RUNOFF, EROSION, AND POLYMER APPLICATION IN MOVING-SPRINKLER IRRIGATION

Irrigation strategies must be designed to maximize or optimize production while conserving water, minimizing irrigation cost, and avoiding pollution of the environment. Self-propelled moving sprinkler irrigation systems (MSIS) have become increasingly popular in recent years. Runoff and erosion during irrigation with MSIS can be high under some conditions. The objective of this review was to address three aspects related to runoff and erosion with irrigation by MSIS: (i) factors that lead to an increase in runoff and erosion during irrigation, (ii) effect of runoff on crop production, and (iii) evaluation of the beneficial effect of polymer application by reducing runoff and erosion and increasing crop yield. Surface runoff from 3-m2 fallow plots in a slit loam loess and a clay vertisol under irrigation with linear MSIS at an average application rate of 100 mm h-1 was 53% and 39%, respectively. The high runoff levels were caused mainly by seal formation at the soil surface. Prevention of surface runoff movement along the slope in a field increased the available water distribution uniformity in the soil and increased the average pod peanut yield by 882 kg ha-1. Application of 20 kg ha-1 polyacrylamide (PAM) and 40 kg ha-1 polysaccharide (PS) on the soil surface prior to the irrigation season reduced runoff and erosion levels significantly, and increased the cotton and potato yield under irrigation with MSIS. The application of PS in the field was more convenient than PAM application because of the higher dissolution rate in water and lower viscosity of PS.