Effect of Polyacrylamide Application on Runoff, Erosion, and Soil Nutrient Loss Under Simulated Rainfall

Abstract

Soil erosion affects soil productivity and environmental quality. A laboratory research experiment under simulated heavy rainfall with tap water was conducted to investigate the effects of anionic polyacrylamide (PAM) application rates (0, 0.5, 1.0, and 2.0 g m −2) and molecular weights (12 and 18 Mg mol −1) on runoff, soil erosion, and soil nutrient loss at a slope of 5°. The results showed the two lower rates of PAM application decreased runoff while the highest rate increased runoff as compared with the control. Sediment concentration and soil mass loss increased significantly with the increasing PAM application rate. Compared with the control, PAM application decreased K +, NH + 4, and NO − 3 concentrations in sediment and K + and NH + 4 concentrations in runoff, but significantly increased the mass losses of K +, NH + 4, and NO − 3 over soil surface except for the NH + 4 at PAM application rate lower than 1.0 g m −2. PAM application decreased the proportion of K + loss with runoff to its total mass loss over soil surface from 60.1% to 16.4%. However, it did not affect the NH + 4 and NO − 3 losses with runoff, and more than 86% of them were lost with runoff. A higher PAM molecular weight resulted in less soil erosion and K + mass loss but had little effect on runoff and NH + 4 and NO − 3 losses. PAM application did not prevent soil erosion and the mass losses of K + and NO − 3 under experimental conditions.