Effectiveness of wheat straw mulch and Polyacrylamide on shallow stability of roadside slopes

Abstract

Soil aggregate instability on unprotected roadside slopes can cause landslide, soil erosion and sedimentation. Different biological and chemical soil stabilizers are used to reinforce the instable slopes. In the present study, straw mulch and Polyacrylamide (PAM) combinations were investigated on a clay soil of road cutslope in campus of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The selected cover treatments were Polyacrylamide (2, 3 and 4 g·m–2) with wheat straw mulch (50, 150 and 250 g·m–2) which was spread by hand to attain 75% groundcover on a 1:1 slope. After the three months, soil sampling was done to determine the changes in aggregate stability of soil. Results showed that the most efficient treatment with respect to mean weight diameter of soil aggregates in dry and wet sieving (MWDdry and MWDwet), aggregate stability index (AS) and aggregate destruction index (DI) was treatment of B (150 g·m–2 wheat straw mulch and 3 g·m–2 Polyacrylamide tackifier) with 34%, 68% and 47% increment in MWDdry, MWDwet and AS, respectively as well as 37% reduction in DI as compared to the bare soil control.<br /><br />