Runoff and erosion as affected by tillage system and polyacrylamide in two sandy loam soils differing in silt and clay contents in semi-arid regions

This study aims to investigate the effect of three tillage practices and the effect of polyacrylamide application rate on surface runoff and erosion of sandy loam soils differing in silt and clay contents. Field experiments in split-split plot with four replications were carried out in two different locations; location A that consists of 25.2% silt plus clay and location B which consists of 38.5% silt plus clay. Three tillage practices were investigated; no-tillage (NT), mouldboard ploughing with rotor tiller (CT1), and chisel ploughing with disk harrow (CT2). Three polyacrylamide (PAM) rates were implemented in each tillage system; 0, 10 and 20 kg ha-1. The experiment was conducted during December 2015 to April 2017 and wheat was sown for the two seasons. Results showed that the CT1 and CT2 treatments reduced runoff by 15.3% and 50.0%, respectively in location A and by 6.4% and 13.8%, respectively, in location B compared to the NT treatment. Applying 10 and 20 kg ha-1 of PAM decreased runoff by 9.5% and 22%, respectively in location A and by 4.5% and 12%, respectively in location B compared to the 0 kg ha-1 PAM treatment. Applying 10 and 20 kg ha-1 PAM reduced soil erosion by 19% and 28%, respectively, in location A and by 26% and 33%, respectively in location B compared to the 0 kg ha-1 PAM application rate. Comparing the effect of tillage practices in location (A), the CT1 increased soil erosion by 16.5 % and 46.5% compared with the NT and CT2 treatments, respectively. Comparing the effect of tillage practices in location (B), the CT1 increased soil erosion by 38.6% and 75.6% compared to the NT and CT2, respectively.