Sugarcane yield gap analysis in Brazil - A multi-model approach for determining magnitudes and causes

Brazil is the largest sugarcane producer in the world playing a pivotal role on global ethanol production. The sugarcane yield levels across the producing regions of the country vary substantially, resulting in yield gaps of different magnitudes, which represent a huge opportunity for increasing sugarcane and ethanol production. According to that, the present study aimed to investigate the sugarcane yield gap in Brazil, their magnitude and causes (water deficit or crop management), considering a multi-model approach. Three different sugarcane simulation models, FAO-Agroecological Zone, DSSAT/CANEGRO and APSIM-Sugarcane, properly calibrated and validated for sugarcane in Brazil, were used to estimate potential and water-limited yields and yield gaps for 30 locations across the country. The average of total yield gap for the 30 locations was 124 t ha^-1. The main proportion of the total yield gap was caused by water deficit (about 89 t ha^-1, representing 73% of the total), followed by sub-optimal crop management (about 35 t ha^-1, representing 27% of the total). The highest yield gap by water deficit was found in the Northeastern region, whereas São Paulo State showed the lowest yield gap by crop management. The main causes of yield gap by crop management are possibly related to the production system based on long-term monoculture and soil compaction due to intense crop mechanization in recent years. Reducing sugarcane yield gap caused by crop management by 20 to 100% would allow to diminish the cultivated area with this crop, respectively, from 9 to 32%. Possible solutions to mitigate the yield gaps, such as use of irrigation, adoption of drought tolerant cultivars, better traffic control, periodical crop rotation, among others, were also discussed.