Abstract
In this study we assessed the effectiveness of artificial zeolite and hydrated lime, as amendments, to reduce surface runoff (SR) and sediment generation from acid soil taken from Yamaguchi prefecture in Japan. Air-dried soil aggregates (≤2 mm) were amended with 10 % and 15 % zeolite and 0.5 % and 5 % lime. The amended and unamended aggregates were packed to an average dry-bulk density of 1.30 Mg m-3 in small soil plots and subjected to simulated rain intensities of 30 and 60 mm h-1. Time incremented SR samples were collected for sediment concentration (SC) determination. The data indicated that both SR and SC were characterized by three phases. The amendments' impact was most significant during the first two phases. During these two phases both SR and SC were decreased by amendments and the reduction increased with the rates of incorporation. The largest reductions in SR and SC were found for zeolite at 15 % and the lowest for lime at 0.5 %. The amendment incorporation led to increases in wet aggregate stability, soil water retention, infiltration, and sub-soil water transport, and to decreases in dispersible clay. We suggest that SR and SC in acid soils can be substantially reduced by zeolite or lime, and this is attributed to amendment induced increase in wet aggregate stability and decrease in clay dispersion, and in this regard zeolite is more effective than lime.
