Circular agriculture increases food production and can reduce N fertilizer use of commercial farms for tropical environments

Abstract

World food production must increase in the coming years with minimal environmental impact for food and nutrition security. Circular Agriculture has emerged as an approach to minimize non-renewable resource depletion and encourage by-product reuse. The goal of this study was to evaluate Circular Agriculture as a tool to increase food production and N recovery. The assessment was conducted for two Brazilian farms (Farm 1; Farm 2) with Oxisols under no-till and a diversified cropping system, including five species of grain, three cover crop species, and sweet potato. Both farms implemented an annual two-crop rotation and an integrated crop-livestock system with beef cattle confined for 2-years. Grain and forage from the fields, leftovers from silos, and crop residues were used as cattle feed. Grain yield was 4.8 and 4.5 t ha−1 for soybean, 12.5 and 12.1 t ha−1 for maize, and 2.6 and 2.4 t ha−1 for common bean, for Farm 1 and Farm 2, respectively, which is higher than the national average. The animals gained 1.2 kg day−1 of live weight. Farm 1 exported 246 kg ha−1 year−1 of N in grains, tubers, and animals, while 216 kg ha−1 year−1 was added as fertilizer and N to cattle. Farm 2 exported 224 kg ha−1 year−1 in grain and animals, while 215 kg ha−1 year−1 was added as fertilizer and N to cattle. Circular practices, i.e., no-till, crop rotation, year-round soil covered, maize intercropped with brachiaria ruziziensis, biological N fixation, and crop-livestock integration, increased crop yield and decreased N application by 14.7 % (Farm 1) and 4.3 % (Farm 2). 85 % of the N consumed by the confined animals was excreted and converted into organic compost. Overall, circular practices associated with adequate crop management allowed recovering high rate of applied N, reducing environmental impacts, and increasing food production with lower production costs.