Leaching Studies in Salt-Affected Black Soils of Upper Krishna Command, Karnataka

Leaching was more efficient and faster during January-February months compared to July-August months because of low salt concentration in the surface layers and wet profile. However, July-August months were beller for leaching because, water table was deeper, prevention of resalinization and continuation of leaching by monsoon rains occurred in following months, and there was beller establishment of seedling of kharif or bi-seasonal crops sown in following months. Amount of water required to leach 80 per cent salts varied between 4 and 4.66 cm. The higher water requirement might be due to absorption of water by soils and higher initial salt content. Water required for continuous impounding varied from 10 to 80 cm depending on season, water table depth and initial salt content, to leach salts in highly saline black soil (8.1–17.5 dS m⁻¹) beyond the zone of root activity (30–45 cm). To reduce salt content in surface 0–15 cm to 50 per cent or more, 2 cm of water was required for unit depth of soil. Leaching efficiency was higher under deep water table conditions compared to shallow and medium water table conditions at the zone of higher root activity (15–45 cm depth). Empirical equations to know leaching requirement of the soils were developed by power regression analysis.