Productivity and profitability of four crop rotations under limited irrigation

Authors: SCHLEGEL, ALAN - Kansas State University; ASSEFA, YARED - Kansas State University; O'BRIEN, DANIEL - Kansas State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2019
Publication Date: 7/7/2019
Citation: Schlegel, A.J., Assefa, Y., O'Brien, D. 2019. Productivity and profitability of four crop rotations under limited irrigation. Applied Engineering in Agriculture. 36(1):1-9. https://doi.org/10.13031/aea.13416.
DOI: https://doi.org/10.13031/aea.13416

Interpretive Summary: Groundwater availability from the Ogalala Aquifer is decreasing, and in parts of the Southern Ogallala Aquifer region, groundwater districts and other local and state entities are setting withdrawal limits. To adapt to such changes, farmers may need to seek new crops or new crop rotations that promote efficient groundwater use. Working in a project funded by the USDA ARS Ogallala Aquifer Program, scientists from Kansas State University sought data regarding grain yields for four crop rotations when the total irrigation depth was limited to 10 inches per growing season. The rotations were: 1) continuous corn; 2) continuous grain sorghum; 3) two 2-year rotations of corn-grain sorghum; and 4) a two-year rotation of corn-winter wheat. Overall corn yield after wheat was about 25 bushels/acre greater than for continuous corn. Despite greater corn grain yield in corn-wheat rotation, the economic analysis showed that wheat was the least profitable of the three crops causing the corn-wheat rotation to be least profitable. In this study, the most profitable limited irrigation crop rotation was corn-grain sorghum. These results suggest that a careful selection of crops in a rotation may improve farm profitability when groundwater withdrawals are limited.

Technical Abstract: Selection of optimal crops and cropping systems for most efficient water use specific for local environments can improve global water security. Limited irrigation with ground water is one alternative to alleviate crops from low amount or unevenly distributed water in the growing seasons in semi-arid regions. The main objectives of this research were to quantify yield-water use relationships of three limited irrigated crops, determine effect of crop selection on profitability with limited irrigation, and identify profitable and alternative crop production systems. A field study was conducted at the Kansas State University Southwest Research-Extension Center near Tribune, Kansas, from 2012 through 2017. There were four treatments in the study, two 1-yr systems of continuous corn ( L.) (C-C) and continuous grain sorghum (L.) (GS-GS) and two 2-yr rotations of corn-grain sorghum (C-GS) and corn-winter wheat ( L.) (C-W). Overall corn yield after wheat (C-W) was about 1.4 Mg (ha)-1 greater than C-C. Corn and sorghum yields were similar grown as monoculture or in rotation with each other. Available soil water at corn planting and during the growing season were 20 to 40 mm (240 cm profile-1) less in the C-GS rotation compared with C-C and C-W rotations. Corn yield increased as water use (yield-water use) increased in C-W rotation but yield-water use relationships tended to be negative in C-C and C-GS rotations. Grain sorghum yield increased with water use in both rotations but at a greater rate in GS-GS compared with C-GS. Despite greater corn grain yield in C-W, our economic analysis showed that wheat was the least profitable of the three crops causing the C-W rotation to be least profitable. In this study, the most profitable limited irrigation crop rotation was corn-grain sorghum (C-GS).