Integrating the land–water–climate nexus approach with spatial-based sustainable agriculture production

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CONTEXTA policy on agricultural land zoning, based on land suitability maps, has been introduced to optimize the use of resources for crop production in Thailand. However, the impact of activities occurring during cultivation in different land suitability classes has not been considered. A land–water–climate nexus index (LWCNI) has therefore been introduced as a holistic analysis that integrates three indicators––land-use intensity, water-use intensity, and climate change impact in terms of GHG emissions. This can guide resource allocation by highlighting areas that need improvement. OBJECTIVEWe aimed to assess the land–water–climate nexus in different land-suitability classes for sugarcane and cassava in Thailand in order to compare the nexus performances and improve the planning and management of resources for sustainable production. METHODSThe LWCNI was developed and assessed by combining it with geographic information system–based tools for evaluating the nexus performances of sugarcane and cassava cultivation as per the agricultural zoning policies. The scope of the work was “from cradle to farm-gate”, and the final products considered were sugarcane and fresh cassava. RESULTS AND CONCLUSIONSThe results revealed that sugarcane cultivation in moderate-suitability areas is the most effective, with the best LWCNI score being 0.87, suggesting efficient cultivation practices with a minimal use of land and water resources, and a minimal climate change impact. The three indicators of land-use intensity, water-use intensity, and GHG emissions for sugarcane were estimated at 0.010 ha/t, 108 m3/t, and 6.2 kg carbon dioxide equivalent (CO2e)/t, respectively. Cassava cultivation in the high-suitability area was the most efficient, with the best LWCNI score, at 0.95, and using less land, fewer water resources, and having less of a climate change impact. The land-use intensity, water-use intensity, and GHG emissions of cassava were estimated at 0.030 ha/t, 255 m3/t, and 35.7 kgCO2e/t, respectively. Growing crops in marginal and unsuitable areas presented a risk of a high climate change impact as well as competition for water resources due to limited local resources. We found that, even in the same land-suitability class, the amount of fertilizer used by the farmers varied depending on their knowledge, experience, and finances. Excessive fertilizer application increased GHG emissions, which in turn brought about a decrease in the LWCNI score, leading to a poorer nexus performance. SIGNIFICANCEThe findings emphasize the relationship between land and water use and climate change impact across varying spatial contexts. The LWCNI approach offers valuable insights for supporting agricultural zoning policy.