Environmental impacts of agricultural intensification: Evidence from Brazil’s double-cropping boom

This article examines the environmental impacts of agricultural intensification in Brazil, particularly the significant expansion of a double cropping system involving soybeans and corn, which has transformed Brazil into the world’s leading exporter of corn. We use econometric models with instrumental variables to assess the impact of double cropping on pesticide runoff and land-use change, focusing on regions near tropical forests. Our results reveal that double cropping substantially reduces pesticide contamination in surface waters, with a 0.5 percentage-point increase in double cropping share reducing pesticide exceedances by 5–12% across five distinct instrumental variable strategies. Our results indicate that double cropping reduces pesticide runoff by acting as a cover crop that limits chemical leaching. In our analysis of land-use change, we observe notable regional variation. In traditional agricultural zones, double cropping has minimal influence on cropland expansion due to high land-conversion costs. However, double cropping significantly drives cropland expansion in frontier areas where land conversion barriers are lower. We estimate that 44% of the cropland expansion in the frontier region would not have occurred without the practice of double cropping. This finding suggests that the recent growth of second-crop corn for ethanol production may have more substantial environmental impacts in the frontier than previously anticipated.