Research Project: Agronomic and Engineering Solutions for Conventional and Organic Conservation Agricultural Systems in the Southeastern U.S.

Location: Soil Dynamics Research

2024 Annual Report

Objectives
1. Optimize cropping system best management practices, based on long-term research data, and accounting for variable weather conditions, for single and mixed species high-residue cover crops in cotton, corn, peanut, soybean, and vegetable cropping systems. 1A. Evaluate single and mixtures of cereal, legume, and Brassica cover crop species on weed suppression (herbicide resistant and troublesome weeds) in vegetable and row crop production systems, including organic. 1B. Determine optimal cover crop performance across different management strategies to develop best management practices (BMPs) for cover crops. 1C. Develop and evaluate UAV technology to improve the production efficiency and reduce the environmental impact of agricultural operations in a variety of physical settings (i.e. row crop, turfgrass, forestry, high-tunnel), including improved detection (i.e. crop pests, ground cover status, nutrient status), conducting precision pesticide applications to optimize chemical usage and efficacy, conducting field operations such as cover crop seeding and monitoring environmental conditions to enhance system sustainability. 2. Develop cover crop termination and smallholder no-till equipment engineering solutions to enhance soil quality in conventional and organic production systems. 2A. Develop no-till equipment including rollers/crimpers, planters, and transplanters for small farming operations to reduce manual labor and increase work efficiency using both 2-wheel walk-behind and a category 1 hitch Oggun 4-wheel limited resource light tractor. 3. Enhance and develop innovative, economically feasible, sustainable, and resilient pasture and forage-based production systems for the Southeastern U.S. 3A. Determine the feasibility of using plant growth promoting rhizobacteria for a sustainable production system of forage crops and pastures that is resilient to the changing southern climate. 3B. Develop an integrated pest and input management system for improved production of forages and pastures that promote ecosystem service.

Approach
Southeastern row crop and specialty crop producers are challenged to adopt and/or maintain conservation tillage systems due to increasing production costs, threats due to pests, and equipment limitations. Due to soil health and productivity concerns, crop and livestock producers in the Southeastern U.S. who grow cover crops or forages are requesting optimized best management practices and scientifically sound data to maximize return on investment (ROI). Producers of all farm sizes desire to increase production efficiency, specifically in innovative ways to reduce the time, labor, and other costs associated with planting cover and crops, while enhancing the benefits of including cover crops in production systems. In addition, livestock producers desire improving forage quantity and quality. Concomitantly, the region’s producers are struggling with emerging pest issues including herbicide resistant weeds. Our objectives systematically examine three conservation systems and forage systems objectives to develop integrated, robust, and dynamic best management practices in Southeastern U.S. crop and livestock production operations to improve soil health and agroecosystem sustainability under variable conditions. Our objectives include: (1) Optimize cropping system best management practices, based on long-term research data, and accounting for variable weather conditions, for single and mixed species high-residue cover crops in cotton, corn, peanut, soybean, and vegetable cropping systems, (2) develop cover crop termination and smallholder no-till equipment engineering solutions to enhance soil quality in conventional and organic production systems and (3) enhance and develop innovative, economically feasible, sustainable, and resilient pasture and forage- based production systems for the Southeastern U.S. The success of these three objectives will benefit producers directly through equipment advances for large- and small-scale producers, management techniques to maximize cover crop benefits associated with improved soil health, and improved pasture and forage-based systems. Entities, including other government agencies and university extension services, will also benefit through access to scientifically based results and recommendations related to conservation systems that can be transferred to various clientele.

Progress Report
Experiments have been established for numerous experiments designed to examine how cover crop management affects cover crop benefits and challenges in corn, cotton, peanut, soybean and specialty crops. Experiments are also established that include comparisons between single cover crop species and multi-species cover crop mixtures for soil C levels, microbial activity, and weed suppression across various cropping systems. In addition, experiments evaluating cover crop termination and transplanting machinery design have been established. A collection of beneficial microorganisms including strains of plant-growth-promting fungi (PGPR) and Trichoderma species were made through isolations in the Southeast Area. The initial identifications of the strains were conducted with one set of primer for sequencing and further characterization is ongoing. Greenhouse experiments have been established evaluating PGPR strains for bermudagrass and tall fescue growth enhancement and nutrient use efficiency. Technology transfer activities have continued, which are related to many facets of all the previously described research.

Accomplishments
1. Planting date is critical for grass cover crop performance. Summer crop harvest can interfere with fall cover crop planting, and many growers, as expected, prioritize harvest before cover crop planting. However, delaying cover crop planting reduces biomass production and associated benefits. Growers may increase seeding rates and/or apply more N to enhance grass cover crop biomass production and offset environmental constraints imposed by planting late. Both factors increase production costs, while limited research exists to show these costly inputs can enhance cover crop biomass production for late planting periods. ARS researcher in Auburn, Alabama, Raleigh, North Carolina, and a cooperator from Auburn University, investigated how planting dates, seeding rates, and N rates affected rye biomass production. Environmental constraints of delaying the rye planting date decreased biomass production; therefore, planting rye early, regardless of additional inputs, was imperative to enhance biomass production. These cover crop management guidelines have been presented at numerous grower meetings to illustrate how management affects rye biomass and can maximize the return on investment associated with cover crop production costs.

2. Integrating cover crops and herbicides increases weed control in soybean. The evolution of herbicide-resistant and troublesome weeds has become a significant management challenge for soybean growers. The issue of rising herbicide costs for managing weeds is a great concern, leading to increased cover crop utilization as an integrated weed management strategy for addressing these challenges. An ARS researcher in Auburn, Alabama, conducted field experiments evaluating winter cereal cover crops including cereal rye, crimson clover, oat, radish, and a four-way mixture, and herbicide system integration in soybean. Cereal rye and the cover crop mixture provided weed biomass reduction compared to other cover crop or winter fallow treatments. Furthermore, we observed higher soybean yield following cereal rye than the winter fallow treatment. Herbicide programs including a postemergence and preemergence + postemergence herbicide resulted in lower weed biomass and increased soybean yield compared to a preemergence herbicide used alone or the non-treated check. These results are being shared with growers illustrating how cover crop management can maximize the return on investment associated with cover crop production costs.

3. Recurring rolling/crimping improved termination of iron clay pea and pearl millet summer cover crops and promotes soil moisture retention. In the southern United States using summer cover crops is essential for continuous soil protection after specialty crop harvest. An ARS researcher in Auburn, Alabama, conducted field experiments evaluating summer annual cover crops iron clay pea and pearl millet desiccation rate after single, double, and triple rolling/crimping utilizing a 2-stage roller/crimper. Iron clay pea was planted on a sandy loam and pearl millet was planted on a clay soil. Overall, termination rates for both cover crops were higher for rolling three times, compared to rolling once or twice. Rolling for both cover crops provided higher soil-water conservation compared with the non-rolled control due to mulching effect from soil coverage. Recurrent rolling on the same area showed only minimal increases in soil strength, which was dependent on soil moisture content.

4. Cover crops promote collard production and increase soil quality. Specialty crop producers utilize cover crops to improve soil quality, suppress weeds, and conserve moisture after termination. Cover crop termination methods vary with respect desiccation success and transplanting seedling plants through residue is challenging due to residue interference and transplants requiring ideal soil placement. An ARS researcher in Auburn, Alabama, conducted field experiments evaluating two different cover crops (iron clay pea and pearl millet) following three different termination methods (rolled/crimped, mowed, and mowed/soil incorporated through surface tillage) on soil properties and collard yield. A patented residue manager attachment was also evaluated. Collard yield was not affected by the residue manager. Overall increases in soil quality were measured following all cover crop management treatments. Collards grown following iron clay pea cover crop produced higher yields for all growing seasons compared to those grown in pearl millet.

5. Plant growth promoting rhizobacteria increase nutrient use efficiency and integrated pest management in bermudagrass, corn, cotton and tall fescue. The technology to utilize microorganisms as supplements or alternatives to poultry litter and synthetic fertilizer in plant production and pest management is gaining more acceptance but the technology needs further development to improve efficacy. One of the strategies to achieve improved efficacy is to combine multiple effective strains into microbial blends. An ARS researcher in Auburn, Alabama, in collaboration with scientists at Auburn University evaluated multiple microbial blends in the greenhouse for growth promotion of bermudagrass, tall fescue, corn, and cotton. Blends were also examined for effects on the development and gut microbiota of corn earworm (Helicoverpa zea) and tobacco budworm (Chloridae virescens). One blend microbial blend promoted the growth of bermudagrass and tall fescue, three blends promoted the growth of both corn and cotton while two blends resulted in significant reduction in the larval weight for both insect species compared to the control and caused changes in the taxonomic diversity and evenness of H. zea gut microbiota.

Review Publications
Malhotra, K., Lamba, J., Way, T.R., Williams, C., Karthikeyan, K.G., Budhathoki, S., Prasad, R., Srivastava, P., Zheng, J. 2024. Preferential flow of phosphorus and nitrogen under steady-state saturated conditions. Vadose Zone Journal. 23:e20331. https://doi.org/10.1002/vzj2.20331.
Adesemoye, A.O., Kodati, S., Watts, D.B., Maharjan, B. 2023. Differential shifts in microbiome and pathogen populations associated with suppressive soil in long-term continuous corn field compared to rotation corn field. Applied Soil Ecology. 192:105093. https://doi.org/10.1016/j.apsoil.2023.105093.
Kichler, C.M., Kornecki, T.S., Torbert III, H.A., Watts, D.B., Prasad, R. 2023. Cover crop termination methods and custom residue manager effects on collard production. Agronomy. 13:2595. https://doi.org/10.3390/agronomy13102595.
Kavetskiy, A.G., Yakubova, G.N., Prior, S.A., Torbert III, H.A. 2024. Carbon analysis of large soil samples using the tagged neutron method: Accounting for radiation attenuation. Applied Radiation And Isotopes. 209:111332. https://doi.org/10.1016/j.apradiso.2024.111332.
Prior, S.A., Runion, G.B., Murphy, A., Hoffman, H., Johnson, M.G., Torbert III, H.A. 2023. Influence of biochar addition to nursery container media: Trace gas efflux, growth, and leachate N. Journal of Environmental Horticulture. 41(4):141-151. https://doi.org/10.24266/0738-2898-41.4.141.
Ayelo, P.M., Adesemoye, A.O., Xiong, C., Fadamiro, H.Y. 2024. Plant growth-promoting rhizobacteria differently influence crops growth and physiology depending on cultivar and rhizobacteria consortium’s composition. Biologia. https://doi.org/10.1007/s11756-024-01710-9.
Balkcom, K.S., Read, Q.D., Gamble, A. 2023. Rye planting date impacts biomass production more than seeding rate and nitrogen fertilizer. Agronomy Journal. 115(5):2351–2368. https://doi.org/10.1002/agj2.21418.
Huddell, A.M., Thapa, R., Needelman, B., Mirsky, S.B., Davis, A.S., Peterson, C., Kladivko, E., Law, E., Darby, H., Mcvane, J.M., Haymake, J., Balkcom, K.S., Reiter, M., Vangessel, M., Ruark, M., Well, S., Gailans, S., Flessner, M.L., Mulvaney, M.J., Bagavathiannan, M., Samuelson, S., Ackroyd, V., Marcillo, G., Abendroth, L.J., Armstrong, S.D., Asmita, G., Basche, A., Beam, S., Bradley, K., Canisares, L.P., Devkota, P., Dick, W.A., Evans, J.A., Everman, W.A., Ferreira De Almeida, T., Fultz, L.M., Hashemi, M., Helmers, M.J., Jordan, N., Kaspar, T.C., Ketterings, Q.M., Kravchenko, A., Lazaro, L., Ramon, L.G., Liebert, J., Lindquist, J., Loria, K., Miller, J.O., Nkongolo, N.V., Norsworthy, J., Parajuli, B., Pelzer, C., Poffenbarger, H., Poudel, P., Ryan, M.R., Sawyer, J.E., Seehaver, S., Shergill, L., Upadhyaya, Y.R., Waggoner, A.L., Wallace, J.M., White, C., Wolters, B., Woodley, A., Ye, R., Youngerman, E. 2024. U.S. cereal rye winter cover crop growth database. Scientific Data. 11. Article. https://doi.org/10.1038/s41597-024-02996-9.
Kaur, P., Lamba, J., Way, T.R., Balkcom, K.S., Sanz-Saez, A., Watts, D.B. 2024. Characterization of soil pores in strip-tilled and conventionally-tilled soil using X-ray computed tomography. Soil and Tillage Research. 239:106035. https://doi.org/10.1016/j.still.2024.106035.
Kaur, P., Lamba, J., Way, T.R., Sandhu, V., Balkcom, K.S., Sanz-Saez, A., Watts, D.B. 2023. Cover crop effects on X-ray computed tomography-derived soil pore characteristics. Journal of Soils and Sediments. 24:111-125. https://doi.org/10.1007/s11368-023-03596-7.
Young, S.L., Anderson, J.V., Baerson, S.R., Bajsa Hirschel, J.N., Blumenthal, D.M., Boyd, C.S., Boyette, C.D., Brennan, E.B., Cantrell, C.L., Chao, W.S., Chee Sanford, J.C., Clements, D.D., Dray Jr, F.A., Duke, S.O., Porter, K.M., Fletcher, R.S., Fulcher, M.R., Gaskin, J., Grewell, B.J., Hamerlynck, E.P., Hoagland, R.E., Horvath, D.P., Law, E.P., Madsen, J., Martin, D.E., Mattox, C.M., Mirsky, S.B., Molin, W.T., Moran, P.J., Mueller, R.C., Nandula, V.K., Newingham, B.A., Pan, Z., Porensky, L.M., Pratt, P.D., Price, A.J., Rector, B.G., Reddy, K.N., Sheley, R.L., Smith, L., Smith, M., Snyder, K.A., Tancos, M.A., West, N.M., Wheeler, G.S., Williams, M., Wolf, J.E., Wonkka, C.L., Wright, A.A., Xi, J., Ziska, L.H. 2023. Agricultural Research Service weed science research: past, present, and future. Weed Science. 71(4):312-327. https://doi.org/10.1017/wsc.2023.31.
Kumari, A., Price, A.J., Gamble, A., Li, S., Jacobson, A. 2024. Integrating cover crops and herbicides for weed control in soybean. Weed Technology. 38:1-8. https://doi.org/10.1017/wet.2024.24.
Watts, D.B., Horvath, T., Torbert III, H.A., Adesemoye, A.O. 2023. Effects of selected manure sources on runoff, soil loss, and nutrient transport. Applied Engineering in Agriculture. 39(6):565-572. https://doi.org/10.13031/aea.15651.
Alkhalifa, N., Tekeste, M., Jjagwe, P., Way, T.R. 2023. Effects of vertical load and inflation pressure on tire-soil interaction on artificial soil. Journal of Terramechanics. 112:19-34. https://doi.org/10.1016/j.jterra.2023.11.002.
Simmons, J.R., Ritchey, E.L., Sistani, K.R., Way, T.R., Coyne, M.S., Matocha, C.J. 2024. Spacing of subsurface poultry litter bands: Influence on maize performance and nitrogen use efficiency. Agronomy Journal. 116(3):1513-1527. https://doi.org/10.1002/agj2.21541.