Environmental impacts of water use in global crop production: hotspots and trade-offs with land use.

Global crop production is causing pressure on water and land resources in many places. In addition to local resource management, the related environmental impacts of commodities traded along international supply chains need to be considered and managed accordingly. For this purpose, we calculate the specific water consumption and land use for the production of 160 crops and crop groups, covering most harvested mass on global cropland. We quantify indicators for land and water scarcity with high geospatial resolution. This facilitates spatially explicit crop-specific resource management and regionalized life cycle assessment of processed products. The vast cultivation of irrigated wheat, rice, cotton, maize, and sugar cane, which are major sources of food, bioenergy, and fiber, drives worldwide water scarcity. According to globally averaged production, substituting biofuel for crude oil would have a lower impact on water resources than substituting cotton for polyester. For some crops, water scarcity impacts are inversely related to land resource stress, illustrating that water consumption is often at odds with land use. On global average, maize performs better than rice and wheat in the combined land/water assessment. High spatial variability of water and land use related impacts underlines the importance of appropriate site selection for agricultural activities.