Redesigning subtropical lowland rice systems through crop diversification and livestock integration: trade-offs among energy efficiency, productivity and economic performance

Abstract Sustainable intensification of agrifood systems is essential to reconcile growing global food demand with resource-use efficiency and economic viability. In this context, redesigning production systems through crop diversification and livestock integration can promote greater complementarity in resource use. Rice is a staple food for billions of people, yet in southern Brazil it is predominantly grown as a continuous monoculture under flood irrigation, with high demands for water, fertilizers, and fuel. We hypothesized that diversifying rice-based rotations with upland crops, forages, and cattle grazing would increase resource-use efficiency and economic performance without necessarily increasing absolute energy output. We evaluated five rice-based production systems over eight years (2013–2020), ranging from continuous flood-irrigated rice monoculture to rotations combining rice with soybean, maize, forage crops, perennial pastures, and cattle grazing, quantifying energy inputs and outputs, energy productivity, specific energy, rice-equivalent yield, and economic performance using the full rotation cycle as the analytical unit. This is the first field study to jointly quantify energy efficiency, rice-equivalent yield, and economic performance across diversified rice-based systems over an eight-year period in southern Brazil. Relative to continuous rice monoculture, diversified systems reduced energy input by up to 28%, more than doubled energy productivity (from 0.391 to 0.837 kg per megajoule), and lowered specific energy by 53%. They also increased rice-equivalent yield by 48–54% and net revenue from US$14,499 to as much as US$25,953 per hectare, while the benefit-to-cost ratio rose from 3.3 to 5.2. These findings demonstrate that redesigning crop-livestock rotations, rather than intensifying a single crop, can simultaneously raise resource-use efficiency and economic returns, offering a practical pathway toward more sustainable and food-secure lowland rice production.