Marginal-Quality Water Use as an Ameliorant for Tile-Drained Saline-Sodic Soils in a Rice-Wheat Production System
Appropriate use of marginal-quality waters coupled with crop rotation(s) and management interventions on saline-sodic soils have the potential to transform such water and soil resources from environmental burdens into economic assets. Several long-term field studies in the Indus basin of Pakistan were carried out to evaluate different irrigation and soil management options of using saline-sodic waters on saline-sodic soils for reclamation in a rice-wheat production system. The effect of different amendments like gypsum (gypsum requirement on water RSC basis and on soil SAR basis) and farm manure along with conjunctive use of fresh and saline-sodic waters for irrigating rice and wheat crops was evaluated. The effects of applied amendments were evaluated in terms of change in the physical and chemical properties of soils, yield-based crop growth response and economic implications. The results showed significant improvement in physical and chemical properties of soils with good yields of crops with the application of amendments specially gypsum and farm manure along with conjunctive use of fresh and saline-sodic waters. Salt removal (kg ha−1) was the highest with the application of two pore volume (PV) water. In general, it was concluded that after the application of four irrigations of different PV, highest leaching fraction removed maximum salts from loamy sand soil. Salt removal remained the highest with first two irrigations and then decreased subsequently. Overall, the greatest net benefit was obtained from gypsum plus cyclic use of saline-sodic and fresh waters. It was found that the farmers’ management skills were crucial in the overall success to improve crop yields during reclamation of saline-sodic soils. Based on the results, we propose that saline-sodic water could be used to reclaim saline-sodic soils by using a rice-wheat rotation and a site-specific combination of soil amendments and water application strategies.