Treatments and economic aspects of growing rice and wheat crops during reclamation of tile drained saline-sodic soils using brackish waters.

摘要

We carried out three field experiments on salt-affected soils having tile drainage in place, which differed in ambient levels of electrical conductivity and sodium adsorption ratio. The 3-year cropping sequence consisted of a rice-wheat rotation. These crops were irrigated with waters having different levels of salinity (EC 2.7-4.5 dS m-1), and sodicity (SAR 8.0-28.8 and residual sodium carbonate 1.3-14.9 mmol_c L-1). The treatments on all the sites were the same and consisted of: (1) Irrigation with saline/sodic water without amendment (control); (2) Sesbania green manure each year (SGM_E); (3) Soil-applied gypsum equivalent to gypsum requirement of water (GWR), and (4) Soil-applied gypsum as in treatment 3 plus sesbania green manure each year (G+SGM_E). We found a decreasing trend in soil salinity and sodicity and favourable levels of infiltration rate and bulk density over pre-experiment levels. In terms of overall treatment effectiveness in causing a decrease in soil salinity and sodicity, G+SGM_E caused the greatest decrease. Based on our multi-location and long-term study, we propose a combination of gypsum and sesbania green manuring each year. This is an important resource conservation intervention that helps to mitigate the ill effects of salts and improves crop yields on salt-affected soils where low-quality water is used for irrigation.