Abstract

                                To study the stability indices of permanent manurial experiments under irrigated and dryland agriculture of Tamil Nadu Agricultural University farm at Coimbatore, the post harvest soil amples at three depths were collected after the harvest of cotton and cowpea at OPM and NPM respectively. Analysis of soil from both the experiments showed the improvement in the aggregate stability in the 30-45 cm depth of OPM, 15-30 cm layer and 30-45 cm layer of eastern and western series of NPM due to higher clay content in these layers and organic matter content of the soil. As the clay and organic matter are the prerequisites for the structure formation and stability of structure hence it was reflected in terms of per cent aggregate stability. Similar effects were seen for mean weight diameter and distribution of water stable aggregates.

Key words : Permanent manurial plots, Aggregate Stability, Organic matter