Effects of Biochar and Compost on Soil Physical Quality Indices

Biochar and compost are important organic amendment materials for modifying the distribution of pore size in soils. The main idea of this study was to investigate the impact of date palm biochar, compost and their combination on soil water parameters, pore size distribution curves and soil aggregates stability at the rates of 1%, 2%, 3% and 4% (10, 20, 30 and 40 g kg(-1)). In this study, shape (standard deviation (SD), kurtosis and skewness) and location (dmode, dmedian and dmean) parameters, water stable aggregates (WSAs), mean weight diameter (MWD), geometric mean diameter (GMD) and erodibility factor (Kerodibility) were measured and evaluated. Results showed that the indicators of pore size distribution functions for untreated soil (control) were 31.6, 25.8, 23.5, 3.3, -0.16 and 1.14 for dmode, dmedian, dmean, SD, skewness and kurtosis, respectively. While, WSA>0.25 (macro aggregates), MWD, GMD and Kerodibility were 15.94, 0.19, 0.39 and 0.0895, respectively. Here, dmode, dmedian, dmean, SD, skewness and kurtosis were changed due to application rates of biochar, compost and the mixture of biochar-compost, significantly. The application rate of 4% of the biochar-compost mixture had the highest effects, and dmode, dmedian, dmean, SD, skewness and kurtosis were 18.9, 13.3, 11.3, 4.9, -0.21 and 1.15, respectively. Mixing biochar, compost and biochar-compost mixture reduced equivalent pore diameters, dmode, dmedian, dmean, and increased the indicators of WSA>0.25, MWD, GMD and kerodibility. The factors of WSA, MWD, GMD and kerodibility were enhanced. Thus, the application of biochar, compost and biocharcompost mixture could improve water retention and water use efficiency (WUE) of sandy soils.