Soil Friability Its Effect on Soil Aggregate Stability

In many parts of the world the shrink-swell characteristics of fine-grained material is of considerable importance and of potential economic significance. Expansive soils cause significant damage to structures and roadways by cyclically shrinking and swelling within the active zone, which is defined as the depth in a soil to which periodic changes of moisture occurs. The term �soil friability� has been defined as the tendency of a mass of unconfined soil in bulk to crumble and break down under applied stress into smaller fragments, aggregates and individual soil particles. There is a general concern that low soil organic carbon (SOC) contents may deteriorate soil physical properties. This study has been conducted to illustrate the effect of SOC on soils shrinkage limit (Ws) and friability index (FI) upon four of the arid soils namely black cotton, red, marshy and mountainous soils obtained from organic farms of the study area. Wastes like humus, pressmud, bagasseash and flyash were used as a source of SOC to amend with the soils. SOC inputs were made volumetrically up to 70% in the increments of 10% of the soil columns; there was also a control column without any external addition of SOC. The relation between SOC, shrinkage limits and friability index was analyzed by series of experiments carried in triplicate in three different phases based on the mode of application of SOC. Natural soil was amended with humus, bagasseash, flyash, pressmud to the percentage of 0 to 40 for first phase, 0 to 70 for second phase and laying of amended materials on the natural soil for the third phase. Which are test for 0, 7, 14, 21 and 28 days respectively. The friability index (FI) was tested for black cotton soil whose value increases from 0.20% to 6.32% at 40% pressmud amended with a natural soil where by the values increase from 1.59% to 16.81% at 40% pressmud for the red soil and also the values increase from 0.73%to 13.77% at 70% pressmud amended with natural soil.