Location: Sustainable Agricultural Systems Laboratory
2023 Annual Report
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.
