management of saline-sodic water in cotton-wheat cropping system

a long-term field experiment was conducted for 7 years to evaluate the effect of different amendments to mitigate the adverse effect of saline-sodic water in a calcareous soil under cotton-wheat cropping system. the pooled results over 7 years revealed that the application of saline-sodic water decreased the mean cotton-seed yield by 20.7% as compared to good quality canal water. however, wheat-grain yield was not adversely affected by quality of irrigation water.  among the different amendments, gypsum and farmyard manure were more effective in mitigating the adverse effect of saline-sodic irrigation water. cotton-seed yield reduction was 9.8% with the addition of farmyard manure and remained only 8.8% with the addition of gypsum as compared to good quality water. however, when saline-sodic water was used alternately with good quality canal water, the recorded cotton-seed yield reduction was only 6.1%.  these results suggest that in calcareous soils, farmyard manure is useful in ameliorating long-term deleterious effects of saline sodic irrigation water and sustaining the productivity of cotton-wheat system.