ENHANCED STRUCTURAL STABILITY OF A STRAW AMENDED SOIL IN THE PRESENCE OF GYPSUM

Changes in soil physical properties and structural stability of a sandy soil as a result of straw retention in the presence of gypsum (at a rate of 2.5 t/ha) were investigated in a field pot experiment. After six months of equilibration, significant improvements in soil structure in terms of lower bulk density, lower penetration resistance, and increased water stability were detected in the surface 0.25 mm layer when compared to the straw only treatment. While the increase in stability when straw was applied alone can be explained in terms of reduction in wetting rate, further increase in stability detected due to the gypsum was probably due to formation of additional calcium (Ca) bondings with the clay surfaces and organics.