Organic resource management: Impacts on soil aggregate stability and other soil physico-chemical properties

Effects of different types and amounts of organic matters (OM) on the soil aggregate stability indices as well as some soil properties were investigated. This study was conducted in the form of a split-plot experimental design with OM sources (sheep manure, cow manure, rice husk, finely chopped reeds, wheat straw, licorice (root) dregs) as main plot factors, and OM application rates (5, 15. and 25 ton ha(-1)) as sub-plot factors. Mean weight diameter (MWD), geometric mean diameter (GMD), and water stable aggregate (WSA) were measured using both wet and dry sieving methods. The soil aggregate percents (SAP) > 0.84 mm and soil fragment percents (SFP) < 0.42 mm, water stable aggregate (WSA) > 0.5, WSA > 0.25 mm, soil bulk density (BD), and soil water infiltration were also measured in this study. Results showed that application of OM sources had positive effects on the soil MWD and GMD. The GMD and SAP > 0.84 mm increased following application of sheep and cow manure. The SAP > 0.84 mm, MWD, and GMD showed increasing trend from the beginning of the sowing stage to the end of the growing season. However, the SFP < 0.42 mm decreased for the same period. Applying all rates of OM increased the soil aggregate stability compared to the control treatment. The maximum values of MWD, GMD, WSA > 0.5, and WSA > 0.25 were obtained from 25 ton ha(-1) OM application. In those plots that received cow manure, wheat straw, sheep manure, and rice husk, the WSA > 0.5 mm were higher than that of the control treatment. Application of OM increased CC, P. K, Mn, and Fe in the soil, while pH decreased with OM application. Applying different sources of OM decreased soil bulk density (BD) and increased infiltration rate. (c) 2011 Elsevier B.V. All rights reserved.