Location: Sustainable Agricultural Systems Laboratory
2020 Annual Report
Objectives
Our overall goal for this project is to develop cover crop-based, reduced-tillage grain production systems that improve farm production sustainability, minimize herbicide resistant weeds, reduce weed-crop competition in organic agriculture, and maximize agro-ecosystem services.
Objective 1: Improve the feasibility of using multi-tactic weed management approaches for field cropping systems by developing optimal configurations of cover crops, chemical and cultural weed controls, and soil and crop management. [NP304, Component 2, Problem Statement 2A3]
• Sub-objective 1A. Develop cropping systems that integrate multi-tactic weed management practices (physical, chemical, and biological) to address herbicide resistant weeds and weed-crop competition in conventional and organic systems, through optimal combinations of soil management, cover cropping, and at harvest weed seed removal.
• Sub-objective 1B. Characterize allelochemicals and nitrogen compounds from living and decomposing cover crops; track their influence on crop: emergence and yield, and weed: emergence, growth rates, and fecundity.
Approach
Sub-objective 1A. Develop cropping systems that integrate multi-tactic weed management practices (physical, chemical, and biological) to address herbicide resistant weeds and weed-crop competition in organic systems, through optimal combinations of soil management, cover cropping, and at harvest weed seed removal.
Experiment 1A.1. Determine individual and combined effects of cover crop mixtures, fertilizer source/rate/placement, and herbicides on weed competitiveness and community assembly in high residue no-till corn production.
Experiment 1A.2. Test the impact that harvest weed seed collection (HWSC), herbicides, and cover crops have on weed population dynamics and management of multiple-herbicide resistant weed genotypes in soybean.
Sub-objective 1B. Characterize allelochemicals and nitrogen compounds from living decomposing cover crops; track their influence on crop: emergence and yield, and weed: emergence, growth rates, and fecundity.
Goal 1B.1. Quantify allelochemical and nitrogenous products released into the soil as a function of cover crop: species, growth stage, and termination method.
Experiment 1B.2. Determine the magnitude and duration of weed suppression from cereal rye allelopathic compounds and their interaction with herbicides, and mulch mass on herbicide-resistant weeds.
Progress Report
This is the fifth and final year of this project. Two of three milestones were fully met. The third milestone was not met due to the retirement of the support scientist responsible for conducting laboratory analyses. Over the past year, twenty-eight peer-reviewed manuscripts and a book chapter were submitted, of these fifteen were accepted for publication while the remaining manuscripts are in review or have been revised and resubmitted. The manuscripts presented results from projects on cover crop-based corn and soybean production, cover crop management for optimal weed and nitrogen management, integrated cover crop and manure fertility management, weed management with high residue cultivators, effects of chemical weed management on cover crop performance, allelochemical activity in soil, and cover crop breeding. Our results have led to a better understanding of the behavior of grass/legume cover crops applied in mixtures and in monoculture, and subsequent weed suppression. For Sub-objective 1A, the fifth year of a long-term multi-tactic weed management cropping systems experiment was completed and all samples collected and analyzed. Stationary testing of the Harrington Seed Destructor was completed, the data analyzed, and a manuscript published. Data collection on weed populations and seedbank dynamics in two long-term cropping system experiments was completed and the data analyzed. For Sub-objective 1B, data from field trials were used to validate and calibrate process-based models of nitrogen release from cover crops. Laboratory incubation studies were completed to define cover crop decomposition kinetics. Additionally, allelopathy studies on phenolic acids and benzoxazinoids (BX) from cereal rye roots and shoots determined that roots were the primary contributors of phenolic acids to soil. A manuscript reporting these results was accepted for publication. A companion study determined that BX concentrations in soil were five times greater than phenolic acid concentrations after cover cropping. This directly related to differences in concentration of these compounds in the plants, where there were approximately five-times more BX than phenolic acids. Increases in BX concentrations in soil following cover crop termination were immediate, but declined rapidly, while phenolic acid concentrations peaked three days after termination and declined much more slowly.
Work within the ARS Area-Wide herbicide-resistant weed management project to develop multi-tactic weed management strategies continued. The www.growiwm.org website was updated. This website provides content on integrated weed management (IWM) for U.S. field crop producers including case studies, video content, social media updates, and links to decision support tools. A manuscript on the IWM survey was drafted. An assessment of harvest weed seed control in North America was published. The fifth year of a long-term experiment to examine the independent and combined effects of cover crops, harvest-time weed seed control, and herbicides on weed control was completed at three sites (Illinois, Arkansas, and Maryland). In addition, all 14 cooperating sites in the Area-Wide project completed the fourth year of a cover crop/herbicide interaction study on weed population dynamics. This Area-Wide team is developing a web-based app to guide farmers in herbicide programs that prevent herbicide-resistant weed development. Funding for the area-wide project has come to an end. The final report is being drafted.
Accomplishments
1. Community-based herbicide-resistant weed management. Evolution of herbicide-resistance in weeds is one of the top challenges facing U.S. farmers. ARS scientists in Urbana, Illinois and Beltsville, Maryland, developed a spatial-temporal model describing the impacts of 1) farm-scale weed management strategies on rates of herbicide resistance evolution, and 2) coordinated management practices on the spread and occurrence of herbicide resistance. Our findings demonstrate the importance of large-scale cooperative management strategies that diversify herbicide mode of action and frequency of glyphosate use. This work informs researchers, industry, and growers on the importance of community-based weed management.
2. Improved legume cover crop cultivars for cold tolerance and high biomass and growth rates. Hairy vetch is a common cover crop grown for its cold tolerance, fast growth, large biomass production, and ability to fix nitrogen. However, hairy vetch and other cover crops have received little plant breeding investment, particularly for many of the most important traits for cover cropping. High biomass, early-flowering, and winter hardiness are traits that can maximize benefits of cover crops while not delaying cash crop planting dates. ARS scientists in Beltsville, Maryland developed two new hairy vetch cultivars (‘Purple Bounty’ and ‘Purple Prosperity’) that are both early-flowering and have adequate winter survival for the mid-Atlantic region of the U.S. These cultivars will be particularly useful to farmers trying to maximize legume biomass in their production systems without delaying their cash crop planting date.
Review Publications
Kleinman, P.J., Spiegal, S.A., Rigby Jr., J.R., Goslee, S.C., Baker, J.M., Bestelmeyer, B.T., Boughton, R., Bryant, R.B., Cavigelli, M.A., Derner, J.D., Duncan, E.W., Goodrich, D.C., Huggins, D.R., King, K.W., Liebig, M.A., Locke, M.A., Mirsky, S.B., Moglen, G.E., Moorman, T.B., Pierson Jr., F.B., Robertson, G., Sadler, E.J., Shortle, J., Steiner, J.L., Strickland, T.C., Swain, H., Williams, M.R., Walthall, C.L., Tsegaye, T.D. 2018. Advancing the sustainability of US agriculture through long-term research. Journal of Environmental Quality. 47(6):1412-1425. https://doi.org/doi:10.2134/jeq2018.05.0171.
Thapa, R., Poffenbarger, H., Tully, K., Ackroyd, V.J., Kramer, M.H., Mirsky, S.B. 2018. Biomass production and nitrogen accumulation by hairy vetch/cereal rye mixtures: A meta-analysis. Agronomy Journal. 110(4):1197-1208. https://doi.org/10.2134/agronj2017.09.0544.
Davis, B.W., Mirsky, S.B., Needelman, B.A., Cavigelli, M.A., Yarwood, S.A. 2018. Nitrous oxide emissions increase exponentially with N rate from cover crops and poultry litter. Agriculture Ecosystems and the Environment. 272:165-174. https://doi.org/10.1016/j.agee.2018.10.023.
Bowen, H., Maul, J.E., Poffenberger, H., Mirsky, S.B., Cavigelli, M.A., Yarwood, S. 2018. Spatial patterns of microbial denitrification genes change in response to poultry litter placement and cover crop species in an agricultural soil. Biology and Fertility of Soils. 54:769-781.
Otte, B., Mirsky, S.B., Schomberg, H.H., Davis, B., Tully, K. 2019. Effect of cover crop termination timing on pools and fluxes of inorganic nitrogen in no-till corn. Agronomy Journal. 111:1-11. https://doi.org/10.2134/agronj2018.10.0699.
Otte, B., Rice, C., Schomberg, H.H., Tully, K., Mirsky, S.B. 2020. Phenolic acids released to soil during cereal rye cover crop decomposition. Chemoecology. 20:25-34. https://doi.org/10.1007/s00049-019-00295-z.
Kucek, L.K., Riday, H., Rufener, B.P., Burke, A.N., Seehaver Eagen, S., Ehlke, N., Krogman, S., Mirsky, S.B., Reberg-Horton, C., Ryan, M.R., Wayman, S., Weiring, N. 2020. Pod dehiscence in hairy vetch (Vicia Villosa Roth). Frontiers in Plant Science. 11:82. https://doi.org/10.3389/fpls.2020.00082.
Evett, S.R., O'Shaughnessy, S.A., Andrade, M.A., Kustas, W.P., Anderson, M.C., Schomberg, H.H., Thompson, A.I. 2020. Precision agriculture and irrigation: Current U.S. perspectives. Transactions of the ASABE. 63(1):57-67. https://doi.org/10.13031/trans.13355.
Beam, S.C., Mirsky, S.B., Cahoon, C., Haak, D., Flessner, M. 2019. Harvest weed seed control of Italian ryegrass (Lolium perenne ssp multiflorum), common ragweed (Ambrosia artemisiifolia), and Palmer amaranth (Amaranthus palmeri). Weed Technology. 33(4):627–632.
Caswell, K., Wallace, J.M., Curran, W.S., Mirsky, S.B., Ryan, M.R. 2019. Cover crop species and cultivars for drill-interseeding in Mid-Atlantic corn and soybean. Agronomy Journal. 111(3):1060-1067.
Shergill, L., Bejleri, K., Davis, A.S., Mirsky, S.B. 2019. Fate of weed seeds after HSD processing in Midwestern and Mid-Atlantic United States. Weed Science. 68:92–97.
