Combined effect of reduced dose of gypsum and salt tolerant varieties of rice (Oryza sativa) and wheat (Triticum aestivum) on rice-wheat cropping system in sodic soils

A field experiment was conducted at Lucknow in Uttar Pradesh during 2001-2002 to 2003-04 on a fine loamy, mixed, hyperthermic, sodic soil having high pH, low electrical conductivity, high exchangeable sodium percentage and very low water permeability to find out the combined effect of reduced dose of gypsum and salt tolerant variet- ies of rice ( Oryza sativa L.) and wheat ( Tr iticum aestivum L. emend. Fiori & Paol.) on productivity of rice - wheat cropping system in sodic soil. This study revealed that application of gypsum @ 25% gypsum requirement (G.R.) and growing of salt tolerant varieties of rice CSR 13 and wheat KRL 19 significantly increased the yield attributes and yields of these crops in the system over control treatment as well as 15% G.R. So much so it was at par with 50% G.R. with non- salt tolerant varieties. The magnitude of combined effect of reduced dose of gypsum and salt tolerant varieties was reflected as 17 and 8.2% increase in grain yield over their counterpart varieties. Interaction between gypsum levels and salt-tolerant varieties on grain yields indicated that gypsum @ 25% G.R. with sodicity tolerant varieties in rice-wheat cropping system could save about 43% of the total initial expenditure for the recla- mation of sodic soils over the recommended dose of gypsum (50% G.R.) with non-sodicity tolerant traditional high yielding varieties. Thus, for low-cost effective technology, treating the sodic soils with reduced dose of gypsum (25% G.R.) and growing salt tolerant varieties of rice 'CSR 13' and wheat 'KRL 19' proved highly economical and sustainable technology for resource scarce situations.