Impact of biochar and compost on aggregate stability in loamy sand soil

Abstract

Biochar and compost are important organic amendments which act as cementing agents and increase the aggregate stability in the sandy soils. The main idea of this study was to investigate the impact of date palm waste biochar, compost and their mixture on soil aggregate stability at the rate of 1, 2, 3 and 4%. The objectives were to evaluate the changes in indicators of aggregates stability to water due to biochar, compost, and biochar-compost addition and to study the impact of biochar and compost on sandy soil erodibility. Water stable aggregates (WSA), macroaggregates (WSA>0.25), mean weight diameter (MWD), geometric mean diameter (GMD) and erodibility factor (Kerodibility) were measured and evaluated. The results showed that the indicators of WSA, WSA>0.25, MWD, GMD and Kerodibility were 76.35, 15.94%, 0.19, 0.39 mm and 0.09 for control (unamended soil), respectively. The WSA, WSA>0.25, MWD, GMD and Kerodibility were enhanced with different rates of biochar and compost. However, biochar exhibited a significant improvement in aggregate stability and their effect was slightly better than compost. Accordingly, biochar increased WSA (24.6-31%), WSA>0.25 (69.9-164.2%), MWD (57.5-121.6%), GMD (24-44.2%), and decreased Kerodibility (18.8-31.1%). Compost increased WSA (7.8-45.3%), WSA>0.25 (11.1-45.3%), MWD (9.7-36.5%), GMD (5.1-17.5%) and deceased Kerodibility (4.7-14.5%) compared with unamended soil. Therefore, the amendment materials reduced the soil erosion and led to increased aggregation stability against erodibility. The results of this study can be helpful in predicting the behavior of biochar and compost amendments towards aggregate stability in loamy sand soils.