Methods of Irrigation Dr. Sailesh Prajapati

Irrigation--Considerations When do you water? How often do you water? How much do you water? How do you water? Does it matter?

Getting Water to the Plants Large quantities of water for successful growth Rainfall Inadequate Inconsistent Irrigation

Water Requirements Water loss Plant composition Consumptive water use Transpiration Evaporation Evapotranspiration Plant composition 85-96% of total plant weight is water Consumptive water use Evapotranspiration + plant composition wwwcimis.water.ca.gov

Water Requirements Critical water use periods Soil moisture Constant water supply Foliage crops – uniform water Fruit and seed crops – fruit set/maturation Root, tuber, bulb crops – enlargement period Soil moisture Consider Soil type, texture, depth Field capacity (60% in fine soil, 40% in sandy soil)

Types of Irrigation Systems Sprinkler Surface Flood Furrow Drip (Trickle)

IRRIGATION METHODS   a) Surface Irrigation: Just flooding water. About 90% of the irrigated areas in the world are by this method. b) Sprinkler Irrigation: Applying water under pressure. About 5 % of the irrigated areas are by this method. c) Drip or Trickle Irrigation: Applying water slowly to the soil ideally at the same rate with crop consumption. d) Sub-Surface Irrigation: Flooding water underground and allowing it to come up by capillarity to crop roots.

1. Surface Irrigation (Flood/ Furrow) used in almonds, peaches, walnuts, rice, alfalfa

Surface Irrigation Water is applied to the field in either the controlled or uncontrolled manner. Controlled: Water is applied from the head ditch and guided by corrugations, furrows, borders, or ridges. Uncontrolled: Wild flooding. Surface irrigation is entirely practised where water is abundant. The low initial cost of development is later offset by high labour cost of applying water. There are deep percolation, runoff and drainage problems

2. (a) Surface Irrigation (Flood)

2. (b) Surface Irrigation (Flood)

2. (c) Surface Irrigation (Flood)

Flood Irrigation continued… Advantages: inexpensive less labor large amounts of water leach salts rodent control

Flood Irrigation continued… Disadvantages: land must be leveled or contoured uses large amounts of water water loss through evaporation may cause disease in some crops if applied incorrectly run off water can cause problems (silt buildup in rivers, may contain pesticides)

3. (d) Surface Irrigation (Furrow) Used in row crops such as beans, tomatoes, corn, sugar beets other vegetable crops. Similar advantages and disadvantages to flood irrigation.

3. (d) Surface Irrigation (Furrow)

2. (e) Surface Irrigation Furrow (Surge)

Sprinkler Irrigation Many types micro-sprinklers, solid set, aluminum pipe a. Advantages: use less water, more precise amounts of water can be applied, less run off (tail water), may be used on slightly hilly land b. Disadvantages: expensive (installation, labor, filters, maintenance), salt buildup

Introduction: The sprinkler system is ideal in areas where water is scarce. A Sprinkler system conveys water through pipes and applies it with a minimum amount of losses. Water is applied in form of sprays sometimes simulating natural rainfall. The difference is that this rainfall can be controlled in duration and intensity. If well planned, designed and operated, it can be used in sloping land to reduce erosion where other systems are not possible.

1. (a) Sprinkler Irrigation

1. (b) Sprinkler Irrigation

1. (c) Sprinkler Irrigation

1. (d) Sprinkler Irrigation

1. (e) Sprinkler Irrigation

Drip Irrigation Introduction: In this irrigation system: i) Water is applied directly to the crop ie. entire field is not wetted. ii) Water is conserved (iii) Weeds are controlled because only the places getting water can grow weeds. (iv) There is a low pressure system. (v) There is a slow rate of water application somewhat matching the consumptive use. Application rate can be as low as 1 - 12 l/hr. (vi) There is reduced evaporation, only potential transpiration is considered. vii) There is no need for a drainage system.

Drip Irrigation Used on specific crops, such as grapes, trees (such as almonds, cherries, peaches) a. Advantages: uses less water very precise amounts as well as fertilizer b. Disadvantages: expensive to install, (labor, equipment, maintenance)

Drip Irrigation System The Major Components of a Drip Irrigation System include: a) Head unit which contains filters to remove debris that may block emitters; fertilizer tank; water meter; and pressure regulator. b) Mainline, Laterals, and Emitters which can be easily blocked.

Components of a Drip Irrigation System Control Head Unit Wetting Pattern Mainline Or Manifold Emitter Lateral

Drip Irrigation (1)

Drip Irrigation (2)

Drip Irrigation (3)

Drip Irrigation (4)

Drip Irrigation--Considerations B C A 4-inch spacing between emitters B 12-inch spacing C 12-inch spacing on tightly-pressed beds

Home Garden Irrigation Systems

Sprinkler Irrigation

Sprinkler Irrigation

Furrow Irrigation

Drip/Trickle Irrigation

Comparison of Irrigation Systems Sprinkler Worst method Wet foliage favors disease Splashing of muddy water spreads pathogens Furrow Good method Requires heavier soil (less sandy) and a slope Drip/Trickle Best method Most expensive (but still affordable)

When, how often, & how much to water With sprinkler irrigation, avoid watering very late in the day Otherwise, water whenever needed Avoid moisture extremes (too dry / too wet) Water often enough to keep a consistent soil moisture From: Once a week, wet soil 6-8” deep To: A little every day to keep the soil moist

Too Much vs. Too Little Water What will happen if you don’t water enough? Reduced productivity Poor pollination, cracked fruit (water fluctuations) Delay maturity Reduce quality and yield What will happen if you water too much? Waste water Waste fertilizer Favor disease