Soybean Yield Gap in the Areas of Yield Contest in Brazil

Soybean yield is mainly influenced by the interaction among genotype, environmental conditions and management practices. Based on that, the aim of this study was to quantify the soybean yield gap caused by water deficit (YG(WD)) and sub-optimum crop management (YG(CM)), considering data from the areas of soybean yield contest in Brazil. Potential (Yp) and attainable (Ya) yields were estimated by a crop yield simulation model, whereas actual farmers yields (Yf) were obtained from the contests conducted by the Brazilian Soybean Strategic Committee (CESB), comprising 200 sites. The YG(WD) and YG(CM) were, respectively, calculated by the difference between Yp and Ya, and Ya and Yf. The climate efficiency (EFC) was obtained by the ratio between Ya and Yp, while crop management efficiency (EFM) considered the ratio between Yf and Ya. The mean Yf from CESB was 5021kgha(-1), higher than the national average of about 3000kgha(-1). The YG(WD) and YG(CM) were, respectively, 2931 and 3458kgha(-1), representing 46 and 54% of total yield gap. The weather conditions did not affect Yf in the studied sites with lower EFM. For sites with EFC higher than 0.80, Yf increased in a rate of 92kgha(-1) per percentage of increase in EFM. When comparing the national average and CESB winners, the results showed that average Yf could be increased in 2514 and 2584kgha(-1), respectively, by closing YG(CM) and YG(WD), which shows that there is room to double the present Brazilian soybean yield by adopting the technology already available to the farmers. These results can serve as reference to guide other studies about soybean yield gap around the world, helping policy makers and other stakeholders to elaborate strategies for closing yield gaps and making soybean production more sustainable.