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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Soil and Water Management Research » Research » Publications at this Location » Publication #355036
Research Project: Precipitation and Irrigation Management to Optimize Profits from Crop Production

Location: Soil and Water Management Research

Title: Can cover or forage crops replace fallow in the semiarid Central Great Plains?

Author
item HOLMAN, JONATHON - Kansas State University
item ARNET, KEVIN - Kansas State University
item DILLE, JOHANNA - Kansas State University
item MAXWELL, SCOTT - Kansas State University
item OBOUR, AUGUSTINE - Kansas State University
item ROBERTS, TOM - Kansas State University
item ROOZEBOOM, KRAIG - Kansas State University
item SCHLEGEL, ALAN - Kansas State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2017
Publication Date: 1/4/2018
Citation: Holman, J.D., Arnet, K., Dille, J., Maxwell, S., Obour, A., Roberts, T., Roozeboom, K., Schlegel, A. 2018. Can cover or forage crops replace fallow in the semiarid Central Great Plains? Crop Science. 58(2):932-944. https://doi.org/10.2135/cropsci2017.05.0324.
DOI: https://doi.org/10.2135/cropsci2017.05.0324

Interpretive Summary: Recently there has been a great interest in the use of cover crops to promote soil health and reduce erosion. However, there is a debate whether planting cover crops will be benefical in areas where crop production is limited by rainfall, because the cover crop may deplete soil water for crops that produce farm income. Therefore, scientists from Kansas State University in the ARS led Ogallala Aquifer Program studied replacing fallow in no-till winter wheat–fallow rotation with cover, forage, or grain crops. Plant available water at wheat planting was reduced the most when the fallow period was the shortest with a grain crop. For every inch of saved soil water at planting, wheat yields increased by 2.5 bushels per acre (about $12.5 per acre). Because the fallow period is reduced least by growing an annual forage, these crops have the greatest potential as a cover crop for the Southern High Plains.

Technical Abstract: Growing a crop in place of fallow may improve soil properties but result in reduced soil water and crop yields in semiarid regions. This study assessed the effect of replacing fallow in no-till winter wheat (Triticum aestivum L.)–fallow with cover, forage, or grain crops on plant available water (PAW), wheat yield, grain quality, and profitability over 5 years, from 2007 to 2012. PAW at wheat planting was reduced the most when the fallow period was the shortest (i.e., following grain crops) or when biomass production was the greatest. Winter and spring lentil (Lens culinaris Medik.) produced the least biomass, used the least soil water, and had the least negative effect on yield. For every 125 kg per ha of cover or forage biomass grown, PAW was reduced by 1 mm, and for every millimeter of PAW, wheat yield was increased by 5.5 kg per ha. There was no difference in wheat yield whether the preceding crop was harvested for forage or left as standing cover. In years with above-average precipitation, wheat yield was reduced 0 to 34% by growing a crop in place of fallow. However, in years with below-average precipitation, wheat yield was reduced 40 to 70% without fallow. There was minimal negative impact on wheat yield growing a cover or forage crop in place of fallow if wheat yield potential was 3500 kg per ha or greater. Net returns were reduced 50 to 100% by growing a cover crop. However, net returns were increased 26 to 240% by growing a forage crop. Integrating annual forages into the fallow period in semiarid regions has the greatest potential for adoption.