Research Project: Enhancing Sustainability of Mid-Atlantic Agricultural Systems Using Agroecological Principles and Practices

Location: Sustainable Agricultural Systems Laboratory

2021 Annual Report

Objectives
OBJECTIVE 1: Identify and elucidate agroecological principles that drive the function of grain and forage cropping systems and quantify ecosystem services. ' Sub-objective 1.A. Compare factors controlling crop performance in long-term organic and conventional cropping systems. ' Sub-objective 1.B. Evaluate soil function and ecosystem services in long-term organic and conventional cropping systems. ' Sub-objective 1.C. Identify factors controlling soil biological community structure and its relationship to soil functions and the provision of ecosystem services in organic and conventional cropping systems. ' Sub-objective 1.D. Conduct integrated analyses to assess the impacts of organic and conventional cropping systems on the provision of ecosystem services and overall system performance. OBJECTIVE 2: Develop technologies and management strategies to improve productivity, enhance soil and water conservation, improve efficiency of nutrient cycling and support food safety and nutritional security goals for grain-based and horticultural cropping systems. ' Sub-objective 2.A. Screen and breed cover crop germplasm to improve winter hardiness, biomass production and early vigor in legumes, grasses, and brassicas, and disease resistance and nitrogen fixation in legumes. ' Sub-objective 2.B. Develop optimal cover crop-based agronomic practices for improving nutrient and water availability and use efficiency, soil health, system resilience, production and economics in reduced-tillage field corn production. ' Sub-objective 2.C. Develop strategies to improve beneficial and safe use of organic amendments in horticultural crop production. OBJECTIVE 3: Collaborate with the Hydrology and Remote Sensing Laboratory to operate and maintain the Lower Chesapeake Bay LTAR network site using technologies and practices agreed upon by LTAR leadership. Contribute to LTAR working groups and common experiments. Submit relevant data with appropriate metadata to the LTAR Information Ecosystem.

Approach
Approaches to identifying and elucidating agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, and associated projects: crop performance, soil carbon sequestration and greenhouse gas fluxes, soil microbiological community structure, and integrated analyses that evaluate overall systems performance. Approaches to developing component strategies include: incorporating legumes into organic crop rotations to maximize nitrogen fixation, composting that provides a productive and safe amendment for organic agriculture, integrating cover crop and manure management practices, reducing tillage in organic systems.

Progress Report
Under Objective 1, the 25th and 7th years of research at the long-term Farming Systems Project (FSP) and Cover Crop Systems Project (CCSP), respectively, were completed, testing hypotheses about factors controlling crop yields and crop yield variability. Archived FSP soil and plant samples collected every five years are being analyzed to address questions about soil C sequestration, N retention, and P and K balances. Poultry litter reduction and soybean microplots within FSP are contributing data to test questions related to N and P balance and use efficiency and N fixation. Questions related to cropping systems impacts on soil microbial communities are continuing to be addressed through a data base of information from archived nucleic acid samples extracted from FSP and CCSP soils during the period from 2008 to 2019. Near-continuous soil water measurements continue to be collected from FSP and CCSP to determine effects of cover crops, weeds and nutrient management on soil moisture and corn production. Soil water and N data will be used to determine interactions between water and N availability and use efficiency. To address questions under Objective 2, cover crop breeding trial accessions have been evaluated for biological N fixation efficiency. A subset of promising accessions was evaluated directly for root-associated symbiotic bacteria. Nodule metagenomes were analyzed for 15 accessions of crimson clover. Research was also conducted on-farm to quantify the effects of intrinsic factors, management and their interactions on cover crop performance, corn grain yield, and N and water use efficiency. These data are being compiled for input into regionally specific data decision tools. Researchers in Beltsville, Maryland, along with collaborators nationwide created a system for real-time data acquisition, aggregation, analysis, and visualization (Internet of Things; IoT) to monitor crops, soils, and pests in many fields at once. The low-cost IoT systems: (1) quantify cash and cover crop quality and quantity over space; (2) detect water stress in corn and soybean crops; and (3) provide real-time continuous climate data (soil water, temperature, and humidity). These IoT systems transform the precision and scale (over both time and space) at which scientists can assess agricultural sustainability. Advancements this past year include the development of a multi-sensor forage box that uses LiDAR, multi-spectral, and ultrasonic sensors to estimate plant biomass and quality. The technology underwent the alpha phase testing before release to the national network. Also under Objective 2, ARS researchers in Beltsville, Maryland, along with collaborators from the University of Maryland Eastern Shore completed a two year field plot study on the Eastern Shore to assess three soil management factors—1) manure application methods (banding (bnd) vs. subsurface (ss) trenching); 2) poultry manure products (untreated litter (PL) vs. heat-treated poultry pellets (PP)); and 3) cover crops (hairy vetch (HV) vs. forage radish (FR)), with treatment combinations being: HV+PL-bnd, HV+PP-ss, FR+PL-bnd, and FR+PP-ss. The effect of these treatments on soil health was tested in soils cultivated with cantaloupes (Cucumis melon) and cucumbers (Cucumis sativus). Soil health indicators were determined at the beginning and end of the 2018 and 2019 summer growing seasons from each amended plot. In 2018, poultry litter amendments in combination with cover crops on average improved soil organic matter (175%), active carbon (2%), and cation exchange capacity (60%). In 2019, these treatments also improved these same parameters by 83.3%, 7%, and 4.25%, respectively. All effects were statistically significant. However, these improvements varied significantly (p=0.05) by manure product and cover crop combination. The application method had no significant effect (p>0.05) on these soil health parameters. Results of this study can contribute to development of a decision support tool for use by growers using poultry litter product amendments for soil improvement and health management in specialty crop production systems. These Eastern Shore field plots were also used to compare survival and transfer of E. coli from National Organic Program (NOP)-certified soils amended with PL products to cucurbits, table radish, and spinach. The focus was to determine if the 90- and 120-day wait time intervals between PL application and produce harvest were sufficient to prevent contamination of the edible produce. A cocktail of avirulent, environmental strains of E. coli resistant to rifampicin (Rif) was used as an indicator to assess E. coli survival, persistence, and transfer to harvestable crops grown in the amended soils. All amended soils were positive for the avirulent strains of Rif-resistant E. coli on Day 0 after inoculation (6 log MPN/g). On Day 90, the inoculated Rif-resistant E. coli was present in all plot soils (0.6 log MPN/g). On Days 120 and 150, concentrations declined significantly (p<0.05) to 0.01-0.10 log MPN/g in 2018. In 2019, E. coli persisted at 0.42-0.75 log MPN/g on day 120 but was still detectable in soil at 0.08-0.84 log MPN/g on day 150. Such prolonged soil persistence at these very low concentrations has been reported in several other collaborative studies conducted in the northeastern USA. These declines to very low levels coincided with temperature declines of ~16°C. No additional pathogens (Salmonella, Listeria monocytogenes, Staphylococcus aureus) were detected in the soils at Days 0, 90, or 120. The inoculated Rif-resistant E. coli was detected on 25% of cantaloupes, 25% of cucumbers, and 20% of radish bulbs harvested on Day 90 but not on Day 120 from plots amended with 6-month-aged PL. The 2019 spinach crop failed due to excessive rainfall and damping-off (untreated organic seed was used in these NOP-certified plots). The soil microbiome studies for these studies have been delayed due to laboratory access restrictions associated with the Covid-19 pandemic. Frozen soil samples will be used to determine microbiological community shifts associated with the PL amendments over time and by cover crop and placement of PL amendment. These initial results will be useful to risk assessors as they evaluate the appropriateness of the current NOP-program wait times between biological soil amendment application and produce harvest. Abstracts describing this research are being prepared for presentation at the 2021 (virtual) meetings of the American Society of Horticultural Science and the International Association of Food Protection. Under Objective 3, SASL scientists are conducting research that contributes to objectives for the Lower Chesapeake Bay (LCB) LTAR. ARS scientists provide leadership on the LCB LTAR Executive Committee and the LCB Croplands Common Experiment Working Group, two SASL scientists provide leadership for the Non-CO2 Greenhouse Gases and Soils Working Groups and a SASL scientist provides leadership for a nationwide Soil Biology Network (SBGx). The SBGx is working with the LTAR Network to facilitate implementation of a unified set of standardized techniques and protocols across all LTAR network sites. SASL scientists working on FSP are working closely with the Partnership for Data Innovations (PDI) to serve as a pilot project for uploading LTAR data to AgCROS for long-term data storage and to facilitate sharing of LTAR data.

Accomplishments
1. Legumes improve phosphorus and potassium balances in long-term organic crop rotations. Balancing nutrient inputs and outputs is a fundamental goal of agricultural sustainability, but this can be difficult to achieve when poultry litter is used to supply nitrogen for crops due to its high phosphorus content. USDA-ARS scientists in Beltsville, Maryland, used 13 years of data to compare the balance between inputs and exports of phosphorus and potassium in poultry litter-amended organic crop rotations at the Farming Systems Project. Including legume cover crops or forages and increasing crop rotation length/complexity increased nutrient export and non-poultry litter nitrogen inputs, thereby reducing poultry litter application rates, and improving phosphorus and potassium balances. These results will be of interest to organic and conventional farmers, nutrient management specialists and state and federal employees engaged in nutrient management policies.

2. Cold temperatures limit biological nitrogen fixation by winter legume cover crops. Winter annual legume cover crops can reduce the need for spring nitrogen fertilization via biological nitrogen fixation. However, cold fall temperatures in the northern regions of the U.S. can limit root growth and symbiotic bacterial establishment, thereby reducing the biological nitrogen fixation of these crops. In a pair of studies aimed to examine effects of cold temperatures on nodulation and nodule microbiome compositions in legume cover crops, researchers at the University of Minnesota and ARS researchers in Beltsville, Maryland, found that the lower limits of nitrogen fixation in three common cover crops [Hairy vetch (Vicia villosa), Austrian winter pea (Pisum sativa) and Crimson clover (Trifolium incarnatum)] were different and all species failed to establish symbiotic relationships with bacteria below an ambient temperature of 10°C. This is critical information to estimate annual winter cover crop nitrogen contributions and will be of interest to farmers, scientists, and policymakers considering nitrogen balance in cropping systems.

3. Grazing cover crops increases soil compaction. Grazing cover crops prior to planting summer cash crops offers an economic return to producers. However, grazing animals exert large pressures on soil, which can increase soil compaction that can limit root growth and potentially reduce crop yield. USDA-ARS scientists in Beltsville, Maryland, and Tifton, Georgia, compared the effects of spring grazing versus rolling to terminate a rye cover crop on soil compaction in a rye-cotton no-till cropping system in the Georgia Piedmont. Wet spring conditions during grazing resulted in an increase in soil strength (a measure of compaction) compared to rolling that decreased over time but were still present the following winter. Grazing cover crops under wet conditions presents a risk of short-term negative impacts even for southern Piedmont soils with improved soil quality from a long history of conservation tillage and cover cropping. These results will be of interest to farmers, crop management specialists, and state and federal employees promoting diversified crop-animal production systems.

Review Publications
Roberts, D.P., Vandenberg, B., Mirsky, S., Buser, M., Reberg-Horton, C., Short, N., Shrestha, S. 2020. How to feed the world. In: Wright, D.J., Harder, C., editors. Applying Mapping and Spatial Analytics. GIS for Science. Redlands, CA:Esri Press. p. 110-123.
Vaghefi, N., Kikkert, J.R., Bolton, M.D., Hanson, L.E., Secor, G.A., Nelson, S.C., Pethybridge, S.J. 2017. Global genotype flow in Cercospora beticola populations confirmed through genotyping-by-sequencing. PLoS One. 12(10): e0186488. https://doi.org/10.1371/journal.pone.0186488.
Kepler, R., Epp Schmidt, D.J., Yarwood, S.A., Cavigelli, M.A., Buyer, J.S., Duke, S.O., Reddy, K.N., Williams, M., Bradley, C.A., Maul, J.E. 2020. Soil microbial communities in diverse agroecosystems exposed to glyphosate. Applied and Environmental Microbiology. https://doi.org/10.1128/AEM.01744-19.
Endale, D.M., Schomberg, H.H., Franzluebbers, A.J., Seman, D.H., Franklin, D., Stuedemann, J.A. 2021. Runoff nutrient losses from tall fescue pastures varying in endophyte association, fertilization, and harvest management. Journal of Soil and Water Conservation. https://doi.org/10.2489/jswc.2021.00164.
Goodrich, D.C., Heilman, P., Anderson, M.C., Baffaut, C., Bonta, J.V., Bosch, D.D., Bryant, R.B., Cosh, M.H., Endale, D.M., Veith, T.L., Havens, S.C., Hedrick, A., Kleinman, P.J., Langendoen, E.J., Mccarty, G.W., Moorman, T.B., Marks, D.G., Pierson Jr, F.B., Rigby Jr, J.R., Schomberg, H.H., Starks, P.J., Steiner, J., Strickland, T.C., Tsegaye, T.D. 2020. The USDA-ARS experimental watershed network – Evolution, lessons learned, societal benefits, and moving forward. Water Resources Research. 57(2). Article e2019WR026473. https://doi.org/10.1029/2019WR026473.
Fernandez-Baca, C.P., Rivers, A.R., Maul, J.E., Kim, W., McClung, A.M., Roberts, D.P., Reddy, V., Barnaby, J.Y. 2021. Rice plant-soil microbiome interactions driven by root and shoot biomass. Diversity. https://doi.org/10.3390/d13030125.
Evett, S.R., O'Shaughnessy, S.A., Andrade, M.A., Colaizzi, P.D., Schwartz, R.C., Schomberg, H.H., Stone, K.C., Vories, E.D., Sui, R. 2020. Theory and development of a VRI decision support system: The USDA-ARS ISSCADA approach. Transactions of the ASABE. 63(5):1507-1519. https://doi.org/10.13031/trans.13922.
Lu, Y., Silveira, M.L., O'Connor, G.A., Vendramini, J.M., Erickson, J., Li, Y., Cavigelli, M.A. 2020. Biochar impacts on nutrient dynamics in a subtropical grassland soil - Part 1. N and P leaching. Journal of Environmental Quality. 49:1408-1420. https://doi.org/10.1002/jeq2.20139.
Lu, Y., Silveira, M.L., Cavigelli, M.A., O'Connor, G.A., Vendramini, J.M., Erickson, J., Li, Y. 2020. Biochar impacts on nutrient dynamics in a subtropical grassland soil - Part 2. Greenhouse gas emissions. Journal of Environmental Quality. 49:1421-1434. https://doi.org/10.1002/jeq2.20141.
Moore, V., Maul, J.E., Wilson, D., Curran, W., Brainard, D., Devine, T., Mirsky, S.B. 2020. Registration of 'purple bounty' and 'purple prosperity' hairy vetch. Journal of Plant Registrations. 14(3):340-346.
Marcillo, G.S., Mirsky, S.B., Aurelie, P., Reberg-Horton, S., Timlin, D.J., Schomberg, H.H., Ramos, P. 2020. Using statistical learning algorithms to predict cover crop biomass and nitrogen content. Agronomy Journal. 112(6):4898-4913. https://doi.org/10.1002/agj2.20429.
White, K.E., Brennan, E.B., Cavigelli, M.A. 2020. Soil carbon and nitrogen data during eight years of cover crop and compost treatments in organic vegetable production. Data in Brief. 33. Article 106481. https://doi.org/10.1016/j.dib.2020.106481.
Thapa, R., Tully, K.L., Cabrera, M.L., Dann, C., Schomberg, H.H., Timlin, D.J., Gaskin, J., Reberg-Horton, C., Davis, B.W., Mirsky, S.B. 2021. Effects of moisture and temperature on C and N mineralization from surface-applied cover crop residues. Biology and Fertility of Soils. 57:485-498. https://doi.org/10.1007/s00374-021-01543-7.
Schomberg, H.H., Endale, D.M., Balkcom, K.S., Raper, R.L., Seman, D.H. 2021. Grazing winter rye cover crop in a cotton no-till system: Soil strength and runoff. Agronomy Journal. 113(2):1271-1286. https://doi.org/10.1002/agj2.20612.
Moore, V., Davis, B., Maul, J.E., Kucek, L.K., Mirsky, S.B. 2020. Phenotypic and nodule microbial diversity among crimson clover (Trifolium incarnatum L.) accessions. Agronomy. 10(9):1434. https://doi.org/10.3390/agronomy10091434.
White, K.E., Cavigelli, M.A., Bagley, G. 2021. Legumes and nutrient management improve phosphorus and potassium balances in long-term crop rotations. Agronomy Journal. https://doi.org/10.1002/agj2.20651.
Vann, R., Reberg-Horton, S., Castillo, M., Murphy, J., Mirsky, S.B., Saha, U., McGee, R.J. 2021. Differences among eighteen winter pea genotypes for forage and cover crop use in the southeastern United States. Crop Science. 61(2):947-965. https://doi.org/10.1002/csc2.20355.
Rejesus, R.M., Aglasan, S., Knight, L.G., Cavigelli, M.A., Dell, C.J., Hollinger, D., Lane, E.D. 2021. Economic dimensions of soil health practices that sequester carbon: promising research directions. Journal of Soil and Water Conservation. 76(3):55A-60A. https://doi.org/10.2489/jswc.2021.0324A.