Improving physical quality of a clay loam soil selected from semiarid region using polyacrylamide

A greenhouse experiment was conducted to evaluate the effects of anionic polyacrylamide (PAM) on some physical quality indices and also their time variability in a clay loam soil selected from semiarid region. These indices were mean weight diameter (MWD) of aggregates, dispersion clay (DC), saturated hydraulic conductivity (Ks), and total porosity (n). The rates of PAM including 0 (control), 0.125, and 0.25 g kg-1 of air dry soil were mixed with the soil and uniformly packed in to plastic pans, and incubated in a greenhouse at 0.7-0.8 field capacity moisture content (0.123-0.14 g g-1) and temperature of 22 ± 4 ºC for 6 months . MWD, DC, Ks, and n were measured for the soil taken from the 10-15 cm layer of pans at 30, 90, and 180 days. The results showed that although beneficial effects of PAM on soil physical quality reduced with time, however, both low and high used rates of PAM significantly increased means of MWD by 83 and 127 % and n by 8.75 and 7.75 %, respectively compared with the control even 6 months after the start of experiment. Also, both low and high used rates of PAM significantly decreased mean of DC by 31 and 43 % and increased mean of Ks by 11.5 and 14.5 %, respectively relative to the control. By considering the application cost of PAM, 0.125 g PAM kg-1 of air dry soil is suitable application rate for improving physical quality of fine-textured soils in the semiarid regions.

Keywords:

fine-textured soil , incubation time , polyacrylamide , physical quality parameters