Long-term Conservation Tillage Effect on Soil Organic Carbon and Available Phosphorous Content in Vertisols of Central India

Abstract

Efficient nutrient management in conservation tillage is one of the major concerns in vertisols as residue retention on soil surface and reduction in tillage operation can have a major impact on nutrient dynamics and stratification. The present study examined profile distribution of soil organic carbon (SOC) and available phosphorous under long-term (12 years) imposition of four different tillage systems, namely conventional tillage (CT), mouldboard tillage (MB), reduced tillage (RT), no tillage (NT) and three nitrogen levels, viz. N50%, N100% and N150%. In 0- to 5-cm soil layer, highest and lowest SOC was observed in NT (8.8 g kg−1) and CT (5.9 g kg−1), whereas in 5- to 15-cm soil layer, higher SOC was observed in MB. The stratification ratio of SOC was higher in NT (2.20) followed by RT (1.93), MB (1.68) and CT (1.51). Higher available phosphorous concentration (12.8 g kg−1) was recorded in NT with N50% followed by NT with N100%. Over the year, no significant effect of tillage on soybean and wheat yield was observed. However, effect of N level on yield was significant. Overall, conservation tillage practice imposed no penalty on yield of soybean–wheat system, while it saved energy and time by reducing the number of tillage operations.