Location: Dairy Forage Research2022 Annual Report
1. Develop or improve annual and/or perennial forage production systems that optimize forage production for dairy farms while reducing environmental impacts. 1A. Evaluate management factors for warm-season grass species to develop forage production systems for dairy farms. 1B. Determine manure source and application rate effects on warm season grass productivity, nutritive value, and persistence, and on soil chemical and biological properties. 1C. Determine management and plant biological factors contributing to winterkill and poor persistence of alfalfa and develop strategies to reduce winterkill and improve persistence of alfalfa. 2. Develop or improve warm-season and/or cool-season grass germplasm that enhances yield, quality and resiliency of forage production for integrated dairy systems. 2A. Develop, validate, and apply genomic selection tools to be used in breeding switchgrass for improved forage/biomass yield, cold tolerance, nitrogen-use efficiency, and digestibility. 2B. Determine the role of endophytic fungi in the meadow fescue life cycle. 3. Develop or improve forage legume germplasm that enhances yield, quality and resiliency of diverse forage management systems. 3A. Develop improved red clover varieties that have greater persistence and biomass yield. 3B. Develop improved alfalfa germplasms that are genetically broad and will expand the U.S. alfalfa breeding pool. 3C. Improve underutilized forage legumes for use in forage production and as cover crops. 4. Develop or improve cover crop systems that enhance forage production while reducing nutrient losses and soil erosion in integrated dairy production systems. 4A. Refine management practices for corn grown with interseeded alfalfa. 4B. Develop or identify germplasm that is well suited for interseeding. 5: Develop ration formulation and feeding strategies that experimentally validate chemical methods designed to properly value use of alfalfa in terms of animal performance, milk production, nutrient use efficiency, and enteric methane emissions. 6: Develop cover crop strategies (and tools) for the upper Midwest that explore new plant species and overcome current soil moisture, soil temperature, crop pest and economic limitations to provide incentive to farmers to adopt cover cropping.
Objective 1. Switchgrass, big bluestem and indiangrass cultivars will be fertilized with 0 to 80 kg/ha of fertilizer nitrogen and harvested once or twice per season to assess plant development, dry matter yield and forage quality in relation to nutrient requirements of dairy cattle. The warm season grasses will also be fertilized with 0 to 80 kg of nitrogen in the form of solid and liquid manure to assess nutrient uptake, soil chemical and biological properties, plant persistence, dry matter yield and nutritive value. Objective 2. Genomic selection tools will be developed, validated, and used in breeding switchgrass for improved forage/biomass yield, cold tolerance, nitrogen-use efficiency, and digestibility. The role of endophytic fungi in conferring drought, heat, defoliation, and traffic tolerance to meadow fescue will be assessed in greenhouse and field experiments. Objective 3. An extensive breeding program utilizing phenotypic and genotypic selection of halfsib lines grown as spaced plants and swards at multiple locations will be used to develop red clover cultivars with improved biomass production and persistence. Four alfalfa subsp. falcata syn1 germplasms developed by recurrent phenotypic selection will be harvested for multiple years in sward trials to assess persistence and dry matter yield. Two experimental birdsfoot trefoil varieties differing in tannin content and 15 experimental kura clover varieties will be compared to check varieties in sward trials to assess growth characteristics, dry matter yield, persistence, and forage quality. Objective 4. Field studies will evaluate and refine agrichemical applications as well as planting and harvesting management practices to improve the establishment and overall forage production of alfalfa interseeded into silage corn. Syn1 and hybrid alfalfa entries developed from surviving plants and various corn hybrids will be evaluated in field studies to evaluate their compatibility and dry matter yield potential in a corn silage-interseeded alfalfa production system. Objective 5. This objective will be fulfilled by conducting the following types of experiments: 1. Quantify the nutritional benefits of alfalfa and its interactions with other feed components when fed in various kinds of dairy rations and understand how protein, fiber, and other constituents in alfalfa are metabolized in the rumen and utilized for milk production vs. other less desirable outcomes such as enteric methane emissions. 2. Improve forage quality assays to more accurately predict the nutritive value of alfalfa and optimize its use in dairy rations. Objective 6. Research will focus on incorporating plants beyond alfalfa into existing crop rotations with outcomes that incentivize farmers to adopt cover cropping practices (e.g., improved crop production as mediated by soil health, water use efficiency or provision of nutrients that is more economical than application of chemical fertilizer; increased forage availability for livestock beyond that produced by conventional cropping systems; increased provision of environmental services such as pollinator habitat, soil conservation or soil carbon storage).
Objective 1. No progress report due to scientist retirement in 2018. Objective 2. Highly accurate genomic selection protocols were developed for a wide range of switchgrass populations that represent both biomass and forage types. Application of these protocols to several populations revealed that late flowering and improved winter survivorship were the two key traits that allowed the development of populations with superior biomass yield in the northern USA. Across a broad landscape, late flowering and improved winter survivorship have a strong negative genetic correlation, but this correlation can be partially broken or relaxed by intensive selection. Genetically similar meadow fescue populations with or without the endophytic fungus were evaluated for tolerance to three environmental stresses: heat, drought, and a combination of frequent and low defoliation. The endophyte had no impact on either heat or drought tolerance but increased the tolerance of meadow fescue to frequent and low defoliation over a 3-year period in field experiments. Objective 3. Over 8000 new red clover transplants were established in summer 2022. Red clover nurseries from 2018, 2019, 2020, and 2021 were evaluated for vigor and height. Over 700 plants were selected out of 2018 nurseries and confirmed using DNA markers. 600 of these selected plants were organized into seed production cages in 2022. Close to 20 new red clover polycrosses were established in 2022. Halfsib seed was harvested off over 800 red clover plants from the 2021 polycrosses. Three new red clover synthetics (syn 2) were created from syn 1 seed from the 2021 polycrosses. Red clover, alfalfa, birdsfoot trefoil, and kura clover sward trials established in 2018, 2019, 2020, and 2021 were evaluated for biomass, percent stand, height, flowering, plot health and other characteristics. Austrian winter pea, hairy vetch, and crimson clover legume cover crop advanced line trials were established in autumn 2021 and evaluated through summer 2022. Objective 4. Six studies investigating the interseeding of alfalfa into corn as a dual-purpose cover and forage crop were continued or initiated during fiscal year 2022 in Wisconsin. One ongoing study examined planting time effects on crop development, forage yield, and quality of corn and interseeded alfalfa. A second continuing study conducted in both in Wisconsin and with ARS researchers in Kimberly, Idaho, compared crop development, yield and quality of alfalfa established by interseeding versus conventional methods. A third ongoing study aims to identify key hybrid traits that will minimize yield drag of corn grown with interseeded alfalfa. A new follow-up study is examining how the timing of alfalfa interseeding, the application of protective agrichemicals on alfalfa, and the timing of corn harvest influences the yield of corn silage and the establishment and initial yield of alfalfa. Another follow-up study will examine the response of public and seed industry alfalfa germplasm to recurrent selection under corn. An additional study initiated this year will examine how the application of protective agrichemicals on interseeded alfalfa impacts the establishment of alfalfa and yield of corn on farms in various locations in Wisconsin; this work is being carried out by the University of Wisconsin through cooperative agreement. Objective 5. Work quantifying the nutritional benefits of alfalfa and developing improved assays for alfalfa ceased when a postdoctoral associate unexpectedly departed at the start of fiscal year 2022. Objective 6. Two studies focused on integrating cover crops and precision agriculture technology and management approaches to enhance agronomic and environmental benefits in dairy forage systems were implemented in fiscal year 2022. One replicated, small-plot study investigating the resilience and agroecological benefits of integrating winter annual cover crop mixtures as alternatives to winter cereal rye monocultures in a corn-corn silage rotation was established at Prairie du Sac and Marshfield, Wisconsin. A portion of this work is being carried out in collaboration with the University of Wisconsin.. A second study focused on correlating hyperspectral imagery collected using an unmanned aerial vehicle with free, publicly available satellite imagery to quantify alfalfa yield and nutritive value and variability across a field was initiated at Prairie du Sac, Wisconsin. This work is in collaboration with the University of Wisconsin. Within this study, a nested research project was initiated evaluating the impact of controlled wheel traffic on soil compaction and alfalfa productivity at field-scale. This work is in collaboration with the University of Wisconsin. Project planning and coordination is underway to establish at least two more cover crop projects in fiscal year 2022, one evaluating precision seeding depth control and a second evaluating precision timing of cover crop planting using unmanned aerial vehicle and autonomous robotic technology.
1. Proper use of plant protective agrichemicals promotes intercropping of alfalfa in corn. Improved intercropping of alfalfa in corn with proper use of plant protective agrichemicals. Interseeding alfalfa into a corn silage companion crop can increase yields and profitability of forage production and reduce the risk of nutrient and soil loss from cropland. Unfortunately, poor seedling survival and establishment of alfalfa under corn during wet growing conditions hampers adoption of this practice on dairy farms. Field studies by ARS researchers in Madison, Wisconsin, in collaboration with the University of Wisconsin, found that application of prohexadione followed by fungicide, and insecticide increased plant survival by over 12-fold and promoted improved establishment and subsequent forage production of alfalfa interseeded into corn. Further refinement of agrichemical treatments and other management practices will help to ensure that the benefits of the alfalfa-corn intercropping system can be routinely realized by farmers.
Casler, M.D. 2022. Nitrogen fertilization and harvest management of switchgrass: Impacts on biomass yield and nitrogen removal. BioEnergy Research. 15(1). https://doi.org/10.1007/s12155-022-10435-z.
Osterholz, W.R., Ruark, M.D., Renz, M.J., Grabber, J.H. 2021. Benefits of alfalfa interseeding include reduced residual soil nitrate following corn production. Agricultural and Environmental Letters. 6(3). Article e20053. https://doi.org/10.1002/ael2.20053.
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Osterholz, W.R., Ruark, M.D., Renz, M.J., Grabber, J.H. 2021. Interseeding alfalfa into corn silage increases corn N fertilizer demand and increases system yield. Agronomy for Sustainable Development. 41. Article 58. https://doi.org/10.1007/s13593-021-00711-1.
Bickhart, D.M., Koch, L.M., Smith, T.P., Riday, H., Sullivan, M.L. 2022. Chromosome-scale assembly of the highly heterozygous genome of red clover (Trifolium pratense L.), an allogamous forage crop species. GigaByte. 42:1-13. https://doi.org/10.46471/gigabyte.42.
Franco Jr, J.G., Berti, M.T., Grabber, J.H., Hendrickson, J.R., Nieman, C.C., Pinto, P., Van Tassel, D., Picasso, V.D. 2021. Ecological intensification of food production by integrating forages. Agronomy. 11(12). Article 2580. https://doi.org/10.3390/agronomy11122580.
Grabber, J.H., Smith, D., Osterholz, W.R., Renz, M.J. 2021. Establishment and first year yield of interseeded alfalfa as influenced by corn plant density and treatment with prohexadione, fungicide and insecticide. Agronomy. 11(11). Article 2343. https://doi.org/10.3390/agronomy11112343.
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