Presentation on theme: "Alternative sytem of growing tomatoes"— Presentation transcript:
1Alternative sytem of growing tomatoes The Green Q way.10 February 2010André Kool, crop consultant, Green Q
2Alternative sytem of growing tomatoes Starting pointsDouble screenLow density start heads / m2Single grafted plant (1 on 1)Doubled in spring f.e. 1.673.33Stemdensity and plantload better in balance with natural light
3Content Growing aspects under double screen Advantage Disadvantages Points of extra attentionGenerative crop steeringPlant densityGreenhouse air humidityEconomicsTechnical aspects under double screenUse of heating pipes (rail pipes and growth pipes)Crop planning
41. Growing aspects Goals? Energy saving? Fast early production to get high prices?Stronger crop, less sensitive for diseases (virus…)?
5Installation Movable screen in top Fixed AC-foil below on seperate system of wires above crop wire: condensation drop will be between rowsStable air layer between screens gives extra isolation
6Advantages Better start climate for young plant Higher humidity at start.Lower pipe temperatures.When opening movable screen no cold air falling on crop especially nice in case of pepino virus.Less rduction of light at closed plastic foil compare to closed movable screen.Easier growing at higher temperature levels because of higher isolation of greenhouse (especially with low density start)Energy saving at both screens closed: 50-55%Only movable screen =40%Only fixed foil =20%
7Disadvantages Horizontal temperature differences Because of rolling down of cold air above foil and perforation foil cold air can fall down on some spotscompartments between screens can be made.Light reduction foil 10%Too late removal of foilis higher risk on diseases
8Points of extra attention Keep more generative growing stategy (climate)Plant temperature at day time is lower because of less direct lightPlant temperature at night is higher because of less radiation to outside.Big DIF steering required (warm day, cool night)In the afternoon the greenhouse climate should make the plant evaporate and the plant color should be “dark” at the end of the afternoon.Heating with a growth pipe is a good help….
9Points of extra attention Low density start (f.e heads / m2 versus 2.5 heads / m2 )Less crop under foil will create less problems with humidityLow density and low plantload more light per head higher “growth speed” possiblehigher 24-hr-averageLess problems with humidityBetter utilisation double screenBetter growing conditions in case of pepino-virus
10Points of extra attention Development crop load at 2 start densities
11Points of extra attention…..humidity Maximum tolerance of humidity levels under screen?At cooling down greenhouse air less risk on condensation.At warming up greenhouse air high risk of condensation.HD pre-night >HD after-night >HD morning>HD day >3.0 (preferably in afternoon)
12Points of extra attention…..humidity Humidity control by:1.Ventilation above plastic foil (outside no frost)2.Air-movement by minimum (growth) pipeWarm air can contain more water lower humidityRemoval of plastic foilWhen you humidity control becomes a problemA movable second screen would even be better………
13Economics Costs* Materials plastic foil screen € 0.15 per m² Labour (experienced) € 0.05 per m²Total € 0.20 per m²*Dutch price levelsSavingsDepending on outside circumstances5-20% extra in respectively mild and cold winter
142. Technical aspects Energy saving Type en perforation Ventilation above plastic foilCooling down in pre-nightScreen policyMeasuring box above screenHeating with what pipes?
15Energy saving Movable screen (LS) f.e. 40% (climate computer!!) Fixed plastic foil % ? Check pipe-and greenhouse temperature in graphs“Too slow” reacting pipe, delayed GH –temperature higher energy saving % on computer“Too aggressive” reacting pipe, overreaction of GH-temperature higher energy saving % on computerIn general: too big fluctuations in pipe-and greenhouse temperature can be indication of wrong setpoints for energy saving %Not good for climate and energy consumption.
16Energy consumption at various scenario’s 18 ºC Greenhouse temperature Modern well isolated greenhouse, no windspeed, no radiation, no precipitation mm pipes per 8 m (1,60 meter row distance) Figurs are pipe-temperatures with (….) gas consumption in m3/haT-outsideno screenPlastic foilMovablePlastic+movable-1074 (188)66 (152)58 (120)50 (110)-558 (123)50 (91)46 (76)51 (95)45 (73)41 (59)549 (88)44 (69)38 (52)35 (42)1040 (55)32 (33)30 (26)
17Type and perforation AC, otherwise to dark and dripping No 5 x 5 cm too much cold air falling on lowest pointsStandard 10 x 101-2….poles near sidewalls: 40 x 40With fans blow from warm spots to cold spotsAt highest spot (=warmest spot ) make plastic movable (at middle pathway).
18Ventilation above plastic screen With mild weather and / or very sunny weather :Ventilation above fixed plastic screen because of:Rising greenhouse temperatureToo high greenhouse air humidity
19Ventilation above plastic screen Points of special interest: Ventilation setpoint close to heating setpoint (dead zone 0°C)Reduction ventilation setpoint at high greenhouse humidityQuick ventilation at windside (no delay at 0 m/s windspeed)Maximum window position limited at high windspeed to prevent damage to plastic screen.Sunny and frostVentilation should be possiblefrostprotection setpoint based on radiationAfter removal plastic foil don’t forget to put back “normal” setpoints
20Cooling down to pre-night Difficult at mild weather (>10°C).With ventilation setpoint follow parallel heating setpoint.With “cold” pipes. 25°C is too warm. Pumps out.As long GH temperature moves downno condensation.If necessary ventilation also at the windside.
21Screen policy (movable screen) There is a fixed plastic foil so movable screen….Earlier open, closed later (only closed with frost)Smaller dead bands and delays, bigger steps.Easy gapping based on temperature or humidityVentilation setpoint close to heating setpointAfter removal plastic foil don’t forget to put back “normal” screen setpoints
22Measuring box above screen Measures temperature rise above screenMost direct signal to open screenMeasuring box above screen to open ánd close movable screen above fixed foilIn case of only 1 (movable) screen : measuring box only help to open screen
23Heating with what pipes? (Double) screen means colder pipesLess radiation and less air movementHigher risk on a “dead” climateHeat closer to the plant with growth pipe (=primary heating system)Thinner pipes = hotter pipes locally more radiation and air movementHeat at the point where you need the heat: close to the plant…..
25Heating with what pipes? Thinner pipe Relative big surface compared to water content Relative high lost of heat on the lenght Bigger delta-T (Difference supply-return water temperature)Because of this thinner pipe, preferably a spiral (equal discharge of heat over the lenght of the crop row)Single growth pipe? Preferably a thicker pipe (less delta-T)
26Heating with what pipes? Primary heating with growth pipe results in generatieve, weak and thin plant?Not necessarily.Take care off:When heating primarily with growth pipe heating setpoint slightly lower than “conventional” (1-2°C) will also save energyReduction of maximum growth pipe temperature at low humidityThink more in plant temperature……..Keep LOOKING at plant
27Heating with what pipes? There is only sufficient air movement if pipe temperature is minimal 20°C higher than surrounding greenhouse air temperature..
28Heating with what pipes? Create air movement there where it’s required:Close to the crop (between)Position growth pipe (under of above growth gutter)Influence radiation on truss / fruitsLocally more radiation and air movement with a smaller but hotter pipeThinner rail-pipe (5145 mm= 2-3°C higher pipe temperature)Growth pipe (spiral) versus rail pipe (4528 mm = 10°C higher pipe temperature ) (total consumption energy equal)
29Heating with what pipes? At lower heat demand (double screen) it’s more inportant to bring heat and air movement closer to the plantHeating closer to the plant (primary with growth pipe) result in more air movement close to the plant and a warmer plantBecause of this the heating setpoint can be chosen a little bit lowerGenerally this way of heating results in a more efficient use of energy
30Crop planning “Live” demonstation of Green Scheduler crop planning program