Rules for grown soybean-maize cropping system in midwestern Brazil: food production and economic profits

Abstract

Soybean-maize cropping system is highly dependent on climate condition, especially water deficit, across Brazil, affecting yield, food production and farmers profit. Based on that, the aim of this study was to evaluate the food production and economic viability for soybean and maize for single and soybean-maize off-season production system considering sowing dates, soil types and yield gaps in the Midwestern region. The yield was simulated using FAO-Zone agroecological model. Official yield statistics were used to validate the crop model and to estimate yield gap. We consider single soybean (SSc), single maize (SMc), and soybean-maize off-season systems (SMcs), simulating yield for 35 growing seasons (1981–2015) and six sowing dates (Oct. 01–Dec. 15 for single soybean and single maize; and Jan. 09–Mar. 26 for maize off-season, after soybean harvest). Total production was obtained in function of yield, yield gap, soil type and production intensity. Farmers profit was obtained based on net revenue using independent random function (5000 interactions) for yield, sales price and production costs. The SSc had the largest scenarios with positive net revenue, while SMcs had higher net revenue, reaching R$ 7400.00 ha−1, but with lowest risk for early sowing dates (soybean sowed in Oct. 01 and Oct. 15, and maize off-season in Jan. 09 and Jan. 24). The SMc had higher risk and lower food production in the region. The maximum gross energy production was 2663 billion MJ in SMcs sown soybean on Oct. 01. The SSc had a stable production of gross energy across the sowing dates, with values around 1900 billion MJ. The production of crude protein was similar among SMcs and SSc across sowing dates. The higher crude protein production occurred in the sowing date Oct. 15 for SMcs, with 33.9 billion kg, while SSc produced 32.9 billion kg. The highest net revenue was obtained for the SMcs in the early sowing dates. Nevertheless, the SMcs produced the highest amount of gross energy than single crop systems, but with a very similar crude protein level than SSc. Thus, farmers can be encouraged to grow SMcs to improve food production in early sowing dates. However, public incentive policies through insurance against water deficit can guarantee minimal economic returns and reduce production risks for maize off-season, especially when soybean was sowing late by delay at beginning of rain.