Green and Ampt infiltration parameters under no-till center pivots

Infiltration is an important process that affects the efficiency of center-pivot irrigation systems. No-till planting systems potentially influence the hydraulic properties of soils and, consequently infiltration. The result of long-term no-till use could be higher infiltration, lower irrigation runoff, and may allow for lower-pressure nozzle packages, thus reducing energy requirements for irrigation. This potential was investigated at two locations in eastern and south central Nebraska. Paired treatments were used at each location, one that has been no-till planted for over seven years and one that uses two to three operations per year for seed-bed preparation and cultivation. The Green and Ampt equation was used to develop infiltration functions that are applicable to the analysis of infiltration under center pivots. Saturated hydraulic conductivities were higher in no-till fields (6.2-8.21 cm/h) compared to tilled (2.8-3.9 cm/h). Green and Ampt curves illustrated zero percent runoff with a depth applied in three of the fields. In one tilled field, 11% runoff was calculated. Greater runoff is expected under center pivots on tilled fields.