16. Mapping and Monitoring of Salt-Affected Soils Using Remote Sensing and Geographical Information System for the Reclamation of Canal Command Area of Jammu, India

Salt-affected soils in the canal commanded area of Jammu (Jammu and Kashmir) have been mapped on scale of 1:250,000 using remote sensing data from IRS LISS III satellite imagery. Ground truthing was made through field survey to characterize salt-affected soils under Ravi-Tawi canal command area. The canal command area is mainly located in the Kathua and Jammu districts in Jammu and Kashmir state, North India, and covering an arable area of 75,000 ha. The land use and landscape variability was assessed through integrating RS imagery and ground truthing. It has been found that an area of 25,670 ha becomes unproductive due to salinization and waterlogging. The soils are very strongly alkaline (pH 9.9), with dominance of exchangeable Na (ESP 25.3) and sodium adsorption ratio (SAR) of 78.41 (mmoles L⁻¹)^0.5. Amongst cations, Na was dominant followed by Ca, Mg and K. The highest ESP was recorded in Tarore soil with ustic and aquic moisture regimes associated with hard surface crust, calcic and natric sub-surface horizons. Gypsum requirement (GR) to amend soil sodicity was measured on representative soil samples and applied at 100% GR basis; this application has increased rice and wheat yields 43.3 and 86.9%, respectively, over control treatment. Soil properties were also improved noticeably, pH was decreased from 9.70 to 8.84, bulk density decreased from 1.52 to 1.48 Mg m⁻³ and infiltration rate was slightly improved.