Vertical distribution of soil total carbon and nitrogen stocks and other properties in profiles as influenced by organic and conventional farming systems under southern dry zone of Karnataka, India

A field study was conducted to determine the vertical distribution of carbon, nitrogen and other soil properties in four representative soil profiles, one each from < 3 years, 3 -6 years and > 6 years of organic farming practice and one profile representing conventional farming system under southern dry zone of Karnataka, India during 2008–09. The results revealed that, the vertical distribution of nutrients and biochemical properties in soil profiles sourced from both systems recorded decreasing trend with depth. The enzyme activities (dehydrogenase and phosphatases) were consistently higher in the surface layer (Ap horizon) in all the four representative profiles studied and the activity of dehydrogenase and phosphatases of soil increased significantly in the fields subjected to organic farming for three specified time periods irrespective of cropping systems evaluated over conventional farming, with maximum activity being in the profile where organic farming has been practiced for over six years. Soil chemical and biochemical attributes varied widely and decreased with increasing depth in all the profiles irrespective of farming practice. Over 6 years of organic farming practice recorded significantly higher levels of both Total-C (233.8 Mg ha⁻¹) and Total –N stocks (16.5 Mg ha⁻¹) and least were recorded in the profile under conventional farming system.