Location: Crop Production Systems Research
2019 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
A long-term agroecosystem research experiment was established to examine the effects of cover crop, tillage, and crop rotation on soil health. Treatments included all combinations of the following: cover crop (winter pea) or no cover crop, till or no till, and cotton, sorghum, or cotton-sorghum rotation. The cover crop was planted in October of 2018, allowed to grow over the winter, and terminated in early May 2019. In mid-May, plots were planted with summer crops of either cotton or sorghum. Baseline soil samples were collected shortly after cover crop planting in November 2018, and spring soil samples were collected at planting in May 2019. Preparation for the mid-summer sampling time point is underway. All soil samples were sieved and analyzed for pH, moisture content, soil organic matter, and extracellular enzyme activities (phosphatase, beta-glucosidase, N-acetylglucosamindase, cellobiohydrolase, and fluorescein diacetate hydrolysis). In addition, chloroform fumigation and extraction was performed on each sample for the determination of microbial biomass, and these extracts are awaiting quantification. Aliquots from each soil were set aside and frozen prior to sieving for later microbial community analysis. Remaining soils from each sample were provided to collaborating scientists for nutrient analyses.
A three-month lab incubation experiment to examine the effects of different rates of 2,4-dichlorophenoxyacetic acid (2,4-D) application on bulk soil was postponed to January of 2020, owing to disruption from the government shutdown in January 2019 when the experiment was originally planned to be initiated. Also, the first year of a field study was initiated to examine the effects of 2,4-D+glyphosate application on the microbial communities in bulk soil and rhizosphere soil of corn plants resistant to both of these herbicides. Corn was planted in mid-March, and treatments of 2,4-D+glyphosate, 2,4-D alone, and no herbicide control were applied in mid-April and again in mid-May. Baseline bulk soil samples were collected at planting, and both rhizosphere and bulk soil samples were collected approximately one week after each herbicide application. Soil organic matter, moisture content, and pH were determined in all bulk soil samples. Both bulk and rhizosphere soils were analyzed for extracellular enzyme activities. Aliquots form baseline bulk soil and rhizosphere soil were frozen for later deoxyribonucleic acid (DNA) extraction and sequencing to determine microbial community composition. Bulk soil samples will also be collected at harvest.
Accomplishments
Review Publications
Tyler, H.L., Locke, M.A. 2019. Effects of weed management on soil ecosystems. In: Korres, N.E. Burgos, N.R., Duke, S.O., editors. Weed Control: Sustainability Hazards, and Risks in Cropping Systems Worldwide. Boca Raton, Florida: Taylor & Francis Group. p. 32-61.
Haron, M.H., Tyler, H.L., Chandra, S., Moraes, R.M., Jackson, C.R., Pugh, N.D., Pasco, D.S. 2019. Plant microbiome-dependent immune enhancing action of Echinacea purpurea is enhanced by soil organic matter content. Scientific Reports. 9:136.
Tyler, H.L. 2019. Bacterial community composition under long-term reduced tillage and no till management. Journal of Applied Microbiology. 126:1797-1807.
