MWD of the Aggregates in a Saline-sodic Soil as Affected by Mineral Compounds and Organic Matter Application in Laboratory Conditions

Soil structure and aggregate stability affect soil erodibility and increasing aggregate stability against erosive factors such as wind and water is a necessity. This study was conducted on surface soil samples (0-20cm) collected from agricultural lands susceptible to erosion located in Chahoo Plain, southeast of Fars Province. The experimental design was CRD with 3 replicates and10 treatments as follows: control (without addition of soil amendments), pure gypsum (1% w/w), chopped wheat straw (1% w/w), animal manure (1% w/w), wheat straw + gypsum, animal manure + gypsum, cement (0.3% w/w), cement (0.6% w/w), cement (0.9% w/w) and gypsum (1% w/w) + cement (0.9% w/w). After one, four, seven and ten months, the amounts of soil aggregates in 53-4000 µm sizes were determined by wet sieving and MWD were calculated. Application of wheat straw and wheat straw with gypsum increased MWD compared to the control and other treatments. These increases were significant at p<0.05. The mentioned treatments increased the MWD as much as 2.8 and 2.9 times compared to control, respectively. Generally, for increasing the stability of the soils similar to the soil understudy, application of wheat straw alone or wheat straw with gypsum seems recommendable.