Managing cover crop residues for optimum corn and soybean production

Knerrer, Dalton Lee

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https://hdl.handle.net/2142/129274 Copy

Description

Title

Managing cover crop residues for optimum corn and soybean production

Author(s)

Knerrer, Dalton Lee

Issue Date

2025-05-06

Director of Research (if dissertation) or Advisor (if thesis)

Below, Fred E

Committee Member(s)

• Riechers, Dean E
• Schroeder, Nathan E

Department of Study

Crop Sciences

Discipline

Crop Sciences

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

Management Degradation ATS BIological

Abstract

The vegetation produced by a winter cover crop can help to reduce soil erosion and minimize nutrient loss during the traditional fallow period, and cover crops are becoming more common in Midwest corn (Zea mays L.) and soybean [Glycine max (L.) Merr] production. A potential problem, however, is that the cover crop residue can decrease corn or soybean yield by delaying timely planting or by immobilizing mineral nutrients. The objective of this study was to evaluate management practices and product applications to enhance residue decomposition and to mitigate the negative impacts of cover crop residues on corn and soybean production. Three factors of treatments were implemented over a two-year period (fall 2022 through fall 2024) and included mechanical harvest methods, cover crops, and sprayer applications. The study was initiated with two levels of harvest method of the 2022 corn crop preceding the cover crop establishment, consisting of either sizing knife rollers (chopped) or standard knife rollers (standard). The cover crop factor was established with drilling of a cereal rye cover crop in the fall of 2022 ahead of soybean planted in 2023 and a crimson clover cover crop in the fall of 2023 ahead of corn planted in 2024 using the same field in a static plot design at Urbana, IL. At termination of the cover crops in each spring, the residues were treated chemically with ammonium thiosulfate (ATS, 12-0-0-26S) to provide 9 lbs acre-1 nitrogen (N) and 20 lbs acre-1 sulfur (S), and biologically with either sugar + humic acid (NeoVita™ 43 and Hydra-Hume) or with a microbial blend (Residuce Complete). Both biological treatments were evaluated alone and in combination with ATS, and all chemical × biological sprays were evaluated across the standard and chopped harvested stover of the initial corn-crop. The yield penalty for untreated cereal rye residue on soybean was 10 bu acre-1 (11%) when implemented across the standard harvest method and 5 bu acre 1 (6%) when applied following the chopped harvest method, while untreated crimson clover residue had a 9 bu acre-1 (3.4%) yield penalty on corn in the standard harvest method system and 11 bu acre-1 (4.2%) in the chopped. The ATS treatment decreased the decomposition of both cereal rye and crimson clover residue and delayed their nutrient release during the vegetative growth of both soybean and corn but tended to increase both soybean and corn yields. Conversely, sugar + humic acid tended to increase residue decomposition and nutrient release, while the microbial blend had relatively little effect, and neither biological treatment nor harvest method increased yield. Yield improvements associated with ATS were linked to increased seed numbers, reflecting a positive early growth response. These findings suggest that while chopping corn stover and applying biological treatments can enhance residue decomposition and nutrient cycling, ATS is more effective at reducing the yield penalties associated with cover crops.

Graduation Semester

2025-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129274

Copyright and License Information

Copyright 2024 Dalton Knerrer

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