Location: Dairy Forage Research
2023 Annual Report
Objectives
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.
Approach
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).
Progress Report
Objective 1: No progress report due to scientist retirement during fiscal year 2019.
Objective 2: No progress report due to scientist retirement during fiscal year 2022.
Objective 3: Red clover multisite evaluation nurseries established in 2019, 2020, 2021, and 2022 were evaluated for plant biomass production and persistence. Surviving superior plants from 2018 nurseries were organized into polycrosses for intermating and seed production during the summer of 2022. Polycrosses were also established in 2022 from remnant halfsib seed based on pedigree analysis of phenotypic data collected from breeding nurseries established from 2006-2020. During the autumn of 2022, all polycrosses were threshed on an individual plant basis to generate new halfsib family seed. During the winter and spring of 2023 transplants were initiated and red clover multisite evaluation nurseries were established. In September 2022 superior surviving plants from the 2019 multisite red clover evaluation nurseries were selected and overwintered in the greenhouse. During 2023 polycrosses were established from plants selected out of 2019 red clover nurseries and from plants grown from remnant halfsib seed of superior families that were selected using pedigree analysis of phenotypic data of breeding nurseries established from 2006-2021. Seed of three new syn 2 red clover experimentals was received back from our collaborator at the ARS location in Prosser, WA during 2022. Seed increases for three new syn 2 red clover experimentals were established in Prosser, WA during 2023 by our ARS collaborator.
Objective 4: Five studies investigating the interseeding of alfalfa into corn as a dual-purpose cover and forage crop were continued or initiated during fiscal year 2023 in Wisconsin. The first study, conducted in conjunction with ARS researchers in Kimberly, Idaho, is evaluating the longer-term forage yield of alfalfa established by interseeding compared to alfalfa established by conventional methods. A second study aims to identify key hybrid traits that will minimize yield drag of corn grown with interseeded alfalfa. A third study is examining how the timing of alfalfa interseeding and the timing of corn harvest influences the yield of corn silage and the establishment and initial yield of alfalfa. A fourth study is examining plant survival and disease resistance characteristics of public and seed industry alfalfa germplasm subjected to recurrent selection under corn. The fifth study is examining 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-Madison through a cooperative agreement.
Objective 5: Work evaluating the nutritional benefits of alfalfa and developing improved forage quality assays for alfalfa ceased when a postdoctoral associate unexpectedly departed during fiscal year 2022. We are activity working to fill the postdoctoral position and plan to resume work on the project early in fiscal year 2024.
Objective 6: Four studies focused on integrating precision agriculture technology and conservation systems, including cover crops and alternative perennial forages, were initiated or continued during fiscal year 2023 in Wisconsin. A replicated small plot study continues to investigate the resilience, agroecosystem benefits, and forage production potential of integrating diverse winter cover crop mixtures into corn silage production systems. In collaboration with the University of Wisconsin-Madison, a second study focused on correlating unmanned aerial vehicle (UAV)-acquired hyperspectral imagery and publicly available satellite imagery with alfalfa yield and nutritive value is currently in the data processing and analysis phase and will continue through fiscal year 2024. A complementary field scale study evaluating the impact of controlled wheel traffic on alfalfa production and soil compaction concluded and is in the data processing and analyses phase. Lastly, in collaboration with Cornell University and other partners, a fourth study was established to evaluate the impact of seeding rate on weed suppression in organic intermediate wheatgrass production systems. In addition, project planning and coordination is underway to establish two cover crop and precision agriculture studies to begin late in fiscal year 2023, one that will seek to refine recommendations for aerial seeding of cover crops using UAVs and another that will assess the feasibility of using an autonomous robotic system for interseeding cover crops in corn grain and silage systems.
Accomplishments
1. Measuring the balance between greenhouse gas emission and carbon mitigating processes on a model dairy farm. The dairy industry has set an ambitious target of “net zero” dairy by 2050. Achieving this target will require simultaneous reductions in greenhouse gas emissions from the field, herd, and manure management while increasing carbon storage in farm soils and vegetation. ARS and University of Wisconsin-Madison researchers in Madison, Wisconsin, evaluated the effects of farm vegetation and management practices on carbon balance and ecosystem services. Greenhouse gas emissions and carbon storage were assessed using the Prairie du Sac Agricultural Research Station as a model system and found that 60% of all farm emissions were offset by the 40% of the farm in permanent perennial cover, including pasture, grassland, and woodland vegetation. Net zero production will require strategies to reduce emissions and increase carbon mitigation, and these findings create clues to changes in both parameters that result in reduced emissions, greater carbon conservation and storage in soils and plants, and reaching the goal of net zero production.
2. Breeding alfalfa for successful establishment when it is interseeded with corn. Alfalfa can be established for long-term forage production by planting it with a corn silage companion crop. This intercropping system has the potential to increase forage yields and farm profitability while reducing the risk of nutrient and soil loss from cropland. Unfortunately, excessive loss of alfalfa seedlings under corn during wet growing conditions hampers adoption of this practice by farmers. Field studies by ARS researchers in Madison, Wisconsin, in collaboration with commercial seed companies demonstrated that alfalfa seedlings that survive under corn can be intermated to produced progeny with 35% greater survival in the intercropping system. Further breeding efforts for improved varieties of alfalfa, other forages, and cover crops that can be reliably, profitably, and sustainably be intercropped with corn on farms will have great benefits to production efficiency and nutrient loss in corn production.
3. Discovering genes associated with seed dormancy of hairy vetch for use as targets to improve its utility on the farm. Hairy vetch is a winter hardy annual legume that can be planted in late summer, grown in the fall and early spring, and then killed to provide soil protecting ground cover, supply nitrogen, and boost yields of subsequent row crops such as corn. Unfortunately, hairy vetch produces a high proportion of dormant seed that limits germination, discouraging its use. ARS researchers in Madison, Wisconsin, in collaboration with the Noble Research Institute conducted a study that identified over 24,000 gene products (RNA transcripts) associated with seed dormancy in hairy vetch by comparing RNA transcript samples from seed of hairy vetch plants that produced a high and low proportion of dormant seed. This work will ultimately help scientists develop new varieties of hairy vetch whose seed will germinate quickly and vigorously create ground cover while minimizing the risk of hard seeding lying dormant in the soil risking a contribution to future weed issues on farms.
Review Publications
Osterholz, W.R., Ruark, M.D., Renz, M.J., Grabber, J.H. 2023. Interseeded alfalfa N fixation and transfer to maize are reduced by N fertilizer. Nutrient Cycling in Agroecosystems. 126:67-79. https://doi.org/10.1007/s10705-023-10276-y.
Casler, M.D. 2023. Impact of ploidy on biomass yield of upland switchgrass (Panicum virgatum L.): A meta-analysis. Genetic Resources and Crop Evolution. 70:1115-1122. https://doi.org/10.1007/s10722-022-01489-1.
Casler, M.D., Lee, D. 2023. Registration of 'Cedar Creek' Switchgrass. Journal of Plant Registrations. 17(3):483-487. https://doi.org/10.1002/plr2.20294.
Casler, M.D., Lee, D. 2023. Registration of 'Empire' big bluestem. Journal of Plant Registrations. 17(2):223-227. https://doi.org/10.1002/plr2.20280.
Tilhou, N., Casler, M.D. 2021. Subsampling and DNA pooling can increase gains through genomic selection in switchgrass. The Plant Genome. 14(3). Article e20149. https://doi.org/10.1002/tpg2.20149.
Tilhou, N., Casler, M.D. 2022. Surveying Grassland Islands: The genetics and performance of Appalachian Switchgrass (Panicum virgatum L.). Genetic Resources and Crop Evolution. 69:1039-1055. https://doi.org/10.1007/s10722-021-01282-6.
Barre, P., Asp, T., Byrne, S., Casler, M.D., Faville, M., Rognli, O., Roldan-Ruiz, I., Skot, L., Ghesquiere, M. 2022. Genomic prediction of complex traits in forage plants species: Perennial grasses case. Ahmadi, N., Bartholomé, J., editors. Methods in Molecular Biology. Vol 2467. Humana, New York, NY. p. 521-541. https://doi.org/10.1007/978-1-0716-2205-6_19.
Poudel, H., Tilhou, N., Sanciangco, M., Vaillancourt, B., Kaeppler, S., Buell, C., Casler, M.D. 2021. Genetic loci associated with winter survivorship in diverse lowland switchgrass populations. The Plant Genome. 14(3). Article e20159. https://doi.org/10.1002/tpg2.20159.
Grabber, J.H., Riday, H., Enjalbert, N., Wagner, S., Mickelson, D. 2023. Establishment of alfalfa interseeded into corn in response to one cycle of selection and hybridization. Crop Science. 63(3):1139-1147. https://doi.org/10.1002/csc2.20923.
Kucek, L.K., Dawson, J., Darby, H., Mallory, E., Davis, M., Sorrells, M. 2021. Breeding wheat for weed-competitive ability: II. Measuring gains from selection and local adaptation. Euphytica. 217. Article e203. https://doi.org/10.1007/s10681-021-02905-w.
Kucek, L.K., Mallory, E., Darby, H., Dawson, J., Sorrells, M. 2021. Breeding wheat for weed-competitive ability: I. Correlated traits. Euphytica. 217. Article e202. https://doi.org/10.1007/s10681-021-02930-9.
Ali, S., Kucek, L.K., Riday, H., Krom, N., Krogman, S., Cooper, K., Jacobs, L., Mehta, P., Trammell, M., Bhamidimarri, S., Butler, T., Saha, M.C., Monteros, M.J. 2023. Transcript profiling of hairy vetch (Vicia villosa Roth) identified interesting genes for seed dormancy. The Plant Genome. 16(2). Article e20330. https://doi.org/10.1002/tpg2.20330.
