Effect of straw- bentonite-PAM improved material on saturated hydraulic conductivity of sandy soil

In order to improve the water holding capacity of sandy soil, the improved material that was confected by crop straw, bentonite and polyacrylamide (PAM) was applied. The effect of straw improved material on saturated hydraulic conductivity of sandy soil was studied using the double rings method of constant waterhead infiltration. The tested soil was the sandy yellow soil that is wildly distributed in Chongqing. The results showed that the saturated hydraulic conductivity of sandy soil increased with straw improved materials applying. The saturated hydraulic conductivity of sandy soil increased gradually with the increasing amount of application. The saturated hydraulic conductivity of sandy soil which increased at first and then decreased with the cultivated time reached maximum when the soil cultivated time was 60 d; The improved material of wheat straw (dose of 10 g, PAM content of 2%) worked best whose saturated hydraulic conductivity reached maximum （4.97 times as the control） when the soil cultivated time was 60d. Therefore, the modified straw material is able to improve sandy soil, and this research can provide theoretical basis for applying modified straw materials into sandy soil.