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IRRIGATION WATER CONVEYANCE AND REQUIREMENTS
WHAT HAPPENS AFTER DIVERSION? ? ? ? ? ? ? ?
PIPE FLOW BY GRAVITY OR PUMPS
Apply water to meet the crop needs HAY PRODUCTION
MODIFIED ROOT DEVELOPMENT 50% 33% 17% 0
EFFECTIVE ROOT ZONE HIGH WATER TABLE LIMITS ROOT DEVELOPMENT
WE OFTEN USE THE METHOD THAT SEEMS MOST FAMILIAR EVEN WHEN THERE ARE BETTER WAYS TO DO IT. ONE SIZE DOES NOT FIT ALL!!!
APPLICATION METHODS MANAGEMENT IS THE ESSENTIAL REQUIREMENT
TOO MUCH WATER MAY CAUSE Inflow Source Detachment Infiltrating furrow stream Runoff and sediment loss Transport Deposition Tail Ditch NWISRL Kimberly, ID
TOO MUCH WATER IN ANY SYSTEM Poor Design, Soil & Landscape Variability, Application Rate, etc. Can Create Problems NWISRL Kimberly, ID
MAY LEAD TO OTHER PROBLEMS OVER IRRIGATION AND EROSION
Sprinkler Efficiency Overview • NRCS NATIONAL IRRIGATION GUIDE (Table 6-4) • Periodic move lateral 60-75% • Traveling sprinkler (big guns) 55-65% • Center pivot - standard 75-85% • Linear (lateral) move 80-87% • LEPA Center pivot or linear 90-95
GROSS Vs NET REQUIREMENTS The Gross application is that amount applied over the whole area to get the Net amount in to the soil where it can be used by the plant. • To obtain a 1inch NET application with a 50% efficient system one must apply 2 inches. • A 75% efficient system would need to apply a 11/3 inch Gross to get the same 1 inch NET.
EFFECT OF LIGHT APPLICATIONS SHALLOW APPLICATIONS DATA BREAK LOWER SOILS NOT IRRIGATED
SUMMARY • Conveyance losses (control limits, evaporation, leakage, etc.) reduce the amount of H2O taken from a source that is available for application to the field. • Application losses come in many forms: • Weather – Wind, heat, humidity, evaporation, etc. • Soils – Intake limits, water holding capacity effects • System – Uniformity, leaks, maintenance effects • Management – Flow controls, Time limitations, & lack of Measurements of Flow rate and Soil Moisture • The remaining water getting to the root zone is what is available to the plant for growth.