Influence of Agricultural Wastes and Incubation Period on Aggregate Stability in Sandy Soil

Abstract

A laboratory experiment was conducted to examine the influence of various organic materials on soil aggregate stability of sandy soil collected from Al-Bustan region, Egypt. The study involved five treatments: control, incorporating 1% of wheat straw, 1% clover straw, 1% mixture of wheat & clover, and 1% chicken manure into sandy soil on the basis of air dry weight. Soil samples were incubated at field capacity for 7, 14, 28, 42 and 56 days at 30 Co±1. Water-stable aggregate size distribution (1.19-2, 0.5-1.19, 0·25–0.5 mm) was determined through wet sieving. The organic wastes treatments improved soil aggregate stability compared with control treatment. The changes in aggregate stability indices (mean weight diameter (MWD), Structure coefficient (Cr), detachability index (DI), percentage of aggregate destruction (PAD) and Wet aggregate stability (WAS) were determined and calculated weekly over the periods of incubation. The application of organic wastes significantly increased all aggregate stability indices compared to the control treatment except PAD. Soil aggregate indices had significant positive correlations between each other. MWD, Cr, WAS and DI values were the highest in chicken manure treatment, while the PAD values were the lowest. Disaggregation occurred in all treatments after 28 days of incubation. Polynomial function brought higher correlations between MWD, Cr, DI and PAD vs. the incubation period of sandy soil amended with organic wastes. The Cr, DI and PAD vs. MWD produced linear relationship with high correlations.