The Land-Water-Food-Environment nexus in the context of China's soybean import

Abstract

Soybean import accounts for 90% of China's total domestic soybean supply. Such import has a substantial impact on how the country's resources are used as well as on its environment. In this study, we performed a national-scale assessment of the impact of soybean import on domestic cropland conversion, crop production, water use and nitrogen (N) fertilizer application. Results show that soybean production in China decreased by 26% (4.46 million tons) and sown areas were reduced by 25% (2.39 million ha) from the peak of 2004 to 2016. Of the areas taken out of the soybean production, 70% were converted to maize, 20% to rice, 3% to vegetables and 7% to fruits during this period. As a result of the cropland conversion, the production of maize, rice, vegetables and fruits increased by 10.42, 3.34, 2.49 and 3.26 million tons respectively. However, irrigation water use in the areas that were converted to the cultivation of the four types of crops increased by 96.42% (3.05 km3), with much of it coming from northern provinces where water is generally scarce. The application of N fertilizer increased by 256.65 thousand tons (almost 5 times) on the converted areas, partly due to the loss of the N-fixing soybean cultivation. Although a large quantity of virtual water and land were imported through soybean trade, the water use and N application were increased in reality. The analysis of the land-water-food-environment nexus in the context of soybean import provides comprehensive and useful information about the benefits and trade-offs associated with China's international soybean trade.