GIS-Based Land Utilization and Suitability Analysis for Optimal Crop Selection in Ratnapura District of Sri Lanka: Case Study for Tea, Paddy and Rubber

Abstract

Land suitability evaluation for agricultural crop cultivation is crucial to maximum agricultural productivity with sustainability of the environment. Land suitability evaluation for tea, paddy and rubber plantations in the Ratnapura District in Sri Lanka is conducted in this research using remote sensing and GIS technologies. Significant environmental conditions like slope, aspect, elevation, rainfall, minimum and maximum temperature, soil type and pH were analyzed and reclassified. Fuzzy membership functions and fuzzy overlay techniques were used to generate crop-specific suitability maps. Supervised classification using the Random Forest method was employed for getting the most recent land use map with 81.42% accuracy and 0.7683 Kappa coefficient, confirming good reliability of classification. Mismatch analysis revealed that 19.45% of tea, 31.98% of paddy and 29.06% of rubber plantations are performed in low or not suitable places, reflecting inefficiency in land utilization currently. To this, a crop reallocation study was conducted to identify substitute crops that are suitable for these unsuitable regions. Results showed that a significant proportion of these lands is highly convertible to other crops, for example, 46.58% of tea mismatch lands are convertible to paddy and rubber, while 46.11% of rubber mismatch lands are convertible to tea and paddy. These findings support the use of alternative or mixed cropping systems to enhance land use efficiency and sustainability. The study recommends data-driven planning, environmentally friendly methods such as terracing and best irrigation and regular GIS-based monitoring for agricultural sustainability. Overall, GIS-based land suitability analysis is an effective means of land use optimization and minimizing environmental impacts in the Ratnapura District.