Salt Leaching with Monsoons and Yield of Indian Mustard as Affected by Saline Irrigation Waters of Varying Cl:SO₄ Ratios

The effects of salt leaching in soil irrigated with saline waters (ECw.16 dS m⁻¹) of varying Cl:SO₄ ratios (3:1. 1:1. 1:3) during rabi, and mulching (black polyethylene), cropping (sorghum) or bare fallowing during monsoons were evaluated on the following Indian mustard crop for two years (1989–91). Calculated amounts of rain water required to leach out 80 per cent of salts were 0.60, 0.89 and 0.92 cm per cm soil depth for soils irrigated with saline water having Cl:SO₄ ratio of 3:1, 1:1 and 1:3, respectively. Keeping the soil mulched did not show much benefit for salt leaching but the improvements in residual soil water storage caused marked enhancements in mustardyields, i.e. of the order of 8.0q ha⁻¹ overbare fallow (14.7 q ha⁻¹). On the contrary, growing of sorghum during kharif reduced yield by 2.2 q ha⁻¹. Mustard yields remained unaffected by different CI:SO₄ ratios in saline waters. 20 to 26 per cent of the added salts with high sulphate waters were calculated to be getting precipitated.