Lessons about soil health and corn yield after a decade of cover crop and corn residue management

Context

Including cover crops (CCs) in no-till cropping systems can improve soil health, but little is known how much improvement occurs when CCs are terminated at different times combined with corn (Zea mays L.) residue removal at different rates.

Objectives

Our objective was to study how cereal rye (Secale cereale L.) CC terminated early (2–3 wk before corn planting) and late (at corn planting) affected CC biomass production, corn yield, and soil properties under corn residue removal at 0, 25, 50, 75, and 100 % in a rainfed and an irrigated site under no-till continuous corn after 10 years (yr).

Methods

Corn grain yield and CC biomass production was measured annually throughout the 10 yr of this study. After 10 years, soil samples were collected from the 0–5 cm depth and a comprehensive analysis of soil properties was done. Soil properties measured included bulk density, wet aggregate stability, water content at −33 and −1500 kPa matric potentials, plant available water, organic matter, soil nutrients. and soil microbial groups. Only cover crop biomass and corn yields from years 6–10 is included in this manuscript.

Results and discussion

Corn residue removal increased CC biomass production in 4 of 8 site-years in years 6–10 of this study, and late CC termination increased CC biomass production from 0.17 to 0.31 Mg ha⁻¹ at the rainfed site and from 0.25 to 1.21 Mg ha⁻¹ at the irrigated site over early-terminated CC. Corn residue removal and CC termination timing did not affect corn yield. At the irrigated site, corn residue and CC management did not affect most of the soil properties. However, at the rainfed site, 25–50 % or greater of corn residue removal reduced soil organic matter (13 %), particulate organic matter (19 %), and plant available water (43 %). Late-terminated CC reduced bulk density by 10 % and increased soil organic matter by 9 % over no CC at the rainfed site.

Conclusion

After 10 yr, late-terminated CC had greater biomass production and benefits soil health. However, this did not enable higher rates of residue to be removed before negatively affecting soil properties. Removing crop residues and CC termination timing did not affect corn grain yield.

Implications

Cereal rye CC can be terminated as late as corn planting to optimize biomass production and does not affect corn grain yield. Long term corn residue removal for expanded uses does not affect corn grain yield but can have negative effects on soil health. Late termination of CC did not allow for more corn residue to be removed before degrading soil health.