Understanding Agronomy

Understanding Agronomy

Irrigation

Objectives • Describe the benefits of irrigation; • Identify ways to determine the need for irrigation; • Explain methods of water application; • Describe irrigation scheduling; and • Describe efficient use of water.

Benefits of Irrigating • What are some benefits of irrigating your lawn? • Green all summer • Healthy • Less weeds • What are the benefits of irrigating crops? • Grow to maturity • Healthy • Produce highest yield possible

Benefits • Irrigation also: • Provides water when it is not naturally available • Is a method to apply fertilizers • Can protect crops from frost • Reduces dust

Benefits • What can happen if a plant is deficient in water? • Poor growth • Stunted mature plants • Lower crop yields (less $$) • Death of plants • Stress; more susceptible to disease • Loss of aesthetics(looks)

Determining a need • Knowing when to irrigate is important in soil moisture balance • Waiting for signs of stress is probably too late • Irrigate before the wilting point • Wilting Point: plant cannot take in water as quickly as it is lost

Determining a need • Once a plant wilts damage has already been done to production • You should check soil moisture before irrigating

Determining a need • Lots of methods can be used to test soil moisture without stressing the plant • Ribbon test • We’ve done this • Ball test • Roll a ball in your hand – if it crumbles you need water • Moisture sensor • Single electronic probe that tests moisture content • Sap flow sensor • Usually for trees or shrubs

Determining a need • More methods • Tensiometer • Determines pull of soil particles • Permanently placed in soil • Can be damaged by extreme weather • Moisture meter • Uses two probes in the soil • Remote sensing • Usually done with satellites • Ground truthing • Verifies accuracy of remote sensing

Methods of Applying Water • What made the “Fertile Crescent” Fertile? • Irrigation • How did they do it? • What are some methods we use today?

Methods of Applying Water • Subsurface irrigation • Piping system that is underground • Saturates the soil below plants and through capillary action, water will rise to the root zone • Not common and can be expensive

Methods of Applying Water • Trickle/Drip irrigation • Very controlled amounts of water • Similar to subsurface but usually runs above ground

Methods of Applying Water • Surface irrigation • Border Strip Irrigation • Both are very similar • Best on level to slightly sloped ground • Canals and ditches are used to carry water to the field • Can be piped • Evaporation can cause large amounts of waste Covers entire field Covers sections of the field

Methods of Applying Water • Furrow irrigation • Similar to the flooding • Water runs down furrows in between rows of crops • Usually same delivery system as flood • Can be piped

Methods of Applying Water • Sprinkler Irrigation • Several types • Usually pump water through a system of pipes • Good on ground that is not level

Methods of Applying Water • Hand-Line sprinklers • Least expensive start-up • Very labor intensive

Methods of Applying Water • Solid Set • Same equipment as hand lines, but set in place and never moved • Much more equipment = higher cost

Methods of Applying Water • Wheel lines • Pipe mounted on wheels • The pipe plays the role of the axle • Entire line moves all at once • Less equipment than solid set, but less labor than hand lines

Methods of Applying Water • Traveling Gun • One large sprinkler head mounted on a cart that travels across the field • Can be affected greatly by wind

Methods of Applying Water • Center Pivot • Central pivot point that an elevated pipe on wheels rotates around • Lowest labor requirement • Sprinkler heads must be engineered to release more water on the outside of the circle and less on the inside

Methods of Applying Water • Linear systems • Same type of equipment as center pivot • Entire line moves in a line • No pivot point • The end tower carries a pump that draws water from a ditch that runs the length of the field

Irrigation Scheduling • Irrigation scheduling is providing the right amount of water at the right time • Scarce water supplies are used more efficiently through scheduling • How is irrigation scheduled?

Irrigation Scheduling • Water supplies are usually increased before peak need • Usually in the middle of the growing season • Most crops are not watered each day • Needs are calculated and then water is applied at a very specific period of time • Some specialty crops are irrigated daily • The method of irrigation helps determine this • Part of scheduling is acquiring an allocation and time with the local water management district

Using Water Efficiently • Why should we use water efficiently? • How does it benefit us? • It is valuable; using more than you need will cost you lots of money • Your crops will be more productive if they are watered properly

Using Water Efficiently • Some ideas to think about when irrigating • Use during cool parts of the day or night time • Use when wind is not blowing • Lots of water is lost through evaporation when it is hot or windy

Using Water Efficiently • Monitor moisture in the root zone • Saturating beyond the root zone can lead to leaching

Using Water Efficiently • Avoid leaky irrigation systems • Apply water uniformly • Do all areas of a field need the same amount? • Do all areas of your lawn need the same amount? • No

Using Water Efficiently • Use irrigation method best suited for your land • Avoid runoff • It can contain fertilizers, pesticides and sediment that can pollute surface and ground water

Understanding Agronomy