Location: Dairy Forage Research2020 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. 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 2. The second year of phenotypic data collection and DNA sequencing was completed, providing a data base of over 2000 sequenced individuals from which to develop genomic predictions for flowering time and winter survivorship of switchgrass. Prediction equations have been developed and refined for use in the switchgrass breeding programs focused on either biomass or forage. Objective 3. Over 7000 new red clover transplants were planted into selection nurseries in 2020. Over 400 red clover plants were selected from 2016 red clover nurseries in 2019 and organized into 16 new polycrosses for pollination in 2020. Eight United States Dairy Forage Reasearch Center (USDFRC) red clover experimental synthetics continue to be evaluated for potential release as varieties. Experimental yellow flowered alfalfa populations sward trials were established in fall of 2019 for evaluation. High tannin containing trefoil was evaluated in 2019 and 2020 for potential variety release. Objective 4. In seven studies we investigated interseeding of alfalfa into corn as a dual-purpose cover and forage crop; portions of this work were done in collaboration with the University of Wisconsin through a cooperative agreement. The first study conducted in Wisconsin, Idaho, Michigan, and Pennsylvania, and completed in 2019, focused on identifying crop management and growth conditions needed to optimize the establishment of interseeded alfalfa in diverse production environments. A second Wisconsin study completed in 2019 investigated the effect of corn population and agrichemical applications on the survival and first year forage production of alfalfa interseeded into silage corn. A third Wisconsin study conducted in 2018 and 2019, and initiated again in 2020 aims to optimize the application rate and timing of agrichemicals to enable good survival of interseeded alfalfa at the lowest possible cost to producers. A fourth Wisconsin study planted in 2019 is evaluating if alfalfa can be bred to improve its ability to survive under densely planted corn. A fifth Wisconsin and Idaho study partially initiated in 2020 will examine how the timing of corn planting and alfalfa interseeding and corn harvest affects the yield of corn and the establishment and yield of alfalfa. A sixth study Wisconsin partially initiated in 2020 with a series of corn hybrids aims to identify key traits that will minimize yield drag of corn grown with interseeded alfalfa. A seventh Wisconsin study initiated in 2020 will examine fertilizer application strategies to help favor nutrient uptake and yield of corn grown with interseeded alfalfa. An eighth Wisconsin study planned in 2020 to examine uptake of 15N fertilizer by corn and interseeded alfalfa was not initiated.
1. In order to accelerate red clover variety development image object recognition technology was developed to increase the speed and efficiency of plant evaluation during the breeding process. ARS scientists at Madison, Wisconsin, successfully used inexpensive and ubiquitous image acquisition technology (i.e., hand held cameras) and publicly available machine learning code to evaluate individual plants in their red clover breeding nurseries for persistence and biomass yield production. The techniques developed will allow multiple plant traits to be assessed in forage plant nurseries at lower cost, and its adoption by public and private forage breeding programs will speed the development of new forage varieties for use as livestock feed and for soil and water conservation efforts.
2. Alfalfa establishment under silage corn projected to increase dairy farm profitability. Crop rotations of corn silage and alfalfa are widely grown on dairy farms in the United States, but slow establishment of spring seeded alfalfa limits first year yields and farm profitability. ARS and University of Wisconsin scientists at Madison, Wisconsin, used forage yield data and estimated feed values and production costs to compare net returns of rotations using conventional spring-seeded alfalfa to an alternative system where alfalfa was established by interseeding into corn for use as a cover crop and to jumpstart full alfalfa production the following year. Alfalfa establishment in corn was projected to increased net returns by about 15%, indicating this system has potential to enhance farm profitability in addition to improving forage yields and providing cover crop benefits for protecting soil and water resources.
Poudel, H., Lee, D., Casler, M.D. 2020. Selection for winter survivorship in lowland switchgrass. BioEnergy Research. 13/109-119. https://doi.org/10.1007/s12155-020-10091-1.
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