Technical feasibility of using suboptimal irrigation in maize cropping

Maize (Zea mays L.) is one of the main cereal crops grown around the world and is widely used as food, feed and raw material in various industries. However, the crop is sensitive to weather conditions, and this causes large variations in yield between crop seasons. Suboptimal irrigation can be used to secure reasonable yields with increased water productivity. For maize grown offseason in the Cerrado biome of Brazil, there is little knowledge about the benefits of suboptimal irrigation. This study was designed to evaluate the effect of different irrigation amounts and two Brachiaria cultivars intercropped with maize on maize grain yield, biomass production for silage and water productivity in the second crop season. The study was conducted at Embrapa Milho e Sorgo Experimental Station, Sete Lagoas, MG, Brazil, in 2018 and 2019. Six irrigation levels were obtained by using a line-source sprinkler irrigation system. The irrigation levels used ranged from 94% to 11% of the cumulative reference evapotranspiration (ET0) in 2018, and from 90% to 34% of ET0 in 2019. Suboptimal irrigation above a certain level did not cause a significant decrease in silage biomass (59% and 71% of the ET0, in 2018 and 2019, respectively) and grain productivity (48% and 60% of the ET0, in 2018 and 2019, respectively). Additionally, there was an increase in crop water productivity and irrigation water productivity, for biomass of both silage and grains. The results demonstrate the potential of suboptimal irrigation as a strategy to reduce water resource usage while maintaining acceptable productivity levels.