Adding cover crops and animal manure after corn residue removal for 10 years: did it maintain soil mechanical properties?

Authors: Klopp, Hans; BLANCO-CANQUI, HUMBERTO - University Of Nebraska; SINDELAR, MICHAEL - University Of Nebraska; Jin, Virginia; Schmer, Marty; FERGUSON, RICHARD - University Of Nebraska

Submitted to: Journal of Agriculture and Food Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2023
Publication Date: 10/27/2023
Citation: Klopp, H.W., Blanco-Canqui, H., Sindelar, M., Jin, V.L., Schmer, M.R., Ferguson, R.B. 2023. Adding cover crops and animal manure after corn residue removal for 10 years: did it maintain soil mechanical properties?. Journal of Agriculture and Food Research. 14. Article 100802. https://doi.org/10.1016/j.jafr.2023.100802.
DOI: https://doi.org/10.1016/j.jafr.2023.100802

Interpretive Summary: Removing crop residues after harvest can have a negative impact on soil mechanical properties. Soil mechanical properties are affected by the amount of carbon in the soil, so harvesting crop residues takes away an important source of carbon return and introduces additional machine passes that disturb the soil after grain harvest. Using cover crops or adding livestock manure to soils could help offset the negative effects of residue removal on soil mechanical properties. Here, we measured soil mechanical properties after 10 years of annual corn stover removal in an irrigated no-till continuous corn system in south-central Nebraska USA. We found that removing corn stover negatively effected soil mechanical properties in only the top 10 cm (or 4 inches) of soil. In those near-surface soils, stover harvest increased soil compaction and decreased soil consistency. Both cover crop use and manure use had only minor benefits on maintaining soil mechanical properties after stover removal.

Technical Abstract: Crop residue removal may negatively affect soil mechanical properties, which affect soil quality as well as crop production, and plant growth. Adding C amendments may be necessary to offset any potential negative effects of residue removal on soil mechanical properties. We assessed: 1) the 10-yr impact of corn (Zea mays L.) residue removal at 59% and addition of winter rye (Secale cereale L.) cover crop and animal manure (24 Mg ha-1 biannually) on soil mechanical properties under irrigated no-till continuous corn on a silt loam in south-central Nebraska. Measurements included soil penetration resistance, field bulk density, aggregate strength, Atterberg limits (liquid limit, plastic limit, and plasticity index), Proctor maximum bulk density, and the water content at which the Proctor maximum bulk density (optimum water content) occurs. Corn residue removal increased penetration resistance by 40% for the 0 to 20 cm depth and reduced field bulk density by 5%, aggregate strength by 44%, plasticity index by 22% and optimum water content by 13% in the 0-5 cm depth. It also reduced liquid limit by 12%, and plastic limit by 10% in the upper 10 cm depth., whereas it increased Proctor maximum bulk density by 8% in the 0-5 cm depth. Cover crops reduced field bulk density by 5 % and increased penetration resistance by 52% in the upper 20 cm depth. Manure had the smallest effect on soil mechanical properties. It only increased liquid limit by 8 % and plastic limit (8%) in the 0-5 cm depth. Changes in Atterberg limits (r=0.64, p=0.001), aggregate strength (r=0.6 p=0.011), and optimum (r=0.48 p=0.017) water content were positively correlated whereas, penetration resistance (r= -0.5, p= 0.012) and maximum bulk density (r= -0.60 p=0.018) were negatively correlated with changes in soil organic C concentration. Our findings, after 10 years, suggest corn residue removal can have negative effects on near-surface soil mechanical properties, but cover crop and manure amendments appear to have little effect on offsetting such adverse effects.