Cover crops and soil health in rainfed and irrigated corn: what did we learn after 8 years?

Authors: BLANCO-CANQUI, HUMBERTO - University Of Nebraska; Ruis, Sabrina; KOEHLER-COLE, KATJA - University Of Nebraska; ELMORE, ROGER - University Of Nebraska; FRANCIS, CHARLES - University Of Nebraska; SHAPIRO, CHARLES - University Of Nebraska; PROCTOR, CHRISTOPHER - University Of Nebraska; FERGUSON, RICHARD - University Of Nebraska

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2023
Publication Date: 6/27/2023
Citation: Blanco-Canqui, H., Ruis, S.J., Koehler-Cole, K., Elmore, R.W., Francis, C.A., Shapiro, C.A., Proctor, C.A., Ferguson, R.B. 2023. Cover crops and soil health in rainfed and irrigated corn: what did we learn after 8 years? Soil Science Society of America Journal. 87(5):1174-1190. https://doi.org/10.1002/saj2.20566.
DOI: https://doi.org/10.1002/saj2.20566

Interpretive Summary: Cover crop (CC) effects on soil physical, chemical, and biological properties could be driven by a variety of factors including duration under CC management, CC biomass production, and site-specific factors. Research conducted measured soil physical, chemical, and biological properties after 8-yr of winter rye CC in corn-based systems under rainfed and irrigated conditions in the western U.S. Corn Belt. Across the 8-yr experiment, winter rye CC biomass yield was about 0.6 Mg ha-1 (megagram per hectar) at the rainfed site and about 1 Mg ha-1 at the irrigated site. After 8 yr of CC, CC effects on soil properties were confined to the soil surface (0-5 cm). The CC increased easily decomposable organic matter and soil wet-aggregate stability at both sites relative to no CC. At the rainfed site only, CC increased soil C. The winter rye CC increased microbial biomass but had no effect on water infiltration or storage at either site. While CCs improved many soil properties after 8-yr, a companion paper after 4-yr for the same sites reported no CC-induced changes to soil properties. These data indicate that when CC biomass is low, CC impacts on soil properties may take time to accumulate. Overall, a winter rye CC can enhance soil properties at the soil surface in the long-term. This information will be valuable to scientists, farmers and others to understand which soil properties may change with a winter rye CC and how long it may take those changes to occur in corn-based systems of the western U.S. Corn Belt.

Technical Abstract: Duration of cover crop (CC) management, CC biomass production, and other factors could impact how CC affects soil health. We studied the 8-yr cumulative impacts of winter rye (Secale cereale L.) CC on soil physical, chemical, and biological properties in rainfed and irrigated no-till corn (Zea mays L.)-based systems in the western U.S. Corn Belt. Average annual CC biomass production was 0.56 ± 0.51 Mg ha-1 at the rainfed site and 0.98 ± 0.95 Mg ha-1 at the irrigated site. After 8 yr, CC improved particulate organic matter (POM) and mean weight diameter of water-stable aggregates (MWD) compared with no CC in the 0-5 cm soil depth at both sites. Cover crop increased total POM concentration by 2.8 mg g-1 at the rainfed site and by 13.4 mg g-1 at the irrigated site, while it increased MWD by 0.39 mm at the rainfed site and by 0.79 mm at the irrigated site. Also, CC increased soil C at a rate of 0.125 Mg ha-1 yr-1 in the 0-5 cm depth but only at the rainfed site. Cover crop affected neither water infiltration nor available water but improved microbial biomass. Changes in other properties were site-dependent. Cover crops improved many soil properties after 8 yr, but an earlier, 4-yr study for the same sites reported no CC effects, which indicates CC slowly impacts properties in this environment. Low CC biomass production may explain the slow soil response. In general, winter rye CC enhances near-surface soil properties in the long term.