Location: Crop Production Systems Research
2023 Annual Report
Objectives
Objective 1. Evaluate different cover crop species, tillage practices, and management strategies for increasing soil health and crop productivity.
Sub-objective 1A. Determine the effects of different cover crop combinations on soil health and crop yield in corn production systems.
Sub-objective 1B. Assess the long-term impact of crop rotation, cover crop, and no till practices on soil health.
Objective 2. Determine the impact of 2,4-D on soil health in corn, cotton, and soybean production systems.
Sub-objective 2A. Assess the potential impacts of 2,4-D+glyphosate application on biological parameters in bulk soil.
Sub-objective 2B. Evaluate the efects of 2,4-D+glyphosate application on soil biological parameters in corn, cotton, and soybean systems.
Approach
Agricultural management practices, such as tillage and herbicide application, can have detrimental effects on soil quality that may ultimately impose limitations on sustained crop production. As such, better management practices are needed in modern cropping systems that promote soil health while sustaining optimum crop yields. Cover crops have gained increased attention as a way to promote soil heath and water quality through reduced soil erosion, improved soil tilth and organic matter, and enhanced activity of microbial communities in soil. Cover crop use in the Mid-South United States has been limited, but farmers in the region are beginning to show an interest in incorporating them as a management practice to improve soil health and ensure sustainable production. Proposed research will evaluate how different types of cover crops impact key aspects of soil health and row crop yields, including corn, cotton, and sorghum. With this knowledge, recommendations can be made to farmers on what cover crop combinations are best for improving soil health while optimizing crop production in the Mid-South region. Agricultural systems also face the challenge of controlling glyphosate resistant weed populations. New cropping systems tolerant to both glyphosate and 2,4- dichlorophenoxyacetic acid (2,4-D) are being introduced as a way to combat glyphosate- resistant weeds. However, herbicides have the potential to inhibit microbial populations, and there is limited information available on how 2,4-D might impact soil health. Thus, this research will examine impacts of 2,4-D+glyphosate on soil health in cotton, corn and soybean systems under field conditions. This project will result in guidelines for practices that ensure long-term sustainability of soil health while maintaining optimal crop production.
Progress Report
This is the final report for project 6066-12220-006-000D, which terminates on August 1, 2023. Owing to a combination COVID-19 related work restrictions and weather conditions, many of the experiments planned under this project were prolonged an extra year or postponed, leading to sample processing backlogs and scheduling conflicts between studies planned toward the end of the 5-year project period. As a result, two experiments under Subobjective 2B are still in progress.
Meaningful results were obtained from the experiments that were completed during the project period. Under Subobjective 1A, a four-year field study was conducted to examine the effects of cover crop, tillage, and crop rotation on soil health in cotton and sorghum production systems. The results of this study indicate that increasing plant diversity in cropping systems, either by winter cover cropping or summer crop rotation, can enhance soil health, and that sorghum yield increases in response to these management practices while cotton yield is unaffected. The manuscript reporting results of this study is currently under preparation. Under Subobjective 1B, a three-year field study was conducted to determine the effects of different numbers and combinations of cover crop species, including crimson clover, hairy vetch, and cereal rye, on soil health in a corn production system. The results of this study indicate cover crop treatments that included two plant species were no less effective at enhancing microbial activities in the soil than three-species treatments, and that both two- and three-species cover crop treatments increased total nitrogen, phosphorus, and organic carbon in soil, while the three-species cover crop treatment had in the lowest corn yield. Under Objective 2, three field studies were planned to determine the impact of 2,4-D on soil health in corn, soybean, and cotton production systems. The study examining the effects of 2,4-D on corn was completed after being delayed an extra year, while the studies on soybean and cotton are still in progress. The results from the current data available from Objective 2 indicate 2,4-D application can simulate the activity of multiple enzymes in the top layer of bulk soil, while there were no significant effects of 2,4-D application in the rhizosphere. As this is the final year of the current project, a new 5-year project plan has been written that includes continued studies on cover crops and 2,4-D applications and is currently under review.
Accomplishments
1. Effectiveness of cover crop mixes to promote soil health and minimize yield loss in corn production systems. Winter cover crops can relieve the negative effects that agricultural production has on soil quality and the surrounding environment by decreasing the need for fertilizers and providing natural weed control. However, planting a winter cover crop increases a farmer’s costs and can decrease the summer crop’s yield. Careful selection of cover crop plant species and using mixtures of different cover crops may enhance soil health, improve the release of nutrients back into the soil, and decrease yield inhibition. ARS researchers in Stoneville, Mississippi, conducted a field study on commonly used cover crop species in the region to determine the effects of one, two, and three species mixes on microbial activities in soil, soil nutrient levels, and corn yields. This research showed that two- and three-species cover crop mixes were equally as effective at enhancing microbial activities in soil and increased levels of total nitrogen, phosphorus, and organic carbon in soil by up to 35%. This research also found that cover crop treatments containing only legumes did not inhibit corn yield. These results can be used to make cover crop recommendations to farmers and suggests that a using a grass-legume cover crop mix may provide a balance between soil nutrient enhancement with minimal loss in corn yield.
2. Benefits of crop rotation in cotton and sorghum production compared to no-tillage and winter cover cropping. Row crop production in the Mississippi Delta predominantly involves a mono-culture approach of growing the same crop in the same field repeatedly over several years while tilling the soil and leaving fields bare over the winter months. However, this approach can result in increased erosion, decreased soil health, depletion of soil nutrients, increased need for fertilizers, and ultimately, reduced sustainability for long-term crop production. Incorporating conservation practices such as decreased tillage, summer crop rotation, or planting a cover crop in the winter may improve long-term sustainability in these systems. ARS researchers in Stoneville, Mississippi, conducted a four-year field study to determine the effects of sustainable versus traditional agricultural management practices on soil health and crop yield in cotton and sorghum production systems. This research showed that adding sorghum in rotation with cotton enhances microbial nutrient cycling activities in soils compared to when cotton was grown as a monoculture and that winter cover cropping increased organic matter in field soils by 14%. While cotton yield was not impacted by management, sorghum yield increased 16% when grown with winter cover crops and 28% when grown in rotation with cotton. These results suggest that rotating different plants in a field by either winter cover cropping or summer crop rotation can be an effective tool for farmers to enhance soil health and potentially increase yield in select crops.
Review Publications
Mubvumba, P., Delane, P.B. 2022. Water quality effects of cover crop implementation or tillage in a long-term no-till wheat system. Soil & Tillage Research. 225. Article 105547. https://doi.org/10.1016/j.still.2022.105547.
Kumar, C., Mubvumba, P., Huang, Y., Dhillon, J., Reddy, K.N. 2023. Multi-stage corn yield prediction using high-resolution (UAV) multispectral data and machine learning models. Agronomy Journal. 13(5):1277. https://doi.org/10.3390/agronomy.
Kharel, T.P., Bhandari, A.B., Mubvumba, P., Tyler, H.L., Fletcher, R.S., Reddy, K.N. 2023. Mix species cover crop biomass estimation using planet imagery. Sensors. https://doi.org/10.3390/s23031541.
Pinnamaneni, S.R., Mubvumba, P., Anapalli, S., Reddy, K.N. 2022. Cereal rye cover crop impacts on soybean (Glycine max L.) root growth and soil properties. Frontiers in Soil Science. https://doi.org/10.3389/fsoil.2022.970380.
Parys, K.A., Davis, K.A., James, S., Davis, J.B., Tyler, H.L., Griswold, T.L. 2022. First report of a gynandromorph of Florilegus condignus (Cresson, 1878) (Hymenoptera: Apidae), with notes on phenology and abundance. Journal of Hymenoptera Research. https://doi.org/10.3897/jhr.89.75857.
Hux, B.A., Delaune, P.B., Schirmarcher, M.T., Gentry, T.J., Mubvumba, P. 2023. Winter cover crop impact on soil health and nutrients in texas rolling plains dryland cotton. Agriculture, Ecosystems and Environment. https://doi.org/10.1002/agg2.20352.
Tyler, H.L. 2022. Impact of 2,4-D and glyphosate on soil enzyme activities in a resistant corn cropping system. Agronomy. https://doi.org/10.3390/agronomy12112747.
