Environmental and economic performance of paddy field-based crop-livestock systems in Southern Brazil

Abstract CONTEXT The adoption of improved crop-livestock (CL) systems is an important strategy to enhance the sustainability of agricultural systems. However, before new CL systems technologies are brought into commercial practice their environmental and economic performance should be scrutinized. OBJECTIVE We apply life cycle assessment and profit analysis to compare two technically improved paddy-based crop-livestock systems with a baseline scenario. METHODS Attributional life cycle assessment and profit analysis is applied to compare the performance of the three CL systems. We selected six impact categories to investigate the influence of production-related and area-related functional units. Each CL system has been evaluated by employing the crop-by-crop approach as well as the whole system analysis. The baseline scenario represents a traditional CL system in Southern Brazil, where flooded rice is grown as the spring-summer crop followed by beef cattle being released into paddy fields to graze rice straw and regrowth after the cereal is harvested. The experimental systems were managed under no-tillage, sowing of ryegrass in winter for cattle, fertilisation based on soil analysis and crop requirements, agrochemical application based on best management practices; additionally, in one of the improved systems, soybean have been introduced in the rotation with rice. RESULTS AND CONCLUSIONS Results indicate that the improved experimental systems presented higher productivity and profitability per ha than the baseline systems. The environmental performance was substantially affected by the functional units selected for the evaluation. Production-related functional units benefited the improved systems; conversely, the area-related functional unit benefited the less intensive baseline system. Generally, the CL system where soybean was included in the rotation presented considerably better performance; this was particularly evident with regard to the global warming potential, agricultural land occupation, and water depletion impact categories. Increasing farm inputs in the CL system without including soybean in the rotation increased profit and production per area but brought little advantages to the environmental performance. SIGNIFICANCE We expand the understanding of the environmental and economic performance of paddy field-based crop-livestock systems in Southern Brazil, and provide valuable information to researchers, as well as the broader audience interested in the sustainability of agricultural systems.