Viewing agricultural trade networks in terms of land and water resource sustainability

Background/Question/Methods

Growth in agricultural trade has important implications for management of global land and water resources. Exports of agricultural commodities embody the characteristics of the production systems they are derived from among different regions. If countries import specific commodities rather than producing them domestically, there may be a shift in the overall efficiency of land, freshwater, and fertilizer used for production. At the same time, because some crops are produced in particular regions for export to global markets, embodied resource use may be concentrated in key ‘hotspot’ areas. Ecological components of agricultural trade have been illuminated by research on virtual water and global land-use displacement, but it is less clear how trade simultaneously affects agricultural land requirements, water quality and water quantity at different scales. We examine the intersection of trade with multiple dimensions of land use by merging international trade statistics for major agricultural crops and derived commodities with global datasets describing crop productivity, water use efficiency, water scarcity, and nutrient application. We apply comparative analyses of net calorie importers and exporters to understand the potential resource efficiency gains or losses linked to trade of particular commodities.

Results/Conclusions

We use illustrative case studies to assess how agricultural trade network configuration impacts global land and water resource requirements. Although major exporters of staple crops tend to have higher yields than their import partners, regional exceptions to this trend related to yield potentials and harvest intensity may reduce the global land sparing attained via trade for some commodities. Net calorie exporters often have lower overall water stress than calorie importers, indicated as percent of available runoff consumed across all sectors. We show how this trend may partially relate to comparative advantages in irrigation water use efficiency, as exporters of wheat, soybean, rice, and maize have higher average caloric returns (kilocalories/liter) than importers. However, these patterns appear to be sensitive to trade variability, with some commodities being sourced from relatively more water scarce regions in particular years. Excess nitrogen remaining in fields per kilocalorie produced, an important water quality indicator, was also lower on average in nations exporting wheat, soybean, and maize, but not nations exporting rice. We close by discussing the role of trade for enhancing global agricultural sustainability. Our study offers a nuanced perspective of agricultural trade networks that uniquely addresses multiple dimensions of land and water resource use.