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

Location: Soil Dynamics Research

2025 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
ARS researchers in Auburn, Alabama conducted ongoing 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 are ongoing. A collection of beneficial microorganisms including strains of PGPR and Trichoderma species were made through isolations in the Southeast Area. Greenhouse and field experiments have been ongoing evaluating PGPR strains for bermudagrass and tall fescue growth enhancement and nutrient use efficiency. Foundational agreements and purchases are moving forward that will facilitate drone research progress. Significant progress has been made in developing custom designed swarm UAVs to enable low-cost autonomous agricultural crop monitoring. In addition, new methods to collect and process datasets and models to enhance plant recognition using low-cost drones as well as new methods for autonomous, unified, focus-assisted navigation have been developed for UAVs for agricultural field operations have been developed. Technology transfer activities have continued, which are related to many facets of all the previously described research.

Accomplishments
1. Winter cover crop grazing produced mixed effects on soil health and crop yield. Integrated crop-livestock systems promote income diversification through cover crop grazing on degraded soils of the southeastern United States, but effects of these practices on crop yields and soil health in Coastal Plain soils are not well established. Collaborators from Auburn Univ. and an ARS scientist in Auburn, AL investigated effects of grazing intensity on cover crop biomass, chemical, physical, and biological soil health indicators, and crop yield. Longer regrowth periods following moderate grazing produced the greatest biomass levels with no adverse effects on soil physical properties, but biomass levels were below no grazing levels. Extended grazing periods negatively affected soil physical properties, specifically soil strength and aggregate stability. Biological soil health indicators were not affected by grazing duration, but chemical indicators, such as soil organic carbon was greater for no grazing compared to the longest grazing period. Results suggest Coastal Plain producers may adopt integrated crop-livestock systems with proper management to maximize economic advantages from cover crops while simultaneously preserving or enhancing soil health benefits.

2. Nitrogen credits following peanut. Throughout the peanut growing region of the US, Cooperative Extension Services recommend a N credit to crops following peanut between 22 and 67 kg N/ha. Since peanut is a legume, there is an assumption that peanut contributes N to the following crop. However, collaborators from Univ. of Florida and an ARS scientist in Auburn, AL found N credits from peanut to the next crop were negligible based on an examination of related peer-reviewed literature. Crop yield differences following peanut compared to non-legumes likely results from non-legume crop residue favoring N immobilization (N reduction) rather than N mineralization (N credit) from a previous peanut crop. Recommendations should be revised to decrease N credits following peanut, if recommended at all. These findings highlight that correctly applying N credits through N recommendations ensures N under-fertilization of the following crop does not occur, which can significantly reduce grower yields and profits. Cover crops suppress weed growth and reduce reliance on chemical herbicides. Collaborators from Auburn Univ. and an ARS scientist in Auburn, AL conducted greenhouse and field experiments to evaluate the emergence and growth response of troublesome southeastern weeds to various cereal rye residue levels. In the greenhouse Palmer amaranth, sicklepod , ivyleaf morningglory, and large crabgrass were covered uniformly by four different levels of cereal rye biomass. A similar field experiment was conducted, and in both greenhouse and field conditions, increasing the biomass of cereal rye residue is effective in suppressing Palmer amaranth seed emergence but not ivyleaf morningglory. These results will be used in guidelines for weed management and subsequent retention of conservation systems throughout the U.S.

3. Integrated insect pest management utilizing rhizobacteria to promote synthetic pesticide reduction. Integrated insect pest management strategies utilizing rhizobacteria can help reduce the negative impacts following long-term use of inorganic fertilizers and pesticides while maintaining high plant yields. An ARS scientist from Auburn, Alabama collaborated with researchers at Texas A&M determining the mechanism and ecological ramifications of rhizobacterial mediated plant-insect interactions to enhance plant health. Two bacterial blends were found to significantly reduce the growth of two highly important insect pests - corn earworm (Helicoverpa zea) and tobacco budworm (Chloridae virescens) and reduce the larval weight and development compared to the control. The bacterial blends also caused changes in the taxonomic diversity and evenness of H. zea gut microbiota. Thus, the bacteria blends proved to be very good candidates for the control of the two important pests. These results reveal candidates that could be used in potential bio-pesticide products.

U.S. DEPARTMENT OF AGRICULTURE

Soil Dynamics Research: Auburn, AL