Winter rye cover crop seeding rate and termination timing effects on cover crop biomass and quality

Authors: BROCKMUELLER, BEN - South Dakota State University; SEXTON, PETER - South Dakota State University; Osborne, Shannon; CHIM, BEE KHIM - University Of Maine

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2023
Publication Date: 6/6/2023
Citation: Brockmueller, B., Sexton, P., Osborne, S.L., Chim, B. 2023. Winter rye cover crop seeding rate and termination timing effects on cover crop biomass and quality. Communications in Soil Science and Plant Analysis. https://doi.org/10.1080/00103624.2023.2221299.
DOI: https://doi.org/10.1080/00103624.2023.2221299

Interpretive Summary: Incorporation of cover crops into conservation systems including no-till and diverse rotations has demonstrated potential to improve soil biogeochemical parameters, enhance crop production, and promote ecosystem services. Integrating a winter rye cover crop has shown to achieve these goals in many Upper Midwest areas but their adoption is limited and under-studied in the Northern Plains area. Two separate field studies located in eastern South Dakota were conducted to evaluate how rye seeding rates and termination timings impact rye biomass, nutrient and fiber composition important for nutrient cycling. Rye biomass was strongly influenced by climatic conditions. It was evident from this study that both seeding rates and termination timing impacted both biomass and quality of rye with all other factors being equal. The most dramatic differences in biomass were achieved from altering termination timings. Increases in carbon to nitrogen ratio and concentrations of cellulose and lignin in rye tissues were observed as seeding rate increased and termination date delayed. Results of this study indicate that delaying termination has a stronger impact on rye biomass and quality than altering seeding rates. Ultimately, both seeding rate and termination timing may be used to help manage winter rye to effectively meet cover cropping goals.

Technical Abstract: Managing winter rye (Secale cereale L.) cover crop biomass and residue quality plays an integral role in achieving environmental and agronomic success. Two independent studies located in South Dakota examined 1) five rye seeding rates and 2) five rye termination timings to determine the effects of winter rye management on plant parameters influencing nutrient cycling. Plant samples were collected to evaluate changes in biomass, nutrient content, and quality. Rye biomass production increased at the seeding rates of 90 kg ha-1, and 67% of total rye biomass accrued between May 13 (819 GDD) and rye bootstage on May 30 (GDD 1084). Increases in C:N ratio and concentrations of cellulose and lignin in rye tissues were observed as seeding rate increased and termination date delayed. A strong inverse correlation was noted among rye fibrous components and nutrient concentrations with crude fiber and cellulose showing a negative relation to nitrogen (N) (r = -0.81, -0.79 respectively). Nitrogen, phosphorus and sulfur concentrations were negatively correlated with rye cellulose content, suggesting that nutrient cycling is likely to slow down at higher levels of cover crop biomass accumulation Results of this study indicate that delaying termination has a stronger impact on rye biomass and quality than altering seeding rates. Yet, lowering seeding rates of rye could be used to cycle nutrients quicker without sacrificing biomass production.