Location: Sustainable Agricultural Systems Laboratory
2023 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
This is the final report of Project 8042-21660-005-000D, which will end August 14, 2023. The new NP216 project, entitled “Developing, Evaluating, and Optimizing Diversified Agricultural Systems for a Changing Environment in the Mid-Atlantic Region” is being reviewed via OSQR. Substantial progress was made on the expiring project over the past five years. Objective 1 focused on long-term research conducted at the Farming Systems Project (FSP) and the Cover Crop Systems Project (CCSP). An economic analysis of the five FSP cropping systems showed that economic risk was inversely proportional to crop rotation length among organic systems, demonstrating that longer rotations that include a perennial forage reduce overall risk, even in comparison to a conventional no-till system. Crop rotation length for organic systems was also related to improved phosphorus and potassium balances. The shortest rotation, Org2, had substantial surplus phosphorus while the longest rotation, Org6, had essentially balanced inputs and outputs. In the conventional systems, conservative applications reduced initially high soil while maintaining yields. A separate analysis of 18 years of FSP weed cover data demonstrated the complex interactions that define the abundance of weeds in organic systems. In general, though, practices that enhance crop competitiveness provide the most successful weed management. Results from microplots established in FSP plots to isolate individual factors that affect system performance provided additional insights. Metabolomics analysis of archived corn grain sampled from crop variety microplots (conventional and organic varieties planted side-by-side in each corn and soybean plot) showed that cropping systems had minimal effect while crop variety and annual weather variation had large effects on this measure of corn grain nutritional content, indicating that crop breeding is the best way to impact corn metabolomics. Archived soybean grain samples from variety microplots are also being used to assess the impacts of cropping systems on soybean nutritional content (protein, fatty acids, and metabolomics) by University of Kentucky and ARS collaborators. Data on crop yields, weed seedbanks and weed percent cover from weedy (ambient weed populations) and weed-free (hand-weeded) microplots are being analyzed by Cornell University collaborators to evaluate how changes in weed community dynamics impact crop yields in organic systems. Data from poultry litter application rate microplots (4 rates) established in the corn phase of organic rotations have been summarized. Initial results show that poultry litter application rate can be decreased by 50% (Org2), 67% (Org3) and 100% (Org6) without impacting corn grain yield, thus improving phosphorus balances in shorter rotations. Data from these microplots show that emissions of nitrous oxide, an important greenhouse gas, can be reduced by 27% to 59% at optimal poultry litter application rates. Soil samples archived from these microplots are being used by University of Maryland collaborators to quantify the impact of poultry litter applications on formation, persistence, and turnover of soil organic matter fractions that impact plant available nitrogen and soil carbon sequestration. In the realm of soil microbiology, SASL scientists developed an app, Qseq, that performs statistical analysis and synthesis of multiplexed-amplicon sequencing raw data, and outputs formatted data for use in commonly used complementary downstream algorithms. This app and other SCINet-based bioinformatic tools were used to complete the two FSP studies outlined in Accomplishments 03 and 04. In late winter/spring of 2022 all FSP plots were sampled to 50 cm depth to assess soil organic carbon and total nitrogen as part of standard periodic sampling. During the 2022 summer field season all plots typically planted to corn, soybean and small grains were planted to sorghum-sudangrass—while maintaining other characteristics of each cropping system—as a means of reducing labor and sampling demands. Standard crop rotations were reinstated in fall 2022 and are being maintained in 2023 although sampling intensity is greatly reduced as SASL scientists and staff focus on compiling and analyzing the first 27 years of data. Under Objective 2, the cover crop breeding program expanded significantly over the past five years.
This project has secured funding in competitive grants, increased to 20 advanced line testing sites, built strong interagency partnerships with NRCS Plant Materials Centers, and greatly improved the historically available cover crop germplasm. Two hairy vetch cultivars and additional lines will be licensed by a seed company. The cover crop breeding team characterized 18 winter pea genotypes and the phenotypic and nodule microbial diversity of crimson clover accessions. It was also demonstrated that seed dormancy in hairy vetch is regulated by genotype and environment. Ten cover crop species and their respective commercially available germplasm were assessed across the U.S. and regional adaptations of these lines were documented for cover crop use. Surface cover crop residue decomposition and subsequent nitrogen release was demonstrated to be predominantly driven by moisture, not temperature. ARS scientists in Beltsville, Maryland, with University of Georgia collaborators, conducted laboratory and field experiments and built a model based on hourly relative humidity, air temperature, and rainfall as inputs. The model was calibrated and validated using data from the large, on-farm Precision Sustainable Agriculture Network and shown to successfully simulate cover crop decomposition. The model was incorporated into the Cover Crop Nitrogen Calculator. To make the tool broadly available, the team built a weather Application Programming Interface to provide hourly weather data. This tool enables farmers to manage nitrogen requirements more efficiently, lowering production costs, excessive nitrogen leaching, and greenhouse gas emissions. Research was conducted on certified organic farms to evaluate the National Organic Program rules that stipulate a wait-period of 90 or 120 days between application of untreated or inadequately treated manure and harvest of fresh produce where the edible portion does not or does, respectively, have direct contact with the amended soil. Pathogen presence, concentration, prevalence, survival duration, and transfer to harvestable fresh produce was determined in response to concerns about the potential for contamination of commodities likely to be consumed raw, and thus potentially at risk of causing foodborne illness. Results from a two-year field study showed that at 90 days after inoculation with generic E. coli it was still present in all soils, but at 120 days generic E. coli concentrations had declined significantly in both growing seasons. No Salmonella, Listeria monocytogenes, Staphylococcus aureus, or pathogenic E. coli were present in any samples 90 days after soil was amended. Similar research was conducted in Integrated Crop-Livestock Farm environments, where animals are in very close proximity to the fresh produce commodity production areas. Results from addition of biological soil amendments to soils significantly increased mesophilic aerobic bacteria as well as generic E. coli populations. Results show that greater detection rates of toxigenic E. coli with their virulence factor genes in animal rearing facilities, soil, and produce samples indicates increased contamination risks associated with Integrated Crop-Livestock Farm systems from biological soil amendment application. These studies aid organic growers and decision-makers in evaluating food safety risks and indicates that factors other than fixed ‘wait times’ between manure application/incorporation and harvest of fresh produce need to be considered. Under Objective 3, project scientists are active in the LTAR Network, leading two Work Groups (Soils and Non-CO2 GHGs) and participating actively in the Water Quantity WG and the Croplands Common Experiment WG, including in the Productivity and GHG and Air Quality Metrics Sub-Groups. Project scientists have contributed to two publications highlighting the value of LTAR to address sustainable intensification and two publications as part of the Manuresheds project. In addition, project scientists are coordinating and contributing data to two other long-term research networks: DRIVES (Diverse Rotations Improve Valuable Ecosystem Services) and the Northeast Climate Hub-led Economics of Soil Health Network. DRIVES is assessing the effects of crop rotation diversity on system sustainability using data from 20 sites in North America. Initial findings show that rotation-level yield is greater with increased rotational complexity under poor growing conditions. The Economics of Soil Health Network is quantifying economic performance of long-term no-till and cover crop use from 8 long-term experiments in Northeast and adjacent states. Initial results indicate that economic returns for no-till are greater than for conventional tillage systems due to lower production costs, and that this difference increases with time in no-tillage over 24 years.
Accomplishments
1. Interseeding cover crops increases soil water availability and corn yield. Cover crop interseeding, which refers to planting a cover crop into a standing cash crop to promote earlier establishment, can increase biomass production, which helps improve infiltration of rain and reduce evaporation from soil. Soil water data collected over four years in the Cover Crop Systems Project at USDA-ARS, Beltsville, Maryland, indicated that soil water storage during the corn growing season was 10 to 20 mm (0.4 to 0.8 inches) greater in systems with interseeded cover crops than with no cover crop. Corn grain yields over four years averaged 24 bu/a (1.5 Mg/ha) greater with a cover crop than without. Average water use efficiency was also greater with a cover crop than without. The increased yield was more than sufficient to cover the cost of cover crop establishment and demonstrates the benefits of interseeded cover crops in humid regions of the United States of America. Farmers, extension personnel, researchers, and policy makers can use this information to understand the benefits of cover crops for water conservation, which is important due to increasing societal demands for water.
2. Corn variety and annual weather variability influence corn grain nutritional quality (metabolomics) more than cropping system. Improving nutritional content of crops is a key goal of developing more sustainable agricultural systems. Metabolomics, which identifies a host of bioactive compounds in samples, can be used to provide a more precise understanding of crop nutritional quality. It is unknown if cropping systems management could be used to manage crop metabolomics. ARS scientists in Beltsville, Maryland, working with colleagues in Serbia, compared the metabolomic profiles of two corn grain varieties grown under five management regimes over three years. While cropping system had small impacts on metabolomic profiles, corn variety and year had much larger effects, indicating that crop breeding will be a more productive method of manipulating corn grain metabolomes than field management. These results will be of interest to plant breeders, nutritional scientists and policy makers interested in crop nutritional quality.
3. Soil depth is a more significant determinant of soil microbial community than cropping system. The soil microbial community is responsible for transformation and storage of carbon and plant nutrients in agricultural soils. Models of stocks and flows of carbon and nutrients currently use outdated estimates of soil metabolic kinetics, which do not consider how cropping systems regulate and impact transformation of carbon and nutrients. Considering microbial gene abundances and diversity may give insight into the potential transformations of soil carbon and nutrients. USDA-ARS scientists in Beltsville, Maryland, extracted and analyzed DNA from fungal, bacterial, and archaeal communities and reported data to 30 cm, from three different cropping systems at the Farming Systems Project in Beltsville, Maryland. Results showed small differences in soil microbial community structure at 0 to 15 cm among the three cropping systems. Below 15 cm depth, soil type and physiochemical attributes were more predictive determinants of soil microbial community than cropping system. Results from this study are important to scientists and will be used to improve models of soil carbon and nitrogen dynamics, which are needed to improve soil carbon sequestration and plant nutrient availability assessments.
4. Glyphosate application to corn and soybean crops does not significantly change the microbial community structure but may impact select microbial traits such as nitrogen fixation. The impacts of the herbicide glyphosate on the plant and soil microbial community structure are unclear and there are concerns regarding non-target ecosystem effects. A variety of cropping systems using Round-up Ready® corn and soybean at USDA-ARS locations in Beltsville, Maryland, Stoneville, Mississippi, and Urbana, Illinois, were analyzed for soil microbial community structure and function to resolve these issues. Glyphosate impacted nitrogen fixing metabolism, resulting in increased biological nitrogen fixation in some cropping systems and decreased nitrogen fixation in others. This indicates that herbicides can have non-target impacts on the soil microbial community in important agroecological functions. Other findings, reported in a series of seven papers, were that, in modern corn and soybean farming operations, use of glyphosate does not significantly change crop metabolic profiles or populations of pathogenic and endophytic fungi associated with the crop.
5. Corn yield optimized when cover crops and poultry litter are nitrogen sources. Cover crops can be used to provide some of the nitrogen needs of a cash crop to complement mineral fertilizers or manure, but there has been limited work to describe how cover crop quality interacts with these other sources of nitrogen to impact corn yield. ARS scientists investigated the response of corn yield to gradients of the preceding cover crop carbon:nitrogen ratio (6 ratios of hairy vetch:cereal rye) and four poultry litter application rates in Beltsville, Maryland. Results show that corn yield responded to both gradients. At a given subsoil applied poultry litter rate, corn yield decreased with increasing carbon:nitrogen ratio of cover crops. A model was developed to determine the rate of increase of PL required to optimize corn yield as carbon:nitrogen ratio increased. Application method for poultry litter did not affect corn yield. The approach used to quantify yield response across cover crop quality and poultry litter rate can be widely used to guide adaptive N management in subsequent cash crops following winter cover crops, thereby balancing both economic and environmental objectives in cover crop-based cropping systems. These results will be of interest to farmers and agricultural professionals.
Review Publications
Epp Schmidt, D.S., Cavigelli, M.A., Maul, J.E., Schomberg, H.H., Yarwood, S.A. 2023. Un-coupled effects of glyphosate on N-fixation components of agroecosystems. Applied Soil Ecology. 278: Article 108167. https://doi.org/10.1016/j.apsoil.2023.104859.
Schomberg, H.H., Mirsky, S.B., White, K.E., Thompson, A.I., Bagley, G.A., Garst, G.D., Bybee-Finley, K.A. 2023. Interseeded cover crop mixtures influence soil water storage during the corn phase of corn-soybean-wheat no-till cropping systems. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2023.108167.
Hoover, D.L., Abendroth, L.J., Browning, D.M., Saha, A., Snyder, K.A., Wagle, P., Witthaus, L.M., Baffaut, C., Biederman, J.A., Bosch, D.D., Bracho, R., Busch, D., Clark, P., Ellsworth, P.Z., Fay, P.A., Flerchinger, G.N., Kearney, S.P., Levers, L.R., Saliendra, N.Z., Schmer, M.R., Schomberg, H.H., Scott, R.L. 2022. Indicators of water use efficiency across diverse agroecosystems and spatiotemporal scales. Science of the Total Environment. 864. Article e160992. https://doi.org/10.1016/j.scitotenv.2022.160992.
Kumar, V., Singh, V., Flessner, M., Reiter, M., Mirsky, S.B., Haymaker, J. 2023. Cover crop termination options and application of remote sensing for evaluating termination efficiency. PLOS ONE. 18(4). Article e0284529. https://doi.org/10.1371/journal.pone.0284529.
Mirsky, S.B., Davis, B.W., Poffenbarger, H., Cavigelli, M.A., Maul, J.E., Schomberg, H.H., Spargo, J.T., Thapa, R. 2023. Managing cover crop C:N ratio and subsurface-banded poultry litter rate for optimal corn yields
. Agronomy Journal. https://doi.org/10.1002/agj2.21369.
Gao, F.N., Jennewein, J.S., Hively, W.D., Soroka, A., Thieme, A., Bradley, D., Keppler, J., Mirsky, S.B., Akumaga, U. 2022. Near real-time detection of winter cover crop termination using harmonized Landsat and Sentinel-2 (HLS) to support ecosystem assessment. Science of Remote Sensing. 7. Article 100073. https://doi.org/10.1016/j.srs.2022.100073.
Jennewein, J.S., Lamb, B.T., Hively, W., Thieme, A., Thapa, R., Goldsmith, A.S., Mirsky, S.B. 2022. Integration of satellite-based optical and synthetic aperture radar imagery to estimate winter cover crop performance in cereal grasses. Remote Sensing. https://doi.org/10.3390/rs14092077.
Thieme, A., Hively, W.D., Gao, F.N., Jennewein, J.S., Mirsky, S.B., Soroka, A., Keppler, J., Bradley, D., Skakun, S., McCarty, G.W. 2023. Remote sensing evaluation of winter cover crop springtime performance and the impact of delayed termination. Agronomy Journal. 15:442–458. https://doi.org/10.1002/agj2.21207.
Thapa, R., Cabrera, M., Reberg-Horton, C., Dann, C., Balkcom, K.S., Fleisher, D.H., Gaskin, J., Hitchcock, R., Poncet, A., Mirsky, S.B., Schomberg, H.H., Timlin, D.J. 2023. Modeling surface residue decomposition and N release using the Cover Crop Nitrogen Calculator (CC-NCALC)
. Nutrient Cycling in Agroecosystems. https://doi.org/10.1007/s10705-022-10223-3.
