Location: Dairy Forage Research2019 Annual Report
1a. Objectives (from AD-416):
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.
1b. Approach (from AD-416):
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.
3. Progress Report:
Objective 1. Field experiments for Sub-objective 1A were successfully established. The purpose of these experiments is to evaluate several warm-season grass species for suitability as forages in dairy rations, using several management factors as a mechanism to generate high-quality forage. Plots were successfully planted at two locations. Sub-objective 1B, the evaluation of manure source and application rates, was put on hold due to a critical vacancy. Objective 2. Field experiments to evaluate 250 half-sib families of switchgrass for biomass yield and nitrogen-use efficiency were planted at two locations. Field experiments to evaluate meadow fescue populations with endophyte infection (E+) vs. isofrequent populations without endophyte infection (E-) were successfully established. All plots were fertilized and prepared for harvesting and data collection during the 2019 growing season. Greenhouse experiments of all E+ and E- meadow fescue populations were successfully established and prepared for treatment applications and data collection during summer 2019. Objective 3. In spring 2019 over 12,000 red clover plants were transplanted into nine space-plant evaluation nurseries at four different Wisconsin Research Farms. Over 20 space-plant evaluation nurseries were analyzed for vigor during the summer of 2018 and the spring of 2019. Individual halfsib seed from over 20 polycrosses were produced during 2018 and 20 new polycrosses were established during spring of 2019. Three new Syn2 red clover synthetics were generated during 2018. Three new Syn2 red clover seed production blocks were initiated in 2019. Due to wet spring falcata sward trial will be established during fall 2019 towards the end of FY2019. A Birdsfoot trefoil variety trial was also established. Objective 4. In five studies we investigated interseeding of alfalfa into corn as a dual-purpose cover and forage crop; much of this work was done in collaboration with the University of Wisconsin through a cooperative agreement. The first study conducted from 2017 to 2019 investigated the effect of corn population and agrichemical applications on the survival and first year forage production of alfalfa interseeded into silage corn. This study demonstrated that alfalfa established under densely planted corn required foliar applications of prohexadione growth retardant, fungicide, and insecticide to ensure good seedling survival and subsequent forage production of alfalfa. Based on this work, a second study was conducted in 2018 and 2019 to optimize the application rate and timing of these agrichemicals to enable good survival of interseeded alfalfa at the lowest possible cost to producers. The 2018 trial was successfully completed, but heavy and frequent spring rains adversely affected alfalfa seedling emergence in 2019, thus the study may need to be repeated in 2020. A third study was planted in 2019 to evaluate if alfalfa can be bred to improve its ability to survive under densely planted corn. This study utilized seed of five alfalfa Syn1 populations and four hybrids that were produced from alfalfa plants collected in 2017 that had successfully established under corn without the use of agrichemical treatments. A fifth study focused on identifying factors to optimize establishment of alfalfa interseeded in corn. Thus far, the on-farm and experiment station trials in Wisconsin, Idaho, Michigan, and Pennsylvania have shown that good establishment of interseeded alfalfa requires good seedbed preparation and weed control, while agrichemical treatments proved most useful when alfalfa was grown under wet humid conditions that favored both foliar disease on alfalfa and high silage corn yields.