Forage sorghum grown in a conventional wheat–grain sorghum–fallow rotation increased cropping system productivity and profitability

Abstract Intensifying winter wheat (Triticum aestivum)–grain sorghum [Sorghum bicolor (L.) Moench]–fallow (W–GS–FL) crop rotation with annual forages can increase productivity and resource use efficiency. The objective of this research was to quantify the impact of increasing crop intensity by growing forages in a traditional W–GS–FL rotation on cropping system productivity, water use, precipitation use efficiency, and net income. The study was conducted at the Southwest Research-Extension Center near Garden City, Kansas, from 2013 through 2020. Winter wheat (W), grain sorghum (GS), forage sorghum (FS), and forage oats (FO, Avena sativa L.) were used to generate six crop rotation treatments. These rotation treatments interspersed with fallow periods (FL) were W–GS–FL, W–FS–FL, W/FS–GS–FO, W/FS–FS–FO, W/FS–GS–FL, and W/FS–FS–FL. A W/FS indicates winter wheat double crop FS planted in the same year. The yield of FS was 45%–56% more with W/FS–FS–FO and W/FS–FS–FL compared with W–FS–FL. Available soil water at GS planting was 23%–30% less, and GS yield was 52%–60% smaller with W/FS–GS–FL compared to W–GS–FL. Water productivity and pre-season soil water storage were greatest with W/FS–FS–FL and W/FS–FS–FO. Inclusion of W/FS increased cost of production compared with W–GS(FS)–FL rotations. Gross return was greatest with W/FS–FS–FO and W/FS–FS–FL. The W/FS–FS–FO increased cropping intensity, productivity, resource use, and gross margin relative to other rotations in the semi-arid Great Plains. Producers should consider double-cropping of FS after wheat harvest, followed by a second year of FS in dryland cropping systems if there is sufficient forage demand.