Benchmarking sorghum and maize for both yield and economic advantage in the US Great Plains

Abstract

Context or problem

The Great Plains region of the United States (US) has a rich history of growing summer crops such as maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench). Sorghum is highly valued for its resilience to environmental stressors, particularly drought, while maize is favored for its high yield potential and responsiveness to inputs.

Objective

The aim of this study was to provide a quantitative analysis of the overall competitive advantage, both from a yield and economic perspective, and a weather characterization for growing sorghum relative to maize crops across Kansas, US, using a 40-year dataset covering multiple hybrids and 13 unique locations.

Methods

Data were retrieved from the Kansas Crop Performance Tests, conducted between 1984 and 2023 including environments tested in the same site and year for both sorghum and maize crops. Tests were conducted simultaneously, comparing genotype means across low-, medium-, and high-yield environments. Climate characterization and identification of the key weather variables driving grain yield for each crop were investigated using principal component analysis. The economic analysis focused on data from 2013 to 2022.

Results

Maize outperformed sorghum in medium- and high-yield environments, whereas sorghum outperformed maize in low-yield environments (<5.4 Mg ha⁻¹). Sorghum had lower variability (coefficient of variation of yield) than maize in low-yield environments, whereas maize was more stable than sorghum in high-yield environments. Precipitation and heat stress during the growing season were the main factors affecting grain yield of both crops. Water use efficiency (grain yield per mm of precipitation during the growing season, WUE) was greater in sorghum than that of maize when precipitation was less than 312 mm, and the opposite scenario occurred, with maize WUE greater than that of sorghum when precipitation exceeded this threshold. Yield losses due to heat stress were greater in maize relative to sorghum (45 vs. 22 kg of yield decline per °Cd of cumulative maximum temperature above 35°C, respectively). Economically, sorghum became more competitive when maize yield was below 11.6 Mg ha⁻¹ using a 1:1 grain price ratio.

Conclusions

This study demonstrates that sorghum is still more favorable under current farming practices in the US central Great Plains region in low-yield environments, while maize outperforms sorghum in high-yield environments.

Implications

This study offers a comparative analysis of sorghum and maize under current farming production conditions, utilizing a long-term dataset spanning over four decades. This comprehensive dataset encompasses a diverse range of genotype-site-year combinations. The main findings of this study suggest that sorghum is a viable alternative for summer cropping, especially in low-yield environments mainly connected with less precipitation and high-temperature stress, achieving yields comparable to those of maize while offering a more favorable economic outcome.