Spatiotemporal Trade-Offs and Synergies Among Environmental Footprints of Grain Crop Production in China

Human agricultural activities have exacerbated multiple types of natural resource depletion and environmental impacts through complex interactions with land, water, carbon, and nutrient cycles, which can be measured as corresponding environmental footprints (EFs). However, the spatiotemporal trade-offs and synergies among multiple EFs in agricultural systems remain under-quantified, hindering effective mitigation strategies. Here, we propose an assessment framework of spatiotemporal trade-offs and synergies among multiple EFs of crop production, with a case study on blue water, green water, land, carbon, nitrogen, and phosphorus footprints for wheat, maize, rice, and soybean production across 31 Chinese provinces over 2000-2018. In total, 3630 pairwise EFs were analyzed. Results show that, although the EFs of unit mass crop production generally declined across provinces, national total EFs increased, with land, carbon, and phosphorus footprints rising by 16%, 17%, and 23%, respectively, during the study period. Synergistic interactions among EFs prevailed, comprising 50% positive and 32% negative synergies. The spatial distribution of trade-offs and synergies varies by crop and region. Land use intensity is the main factor limiting the positive EF synergies.