓↓↓ % of transmittance light in a noticed manure, so can be applied later on when P.S. rare ↓↓ and not affect negative the yield. - -- thermo blankets.
12- Plastic shelters for protection of tomato fruits from cracking as a result of heavy rainfall. This sheet is spreaded over frames of tomato crops grown in open field but vertically and also covering the sides exposed to strong wind that may also port rainfall to fruits. 13- Plastic houses: high tunnels that characterized by following points in relation to low tunnels: a- Longer period of production. b- Better vertical expansion and very high plant density (No. of plants/m 2 ). c- Good production of qualified early crop that gives higher prices. d- Increase the productivity as it is possible to improve pollination and fertilization % by using Bumbles and as a real capital is employed which better factors of services and cultivation. e- Better exporting activity since the quality is more and contained for longer period. f- Easier to prepare the soil, serve plants and to overcome pests or fertilizer or water shortage problems. g- Faster cycle of the capital to have return → private sectors are highly involved in this sector -
*Glass houses: plastic houses are characterized by: a.More safety against wind than pH. b.Higher efficiency of solar radiation (that incident/unit time) transmittance and captured → better energy conservation. c.Easier and better control of micro condition under protective G.H. structure than pH since they are provided with all facilities that. d.Enable faster conditioning and minimum variation between day and might conditions. e.Lower water vapor condensation → lower risk related to dropping of condensate water vapor.
*Plastic houses: Glass houses are characterized by: a.Lower construction cost that = 1/10 of glass houses cost. b.Arc structure of plastic house enable long period of perpendicular light/day than GH → continuous transmittance of great portion of incident solar radiation. c.Changing the location of your protective structure is more easy with pH than GH which may occur every group of year for crop rotation reasons or for eliminating the risk of certain epidemic diseases since possibility of nutrient elements shortage and high diseases diffusion is very high under intensive cultivation. d.Shading induced by pH frames is much lower than that induced by frames and other components of GH. e.GH maintenance during its life is more applicable and costed more than pH. f.pH’s are more adapted for summer and warm areas since they show lower warming condition than GH’s which are more adapted for cold regions and winter time → cooling cost is so > in GH then in pH.
Covering Materials 1-Glass: that covers that great part of glass house structure (Roof and upper party walls), non colored, pure of 3-4mm for roofs and 2.5-3mm as thickness for walls that face lower accidental weight. Glass plates dimension are of 40cm × 45-60cm, some time reach to 100cm length but the smaller the dimensions, the greater the resistance to any presser and the lower the risk to be broken and if broken the lower the cost to be changed > 90% of incident light is transmitting and low portion of that will be lost (to outside) as reradiated easy to be cleaned and of long duration up 25 year if not broken, so easy to be broken but not burned, conserve for-red radiation.
2-Plastic: either of P.E or P.V.C (poly vinyl chloride) of 180-200m for plastic houses as thickness. Treated against negative effect of U.V light so as to elongate the duration. Also can be provided with silicon atoms which keep the expansion rate at low level → better conservation of reflected light since remain straight for longer period than non treated. Double cover of plastic can be used with a space of 4-20cm (not more, not less) by pumping the air to the space. This can increase temp. inside up to 6˚c greater than out during the night of winter time. Since there is a kind of isolation. Easy to be burned, light in weight, lower cost than glass, permeable and O2, CO2 but not to water vapor, but of lower transmittance rate that is about 90% when new which decrease to 50% after one year. Allow passing of reflected for red radiation. So loss of energy from these covers is > than from glass and water drop will be condensated and after being accumulated at these rough surface (inner side) will drop down over plants → ↑ R.H% + ↑ incidence of diseases P.E is more affected by heat, light so they are changed every 2 years while P.V.C each 3 years- 5 years.
3-Fiberglass: that used to cover structures that manufactured from aluminum frames with which easy to fix the fiber plates, also can be used to cover tunnels (arc length = width of fiber plate). Also can be used to cover plastic houses but should be fixed in a special way. (cross in inverted manner and straight wire over each over lapping area) plate are either corrugated or flat of (1.3m×7.3m×1cm as thick) light in w.t., allow passing of 80-90% of incident light when new, this % ↓ gradually with plate aging as a result of changes induced on plate surface which are related to environmental conditions (friction of sand particles that are carried by wind to → rough surface that enable development of decay organisms → green or black color → low transmittance percent). High in cost compared with plastic and easy to be burned. 4-Cloths: to protect the plants from insects attachment and shading plants against strong light intensity also can be used as a second door in plastic houses, GH. For having efficient control of insects filtration to cultivated plants with entrance of labors and technicians. From the kinds used: muslin, agryl.p.17 and agronet. Raished cover in west bank.
Types of plastic houses used in Jordan: 1.Local types: that make of water pipes that prepared manually (arcs are wounded according to model frame) from pipes of “½ -1”. Width is varied from 3.5-7m×2-2.5 height of the upper point and 1.5 is the distance between each arc and other having woody doors and plastic cover which is treated against U.V. radiation, transparent and of 80- 120m and can persist to 3 seasons. 2.Imported types: a- Filcluir: French, of galvanized tubes that reach to mmӨ and of 64m length × 7-8.5m width ×2.75-3.2m height ×1.5m between first and arc then 3 or 2.5 or 1.5m between each other arcs. They have lefting bars as much as No. of arc for climbing of plants and rein forcing the arcs to inside they have winders for ventilation that can be opened by manawille. b- Fornir: French, of galvanized iron 50-60mmӨ, reach to 54m length as plastic structure ×7-8-9m width ×2.65-3-3.33m as height. 1m is the distance between 1rst and 2nd are then 2-2.5m the other arcs are spacing. Having manawella to open and close the windows.
Construct ruction of protective structures Before the establishing of P. structures, there are general conditions and others special to be taken in consideration: a.The General: 1- Capital that facilitate the application of all inputs needed for the production process (P. structures, wind breaks, seedlings production from qualified seeds, fertilizers, O.M., soil preparation and leveling, irrigation, machines, labors cost, transportation, conditioning ------etc). 2- Presence of water sources or wells or rainfall collection as the source is closer, it will be better. 3- Presence of roods to and from the farm to provide it with production inputs and take from the frame the product.
4- Availability of labors centers near farm area (especially at the harvest time and planting time) experienced labors are optimum. 5- Presence of professional people that can do a successful management throughout: * Employing input factors in a best manner (minimum cost → higher qualified input production and lower impact to the environment (fertilizers and pesticides). *Ready to make any design to face any sudden event so as to resolve problems related to that event in relatively short time and with minimum risks or side effects to environment. *Ready to work with his hands, to plow, to drive lorry or tractor and not feel the superiority → well trained and experienced.
*Able to use and understand the useful results of new techs that may ↑ or improve the production process as (PH meter, E.C. programming of irrigation and fertilization and computer). * Able to forecast the productivity of various crops in his region. 6- Good market facilities by instructions (cleaning, grading, packaging, labeling, cooling, distribution) and good programming for production.
a.The special factors: 1- The proper location that protected from winds, building shadings or trees, connected with roads to and from the location, near to water source (good water and continuous), well drained soil (sandy to sandy loam), near to labor centers and large area that enable any future extend or development. 2- If wind breaks are needed and natural not presented, then the construction of netted plastic breaks that allow passing 50% of the wind (filtration of wind force) which can ↓ wind speed up to 60% (40% the remain) of total wind speed at 5 × the height and up to 20% (80% the remain) of total wind speed at 20 × the height of break, so 180-240cm height are sufficient since these wind breaks rises the flow of wind up ward, that means above the top of vegetables.
3- Direction of protective structures: in calm locations, all types weather simple or multi-span should be fixed in our region at North-South direction, with which the solar radiation can reach to the plants along the day from the both longitudinal east and west sides and there is shifting of shading by frames during running of day hrs. But in windy areas, the blown winds should hit the structure in a perpendicular manner with the length of structure body (smooth hit). 4- Land leveling, sloping (especially for soil less cultivation), heating, and establishing of various facilities (election, irrigation, draining, steam system) taking in consideration that all these systems are of high cost and ↑↑ area to be covered is advised so as to ↓↓ the spent cost of all these facilities/m 2 of the covered area and this within certain limits (not absolute).
5- In multi-spans → sloping of structure to certain side is important so as to collect the rainfall avoiding risks related to it’s accumulation and also can be used during water shortage if stored in prepared pools. The design, also should tolerate the possible wt’s related to snow accumulation by having additional supporting columns. Or to use single units that spaced longitudinally at 2m. 6- 60m is maximum length of the structures so as to have good ventilation and efficient movement and labors activities. 7- 2m is the minimum width (height) of the main door in both heads to allow entrance of tractors and other machines. 8- Keeping the stoages, management offices, nursery, maintenance serves at the central part.
*Construction of GH’s: that depending on special designs. The bases are prepared by engineers since not easy to be done by the farmer and so should be constructed by certain companies and what to be awarded by the farmer is the characters and purposes which can serve our plants inside the structure where certain part has been discussed and the part related to conditioning will be explained later on. *Construction of plastic houses: it varies in certain techniques from company as a producer (manufacture) to other. Each company has certain catalog that explain in detail various steps of P.H. construction where if the farmer follows can easily do the construction. And the general method includes: 1)Land leveling with dimensions ≈ equal (No. of PH. × width + m’s of space between each 2 lines) × (No. of rows × length of PH + m’s of space between each 2 rows). 2)Selecting of referring point as a partition point from which you make the angle of 90˚ by Fithagoris theory.
3)Fixing 2 pieces of │╞ as bases for both ends of the first arc, the longer side in the │╞ is immersed in soil. 4) Connecting the 4 pieces of first arc by 3 │╞ (½״ ×2״) since arc Ө is ≈ 60mm. then inserting this arc over both │╞ bases. 5) Connecting the 2 galvanized pipes of ¾״ to the 2 │╞ over the soil surface with 2 pieces of ╡╞ which supposed to fixed in soil as a bases for the next arc at the right space = to the length of the pipe. 6) Repeating step 4 to make next arc but by 3 ╡╞ (½״ ×2״) then connecting first arch with 2nd with 3 galvanized pipes of ¾״. 7) Repeating step 6 for each arc until the last one (first arc from other side) where step 4 is repeated for it.
8)Reinforcing the first arc with the neighboring one by further pipes that ended with clips from both ends (4 for each head), these clips are fixed to pipes by screws. 9) Fixing the main bar pipes which is of greater Ө than Ө of arcs by screws, this bar is at ≈ 2m height above the soil to carry the door 10) Reinforcing the structure, also by connecting the main bar with the 2 nd arc by other pips that ended with clips as mentioned in step 8. 11) Reinforcing the structure by tying the trailing wires to the main bar from each side. 12) Reinforcing the structure also by tying both outer arcs of plastic houses with No. of wires ≈ 36-34, (34= 8.5m width and 36 for 9m as width). This done by starting from upper point of the arcs (middle point) then going in both sloping sides increasing the space as we are far from middle upper point (starting with 20cm between each 2 wires as space and ending with 50-60cm down in both sides).
13) Reinforcing each arc from the inner side by connecting a pipe of (¾×״ 7-9m length = width of PH.) to hocks (collar) presented over 2nd ╬ presented over soil from each side. These pipes are also useful in carrying and trailing of the growing plants where wires that fixed longitudinally into the main bars, are passing over these pipes and No. of wire should = to No. of lines of growing crop. 14) Covering the structure as follows 15) Fixing the doors, fans, windows and roof ventilation system if presented.
The use of PH’s or GH’s They are structures formed of iron frames having gable ( جمالون ) or Quonset (half cylinder) roof to avoid water or snow accumulation over the roof and so the damages related to these actions. Their volume enable entrance of labors, tractors and other machines and serving plant in an optimum way. They are of high cost but their return is profitable especially under the following conditions: 1.No. of structures to be utilized at the same time, effort and management (area to be covered / complete unit of services). As the area ↑ (to limit 40 structure), then the cost involved /m² covered ↓↓ under normal conditions. 2.Volume of covered structures (No. of m³of heated air /m² of the covered area) proportional relationship but from economic point of view it is to certain height.
3) Types of frames, woody (more shading), or Aluminum (longer duration), or galvanized iron ≈ 25 years and both Aluminum and Iron are more safety against diseases and pest, since they can’t hide while in woody yes. 4) Type of cover, wither glass, fiberglass or plastic and it’s newly degree. 5) Availability of heating, cooling, mist, irrigation system and to which level can be control automatically + presence of pool 6) Presence of most suitable cv’s, protecting condition and tolerating pollination problem + various diseases. 7) Programming of production to be at off seasons and during periods of no competition with open field production. 8) Exporting the production into outer markets (presence of facilities to export and compete out side).
*In spite of all these considerations, the protection becomes necessary in the following cases: 1.In cold regions and during winter: for both northern and southern sites to line 35˚ as latitude of the earth where heating is required and open field in these areas is blocked. 2.In Hot regions and during summer, by using conditioned GH where open field is also blocked. 3.While in temperate region, the protection is done by controlling the productive factors at the non favorable conditions. *It is possible to employ the capital in a best manner through out the following points: 1.40 PH (9×50m) as one unit. 2.Two PH as nurseries for seedlings production which can be shaded during summer by black or green plastic net.
3) Effectuating the drip system to irrigate space in between PH’s so as to be planted with low plants or covered partially with low tunnels → cost of m² to be irrigated ↓ as area to covered with drip system ↑ (within the capacity (pump + filters) of the irrigated system). 4) Distribution of crops according PH’s dimensions, volume, facilities where most valuable and tender plants supposed to be in the well prepared ones and dwarf, strawberry and lettuce in low type…….. and those that tolerate high temp. water shortage in structure of low facilities. 5) Construction of pool or tank from concrete for collecting the rainfall and storing also water from other sources during non shortage time, so as to be used at water stress or shortage time. 6) Minimizing cost of construction by use big plastic houses. 7) Availability of necessary equipments that can serve in or various activity and realize profits from various services weather in or out of the farm.
8) Presence of experienced team which ready to work at any time and any work. 9) Control the close and open of protective structures to minimize energy loss especially during winter and so ↓↓ cost of heating if system of heating is presented + using most economic, efficient and practical methods for ↓ temp. during hot summer in order to elongate the plant cycle with minimum conditioning cost. 10) Using of hybrid seeds that characterized by ↑ productivity and ↑ quality in order to achieve profits > as much as possible than the spent cost. Since these CVs are highly adapted to protect structures and for some crops are planted for more than 4-5 cycle/year under protection as like lettuce →↑↑ use of protective facilities.
Shapes of protective structures 1.Lean-to-building: single, beside building, sloping part towards sunshine (south and south east). 2.Gable uneven span: for both PH or GH, but over sides of hills so it is adapted to sloping area, can be single or multi-span but more adapted to single. 3.Gable even span, for both PH or GH, multi or single and it most diffused for GH over leveled land. 4.Gothic arc of the roof that shows pointed upper part. 5.Elliptical or modified Quonset that more diffused for multi-span of PH’s. 6.Quonset or half cylinder: just for single and more diffused for PH’s. Methods of controlling the environmental factors in
protective structures It means to control environmental factors of atmosphere, soil factors in order to realize as much as possible the optimum conditions for plant growth → greater return/cultivated unit. The factors to be controlled are: 1)Temp: that can be modified by heating, cooling,……., which should be utilized after understanding the basic as methods of heat transport which helps in: a-Effectuating the controlling heating in efficient manner by ↑↑ % of energy gaining from solar source during the day of cold condition and by minimizing energy loss throughout reflected radiation from solid heating bodies, plants presented inside the protective structure →↑↑ cost. b- Increasing the efficiency of cooling by ↓↓ energy gaining during cooling the day of hot condition and enhancing the loss of the gained energy →↑↑ cost.
The main methods of heat transmission are: a-Radiation: light is presented as electro-magnetic wave which converted into heat as incident over bodies. So radiations that pass in plastic sheets or glass and hit bodies inside protective structures will change into heat (continuous rising in temp. of bodies as there is an incident of light. In the other hand, the heated bodies radiate energy: - loss of their heat to the cooler bodies (outer) as Far-Red. This continues as temp. inside> outside during night or day. – these facts can be useful in: a- in cold weather, it is important to maximize the solar energy gain during the day by selecting the right design, direction proper cover that allowing passing of maxi ratio + minimizing loss of Far-Red. b- In hot weather: lower light permeability to inside + higher permeability to Far-Red outside to get rid of energy presented which can induce a lot of problems. c- In temperate regions: that are of temperate weather during day and of moderate –cold during night, then the non permeable cover to Far-Red is preferred in-order to raise night temp. about 2-3˚c than out → × heating which could be in-economic in this case.
* According to their permeability to Far-Red covers can be subdivided to: - Glass + PVC of 350m → not permeable Far-Red. - Fiberglass + PVC of 75m → low permeable to Far-Red. - PE → permeable to Far-Red, but condensation of water vapor at the inner side → ×permeability since water vapor film block Far-Red filtration.
b) Conduction: transmit of energy from hot point to cold one throughout mean such as loss of energy from heated GH of ↑↑ temp to atmosphere. than outside through (in both cases) the cover. So having more than one cover (double) reduces heat loss by condition because of isolating space while in other case (gaining no need of double cover). Double cover is related to heated structures and not to these depend on Solar Radiations c)Convention + infiltration: the structure body and plants presented inside are reradiating heat (after being heated by incident light) which will be carried by the means as air or water →↓ their density (heated means) → raising of air or changing water or condensate water into water vapor and going up to be replaced by colder air which in turn will gain energy and soon circulation +loss of energy as the heated means come in touch with cover or some filtrated throughout cracks, openings… d)Energy reflection from sealed surfaces as the reflection of the light from sealed ironic surfaces as Far-Red.
Energy lost by conduction is expressed in British thermal units = (quantity of energy needed to raise temp. of 1pound of water a 1˚F)/this quantity to be lost through 1ft²/hr when the outer temp. is 1˚F lower than inner one. * * Infiltrated energy is expressed in No. of air changed of protect structure/hr. energy loss by conduction is referred to a medium wend speed of 24km/hr.
Reflection (%of total loss) Infiltration ** 1st study 2nd study Conductio n Btu /ft2 / hr Type of cover 4.4%1-221.13Glass 1.0%0.75-1.510.95-1.00Fiber-glass 70.8%0.5-1.001.2P.E-one layer ---- 00.7P.E-two layer ---- 00.6P.E-two layer
-by increase No. of layers → ↓ heat loss and it has been proved that the most efficient in reducing heat loss is 3 layers of glass with 6mm space between each 2 layers while the lowest is fiber glass, then P.E of one layer but of 50-150M then glass of one layer (glass > P.E > fiber in reducing heat loss when of one layer). Other traits as P.E (2layers), PVC (2layers) had showed medium results.
*Calculation of needed energy for heating: There are many equations, but each needs a lot of data input and factor for each input of the equation, where it is likely difficult for farmer to have all data and factors. So it is diffused to use simple equation: H=U×A(t 1 -t 0 ) where: H=Energy needed in British thermal units/hr U=Constant which related to type of cover (=energy lost by conduct in Btu/ft ² /hr. which explained before) at a medium wind speed of 24km/hr. Which increase at presence of wind than at calm condition A=Out surface area of protective structure in ft ². t 1 =Inner temp. in ˚F, t 0 =outer temp. in ˚F. *For example, if U value of P.E cover (one layer) is 1.15 Btu, then how many Btu are needed to raise temp. inside 10˚F than outside of protective structure that has a surface area of 1000ft ² H=1.15 ×1000(10)=11500Btu/hr.
How to calculate surface area of the structure? In case of Gable structure (even span one) = Sum [(area of 2 rectangle along the structures) + (2rectangle in both heads) + (2rectangle of the roof) + (2triangle over the rectangle in both heads)]. The triangle area = ½ × base × H as it supposed to be of equal bars (lines from upper angle to the base. In case of half cylinder = ½ (2 π rL+2 π r ² ) where: π =3.14, r: Distance of highest point in the arc from the soil, L= plastic house length. But very important to remember that volume of protective, efficiency of heating system and the environmental conditions dominating outside are factors to determine No. of hrs of heating system running to raise the inside temp. to the required level. This done, practically, by fixing thermo regulator (Thermostat) to operate automatically leading to run and stop of system when temp. drops or rises respectively, even can be connected to ventilation system and to cooling apparatus.
The Thermostat to be used should be of high level of sensitivity in order to feel small variations in temp. so as to: 1- Makes order directly and at proper time 2- Avoiding deep changes which may damage plants 3- Save in cost of conditioning. Also the following points can enable working of thermostat in efficient manure: a- location at a representative position where accurate medium temp. can be recorded ………. Far from blowing wind and from lower side of plastic or glass cover. b- it should be always in a position parallel to growing point level. c- not exposed to direct sunshine, but in perforated woody box that painted with white color, or the box should be provided with fan to keep uniform temp. level by cont. blown of gentle wind. d- an other thermostat should be established in the box which supposed to do alarm at 10˚c (during winter) and this alarm should be transferred into bell presented in the house of the farmer to inform about dropping of temp. to that level which means blocking of heating system and should be repaired before reaching 0˚c (you have enough time for repairing). Same thing can be done during summer (alarm at 35˚c for example). Indicating that cooling system is blocking. Source of electricity to the all arm, should be separate to avoid any trouble in it ’ s function induced by electricity stop by other machines. e- keeping a mercuric thermometer in the box to evaluate the accuracy of electronic thermostat from time to time.
* To save in the energy consumed by heating system: the following points to be noticed: 1- Protective structure and it ’ s design. 2- Type of cover (max permeability to light + minimum loss by conduction, convention, filtration and reflection). 3- No. of layers where the thermal condition factor ↓↓ as No. of layers ↑↑. 4- To be protected by wind breaks to minimize the negative effect of the wind by ↓↓ wind speed factor. 5- Level of control (close, cracks …..). 6- Uniform distribution of heating system and not to be concentrated beside the outer walls of stricture to avoid great loss of energy by conduction and replacement the hot air with cold one at the mid area.
7- Good and efficient ventilation (planning is very important) may decrease or avoid using of cooling system especially in temperate area. 8- Using of shading nets, lime or clay may also ↓↓ cooling costs and the use of thermo blankets to: protect plants from direct sunshine and ↓↓ loss due to reflection during winter + ↓↓ area to be heated. 9- Presence of plastic tubes beside and along he plant lines that are filled with water = which gains energy during the day of reradiate it to the atmosphere during the night may ↓↓ heating costs.
The use of double plastic layers: to ↓ the factor of heat conduction, that can be realized by keeping a space of at least 4 cm of pumped air and the space not to exceed 20 cm to have effective isolating process, otherwise: 1- if space 20cm → blowing or movement of air → circulating air from inside portion to outer portion with the space → continuous energy loss. Normally inner layer of 100 m and the outer one of 150 m and presence air pump to keep continuous isolating layer. Main characters related to double layer use: 1.Decreasing the heat conduction factor from 1.35→0.7 this leads to save in heating or cooling cost up to 40%. 2.Minimizing or avoiding the condensation process →↓↓ the possibility of diseases diffusion → more safety condition for plant growth and production.
3) Decreasing the heat conduction factor from 1.35→0.7 this leads to save in heating or cooling cost up to 40%. 4) Minimizing or avoiding the condensation process →↓↓ the possibility of diseases diffusion → more safety condition for plant growth and production. 5) The inner layer represent a second barrier for plant protect by which possibility of damage if the outer is broken is very low since the inner can also protect them. *As disadvantage: ↓↓ the % of light transmittance from outside to inside which can be critical at cold regions → need heating or to be during night.
Methods of heating: for any method, the thermo regulator is very important to control running and stopping in order to have temp. continuously within the required range, central heating system is more preferred at multi span to ↓↓cost of heat/m ². 1.By hot water or steam water : Boiler to heat the water, then transferred as hot or steam in pipes which during it is circulation will radiate energy and conduct air to pipe will gain energy from heated pipes. Thermo regulator is directly connected with pump. In order to induce (throughout signal) pumping of hot or steam water as temp. drops to lower level accepted or programmed. An other regular is connected to boiler to control temp. of water in boiler at a range of 80-85˚c incase of hot water and at a 102˚c incase of steam water which will be delivered to circulating system throughout automatic value which not allows return of condensate water after it ’ s circulation to the boiler except from other side so as to be heated again up to water vapor state.
Un uniform heating efficiency is the disadvantage, since plants close to pipes may damage by being heated > far plants. This may be minimized by distribution of pipes uniformly over plants in the mid area and in both side along the structure to avoid formation of circulating air from sides into mid area that reach to the plant in mid area after loosing great part of their energy since during circulation will touch inner surface of cover. 2- Hot air: hot air will be generate in hot generator (electrical or by fuel). Then hot air will be blown inside plastic tubes (of 50cm Ө perforated of 5-7cm Ө of each open) by electrical fans. These tubes are fixed above plants along the structure at 10m space incase of multi span → heating capacity is 500m ² / tube. It is also effective in ventilation system. 3- Kerosene or Paraffin heaters (So 2 ) عدم التجانس وشغل حيز وتصاعد
4- Electrical heaters: that release heat from radiated tubes which may also connected to fans that blowing wind across these tubes to atmosphere of protective structure, of high cost. 5-Solar radiation formed from isolating pool, collectors with tubes of radiant mulch, radiant mulch spread along protective structure beside lines of plants over the soil surface, isolating main lines to connect pool with collectors, collectors with pool, pool with protective structures and protective structures with pool and pumping system + photo cell + computer system …
Cooling methods: That are applied during hot summer condition. They are applied in the regions of mean monthly temp. up to 40˚c and the max of 48˚c-50˚c (were open field production is impossible) × low RH% that drops up to 15% which is below the optimum level required for plant growth, pollination, fertilization of flowers and fruiting. So to produce, it is important to drop temp. about 15˚c × ↑↑ RH% up to 70-80%, so cooling of protective structures is the only solution : 1- Cooling by mist system or fogy: by pumping the water under n pressure, water will go out through atomizers (Nozzles) in a mist form or fogy form (fine water drops) → which easily evaporate →↓ temp. × ↑ RH%. This process needs a lot of water (pure that nearly free from salts) → - By ↑ RH% → Better pollination, fertilization and fruiting. - By ↓ Temp. → Better conditions for plant growth. + providing plants with certain portion of needed irrigated water. But may induce flooding of soil of structure. So passing area can be covered with sand. Or planting in straw pallets that may absorb most of misted water.
2- Fan and Pad system: the pad that formed from cork cells will be fixed in the front wall and over which a group of drippers are established for continuous moistening of the cork cells, while the suction fans of the air from inside are established in the opposite wall. By succession, the air pressure inside drops down → flushing of colder air from outside to equilibrate the pressure and so will pass through the cells (moistened) having low temp since touch ’ s the cells during it ’ s passing. Regulators for fans working and for opening and closing the valve of dripping system over the pad are required. Fans should be fixed in the side receives calm wind while the pads are fixed in blowing wind side. More eff. occurred as the lines of plant are in straight rows along with wind passing inside and at or over plant growing points level. The entered air will be resisted by plants → slow shifting up ward from plant to other (at a rate of 1m/8m distance = ≈ 7°): so a sheets of plastic (transparent) are hanging, from top of structure, vertically over growing points of plants at 10m space along the structure in order to shift the air movement down ward between plants lines. If the pads are near the soil surface while plants are grown in beds, then a sheet of plastic should be fixed in front of pads under the beds surface to shift the running air to wards the plants (up ward). Also temp. will not be uniform in the structure (↑↑ in the angles where pads are not presented and as the structure is longer then eff. of cooling → lower in mid area).
The eff. of cooling depends on: 1)Distance between the pad and the fan, if it is > 33-45m, then the fans should be of greater capacity to ↑ the rate of air succession. Or dividing structure into 2 units →shorter the distance between pads and fans. Normally each 250fts of succession air/mint, needs ft2 ×10cm thickness of pads area. 2) The area of the pad. 3) The location and it ’ s elevation above sea surface, since the air density ↓↓ with elevation. So elevated locations means more effectuation of succession since cooling depends on air (prevue) but not on it ’ s volume. → needs more succession to induce good differences to have flown of air. 4) Light intensity in the structure, direct relationship, since light intensity induces energy or heat. → more succession to have better cooling. X shading if at summer conditions. 5) RH% in out atmosphere, as it is ↓↓, then their will be more eff. in evaporation (cooling of cells = better cooling) while at 80% of RH → cooling will be inefficient since air temp. ↑↑→ cant induce cooling.
Ventilation: which is important in: 1)↓↓ temp. rapidly →↓↓ the cost of cooling or intemperate region cooling can be blocked. 2)Renewing the air in structure → keep normal CO2 conc. 2)↓↓the RH% of the atmosphere in structure + ↓↓ the condensation rate →↓↓ possibility of diseases diffusion. It can be By: a-Through openings (windows) in both sides and in the roof when the air change normally or naturally by raising of warmed air up and flushing of cold air from outside through openings to replace the worm one. As the area of openings ↑, → faster air change → faster ↓↓ in temp. the area of openings should not be below 17% of total structure area. As temp. ↑ then openings area should ↑↑ but not forget to close those that facing the wind at windy conditions. These openings can be covered with cloth layer (muslin) and opening is operating either manually or automatic by being connected to thermo regulator.
b) Throughout succession fans + openings: that used in big structures with which the natural ventilation is not sufficient same establishment as (pad + fans) but instead of pads the openings can be covered with cloth or free at summer conditions the fans are connected with thermo regulator. The efficient fans are those that can change the air of structure one time/mint noticing that area of openings should be 4-5 × area of used fans. C) Through out perforated plastic tube: using the same apparatus of hot air, but the air to be blown is the cold or conditioned one. That distributed at 10m space and the holes are of 5-7.5cm in Ө while tube it self of 50-75cm as Ө. Also this tube can be used for ventilation during cold condition by connection it to succession fan and from other side to opening in wall which will induce vacuum in tube → flushing of air from out p. structure to tube that will distribute the air in structure gently with out damaging or harm plants as if entered to structure directly as cold air.
The fan and outer open are connected to regulator to induce opening and running of fan at the same time (simultaneous). Eff. of fan to success is important in order to ↓ the difference of temp. between outside and inside and those of 2ft ³ /mint is optimum, more uniform air distribution can be realized by fixing an other fan at opened wall of structure to push their inside in an equal force to that of sucking air which also can continue to push even after the block of sucking one → better uniform distribution of air → good ventilation. *Control of light: intensity, period → either ↑ or ↓ a)↓ light intensity: by using shading plastic nets where the degree of shading depending on intensity of tissue knitting ( حياكة النسيج ) that can realize 10% to 90% of shading. By lime solution during summer time at which light intensity ↑↑→↑↑ temp. degrees, since a great portion of light converted into energy. More applicable to shaded or in mental plants and to seedlings. This layer should be washed as cold season started.
b)↑ light intensity: applied as the angle light incidence become sharp or at cloudy days as what occurred in northern hemisphere at winter time. CO2 fertilization × ↑↑ light intensity → high photosynthesis is the indication for importance of light. It is practically done by artificial light (Tungsten or phlorecent light) or both light types : 1- first rich in infrared →↑ temp. as it is a source of energy. 2- second rich in other light spectrums than infrared → Efficient in photos. that is highly at 480nm and 680nm. Also, structure dimension, cover type, structure form, cleaning of cover are important factors to ↑ light intensity, cleaning by 5% of oxalic acid then water at the beginning of each winter. This oxalic acid can react with lime and pulverizing it.
Interaction of light intensity X Temp. X CO2 Conc.
C) Control of period: positively (more) by artificial light or negatively (less) by dark blankets to be fixed over plants →exact No. of dark or light hrs. Control of CO2 Concentration in atmosphere of structure: If the structure remains closed (especially during winter time=Heating) → CO2 conc. ↓↓ especially at mid day (↑↑ temp.) X artificial light X active vegetative parts →↓ photos. Rate. For example if CO2 conc. ↓ to 160 ppm → decreases in photos up to 50% while if CO2 level ↑ from 335 ppm to 1000ppm increases the photos up to 100% especially at ↑↑ temp X ↑ light intensity to avoid the limiting of photos by any of the 3 factors (any one if limits photo →(( منحنى even if others are at optimum conc. The best 30˚c X 1300ppm CO2 X increasing in light intensity up to 3000f.c. (30,000lux).
Response of vegetables to CO2 fertilization: 4 examples: 1- Tomato: ↑↑ CO2 conc. Leads to: --Early maturity + ↑ average fruit wt →↑↑ production ≈ 35% more as the enrichment of CO2 effectuated daily to 6.5hr. -Other trial: increasing CO2 conc. From 400 ppm to 800 ppm →↑ production X ↑ fruit size. -Third trial: increasing CO2 conc. from 400 ppm to 1200ppm →↑↑ the early product to 15% more. ↑↑ light intensity or ↑↑ temp. don ’ t variate the production which remain very high as fresh or dry at ↑↑ CO2 conc. -2- Pepper and Eggplant: 6.5 hr of CO 2 fertilization/day leads to ↑↑ production up to 31% more in pepper more and to 24% more in eggplant.
3-Cucumber: positive response to ↑↑ CO2 conc. Is related to good light intensity X proper temperature → better flowering, leaves formation, early crop and total crop + ↑↑ dry matter. ↑↑the CO2 conc. From 350 ppm to 2150 ppm X light intensity of 1400f.c. → best response of fresh, dry wt, fruit No., plant height→showing a positive linear correlation between production and CO2 conc. As average of 450ppm during summer and 1000 ppm during winter. 4- Lettuce: shows a positive response to CO2 enrichment without being deeply affected by polluted gas evolved during CO2 generation.
Raising the CO2 conc. To 3X to 6X the normal conc. (0.03%) leads to: a)early production at least 10 days earlier →↑↑ No. of planting times/season or year. b)↑↑ the productivity up to 40-100% more especially by using cv ’ s of fast growing rhythm. c)↑↑ the dry matter percent and the better response is realized with: 1-↑↑ temp. 6-8˚c (during day) more and 3˚c more during night. 2-↑↑ irrigation rate. 3-↑↑ fertilization rate. In 2 to 3 fraction → to be added especially the N fertilizer. But in a wise manner to avoid NO3 accumulation.
Sources of CO2 that utilized in protective structures: a- Some kinds of fuel as like Paraffin or (Propane Gas C3H8) that burning in especially burners → evolving of pure CO2 that not have sulfur which will be converted into SO2 that easily dissolved in water → sulferose (S++) that forming H2SO4 which is harmful to plants by burning the leaves. Also burning should be complete to avoid formation of Ethylene (C2H4) and CO=. Both are harmful for plants and the 2nd is toxic to human being. Blue flame is the indication for complete burning. b- Evaporating the CO2 liquid then to flush fans through the P.Ethylin tubes that used for heating or cooling processes. c- Distribution of solid ice pieces of CO2 in a representative position which will evaporate in protective structure atmosphere.
*The Economic benefits of CO2 fertilization: more benefit in cold areas where GH remain closed to minimize heat loss → shortage in CO2 since air change is not effectuated X plant do assimilate CO2 for photos. Latitudes of 35˚ in north and south to the equator are the line for economic benefits. In between these lines → temp. inside GH, and during winter ↑↑→ ventilation → substitute the CO2 shortage and not economic or benefit to do CO2 enrichment at ventilated GH ’ s. while beyond these lines it is possible to fertilize with CO2 since GH remain close during winter X day time (photos. is ↑↑↑) of sunny days or by artificial) light X temp. of good level (heating → in period of October to May). *Degree of CO2 requirement depends on: a- Rate of GH ’ s air exchange through openings, cracks even at complete close of structure where new constructed, GH ’ s show that ¼ - ½ of total as is exchanged/hr while those of moderate while the complete close PH ’ s change ½ - 2/3 of total air/hr which mainly related to wind speed of outside wind.
b- Method of CO2 application: pure gas has temp = nearly to air temp. of protective structure → keeping CO2 near plants → more benefit from it by the plants, while that comes from burning fuel has higher temp. than air of structure → missing of CO2 upward since of lower specific w.t → getting outside from cracks, opening in the roof → lower rate of utilization or eff. which related to oldness of structure. c- Volume of growing plants, temp. of structure and light intensity; all these are factors that determine Q. of CO 2 utilization and rate of CO 2 assimilation. Max. CO 2 utilization at complete vegetative coverage of land X optimum temp. for growth X high light intensity which together → highest rate of photosynthesis. d- Micro organism activity and respiration: more active M.O. → higher decomposition of organic matter →↑↑ CO 2 evolvement + what produced by respiration. A noticed ↑↑ in CO 2 %, has been observed by using straw pallets in beds →↑↑ CO 2 % from 0.07% (700ppm) to 0.1% (1000ppm) as a result of straw decomposition then this % was fixed at 0.04% (400ppm) when decomposition was ↓↓↓ after certain months.
By experiment, it has been found that the average quality of CO 2 to have 0.1% is 30 -90 pound/acre/hr which deeply relate to average rate of air change as No. of times/hr. if total air change /in hr → need 40 pound/acre/hr. But if total air change /in 2/3 hr → need 60 pound/acre/hr. and if 3 pound of CO 2 produced by one pound of burned Propane C 3 H 8 gas or from 0.125Gallon of paraffin then Quantity of Propane/hr = 60/3 = 20 pond/hr if 2/3 of air change/hr, or 40/3 = 13.3 pond/hr if air change/ 1hr. Quantity of propane/day if they are 6.5dayhrs of eff. photosynthesis = 6.5X20=130 or 6.5X13.3=86.45 → pound of propane/day. Computer can be helpful in this case by being programmed to control: 1- Temp. with heating, ventilation, cooling. 2- CO2 enrichment. 3- Soil moisture by irrigation program. 4- Fertilization programming. 5- PH and salinity of irrigated water All these activity can be done accurately, with lower No. of labors.
The response of crop to CO 2 enrichment will be ↑↑ as the crop more healthy, vigorous, juvenile and optimum Temp. and light intensity, 1000- 1500ppm are not harmful to human being, even can tolerate up to 5000ppm.
Growing Media They are the media in which roots are developed and from which they absorb 1- water 2- nutrient solution 3- anchorage the roots and plant 4- provide the roots with O2. Using of soil alone as growing media in not preferred since as the soil transferred into pots → loose aeration character (↓O 2 level) because of loosing aggregate property → flooding with irrigated water as water added → suffocation of roots. So, Alternatives are very important as like decomposed plant residues and animal manures that can be mixed with sand or artificial substance to improve aeration character of mixed media. Then more stabilized material (that resists fast decomposition by being exposed to water vapor or moisture as peat moss, saw particles, rice seed coat are incorporated and perlite, vermiculite to substitute sand.
Properties of growing media: 1)Stability of organic matter: slow rate of decomposition → keep its volume for longer period, which is important to have full pots or eyes for longer period. Straw or saw particles are preferred since they are not rapidly decomposed. 2) C/N Ratio: if this ratio is less than 30:1, then M. organism will be more active (since N is ↑↑) and use most of added Nitrogen (NO 3 ) during their decomposition function. So more nitrogen should be distributed to substitute N storage. For example in saw particles it is 1000:1 → so 12kg of N/ton of saw to facilitate M. organism function in decomposition within few months. In woody bark it is 300:1, → 3.5kg of N /ton of woods → that will decompose within 3years X no shortage of N. 3)Specific weight of the media: important to avoid turning down of pots as seedlings develop, become big and tall enough. So ↑↑ specific w.t of media is more preferred, for example perlite or vermiculite have a specific wt of 32pound/ft ³ at saturation point → which ↓↓ into 6.5pound/ft ³ at dry point → possibility or turning down is high while these that have 40-75pound/ft ³ at saturation are more stable against blown wind.
4) Good water holding capacity X aeration: A balance between moisture and air which realize 10 – 20 % of total volume as air X 30 – 50% of total volume as water at saturation. This done by adding substances as peat moss that improves water holding and as vermiculite that ↑ aeration character. 5) Cation Exchange Capacity: supposed to be from 10 – 30 mlequivalent/100gm of the media. As C.E.C ↓↓→ more fertilization frequency required. It is ↑↑ with adding peat moss and other organic matter sources and ↓↓ at the addition of sand, perlite, polystriol and non decomposed seed coats of rice, beans (Sudan bean). Meq=(Molecular wt/valence) /1000. 6) pH: Optimum is between 6.2 – 6.8, peat moss woody bark and non decomposed → show acidic media while sand of neutral PH. But in any case pH can be modified according to plant species requirement. 7) Nutrient content: It is likely to add chemical fertilizers to the mixture since the seedlings depends totally on what found in the media for about 3 – 4 weeks. So N and K form are added during seedling (to avoid accumulation of toxics if added early.) development while P – fertilizers are added during mixture preparing. Also micro – elements some times are added (nutro-leaf).
The media supposed to contain: N as NO 3 = form (50 – 250ppm), P (125 – 450ppm), K (0.75 – 1.5 ml-equivalent/ 100gm of media), Ca (8 – 13 ml- equivalent/ 100g of media), Mg (1.2 – 3.5 ml-equivalent/100gm of media). *Good growing mixture that characterized by: 1-Highly uniform → facilitate mixing of their components. 2-Not affected negatively as chemical component if treated with water vapor or with chemicals. 3-Good aeration capacity. 4-↑↑ Water holding capacity. 5-Conserve chemical elements (not easily leached). 6-Proper PH level. 7-Rich in nutrient content of various elements. 8-Low cost. 9-Relatively light in wt. 10-Relatively Low decomposition rate = Slow↓↓ in volume by being filled in pots.
Materials used in preparing the growing media: a-Soil: best type is the colloidal one which is rich in O.M., it is better to be planted with clovers or alfalfa from 1 – 3 years then plowing and incorporating plant residues (partially decomposed) to ↑ O.M content and also ↑↑ N content which has been fixed throughout roots of clover or alfalfa. Also ↑↑ water holding capacity, improving aeration, texture and structure (aggregate) but need treatment before being used. b- Inorganic materials: 1- Sand: formed of inorganic particles of 0.05 – 2m min Ө, heavy in wt → provides firmness and stability for media as it increases the specific wt, low cost, highly aerated and draining substrate, no nutrient content and need treatment before being used.
2- Vermiculite: formed of 2 components (Vermiculite +Biotite). In vermiculite: fine plates of Mica (Hydrated Mg-Al-Fe-Silicate) are connected to water while in the “ Biotite ” : they are connected with K. Heating up 1100˚c → liquefying them and so water converted into vapor → swelling or ↑↑↑↑ in volume of treated material → volume will be ↑↑ up to 12x – 15x the original volume, very low in wt having specific wt. of 75 – 150gm/m ³, spongy character, treated (no need to be treated for the first time of use. has high W.Holding capacity, good aeration and having good level of K, Ca, Mg which could be sufficient to early germinated seed lings. 6.5 – 7.5 is the PH and C.E.C is 19 – 22.5mlequivalent/100gm which is relatively high as a result of abundant – ve charges presented on the fine plates. 2 – 3mm is Ө of particles used in agricultural purposes but as disadvantage → loose it ’ s structure and form with time.
3- Perlite: good alternative to sand for having good aeration but light in wt ≈ 6lb/ft ³ while sand weight 100 – 120lb/ft ³. It is prepared by heating the volcanic lava (of silica base) at 1000˚c → forming white molecules of close air pores. It is sterilized for first time to be used has No C.E.C, of neutral PH = 7.5 and can absorb water at a rate of 3 – 4liters/1kg of substrate. Stable in long run of use and those used in agricultural purposes are of 1.6 – 3mm in Ө of ↑↑ cost than sand. 4- Polystyrene foam: known commercially as Styrophoam. Can alternate sand in improving aeration, light in wt < 1.5lb/ft ³, having a lot of closed particles which are isolated (not absorbing water). Of no C.E.C and neutral pH so cant modify the pH media.
c- Organic materials: 1- Animals manure: of ↑↑ C.E.C, good source of nutrition, so symptoms of deficiency are rarely to appear by it ’ s employment since quantity to be used is high. Even at modest level of nutrient elements content → sufficient for seed lings. Has ↑↑↑ WH capacity, so should be mixed with draining materials. Best types is the decomposed sheep manure since it is not strong as like other sources that contain noticed level of Ammonia (toxic material). Sheep manure is added to the mixture at a rate of 10 – 15% of mixed media, needs treatment before being used to kill the fungal, nematode diseases, insects and weed seeds. Well programmed irrigation is important to wash the evolved Ammonia even before planting seeds in the media. 2- Plant residues → 1- Non decomposed: that added after being cut into pieces of small size in-order to facilitate their mixing with seed (rice, Sudan bean) coats, straw and sugar cane but it has ↑↑ C/N which means ↓N. → 2- Decomposed (fermented): saw particles, woody bark, coats and weed of floods areas which have ↓ C.E.C. before decomposition but the C.E.C. ↑↑ clearly by fermentation and also W.H. capacity ↑ after decomposition.
3- Bark of trees: that has C/N of 300:1, low decomposition rate →↓N content at early stages since utilized by Bacteria (early N deficiency may appear at seedlings, then later on by = death →↑ N in media and ↑ C.E.C. from 8 – 60 ml- equivalent/100gm as media completely decomposed so, this means that capacity to conserve and provide plants with Nutrient element ↑↑ by decomposition. If the media is enhanced with N during decomposition stage at the rate 3lb/yard ³ as for example 9lb of Ammonium nitrate (33%N)/ yard ³ → fermentation within 4 – 6 weeks at the conditions of mixing, moistening every 1-2weeks where the evolved heat can eliminate most of diseases causal agents. 4- Saw particles: should be partially decomposed since the primary decomposition is not fast → highly N shortage. So partially decomposition is important before seeds seeding in order to avoid N deficiency and avoid heats risks on seeds of crop and to get rid of toxic compounds evolved as Tannins (Tannic acid) Compounds which also more clear in case of Bark. Also decomposition → acidic condition so addition of CaCO 3 should be in a continuous manner to ↑ PH.
Growing Containers Good containers are those that characterized by: 1- Strong enough. 2- From none rusted material. 3- Possible to be stored in a limited space by being inserted each in the other called stackable. 4- Light in wt. 5- Of good performance. 6- Low cost. 7- Tolerate (-ve) effects related to high temp.
treatments. They are subdivided into 1- Disposable containers 2- Non disposable type. Disposable containers : (that can be used for many times) includes: a- Pots: 1- clay pots = highly porous, but with time outer surface of the wall show ↓ porous character by salts accumulation → so should be soaked in water for many hr ’ s + washed after that with running water. Also they are heavy in wt. the new clay pots show at the beginning N shortage since M.O. are highly active in consuming NO 3. they can be broken: addition of 7.5g per liter of Ammonium sulfate every 7 – 10 day is important to over come N shortage. But they are highly aerated than non porous which also of low draining capacity (presence of holes in bottom is important). 2- Non porous pots from other materials as iron, cement, rubber or plastic which should have holes in the bottom for draining purposes.
b- Flat boxes: Of woody, ironic or plastic material, 15 – 60cm width X 45 – 90cm length X 10 – 15cm height. Uniform dimensions is very important → facilitate all cultural activities. Of holes at the bottom except incase of woody boxes that formed from strips spaced at 3mm → efficient draining of excess water. Row marker and spotting board are important: to do holes for new seeds or thinned seedlings to be planted in other boxes. c- Speeding trays: from plastic or styrophoam, subdivided into eyes of v shape reaching to 3cm depth. Walls are of compact particles allow roots development down + easier pulling of seedlings at transplanting time + better draining of excess water throughout hole presented in the bottom of each eye → these holes cause air pruning of tap root → allowing development of 2n˚dray root → better for drip irrigation system. They are of 84 (for cucurbits) or of 209 eyes (for easily transplanted spp. as solanacious crops), light in wt, used for many times, most diffused type especially incase of hybrid cost seeds. No need to be treated for the first time of use, but should be treated before every new cycle of seedlings production. As soaking in Benlate solution.
2- Disposable: That placed permanent soil with the seedling (decomposed later on in the soil). They are: a- Peat pots and Jiffy pots: in which growing media is placed and seedlings are grown up to right volume of transplanting then pots with seedlings are planted in the field → decomposition of pots → roots pass to the soil. This means no air pruning and the plant has a complete root system better incase of water ↓. N shortage may appear as a result of M.o. competition on No 3 form during peat decomposition. Addition of Ammonium sulfate with irrigated water at rate 7.5gm/liter each 7 – 10 days is
*For example, a day with a high of.23 °C and a low of 12°C would contribute 7.5 GDDs. GDD`s= 23 +12 _ 10 =7.5 2 A day with a high of 13°C and a low of 10 o~ would contribute 1.5 GDDs. GDD `s=13+10 _10 =1.5 2 *So( M.M.Tempreture_ T base)* number of days / month = GDDs/ month
Soil preparation, planting vegetables and Nursing them in protective structures A. Soil preparation: 1- Removal of plant residues, collecting and burning or incorporating them deeply in the soil removal of plastic mulch and drip system. 2- Soil washing by heavy irrigation (flood) to wash salts accumulated on soil surface with drip system (horizontal diffusion then as dripping stops → salts return into dripper center + changing position from season to other →↑ problem of salts). Eff. of washing of lines ↑ with soil permeability, percolation in ordure to ↓↓ up to 2.5mmohs/cm or below that incase of sensitive crops as cucumber, muskmelon, beans and strawberry and up to 4.5mmohs/cm or below incase of moderate sensitivity as tomato, pepper and eggplant. 3- Soil plowing and preparation: after soil plowing, then sand at a rate of 1m³ (course sand) x 1m³ of manure x 20kg of super phosph are mixed in 100m² of structure heavy land, then plowed again at F, c ↑ then motivate and finally beds building + establishing of drip system while for sandy soil (light): 350kg of manure x 8kg of N:P:K (18:18:5)/100m² are mixed following same steps before.
4- Soil treatment: more necessary since limited No. of spp are cultivated (monoculture) in a sequence short periods → more diseases diffusion us nematodes, wilts and root rots. In any case manure is added before treatment and also motivate. The methods are: a- Solar sterilization: explained before in lab. With the following conditions = (Continuous soil moistening for activation of A.O., The longer the period the deeper the effect.). It is proved as efficient against soil born diseases (many spp.) and against many weed seeds, Orobanchi as temp. reaches to 56˚c in first 5cm and up to 44˚c in first 40cm. it is safety method. That increases No. of beneficial. M.o. (D) manure fermatas treatment. b- Steam sterilization: pumping the water vapor throughout perforated tubes up to 30minutes in order to raise temp to 60-71˚c up to 30cm depth. This means to move the soil up to 30cm to facilitate the process. Soil should be intimately covered with plastic up to 6 – 8hrs. temp. should not raised over 70˚c to keep benefits.
*Problems of steam process are related to errors during it’s running : 1.Non loosed soil. 2.Dry soil. 3.Excess moisture (proper is 15% of A. water). 4.If not moistened for about 2 weeks → weed killing more difficult at 70˚c, so should be raised up 95 - 100˚c → kill benefits. + toxic substances formation. 5.Chemicals of slow – release fertilizer (Osmocoat) should not added before process → since it’s structure (NPK and Mg) especially coat is changing → highly releasing → loss other forms that did not change by steam → yes to be added ……… in any case soil should be utilized within 20 days after treatment and not after. 6. Any crack or not good coverage →↓↓ eff.
7. Period of > 30minuts → excess Mn free quantity → Toxic. 8. Excess quantity of organic matter → release of Ammonia which is toxic to plants especially at the period of low nitrate producing bacteria/high Ammonium producing bacteria which more rapid in recovering it’s activity → may burning the roots by ammonia → plants stunting. fermented manure are not incorporated before steam while non fermented (lower O.M.) are added.
c- Chemical treatments: 1- Formation or formaldehyde: spraying it’s solution (50%) at a rate of 20L/m², then covering the soil with plastic sheet up to 1 – 2 days then leaving it for 10 – 14 days to be ventilated after uncovering. 2- M. Bromide: in a liquid manner under pressure → that evaporate by 4.5˚c. so it is injected through pipes to covered soil (well prepared and motivated) reaching to ≈ 30cm depth or from cans the completely presented under the cover with their punchers at a rate of 1Lb/8-10m². Best results when soil temp. of 20˚c x 50% of F. capacity to be proved and motivated then treated 2 days is the covering pemod and 3 days of uncovered but to be ventilated and can be planted after 1 week. Can be mixed with some chloropicrin to feel it’s danger since alone has no smell. Effective against weed seeds, Nematodes most of fungal diseases (except verticillium), bacterial and insects of soil.
3- Chloropicrin: at the rate 50L(liquid, solution)/1000m² throughout injectors that distributed at 25 x 25cm. Each one injects 3ml. Treated soil should be irrigated directly to avoid chemical evaporation then covered up to 3 – 4 days then leaved up to 7 – 10days to get rid of chemical residues which are toxic for plants wither through roots or shoots. Effective against insects, nematodes, weed seeds and most of fungal diseases but costed and disturbs the users. Treated soil shows better growth as a result of killing soil pasts + ↑↑ No. of beneficial bacteria reaching to 2 – 3 x of non treated after 100 days → releasing of N from O.M. at a rate of 1.25 – 2 x of non treated. 4- Sis tan: liquid chemical that releases the Methyl isothiocyanate as effective material against Nematodes, soil fungl diseases and many insects and weed seeds (especially annual). Soil temp. should not be less than 7˚c - 10˚c → better.
Used at a rate of 1.2L x 120L of water / 10m² or injected to soil at rate of 1.2L/10m². 7 weeks is the waiting period the soil can be plowed and leaved up to 2 – 3 weeks for ventilation then plowed other time and ventilated for other 2 weeks. If temp. less than 7˚c →certain part will be percolated down causing toxicity for plants as being in touch with it, if temp. too high →↓↓ eff. by evaporate. So it’s use is decreasing greatly. ↓↓↓↓↓ 5- Basamid: granular from that has 98% as Dazomet which eff. against Nematode, fungal and insects and weed seeds. Broad casting over motivated, moistened soil at 40 – 60gm/m˚ then mix with soil and spraying with water and leaved 5 – 7 days then soil plowed for ventilation. 6- Vydate and Temik: (each one alone): to kill Nematodes, weeds and fungi but at soil temp. of at least 10˚c. 7- Vapam: to kill nematodes, weeds of most spp. And fungi when soil temp. of 10˚c or more. Irrigation directly after treatment and 2 – 3 weeks is the waiting period.
8- Vorlex: to kill nematodes, weeds and fungi at soil temp. of not less than 10˚c and 2 - 4 weeks is the waiting period x covering soil. Toxic to plants. In general: all soil fumigants (chemicals) are highly toxic for plants. So soil should not planted during treatment period but after enough period of ventilation which depends on : type of chemical, soil temp.(inverse), soil moisture (not dry not moist) and soil texture (heavy → needs longer). In any case: * reading of technical information (instructions). *avoid pollution of soil after being treated from irrigated water or seedlings of nursery or ……….. since any infection will be epidemic for the absence of competition of other organisms.
5- Mulching: related to planning and beds preparation. To kill weeds germination, ↑ soil temp. especially at the surface, Lowe water loss by evaporation since condensate, better soil texture by being moistened for longer period can be utilized for soil sterilization by fermentation and only solar sterilization, ↑↑ CO2 level around seedlings, protect the soil from machines and the hard pan or compactness and ↓↓ the exposing of fruits or harvested parts into dainty conditions (straw berry) + low rooting into fruits, less possibility of roots damage that related to cultivation process since soil movement if should done will be not close to root of your crop and finally movement of salts towards the non covered roads between beds since water loss from these spaces > than from beds them selves → movements of salts with water movements towards the dry areas of between beds.
A- Disadvantages: 1.Decreasing the ventilation especially at heavy soil x ↑ water level. 2.Seedlings may be damaged as temp. ↑ which induces flow of hot air through the holes in which seedlings are presented + the seedling that touch the plastic. 3.Remaining of salts at the surface as a result of capillary movement then water evaporation from the surface without salts + horizontal diffusion of dripped water. 4.Source of pollution for the environment if not recycled ……… or using alternatives that decomposed later on in the soil.
B- Transplanting: the following points should be done before and at transplanting time, with principle point of free diseased, vigorous + true to type. 1- Irrigation of beds the day before transplanting + moistening seedling except incase of Tiffy, paper pots or blocks that irrigated heavily and then irrigating the transplanting after being placed in soil. 2- Transplanting should be done in the same day of seedling pulling + continuous moistening of root of non planted seedling + keeping them in shaded conditions. If remain for next day → wounded with moist. cloth or moistened peat moss. 3- Placing seedling + pressing soil around them to avoid any air bubbles at the roots sites which will be accurate in fine motivated soil. 4- Seedlings of 15cm height (half for roots and half for vegetative) x age of 6 – 10 weeks except incase of lettuce (at 3 - 4 leaves). 5- Days of ↓ EVT rate (↓ temp., ↓ light intensity, still wind, ↑RH%) are best for transplanting that is during cloudy days, in the afternoon → good enough period to be adapted before new sunny, ↑ temp. day.
It is done either by hand or by mechanical → by opening 2 furrows with the machine and 2 labors one over each side for dipping seedlings the machine add some water or fertilizer diluted solution near seedling and covering seedlings with soil. Depth of transplanting should not be > 2 – 3cm over the nursery depth except incase of tall seedling → inserted more to avoid their toppling + enhance formation of Adventitious root from stem of some as tomato.
C- Nursing the plants in permanent soil: includes 1- Weeds control of non mulched parts, sides, corners since weed can be danger hosts for many pests. 2- Pests control with various chemicals according to spp. Time to be sprayed (at fruiting or before), their residues, apt to be mixed. 3- Irrigation: protective structures induce changes in water equilibrium → leading to low or no rainfall + no wind effect. So plants of protective structure are taking their water requirement by irrigation means which should be done under the equation of: Q. added = Q. loss by ETV. + Q. perco.
*Factors on which the time of irrigation and the frequency depends: 1- Plants factors: a- Plant age and volume of it’s vegetative part → direct relation. b- Roots depth and spreading: the deeper → the layer the time (lower frequency) X more Q. /time to have sat. level again at the root zones. Of deep roots: tomato = 180cm, water melon: 150cm and of shallow: lettuce = 30cm, onion = 30cm and of medium that varies from 60-120cm as cucumber, muskmelon, pepper and eggplant. Summer of deeper root than winter crops. Root depth develop. is related to growing season length where root rate is 30-45cm/month of active growing. Irrigation should be done before reaching to the P.W. point that is at 50% of A. water to be loss to return into sat. * Type of crop: leafy needs uniform and continuous irrigation along the growing season while fruiting crop need in critical stages as blooming and fruit development, while potato at tuberization stage and Asparagus during summer time after spear harvesting to enhance vegetative growth →↑ phots. production and storing in rhizomes for spears of next season.
2- Environmental factors: As E.V.T ↑↑ because of (↑temp., ↑wind speed, ↑light intensity) → more quantity and shorter the interval between each irrigation time and the next. 3- Soil factors: Soil texture (%of clay : %of sand : %of silt), sandy → need law Q. + shorter the interval (more frequent) since has ↓ F.C. while in heavy: of longer interval X more quality/time. Hard pan below soil surface →↓ Q. X shorter interval which similar to permeable or gravel layer below soil surface where excess will not ↑ F.C. but ↑ draining + loss of nutrient into deeper zones. Time of irrigation can be determined by 1- taking soil sample from 10- 20cm depth inhand. 2- by tensiometer where at 0.3- 0.5lar → irrigation.
The importance of uniform irrigation is to protect plant from: a- Disadvantages of low X frequent irrigation which are: - Root system mostly will be concentrated in soil surface → risk of dryness is high for any water shortage. - Limiting the nutrient aborbtion from the upper soil layer. -Dryness of lower soil layers → difficult to be penetrated or to use nutrients presented there. But in sandy it is necessary. -b- Disadvantages of excessive irrigation which are: -- Low or no aeration → root suffocation + weak plants + yellow leaves + wilting. -- Delay the maturity as in case of water melon (non irrigated mature one month earlier than irrigated). -- Loss of added fertilizers with drained water.
C- Disadvantages of un uniform irrigation which are: cracking of tomato fruits + Blossom end not of fruits and loosing of lettuce needs. Uniform irrigation leads to: better root growth X plant growth X fruiting rate + more eff. Use of nutrients + continuous steady growth since no exposing to water stress but most likely to be around F.C.
Methods of irrigation: Depends on crop, water availability, Env. Conditions, salinity, economic situation of farmer. Lender protectives: 1- Furrow: porting the water to upper point of the field then to be distributed through main furrows to lateral furrow (on which plants are presented) by gravity because of slope. Water diffusion is varied according to soil texture: Deeper - Narrower in sandy while Shallower - Wider with clay and for silt → in between. *Easier to be as idea applied + lower cost. But as disadvantages: - Need much more labor effort (trained labors). - Wasted quantity of water is very high especially for sandy. - Low uniformity of water distribution. - More difficult be managed as sloping rate ↑↑. - Diseases diffusion is much more as a result of ↑ RH% inside structure.
2- Drip: for porting water drop by drop to a limited area around plant to keep soil moisture around F.C. It is economic system that save in winter (minimum wasted quantity (50% is saving % related other)) + lower percolated amount + ↓↓ evaporated quantity from soil surface since irrigated area is covered with mulch + lower diseases + weeds save in control cost infection + possibility to be done at any time + keeping fertilizers for longer period around roots of plant sine ↓↓ perco. + driving away horizontally salts far from root zone to the reads. Includes: pump, pool, mainlines ≈ 5cm Ө, sub main ≈ 2-3cm Ө, laterals = 1.2cm Ө, filters, drippers 0.9mm Ө, valves, fertizers, pressure gnage, regulators transiomevers. Pressure which directly affecting discharged quantity is ↓↓ along the unes because of friction. This can be relatively over come by having gentle slopping. Wetted portion of soil by dripper forming a pall on structure narrow at surface and bottom and wideat mid part that is the root zone area. Pall on Ө↑↑ with clay X ↓↓Ø while with sandy ↑↑Ø X ↓↓Ө.
Also by this method → saving in labor cost especially with presence electronic regulators, and at water shortage → it is the only solution as cultivating lettuce with 25% of water used by surface or furrow irrigation system + continuous keeping of moisture around F.C. → ↑ production from 25% to 100%. By this technique it is possible to ↑ No. of cropping cycles sequently without wasting time in soil preparation from crop to other. Disadvantages: 1.Any delay in irrigation → return of salts to drip center (root zones) so uniform irrigation from the beginning to the end. 2.Well trained labors that capable to deal new technology. 3.Repairing of lines is practiced from time to time since exposed by damages (by machines, animals). 4.↑↑ establishing cost.
5-Closing of drippers as a result of: a- precipitation of soil particles, or organic matter particles → presor. of filters is very important. b- chemical precipitations that dissolved by flushing with H2So4 or HCL then driving out by water. c- growing of bacteria and algae inside lines that dissolved by adding Cl2 molecule in irrigated water up to 1ppm (not affected (- ve) plant growth). water should be analyzed and conc. Completed to 1ppm or calculated per each 1000 liter of irrigated water. but incase of their development up to close lines and drippers. A solution of 20 – 50 ppm as CL2 should be injected up to 30 minutes according to the formula = (0.01 X ppm to add) / (% of CL2 in used material). So if we want to increase % of CL2 in irrigated water up to 30ppm by using NaCCl (Na – Hypo chloride) or Ca – hypo chloride that includes 5% of it's content as CL2 then quantity to be added / 1000 of water = (0.01 X 30ppm) / 5 = 0.06L / 1000 of water. (30/5 / 100 = (0.01 X 30)/5.
So it is important to have pools, tanks to store water with enough Q. For all plastic houses (protective structures) because it is important: 1.To precipitate the impurities that may close filters, drippers. 2.To face the farm requirement and not to be affected by any water shortage. 3.The harvested is of ↑ quality (No. purification cost or complex to be formed). 4.Incase of hydroponics → excess will be returned to pool to reused.
4- fertilization: includes the 1- organic matter that with soil during preparation at a rate of 5- 7 kg of dry material /m² which sufficient for 1 year. 2- chemicals which added to plant either through the soil or through the leaves, includes: 1)Simple: of one compound that contains one element or more as Ammonium (N) Sulfate (S) or Urea (N) (relatively slow releasing), Potassium (K) or Calcium (Ca) nitrate (N) (high releasing) or mono or di or tri, super phosphate (slow releasing). Potassium sulfate (16-20%) is best source of K (47% of P 2 O 5 ) since it is highly soluble. Sources of P,K are added completely during soil propa. while N sources are added partially as about 50kg of K 2 O, 50kg of P 2 O 5 + 1/3 of N quantity.
2)Compound: that includes N,P,K mainly + some has % of MgO + % of CaO. Could have ↑↑ % of N,P,K or one of them or ↓↓ % of all or one selection of proper formula is depending on: a- Environmental conditions (% of N ↓↓ in cloudy conditions). b- Type of crop (leafy→↑% of N, fruit→↑% of P, root→↑% of K). c- Soil texture ↓% of N in muck or peat soil, ↑% of K in sandy, ↓ P % in heavy. d- Freshment of soil used in cultivation: new soil has ↑ P% and ↑ K%. 3) Slow released: either slow solubility rate in water or takes linger time to be ready (released) out of capsule → remains for longer period in the soil without being fixed in soil or leached with drained water such as: - chelated compounds: organic compound of multi groups to which one element or more is connected → no fixing for it in soil + slow releasing rate since of ↓↓ analyzing rate. The chelated compound could be acids or Na – salts and Fe, Zn, Mn, Cu and Co are elements to be connected with chelated compound.-
-Ozmocoats: contains N,P,K, Mg as main and may have Fe, MO, B, Mn, Zn and Cu that enclosed in a plastic, waxy or cuttin capsule of 3mm as Ө and durate from 2-18 months without being deteriorated with excess moisture or PH or micro organisms that surrounded them. The most deteriorative factor is the soil temp. (↑tem = shorter the duration). -Urea coated with sulfer: the coat is enriched with materials that in activated the M.O. activities as (pentachlorophenol) → ↓ the decomposition rate of the sulfer coat. It includes N, S, waxy, micro biocides, conditioners at the % of 36, 17, 3, 0.2 and 1.8% respective. So, 10% of N in first week to be released = SCU-10 or 26% of N in first week to be released = SCU-26. but in the 2nd and third week the % of N ↓ gradually since coat permeability ↓↓.
Soil-less culture and hydroponics SOIL-LESS : Cultivation production by using various growing media other than the mineral soil as pure sand,gravels,peat,vermiculite, prelite or mixture of some of them or using hard media as compressed straw pallet or rock wool. Hydroponics : Cultivation??? immersing the roots in nutritive solution presented in special containers or allowing the roots to absorb nutrients and develop on Nutrient Film (NFT) over which the solution is circulating.To the hydroponics you can add also the AEROPONIC : keeping the roots in closed air space and the solution is pumped frequently by mist system to the root space in all previous cases plants are provided with nutrient solution containing proper % of all essential elements without being planted in normal soil or irrigated with normal water + supposed to be under protective structure since these techniques are highly cost and so important to protect the cultivated plants. These systems raised as an important technique from 2 nd world war during which the necessity for fresh vegetables production in soldiers camps where soil in them not always suited for cultivation.
ADVANTAGES and DIS ADVANTAGES of the system : It is not logic to deal with these types from economic point EXCEPT in absence of good soil for cultivation but presences of suited productive ????? ( AS stony,hard,salin,infected with soil born that difficult or costed to be controlled cost of soil improving > cost of raising these types) ADVANTAGES: 1.Production in areas where impossible to produces normally especially if environmental condition are too much ????. 2.Higher productivity than open specially non suited land and could be > than traditional protective strew tares or equal-raost economic crop to be cultivation is determined by : DAILY PRODUCTION \ UNIT AREA * No. of PREDUCING DAY Total production\ unit area (where cost of each unit can be calculated)
3.Difficiency of any element is not expected since all are available proper concentration→ continuous ??? growth and production in nice ??? 4. Adsorption of elements or fixation by soil particles is not expected. 5. Not suited system for reproduction or dormant of soil born diseases ??????agents as what happened incuse of protective structure soil. 6. No problem related to variation in soil texture, structure or components which likely to be not uniform which menrs by this system →uniform media. 7. No problem related to weed control or soil preparation that may delay planting time. 8. Early production which may ?of noticed profit. 9. Electronic helpin making accurate designs in the ? time. 10. Better ventilation control (rh%). 11. Longer period of uniform production and high quality.
Disadvantages 1.Components of production should be available without depending on the field in providing enny one. 2.Intensive control and test of PH is required since change quickly. 3.Efficient and accurate instruments should be employed since errors may lead to great loss. 4.?the activity of micro organisms (benefits against destruction )? The function ?organism if infection occurs. 5.The ? of circulating solutions enhances pollution of varions points cannals and medic. 6.High cost of production in this technique and test of re circulating?.
7. Accumulation of ? nutrients :water and all nutrient elements needed for growth,many solutions presented,most important is ? solutions,no one is standered ? is controlled by: 1.Characters of used water in solutions if : 1)Low solinity water of ?????????????????????????????????????????????????? ??????????. 2) shouldn’t be more than 50 ppm and total salts concentrates???????????????????????????????. 3)Slightly hard water (low quantity of HCO3 ions )can be used,?as these ions high and high PH and low availability of Fe ions and high? Ions of CA,MG so water should not used hardness off water can be low by passing the water through filters rise with H+ replacing MG,CA with H+ …..H2CO3 OR H2SO4 then exposing the water in to filters rich with OH- to replace the ions of CL2 to NAOH or CA(OH)2. But by this step not possible to get red of B ions.so best is to collect rainfall water
2. Total salts concentration in solution :salts are coming from either dissolved salts or from presented salts in water.as concentration of salts in water decreases more possibility and ? control of total concentration in circulated water reaching to not more than 0,7 as average at ? pressure since >than that to decrease the growth rate then stop then death …. High 3. concentration leads to delay of flowers parts at upper growing points of tomato and solid stunted leaves of lettuce. Low concentration at the other hand ……symptoms of deficiency at summer a 0,5 ?.pressure is enough and during winter a 1 ?.pressure since during summer ……high ETPsugar? ? can tolerate up to 2,4 ?.pressure by adding NACL. While turnip can be ? up to 1,4 /.pressure and rest of ? are deffected by high salts. 4. Concentration of elements in solutions and the ionic ? between them :all needed elements are presented with a ? of ions between macro=sum of ions (NO3-,H2PO4-,SO4-)=SUM of cations (k,ca,mg)while NA is not from first essential elements and the rest are not noticed effect on balance.
Factors affecting the proper concentration of these solutions : 1.Tem and light intensity :high temperature and high light intensity leads to increasing ?.while K concentration high in cloudy and should be ?? if cloudy condition continues fore long period reaching to 3-4X increase of low light intensity.while in case of high light intensity concentration of K low to the ? since ETP is very high 2.Type of mediate to be used as soil –less where salts noncentration depending on thet media (N,P,K,CA,MG,S) 3.Stage of plant growth :the 6 macro are change as concentration in relation to plant growth stage.while micro not change during solution preparation examples: *Tomato :3 concentration solution,*1/3 of concentration (total). salts from emergence (10-15)up to (35-40) _*2/3 of concentration (total) salts up to 70 height after _ *full salt concentration from 70 to the end
Cucumber =2 concentration,*1/2 of total concentration up to the end first fruit blooming *full concentration salt up to the end of season Leaf crops=2con.solution *2/3 of full con.solution up to 3 weeks age *full con.solution after that.
Symptoms of nutrient elements deficiency or excess: Equal to those appear in case of normal field but faster, more clear in micro. elements since the soil rarely to have miro_shortage Shortage: 1_appears as circular erueking in tomato and long it?????? In pepper as are result of B↓ 2_ deep cracking (division) of tomato fruits at the mature stage resulted from Cu↓ ????of ↑↑ temp. Where ↑↑ temp. →↓the available Cu below 0.5 ppm. Excess: induces toxicity on plants as a result of errors in solution preparation and ↑ salt con. In solution above 3-4 X proper solution con. > below this level but still ↑→stunting, waxy or woody growth +dark green color of leaves. These become more clear if one elements is excess X other not highly available →example: Tomato can tolerate 1 ppm of Cu in solution if others are available but show toxicity with Cu at 0.2 ppm if other are hardly available.
EXAMPLES of interaction. resulted from excess of some: A_ excess (NO3-) con. During early growth stages of Tomato →block B absorption,death of growing points,stunting stem, fluffy flowers X low or no pollens B_excess P→preciptat Fe →appearing of its diff. symp C_ excess K→↓Ca availability and visa versa D_ excess Fe→↓Mn availability and preciption P E_ ↑B above 20 ppm → plant toxicity astrals panrent along vines tiar converted to boron color F_ excess of Zn→toxic of plants as yellowing of areas between vines G_excess Cu above 1 ppm →toxicity as yellowing between vines. To overcome problems of excess by: diluting of used solution or preparation of new solution with proper con. -Washing of the media with pure water for many days.
PH of nutritive solution : the proper is 6_6.5, that affected by the balance between NO3- and NH4+ which should not decrease below 10% as NH4+ and better to be around 25% deveasing PH below 5→↑absortion of some elements up to toxic level as Zn,Cu,B while ↑ PH above 7.5→ precipitates P,Ca,Mg,Fe,Mn decreasing their availability for plants. can be modified by H2SO4 to acidic or by NaOH to alkaline on the recirculation solution. *Conc. Of elements in nutritive solution is expressed as: -Ppm: 1 ppm means 1 g of substance dissolved in 1000 L of water→ 1 g in 1000 000 cm3. -mM : 1 Molar : dissolving the molecular w.t of material in 1 L of water → mM : molecular w.t in 1000 L of water -meq\L: (molecular wt\Valency=eq. w.t)→meq=1\1000 of eq.wt. so, meq\L=1\1000 of eq.wt dissolved in 1 L of water -Osmotic pressure= that expressed as atmospheric pressure, where 1 atmospheric pressure=14.7?????????? or 1032 gm\cm2(453X14.7)\(2.54X2.54
Points to be taken in consideration during preparation of circulating solution: 1_ Using of normal,local, commercial chemical of NPK of low conc. If possible. 2_Used wethable chemicals(easy dissolved) and not granulars hard dissolved 3_ knowing of sources each required elementes (tnve 23-6) 4_ following the steps in preparation is important they are : A_ weighing each substance alone and keeping them in separate piles B_ Filling the tank up to 90% of total volume with water C_ dissolving each substance separately in container then adding it to the tank with continuous stirring. Not water used to hard dissolved D_ Micro are firstly dissolved then the Macro. E_ if quantities that used are small→ you can mix SO4 salts to gather and NO3- salt to gather.
* If the solution is not reused: 3 concentrated solutions are prepared. 1st for NPK, Mg,Ca. 2 nd except if it is??????? Sources then can be mixed with Macro. 3 rd including all the remaining trace elements. then from each solution proper quantity is ejected to avoid precipition. HOW to calculate needed quantity of chemicals in solution: Suppose that the required conc. Of Ca in solution is 200 ppm so 200 mg of Ca\L of water. And if we know that the molecular w.t of Ca(NO3)2 (as source of Ca and N) is 164→ each 164 mg has 40 mg Ca. then q. of Cu(NO3)2 need to reach to 200 mg og Cu is=164\40X200=820mg\L of water. If Ca(NO3)2 is 100% pure normally is 90% purity so q.= 820X100\90=911mg\Lwater then by knowing quantity of water to be circulated in litter X mgs\L= quantity to be added from Ca(NO3)2 to have 200 ppm of Ca but this chemical provides to certain quantity of N which should calculated in order to complete the quantity of N from others=2X14X820\164=140 mg\L of N→140 ppm of N. are conc. From Ca(NO3)2 used as a source for Ca. but suppose the requirement con. Of N in solution is 150 ppm. then remaining 10 ppm (150-140) are to be obtained from other chemicals as KNO3. We need for it the following quantity to obtain the 10 ppm= (10X101\14)X 100\95=76
So 76 mg\L of water are needed from KNO3. By these are method you can calculate how many ppm of K are provided from this KNO3 added in order to complete the requited ppm of K from other solution USING for example K2SO4 as a third compound to finish K ppm and to calculate how much will be obtained from sulfur in order to be completed from 4rth compound and so on As No. of elements included in used chemical↓→easier to be used and lower problems of managing ppms for the included elements. Take care to what provided from any compound as ppm of 2 nd element if his conc. As ppm>required conc. Of the 2 nd, then you should stop using this compounded up to final ppm of the 2 nd and shifting to other compound that completing what required of first and nothing of the 2 nd.
Hoagland solution (transp.of tab 4-9,4-10) and Hewitt solution : Both are used for studying the physiological response of plant while the commercial are according to area are subdivided into: California, Florida, Texas, Engeltra, Japan, Kuwait, Poland and some contain only the Macro. Types of Soil-less culture forms. According to media→hard media for root growth as rock wool →Liquid media for root growth as solution of nutrients → Air media for hanging root air and misting them According to nutritive solution →Open : solution used for one time- enjection of concentration to water →no need to ????? →Closed: recirculation of solution- need to big tank to adjust the conc. From time to time and so big tanks are need to dilute solution and using them directly ::→ no need for ejectors
Farms of hard media include: 1.SAND farms: open system, solution not reused, so tank for standard solution + ejector are needed X drip system. contains sand particles of> 2.38 mm as in a % of 11% + 89% of sand particles with <= 2.38 mm to 0.28 mm, some times < 0.28 mixed with 3% this mixing is important to improve infiltration rate + aeration + moisture conservation sand farms can be done by one of the following system : a.Direct planting on sands of coasts after being washed heavily with water following same techniques used in protective cultivation. b.Spreading a sand layer of 30 cm higher over the soil of structure that separated from the soil with P.E layer of 15%\ 30 m length to improve drainage+ sand washing if it is necessary by fixing draining tubes below sand layer above the plastic sheet along the sloping direction so as to end with main collecting line of draining water.
In cased difficult cont. stopping along the structure, then structure soil can be divided into 2 part of stopping direction to wards the mid and the collecting line in the mid to serve both 2 parts. Draining tubes have holes at the hotrom side of tubes to allow entering of excess water+ no roots to developed insid(low low low possibility). Irrigation by drip system up to 4 times\dayX5-8 minutes\time. Draining crater collected for open field. c. Using special bed of V shape, covered with P.E bleach layer to the inner side and draining tubes in the bottom and all drained tubes end to main collecting line. Beds are of 60-75 cm width X30-40 cm depthX various length and of 15 cm \60 m length as sloping rate. In all sand farms : 1- Asur plus quantity of solution is added where 8-10% of solution to be infiltrated. This quantity is sufficient to wash accumulated salt direct by upon their accumulation 2- Also water should be should be analyzed 2 weekly and if con. Of salt of above 2000ppm → washing of sand with pure water alone. Specially if salts are mainly of Na- salts
3-cheeking of ejector 2\week to evaluate their function +PH check continuously 4-petrmining the salt conc. In pumped water after injection continuously and cleaning the tanks from impurities, precipitation before preparation of new solution. The sand of these farms can be treated with M.B or M.I. (as gas)orvaper with irrigated water or steam water which proved to control the cucumber mosaic virus effectively.
GRAVEL farms : Closed system,solution is revised, no need to have ejector but high tank are need. best types of gravels is grinding gravels of 1.6-18mm in X hard that resist spiting with use,irrigation is either through: diffusion from bottom or by drip system where solution is circulated for 2-6 weeks. Time between each 2 irrigated time is affected by: 1- size of gravels 2-uniform surface of gravels 3- crop X density 4- envi conditions 5- time of day (morning or mid day or evening ) Average No. of irrigation \ day = 3-4 times during winter time of cloudy sky
While during summer= 1 time\hr of day hrs. uniformity of irrigation → no salts accumulation within the membrane layer surrounding the gravels since the con. ↓ with each irrigation. Solution needs titration after each irrigation since pumping solution throughout bottom→driving air in front that contain low O2% and ↑CO2 than atmospheric air and by draining solution to recirculation then air rich in O2 retrns→good techno. For roots ventilation. best results by running solution up to 20-30 minute and draining it avoiding reaching of solution to gravels surface but 2.5 cm below in order to 1.Prevent algae development in surface since surface is cont. dry 2.Low water loss by evaporation+ good RH% near plant base (not high) 3.No roots development on surface which many injury by ↑ temp on surface with ????????? at draining time.
*Draining tuber are of woud(coverd with plastic from inner side) or from ???? but not of irons since easily to be oxidized and detent by presence of chemical salts those tubs are in the bottom of aravel boxes *temp. of solution should be = to temp. of atmosphere to avoid vilting related to low tem. Of water when added near roots →↓ root absorbing gravel boxes are of 60 cm width X 35 cm depth X40 m length and established at 5 slope\30 m length *important to have big tank for nutritive solution at capacity of 2X what required to fill gravel boxes to 2.5 cm bellow gravels level so as to have spare quantity. Pump should be of high force to fill the gravels boxes during 10-15 minutes and draining accord a 10-15 mnt burin case of using drip system, dripper is fixed near plant base and gravel particles should be of 3-6 mmin to ↑ horizontal diffusion of added water. By this possibility of closing tuber by roots is low +ventilate is more efficient but vertical flow of water→↑root development down →↑possibility of closing draining tubes. Gravel media is treated between seasons with NaOCl (sodium hypochloride) or HCl at 10000-20000 ppm for 20 minuts then washed thourly with water and leaved for ventilation for 2 days and as roots in media increase as % then vapam could be better
For defects of this system : 1-↑ establishing cost 2- root accum. Down ward→closing of draining tubes 3- high possibility of diseases diffusion by the accumulated root 4-the reuse of solution for several times → change conc. Of elements as total and as % of each to the other since water is fast be absorbed than chemicals and so the solution should be under gone: renewing each week at fruiting stage, 2-3 weeks during other growing stages, -or each 2-3 months if solution analyzed knowing which chemicals are change and adjusted by adding from those decreased and if E.C is recorded daily in order to keep salinity of solution not>4 mmhos\cm and this done by keeping solution at its proper volume every evening or by ↑↑ the solution > required reaching to end the week with the proper volume that should incased by the end of the week to previors volume. This check and adjustment of volume can be done automatically
3-STRAW BALE culture: Open system, tank for stack solution + ejector are needed and solution not reused. Straw is rapidly de composed, so change annually which is positive in saving cost and risks of treatment+ decomposition Of straw → released energy →↑temp. of root +↑CO2 % around the plants. bales are arranged in lines over P.E sheeds which should enriched with NH4NO3 as food for decomposed lucteria but this is done in a frequent manner + also 300 gm of mono super Phosphate +300 gm of KNO3+ 85 gm of MgSO4+ 55gm of Fe\20 Kg of Bales+ continuous predestining up to be ready for transplanting →when tem. Is =38%→ released of toxic substances is done then irrigation by solution (water + ejected chemical) by dripper according to plants needed quantity which supposed to be > by this system since the evaporation is form 3 surfaces of Bales. Don’t forget that size is↓↓ with running of growing season.
4-Rockwool culture(Farms): Open system, root develop in the Rockwool media that prepared from calcareous stones and Basalt rocksar 1600 %→ liquid fibers, thin and long of 5 M as \ fiber that including 97% of it volume as air space and 70 Kg\m3 is the density. These fibers are arranged vertically to gather to allow root development in between +flow of water vertically. it is not decomposed biologically and :1- particles that can be mixed with other me :2-culics of 4-7.5 cm dimension :3- bed of 7.5 cm X width(15-30)X length(75- 125 cm) Cultivation is done by producing seedling or transplanting ????? in small cubics where seed or seedlings are immured in holes inside them, then covered (holes)with Rockwool particles then these ????? are distributed over the beds that arranged along the structure and enclosed with P.E bleak sheets and perforated as much as the size of the culics and so the roots are deeply developed into these bed. Drip irrigation is the system to be used. And drainage is throughout opening that done at both sides of P.E sheed surrounded the beds. 3 times\day of irrigation are required as average. which ↑ with volume↑ of plants, tem↑, and stopping of water running rightly at solution percolation from beds. N.solution should be analyzed weekly by taking samples from pumped solution and E.C. should not exceed 1.7-2 mmhose\wm treatment of wool is effectuating of 2 years of use then according to pathological condition, the internal is determined
5-Peat mixtures and other materials farms: open system, ejectors to inject water with N. solution. media is filling in bed, long, low, of 15 cm depth X 75 cm withX 40-60 m length. Or filling the medicin cylinder of plastic that open from both ends and of 20-25 cm and fixed vertically over the beds.root development rate may↑ as a result of temp ↑ of media inside the cylinders during the day. Or media can be placed in plastic seeks of 1 m length X 20 cm width the have capacity of 2 cucumber plants or 3 tomato ones. Also sacks can be of 70 cm X35X50 liter volume. these sacks are arranged along the structures as beds. best space is of 14 liter\plant. And black color X white from out side especially from the inner side to have proper conditions for roots development+ reflecting the light in hot region or to be totally of blacken color in cold region to absorb the incident light→↑ temp. of media. Also the peat can be placed in column the arranged vertically formed of many Cup\ column and for each Cup there is an extending open in which plants are placed. Plants in each columns show a DNA structure this a famous system for straw berry and drip system is fixed over the column and draining from the bases of each column.
P.E cover Draining holes Media------------------ ------ bed
FARMS of LIQUID solution as media : Roots are presented in nutrients solution, closed system + big tanks to prepare the total solution for direct irrigation of plants --- tanks have capacity X 2 whit required for circulation or more. plants are supported to grow upright by the cover to the canals of circulating solution. To ensure the success of this system : 1-providing the solution with O2 2-protect the solution from light incidence to avoid algae development and so no competition of algae to plants and no rising of PH and avoid toxicity of Algae when decomposed liquid farms characterized by –a-copmlete control of the media of roots as nutrient content, temp. and also Pathological status is controlled by continuous solution circulation -b- saving in heat consuming during winter by ↓ temp. up to 16 C DURING THE NIGHT AND ↑ up to 23-28 c during the day→ high productivity of tomato
-c- higher early production and also total -d - easy to fumigate the solution if required compairing with sailor with hard media. This system includes: 1 - Nutrient solution culture: solution is circulation in covered beds the cover supports the plant. Since formed from netted plastic and root, are immersed in the solution where seeds can be seeded in plastic net called litter tray→where soil level should reach net at this stage, pumps are utilized to induce air bubbles in solution →in richement of solution with O2, or by having space between solution surface and the cover of 5-7 cm→solution motion →mixing with air →↑O2 level for roots respiration. 2--Tube cultures: of PVC tubes, 4 inch as that cut longitudinally to 2 halves, that covered with black plastic to avoid light in filtration they are used for those of limited vegetative and root system as lettuce where plants are fixed through the holes made in the cover and the root are in the solution, tubes should be fixed with 7.5 cm\30m length as a sloping rate to improve solution of low+ aeration by puthing barriers in the tubes over which water will move and so show higher exposing to air or by falling the returned solution to the tank from eleveted point and during salling→expasing + envichment with air
3—nutrient film techniques: (culture) : closed-root are presented between 2 layers of plastic sheets of narrow space in which solution lows as fine film of 3mm as thickness. canals in which 2 films are presented should be accurately prepared with 1%as slope so as to have no blocking of solution of low and covered from inside with plastic sheet that also cover the surfaces of the canal and cubists of seedling are also covered and seedling stem are passing through holes. This cover is important to: 1---↓water loss by evaporation 2---block the light incident to solution surface→no Algae development 3---avoiding so competition with plants and no blocking of solution flow 4--- helps in controlling roots temp.
Characters of this method: -a- no need to fumigation since the 2 films layers are changed after each season+ presented root and also washing of tubes (canals)+ tanks with formalin 2 % is enough -b-save in consuming water since it is covered, recirculated -c- easy to prepare solution since it is prepared totally +test+modified at the same place -d- chemicals for diseases and insects control can be mixed with solution -e- establishing cost when distributed at long run→become excepted. Disadvantages : 1-faster diseases diffusion when start 2-salt accumulating near stem bases may burn these bases specially by solution setelments. Covering plastic should be of dark color from inner side and white color from the outside in hot regions and of black in cold. Free solution movement+good O2 enrichment is impotent
AEROPONICS: جدول (23-6): اهم الاسمده المستخدمه في تحضير المحاليل المعديه الاسم التجاري للسماد و رمزه الكيماوي الوزن الجزيئيالعنصر الذي يوفره درجه الذوبان في الماء ( ملح : ماء ) التكلفهملاحظات نترات البوتاسيوم KNO3 101.1K+NO3-1:1 منخفضهسريع الذوبانرخيص الثمن نترات الكالسيوم Ca(NO3)2 164.1Ca++1:1 متوسط كبريتات الامونيوم (NH4)2SO4 132.22(NH4+)SO 4- 2:1 متوسط فوسفات الامونيوم NH4H2PO4 115.0NH4+N2PO 4- 4:1 متوسطلا تستخدم هذه المركبات الا تحت ظروف الاضاءه الجيده, او لعلاج حاله نقص الازوت
ثنائي الايدروجين فوسفات الامونيوم 132.12:1 متوسط احادي الايدروجين (NH4)2HPO 4 2(NH4)+ HPO4-- فوسفات البوتاسيوم الاحاديه KH2PO4 136.1K+ H2PO4--3:1 مرتفعه جدا كلوريد البوتاسيوم KCl 74.55K+ Cl-3:1 مرتفعه يستعمل في حالات نقص البوتاسيوم وعندما تقل نسبه الكلوريد الصوديوم في الماء كبريتات البوتاسيوم K2SO4 174.32K+ SO4-15:1 منخفضهتجب اذابته بالماء
فوسفات احادي الكالسيوم Ca(H2PO2)H2 O 252.1Ca++ 2H2PO4- 60:1 منخفضه حديد مخلبي Fe EDTA 282.1Fe++ سريع الذوبانمرتفعهافضل مصادر الحديد يذاب في الماء الساخن حامض البوريك H3BO3 61.8B+++20:1 مرتفعهافضل مصادر الحديد يذاب في الماء الساخن بوراكس او نترابورات الصوديوم Na2B4O7.10H 2O 381.4B+++25:1 كبريتات النحاس 249.7Cu++5:1 منخفضه كبريتات المنجنيز MnSO4.4H2 o 223.1Mn++So4--2:1 منخفضه
كبريتات المغنيسيوم MgSO4.7H2O 246.5Mg++SO4-2:1 منخفضه كلوريد الكالسيوم CaCl2219.1Ca++SO4- - 500:1 منخفضهلا يمكن استخدامه في المحاليل المغذيه حامض الفوسفوريك H3PO489PO4--- حامض مركز 1 مقابل حامض الفوسفوريك العناصر الصغرى كبريتات الحديدوز FeSO4.7H2O 278.0Fe+3SO4--4:1 كلوريد الحديديك FeCl3.6H2o 270Fe+33Cl-2:1
محلول هيوت Hewitt المغذي يحضر محلول الهيوت المغذي كما هو في الجدول (23-11) من الاملاح النقيه و الماء المقطر ويستخدم غالبا " في الدراسات فسيولوجيا النبات ( Devlin 1975) جدول (23-11): الاملاح المستخدمه في تحضير محلول الهيوت المغذي وتركيزاتها به الملححجم \ لترجزء من المليونملل مول \ لتر نترات البوتاسيوم KNO30.505000 البوتاسيوم = 1955.0 نترات الكالسيوم Ca(NO3)20.820000 الكالسيوم = 2005.0 النيتروجين = 140 فوسفات الصوديوم NaH2PO4.2H2O 0.208000 الفسفور = 411.33 كبريتات المغنيسيوم MgSO4.7H2O0.369000 المغنيسيوم = 243.00 حامض البوريك H3BO30.001860 البورون = 0.0370.033 موليبدات الامونيوم (NH4)6MO7O24.4H2O 0.000035 المولبيدنم = 0.0190.0002 كبريتات الكوبالت CoSO4.7H2O0.000028 الكوبالت = 0.0060.0001 كلوريد الصوديوم NaCl0.005850 الكلور = 3.550,01
محاليل مغذيه تحتوي على جميعالعناصر الضروريه للنبات, ويشيع استخدامها في جهات متفرقه من العالم 1. في كاليفورنيا يستعمل محلول مغذ يقارب في قوته نص قوه محلول هوجلاند مع بعض التغير, ويحضر باضافه لتر من محلولين قياسيين (1),(2) الى 200 لتر ماء, وتخزن المحاليل القياسيه في اوعيه منفصله ( يفضل ان تكون بلاستيكيه او مبطنه بالبلاستيك ) لتجنب ترسيب العناصر. وبرغم انه يمكن تخزين المحاليل المركزه دون مشاكل, الا انه يكتفي عاده بتحضير كميات تكفي لعده اسابيع فقط.
الكميات اللازمه لكل 200 لتر ماء نترات البوتاسيوم KNO39.6 كجم فوسفات البوتاسيوم KH2PO45.5 كجم كبريتات المغنيسيوم Mg SO4.7H2O9.6 كجم محلول العناصر الدقيقه المركزه 20.0 كجم ويلزم لتحضير المحلول القياس رقم(1) الكميات التاليه من الاملاح ومحلول العناصر الدقيقه المركزه: KNO3=101mwt Each 101g\L=Molar→0.101g\L=mmolar 0.505g\L=?? =0.505X1\0.101=5mmolar\L