21. Sustainable Management of Salt-Affected Soils and Poor-Quality Ground Waters for Enhancing Crop Production

Two major types of salt-affected soils were distinguished in the study area: saline and alkali (sodic) soils. Saline soils have an excess of neutral soluble salts such as chlorides and sulphates of Na⁺, Ca²⁺ and Mg²⁺. Plant growth is adversely affected due to reduced water uptake and ionic imbalance and/or nutrient stresses. Alkali soils, on the other hand, have Na₂SO₄ and NaHCO₃ which upon hydrolysis produce alkalinity leading to high pH and exchangeable sodium, nutrients unavailability and low yields. The reclamation technology involves integrated use of amendments like gypsum for rice-based cropping system, balanced and integrated use of chemical fertilisers and organic/green manures improving soil health and input-use efficiency. In saline soils, leaching with good-quality water and sub-surface drainage is essential. Use of poor-quality ground water constitutes about 30–80% of total ground water. The management practices for optimal crop production with saline and sodic water irrigation must aim at preventing the build-up of salinity/sodicity and toxic ions in the root zone, to levels that limit the productivity of soils, control the salt balances in soil-water system as well as minimise the damaging effects on crop growth. Efficient, balanced and integrated nutrient management strategies are extremely important to increase yields to match the potential yields obtained under good-quality irrigation water. Therefore, we focus on the ionic interactions and nutrient dynamics as influenced by salinity/sodicity of irrigation water and discuss how these issues relate to the nutritional problems and suggest long-term remedial measures to utilise poor-quality waters for improving and sustaining crop productivity of salt-affected soils.