Soil- site suitability assessment of Bumnoi-mornoi watershed of Kokrajhar district using RS and GIS techniques

Abstract

In the present study, twenty two surface samples from two physiographic units viz., Alluvial plain and Flood Plain of Bumnoi-mornoi watershed in Kokrajhar district of Assam were evaluated for their soil site suitability for growing crops like Ahu rice, Sali rice, Potato, Maize, Banana and Pineapple under rainfed condition. Physiographic units were delineated in the study area using toposheets (1:50,000) and FCC (1:25000 scale) of IRS-P6 L-3. Soil-site suitability evaluation for crops forms an essential part of land use planning programme. Several soil and site characteristics are used as parameters for assessing the suitability of land for crops. Suitability of the soils for these crops was determined by comparing different land qualities and climatic parameters with crop requirement. Based on soil moisture content, drainage, effective soil depth, texture, base saturation, soluble salt content, organic matter and CEC productivity potential were evaluated for each physiographic unit which varies from average to good in both alluvial plain and flood plain. The coefficient of improvement (CI) values indicated that with proper management practices, the productivity of alluvial plain and flood plain soils could be increased to maximum extent of 2.22 to 1.88, respectively. Soils were found to be moderately suitable (S2) to permanently unsuitable (N2) for Sali rice, Ahu rice, Potato, Maize and very suitable (S1) to permanently unsuitable (N2) for Banana. For Pineapple, the soils were found to be very suitable (S1) to moderately suitable (S3). Soil site suitability maps along with potential productivity maps of the study area were prepared using GIS techniques.