ABSTRACT
532Purna valley is an elongated basin in Vidarbha region of Maharashtra having very deep heavy swell shrink soils. The major problems of these soils are native salinity/sodicity, poor hydraulic conductivity, compact, dense subsoil and incomplete leaching of salts from soil due to severe drainage impairments. Field experiments on cotton (2011) followed by green gram in kharif and chickpea in rabi season (2012) were conducted on farmers fields in this valley. The pH of experimental sites varied from 8.27–8.34, electrical conductivity (EC) between 0.20–0.25 dS m−1, organic C content
between 5.23–5.71 g kg−1, CaCO3 content between 9.67–10.60%, the cation exchange capacity between 52.17–53.47 cmol(p+) kg−1) and Exchangeable Sodium Percentage (ESP) between 10.39–11.29. The treatments comprised of five different green manures (sunhemp, dhaincha, cowpea, green gram and leucaena loppings), two crop residues (cotton stalk and farm waste as biomulch), gypsum and control. There were nine treatments replicated on three farmers’ fields on Vertisols treating each farmer as one replication in randomized block design. The significant improvement in chemical properties of soils was observed under gypsum indicating reduction in pH from the 8.31 to 8.19 and ESP from average initial of 11.15 to 8.11, but simultaneously significant reduction was also observed under organic amendments like dhaincha and sunhemp in terms of reduction in pH upto 8.25 and ESP up to 8.82. Among the crop residues and green manures dhaincha in situ green manuring showed the highest significant decrease in exchangeable Na followed by sunhemp and cowpea. The crop residues and green manures although slow in reclamation were found effective in improving chemical properties of sodic soils gradually in addition to addition of significant amount of biomass resulting into more carbon sequestration.
