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Wisconsin farmers reported irrigating about 400,000 acres of land on 2000 farms for a variety of crops with vegetables, potatoes, sweet corn and grain/seed corn being the largest segment covering 81% or 334,000 of the irrigated acres. Sprinkler type irrigation accounted for 91% of the irrigation systems used, of which center pivot systems make up 87% of the sprinkler systems. Traveling gun makes up 6% and solid set makes up 5% of the remaining segment. Irrigators reported that 43% of the systems were operated at high pressures, 42% were medium pressure systems and 15% were low pressure systems as reports in acres irrigated. Irrigation pumps were powered by electric motors on 62.5% of the pumps, diesels engines on 34.5%, Gasoline engines on 2% and 1% were powered by LP gas engines. Reducing center pivot system pressure from high pressure to medium or to low pressure can save approximately 15 to 20% and 30% respectively. With new sprinkler technology, most of the high pressure systems can be changed to medium pressure systems and a few to low pressure systems.
There is testing, uniformity and pump/well testing, that should be done to an irrigation system every 2 to 3 years to uncover maintenance issues that can save energy and improve the utilization of water.
Irrigation scheduling is another management tool to aid in identifying when irrigation is needed.
Uniformity testing is a troubleshooting procedure to check that the water distributed by the irrigation system is being applied uniformly to the field within practical limitations. The test procedure only measures the amount of water applied to the soil surface and is not intended to indicate the amount of water that infiltrated the soil into the root zone. Evaporation, runoff and leaching could all affect the amount of water available to plants in the root zone. A low coefficient of uniformity could lead to plant stress and disease issues because of a water deficit or too much water in different sections of the field despite the average application rate being acceptable. The goal for the coefficient of uniformity is greater than 90%. This test is low cost insurance to determine if the nozzles and sprinklers are applying water evenly. The test will take 1 or 2 people about 4 hours to complete depending on the size of the field. It is recommend that a uniformity test be performed every 3 to 5 years depending on usage and water quality. The University of Wisconsin has a test kit that can be borrowed by Wisconsin growers that contains all the equipment normally needed to check a quarter section straight center pivot system. The kit is located at the Hancock Agricultural Research Station and can be reserved by contacting Jeff at 715-249-5961. Transportation of the kit is the responsibility of the grower. It weighs approximately 500 pounds and is housed in a pallet box that measures 48" x 40" x 46" in height.
Pump testing is another important testing procedure. It is typically done in an open discharge method were the pump is disconnected from the irrigation system and a flow meter, pressure indicator and valve is installed on the pump output. The pump is started and the valve closed partially until the design system pressure is reached. The system is allowed to run for a period of time, generally 15 minutes, and then the valve is opened and closed to obtain enough points to draw a pressure / flow curve. The static water level should be recorded as well as the water level at each flow point. The net positive suction pressure of the pump should be determined to ensure that the pump is deep enough in the well to prevent cavitation from a lack of water. Irrigation contactors or well drillers generally provide this type of testing service at a cost of $150 to $300 per test. It is recommended that pumps and wells be tested every 2 years.
Kansas State University:
USDA Irrigation Handbook - http://www.wsi.nrcs.usda.gov/products/W2Q/water_mgt/Irrigation/irrig-handbooks.html
Irrigation Association - http://www.irrigation.org/default2.asp
Irrigation Contractors in Wisconsin
Irrigation Equipment Suppliers
Center Pivot Systems
Sprinklers and volume guns
Soil Moisture Sensors
Drip Irrigation Equipment Suppliers:
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|This project is funded in part by the Wisconsin Focus on Energy Initiative. For more information, visit http://www.focusonenergy.com or call 1-800-762-7077.|