46-16 Impact of Long Term Management Practices on Soil Chemical Properties Under Cotton Based Organic and Conventional Farming Systems.
See more from this Division: ASA Section: Agronomic Production Systems
See more from this Session: Agronomic Production Section, General II Oral
Abstract:
However, the process of changes in soil chemistry and how it affects the soil fertility during transition from conventional to organic farming is not well explained in tropical environments. A long-term farming systems comparison trial consisting of a two year crop rotation with Cotton-Soybean-Wheat was set up in 2007 on Vertisols of Madhya Pradesh, Central India. Replicated field plots under continuous organic (Organic and bio-dynamic) and conventional (with and without Bt-cotton) management provides a unique opportunity to examine the process of changes in soil chemical properties over time. The results show a significant increase of soil organic carbon (SOC) in top-soil under bio-dynamic management compared to conventional and Bt-conventional system (0.69 v. 0.59 and 0.57). Over a period of seven years, SOC in the top-soil increased by 0.25 ± 0.02 percent points and 0.21 ± 0.03 percent points under bio-dynamic and organic systems management compared to 0.11 ± 0.02 percent points and 0.16 ± 0.02 percent points under conventional and Bt-conventional systems, respectively. However, SOC in sub-soil did not differ among the systems. Organic management slightly increased alkalinity of soil (8.54 to 8.56) whereas Bt-conventional management reduced the alkalinity of soil (8.52 to 8.39). Organic systems had more total N in top-soil compared to conventional systems, while all systems depleted N in subsoil. A vertical stratification was also measured for P: All systems reflected the addition of P in top-soil and depletion in sub-soil. Fe (EDTA) content of soil increased under all systems with significantly higher additions in top-soil than sub-soil. In all systems, the macronutrients K and Mg, and the micronutrients Zn, Cu and Mn showed an increase in top-soil and depletion in sub-soil. It is evident that fertility of top-soil can be improved with organic managements, however none of the tested systems is replenishing the nutrient pool of sub-soil.
See more from this Division: ASA Section: Agronomic Production Systems
See more from this Session: Agronomic Production Section, General II Oral