Interseeded cover crop mixtures influence soil water storage during the corn phase of corn-soybean-wheat no-till cropping systems

Authors: Schomberg, Harry; Mirsky, Steven; White, Kathryn; Thompson, Alondra; Bagley, Gwendolyn; Garst, Grace; Bybee-Finley, Kristine

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2023
Publication Date: 1/19/2023
Citation: Schomberg, H.H., Mirsky, S.B., White, K.E., Thompson, A.I., Bagley, G.A., Garst, G.D., Bybee-Finley, K.A. 2023. Interseeded cover crop mixtures influence soil water storage during the corn phase of corn-soybean-wheat no-till cropping systems. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2023.108167.
DOI: https://doi.org/10.1016/j.agwat.2023.108167

Interpretive Summary: Cover crops (CC) are grown between cash crops to provide beneficial ecosystem services including reducing soil losses from water and wind erosion. When CC residues remain on the soil surface they can reduce water runoff, increase infiltration, and reduce evaporation increasing soil water storage, which is an important ecosystem service. Although CC are usually planted in the fall following a summer cash crop, by planting CC into the summer cash crop during its vegetative growth stage (before it becomes too tall), can promote greater CC biomass production enhancing these beneficial services. Scientists from the USDA Beltsville Agricultural Research Center, Beltsville, MD investigated the potential for increasing soil water storage with interseeded CC from 2017 to 2020. Soil water measurements were collected each year during the corn phase in four corn-soybean-wheat rotation systems. Comparisons were made between cover crops interseeded into the double crop soybean and no cover crop. Average soil water storage during the following corn growing season was 10 to 20 mm greater with interseeded CC compared to without CC. Differences in evapotranspiration and infiltration between CC and no CC systems were small and occurred only in one out of the four years. Four-year average corn yields were greater with interseeded CC compared to without (12.1 vs 10.6 Mg ha-1). Similarly, average water use efficiency (the amount of grain yields per unit of water used; WUE) was greater with interseeded CC compared to without CC (5.55 vs 4.70 kg m-3). The combination of greater yields and WUE demonstrate the positive benefits of interseeded CC particularly in humid regions of the US. The results of this research will be beneficial to farmers, extension personnel, researchers, and policy makers. Promotion of cover crops for their water conservation benefit could be important due to increasing societal demands for water.

Technical Abstract: Cover crops (CC) provide many beneficial services including the potential to increase water storage by reducing runoff, increasing infiltration, and decreasing evaporation. Interseeding of CC into a summer cash crop can increase CC biomass production essential for maximizing beneficial services. The effects of interseeded CC on soil water availability to the following cash crop has not been fully evaluated. Research to address this question was conducted at the USDA Beltsville Agricultural Research Center, Beltsville, MD from 2017 to 2020 in four corn (Zea mays L.)-soybean (Glycine max L.)-wheat (Triticum aestivum L.) (C-S-W) crop rotation systems under no-tillage management that differed by CC use prior to corn. Cover crop effects on water availability were evaluated during the corn phase of C-S-W-DS, C-r-S-W-DS, C-r-S-W-DS(r-hv-cc) and C-r-S-W(rc)-DS-r rotations, respectively, where uppercase letters indicate cash crops and lower case letters indicate CC: cereal rye (r, Secale cereale L.), hairy vetch (hv, Vicia villosa Roth), crimson clover (cc, Trifolium incarnatum L.) and red clover (rc, Trifolium pratense L.). In the latter rotations, CC were interseeded into double crop soybean (DS). In 2017 and 2018 season average soil water storage was 20 mm greater in systems with CC before corn compared to without CC prior to corn. A similar (but not significant) trend was present in 2019 and 2020 (11 mm). Evapotranspiration was lower for CC systems compared to no CC systems only in 2018, while greater infiltration was observed for CC systems only in 2019. Four-year average corn yields were greater with compared to without a CC (12.1 vs 10.6 Mg ha-1). Similarly, average water use efficiency (WUE) was greater with compared to without a CC (5.55 vs 4.70 kg m-3). The combination of greater yields and WUE demonstrate the positive benefits of interseeded CC systems particularly in humid regions of the US.