Effects of tillage intensity and crop diversification on soil bulk density and organic carbon in a vertisol of central India

Vertisols in Central India face issues such as waterlogging, soil erosion, poor drainage, and cracking during dry periods, which hinder crop growth and soil fertility. The study evaluates the long-term effect of conservation agriculture practices on soil bulk density and organic carbon (SOC) stratification in a Vertisol of central India, located at the Research Farm of ICAR-Indian Institute of Soil Science, Bhopal. The experiment used a split-plot design featuring three tillage systems (reduced tillage [RT], no-tillage [NT] with crop residue retention, and conventional tillage [CT]), and four cropping systems: soybean + pigeon pea (2:1), soybean-wheat, maize + pigeon pea (1:1), and maize-chickpea. After ten crop cycles, soil samples were collected from three layers (0-10, 10-20, 20-30 cm), and analyzed. Results indicated that residue retention significantly increased SOC storage, with NT and RT enhancing SOC by 21% and 13%, respectively, compared to CT at the 0-10 cm layer. The NT-based soybean-wheat cropping system exhibited the highest SOC (10.3 g kg^-1) at 0-10 cm, while RT-based maize + pigeon pea achieved the highest SOC at 10-20 cm. SOC stratification ratios also indicated improved SOC distribution under NT and RT, highlighting the benefits of CA practices in enhancing soil C sequestration, contributing to sustainable agriculture in Vertisols of Central India.