Location: Crop Production Systems Research
2022 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
Under subobjective 1a, a study examining the effects of different numbers and combinations of cover crops on soil health was continued into its third year, with the planting of all different combinations of three cover crops (crimson clover, rye, and hairy vetch) in the fall. Cover crops were allowed to grow over the winter and terminated in late spring. The summer crop of corn was planted in May 2022. Post-harvest soil samples from last season were collected in the fall, and spring and mid-summer soil samples have been collected for the current season. Above ground cover crop biomass was also collected in the spring. Processing of these samples has been slowed due to a large backlog of samples. Soil samples from the fall, spring, and summer timepoints have been sieved. Extracellular enzyme assays have been completed for fall and spring samples, while enzyme assays on soils collected at the summer timepoint are in process. Other analyses (pH, moisture content, soil organic matter, microbial biomass, and community composition) have been delayed while more time sensitive assays are performed on backlogged samples from other studies.
Under subobjective 1B, the fourth year of the LTAR study continued with cover crop planting in the fall and cotton and sorghum planting in the spring by collaborators on the study. Spring soil sample collection was missed due to a combination of weather conditions, work restrictions, and scheduling conflicts with sample collection for other studies. Fall soil sample collection will be conducted to be consistent with last year’s sampling schedule.
Under subobjective 2B, the first year of a study examining soil health in 2,4-D+glyphosate resistant soybean was initiated. Soybean was planted in the spring. Due to high variability in the rate of development, soybean plants in the field were at the V4-V6 developmental stage at the time of herbicide treatment application. Most soybean plants in the field had reached the R1-R2 developmental stage by one week after the application. Since the 2,4-D label dictates that applications should be at least one week apart and that 2,4-D should not be applied after R2, a second application was not made. Bulk soil samples were collected at planting, and both bulk and rhizosphere soils were collected one week after herbicide application. All rhizosphere soil samples were analyzed for extracellular enzyme activities. Processing bulk soil samples for soil enzyme assays is in progress. All other soil analyses (pH, moisture content, soil organic matter, microbial biomass, and community composition) are pending the completions of time sensitive assays on backlogged samples.
Accomplishments
1. Effects of tillage and two-species cover crop treatment on soil health and soybean yield. Agricultural production of row crops can have negative effects on soil health. Cover crops can be planted in the winter between summer cash crops, such as corn, cotton, and soybean, to reduce erosion, preserve soil moisture and nutrients, and promote the growth of soil microorganisms involved in nutrient cycling. However, some farmers are reluctant to use cover crops due to their added costs and potential to decrease yield of the main crop. Using different types and combinations of cover crops may help counteract the negative effects on yield while still enhancing soil resources. ARS researchers in Stoneville, Mississippi, conducted a study comparing the effects of one- and two-species cover crop treatments on soil health and crop yield in tilled and no-till soybean fields. This research showed that using both rye and clover as cover crops increased the microbial activities involved in processing nutrients more consistently than cover cropping with rye only. No-tillage was also found to decrease the negative effects that cover crops had on soybean yield. These results can be used to guide future studies to determine better cover crop treatments to optimize yield and to make recommendations to farmers on to manage cover crops in their fields.
Review Publications
Tyler, H.L. 2021. Single- versus double-species cover crop effects on soil health and yield in Mississippi soybean fields. Agronomy. 11:2334. https://doi.org/10.3390/agronomy11112334.
Mubvumba, P., Delaune, P.B., Hons, F.M. 2022. Enhancing long-term no-till wheat systems with cover crops and flash grazing. Soil and Tillage Research. Soil Security p.100067. https://doi.org/10.1016/j.soisec.2022.100067.
