Mapping Areas for Growing Pulses in Rice Fallows Using Multi-Criteria Spatial Decisions

Food legumes play an important role in ensuring food and nutritional as well as environmental security through crop diversification and sustainable intensification in India and elsewhere. India imports nearly 4–5 million tons annually to meet its domestic demand. There is a need to increase both productivity and production to bridge the supply–demand gap, and one such opportunity lies in the potential use of crop fallows such as rice fallows. The rice fields in eastern and central India remain fallow after the main crop has been harvested. Limiting factors are lack of understanding of fallow dynamics, soil moisture regimes, unavailability of suitable crops and crop varieties, etc. Therefore, a pilot study has been undertaken to map and quantify suitable areas for growing short-duration pulses (lentil) in rice fallows of the West Bengal region. Rice area, fallow area, and associated vegetation and crop phenological parameters such as start and end of fallow periods, length of fallow periods, etc. were used for assessing the rice fallow dynamics across the growing seasons and years. The resultant outputs were further analyzed in the geostatistical domain with various causative factors to determine a suitable range, and the resultant values were normalized with a fuzzy-gamma function to produce hotspot index values. The suitability assessment used 16 factors as suitability parameters, including climatic conditions, soil types, soil moisture, nutrient characteristics, and topography data. The fuzzy-set model with analytic hierarchy process (AHP), multi-criteria decision making (MCDM), and geographic information system (GIS) technique were integrated to create the final lentil suitability map. The preliminary results showed that nearly 61% of the analyzed area are suitable for growing lentil, with a range of most suitable (21%) to moderately suitable (40%) followed by marginal (19%) to least suitable (18%) for lentil production. The map and zonal statistics were verified with national statistical data available at district level. This ongoing study needs further analysis to quantify the dynamics of suitability across the years, rainfall pattern, and socio-economic and ecological aspects in order to develop a user-friendly, interactive decision-making tool for sustainable intensification and crop diversification in the rice fallows.