Land suitability class and implications to Land-Water-Food Nexus: A case of rice cultivation in Thailand

Arable land and water resource scarcity for food production to fulfill the growing demand is a global challenge. Expansion of rice cultivation in Thailand without planning increases land and water depletion especially for the low-productivity rice cultivation areas. The Thai government has an agricultural zoning policy on promoting rice cultivation using land suitability classes for efficient use of land and costs; however, there is still some rice grown on land with low suitability. The study evaluated the land suitability class implications on major and second rice cultivation in view of the Land-Water-Food Nexus performance using Chainat, a key province of rice cultivation in Thailand, as the study area. The land and water intensity indicators were calculated using a normalized approach as the Land-Water-Food Nexus Index (LWFNI). The geographic information system (GIS) tool was used to analyze land-use classification, interpolate the rainfall, and overlay the land suitability classification with the Land-Water-Food Nexus of rice. Rice cultivation on highly suitable areas has a higher LWFNI score for resource efficiency and economic value. Scenarios were considered for changing rice cultivation in marginally and unsuitable areas to alternative crops to conserve water and reduce costs. The option for alternative crops to replace the base case with major rice and mungbean scenario was the most water-saving at about 3,601 m3/ha/year and made a profit increase of about 84,106 baht/ha. Additionally, the major rice and peanut scenario achieved the most profit increase of about 302,366 baht/ha and saved water at about 2,081 m3/ha/year.