Increasing rye cover crop biomass production after corn residue removal to balance economics and soil health

Authors: Ruis, Sabrina; BLANCO-CANQUI, HUMBERTO - University Of Nebraska; JASA, PAUL - University Of Nebraska; SLATER, GLEN - University Of Nebraska; FERGUSON, RICHARD - University Of Nebraska

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2023
Publication Date: 10/15/2023
Citation: Ruis, S.J., Blanco-Canqui, H., Jasa, P.J., Slater, G., Ferguson, R.B. 2023. Increasing rye cover crop biomass production after corn residue removal to balance economics and soil health. Field Crops Research. 302. Article 109076. https://doi.org/10.1016/j.fcr.2023.109076.
DOI: https://doi.org/10.1016/j.fcr.2023.109076

Interpretive Summary: Cover crops are often killed or terminated weeks before planting main crops, leading to low cover crop biomass yield and few soil benefits. Cover crops grown until main crop planting can have greater biomass yield and greater soil benefits, especially when crop residue amounts are low or baled. The effects of cover crop kill date combined with different rates of corn residue removal on soil properties, crop yields, and farm income are not well-understood under no-till rainfed and irrigated continuous corn. Across six years, a winter rye cover crop killed 2-3 weeks before corn planting (early-killed) yielded <0.45 ton/ac/yr of biomass. A winter rye cover crop killed at corn planting (late-killed) yielded 0.7 ton/ac/yr at the rainfed site and 1.3 ton/ac/yr at the irrigated site. After six years, early-killed cover crop had no effect on soil properties. The late-killed cover crop with 1.3 ton/ac/yr of biomass improved some soil properties. Regardless of site, high rates of corn residue removal had negative impacts on most soil properties. The negative impacts of corn residue removal on soils were larger than the positive impacts of the late-killed cover crop. Thus, a high yield cover crop can partially maintain soil properties following corn residue removal. Cover crop and residue removal had minimal effects on corn yield. The cover crop reduced farm income due to planting and termination costs. However, high rates of residue removal can offset the reduction in income. Overall, if a winter rye cover crop produces at least 1.3 ton/ac/yr of biomass, it could partially maintain soil properties in systems where corn residue is removed, but the risks of only a partial offset in soil properties must be balanced with farm income. This study provides valuable insights to farmers, researchers, and others regarding how differences in cover crop management affect cover crop biomass yield, soils, crop yields, and income in corn systems with residue removal.

Technical Abstract: Low or variable cover crop (CC) biomass production could limit CC benefits. Longer CC growing periods via late termination could increase CC benefits, especially under limited crop residue return. We studied whether early- (2-3 wk before planting) or late- (at planting) terminated winter rye (Secale cereale L.) CC maintains soil properties, crop yields, and farm income under 0, 25, 50, 75, and 100% corn (Zea mays L.) residue removal in rainfed and irrigated no-till in the U.S. Great Plains after 6 yr. Early-terminated CCs produced <1 Mg ha-1 of biomass while late-terminated CCs averaged 1.6 Mg ha-1 at the rainfed site and 3.0 Mg ha-1 at the irrigated site. At the rainfed site, CC termination date did not affect soils, but =75% residue removal reduced soil organic matter (OM) fraction concentrations and 100% reduced mean weight diameter of water-stable aggregates (MWD) in the 0-5 cm depth. At the irrigated site, late-terminated CC increased MWD by 0.22 mm and OM concentration by 5.1 g kg¬-1 compared with no CC. At the same site, 100% residue removal reduced microbial biomass, while =50% removal reduced OM concentration by 7.6 g kg-1, available water, and MWD by 0.75 mm relative to no removal. Cover crops only partially offset the adverse effects of residue removal if biomass production was 3 Mg ha-1 yr-1. Corn yield was generally unaffected. High residue removal rates offset CC-induced reduction in net income. Overall, late-terminated CC partially maintains soil health indicators following residue removal and minimally impacts crop yields and economics.