Location: Dairy Forage Research2018 Annual Report
1: Develop defoliation & N application management guidelines for temperate grass-legume pastures of the NC & NE USA to improve seasonal yield distribution, extend the grazing season & improve the efficiency & utilization of energy inputs. 1A. Determine influence of manure source & application time on temperate grass productivity, seasonal yield, nutritive value & persistence, pasture composition, & soil chemical & physical properties. 1B. Determine the influence of N source & application date & rate & defoliation management on the productivity & persistence of red clover grown with orchardgrass. 2: Improve establishment, harvest management, & storage methods to reduce N inputs, increase the profitability of crop rotations, increase the recovery of dry matter & nonstructural carbohydrates, improve the energy density of baled hays & mitigate the negative effects of rainfall on ensiling, storage & feeding characteristics of rain-damaged silages. 2A. Identify optimal plant spacing to maximize yield of biomass alfalfa. 2B. Develop improved methods for interseeding alfalfa into maize to bring alfalfa into full production the next year. 2C. For large hay packages, quantify effects of several baling factors on subsequent preservation performance of stored hay. 3: Improve pasture grass & legume production systems through increases in establishment capacity, persistence, productivity, resilience to climate extremes, & quality. 3A. Measure comparative effectiveness of mass selection, maternal half-sib selection, & marker-assisted paternal half-sib selection for persistence & biomass yield in diploid red clover. 3B. Determine optimal plant-selection age to maximize genetic gain for persistence & biomass yield of red clover. 4: Improve profitability, conversion efficiency, & adaptability to climatic variation in forage & bioenergy crops. 4A. Quantify effect of decreased lignin & etherified ferulates on ag fitness of three temperate pasture species, including tolerances to drought, heat, & grazing. 4B. Use a biomimetic model based on artificial lignification of plant cell walls to identify new lignin bioengineering targets for improving fermentability of forage & biomass crops. 4C. Create & evaluate a series of upland x lowland switchgrass hybrids of differing origins to determine if heterosis is related to geographic origin of parents. 4D. Quantify genetic gains made during 3 cycles of phenotypic selection for increased biomass yield in WS4U upland switchgrass. 4E. Identify spaced-plant traits predictive of sward-plot biomass yield of switchgrass. 5: Improve dairy industry production capacity & environmental sustainability for existing & emerging markets, & improve dairy resilience to abiotic/biotic stressors while maintaining economic viability. Use a comprehensive systems approach, along with existing/new databases & models, to identify opportunities & support Livestock GRACEnet, LTAR & Climate Hub efforts to improve environmental performance of dairy systems in the NE, MW & West. 6: Characterize the contribution of cover crops to serve as animal forage, to enhance soil nutrient retention, and to reduce pathogen release from dairy production systems.
Objective 1. Solid and liquid manure applications will be evaluated in a series of grazing experiments designed to improve seasonal availability of nutrients and seasonal distribution of pasture productivity. Defoliation and manure application treatments will be applied to grass-clover mixtures to identify combinations that increase the competitiveness of red clover in mixed grazed swards. Objective 2. High vs. low-density plant spacing will be evaluated to determine the effect on biomass yield for high-biomass alfalfa cultivars. Gibberellin-based growth regulator treatments will be evaluated for their effect on establishment and seeding-year biomass yield for alfalfa interseeded into maize. Propionic acid preservatives will be evaluated to determine their effect on reducing spontaneous heating and nutrient loss of large-rectangular bales of alfalfa hay. Objective 3. The comparative effectiveness of mass selection, half-sib selection, and marker-assisted half-sib selection will be determined in an empirical study designed to improve persistence and forage yield of red clover. The optimal age for selection of red clover plants will be identified by evaluating empirical gains from selection for persistence and forage yield on selection nurseries of various ages and degrees of plant mortality. Objective 4. The effect of lignin and etherified ferulates on persistence and forage yield will be evaluated in a series of field experiments designed to evaluate progeny with high or low levels of each cell-wall component in three grass species. The direct effects of monolignol substitutes on cell-wall fermentability and saccharification will be evaluated by using these novel compounds, compared to classical monolignols, as substrates for artificial lignification of maize primary cell walls. Heterosis between upland and lowland switchgrass ecotypes will be evaluated in a series of experiments to quantify hybrid vigor and to identify sources of variation that contribute to variation in hybrid vigor. Objective 5. Experimental research will a) determine the effect of pasture stocking density and relative sward maturity on carbon and nitrogen sequestration in mixed grass-legume and grass monoculture pastures; b) test the regional application of a new alfalfa forage and cover crop system for improving alfalfa-corn rotations; and c) evaluate tannin-containing germplasm to promote forage production and feeding systems that enhance the utilization of nitrogen on dairy farms. These data plus data from other objectives will aid in development and validation of whole-farm and pasture models of dairy production being developed by ARS at University Park, PA. The models will be used to guide future research and develop a knowledge base that will assist farmers with carbon and nitrogen management.
Objective 1: Develop defoliation and nitrogen application management guidelines for temperate grass-legume pastures of the North Central and Northeastern USA to improve seasonal yield distribution, extend the grazing season, and improve the efficiency and utilization of energy inputs. Conducted field experiments to determine optimum application date of liquid or solid dairy manure to improve nutrient utilization and seasonal yield distribution of temperate pastures. Annual nitrogen utilization efficiency was 25% greater when liquid manure was surface applied to cool-season grasses compared to solid manure, and when manure was applied in spring compared to summer or fall. Manure form or application date had no influence on seasonal yield distribution. Conducted field experiments to determine appropriate nitrogen application and defoliation management of grazed grass-legume pastures to maximize utilization of fixed and applied nitrogen, and legume contribution to pasture productivity and nutritive value. Nitrogen application by fertilizer or manure to grass-legume mixtures in the spring increased annual pasture production by less than 10%, while application in early or late summer reduced annual production up to 20%. Legume persistence and forage nutritive value was reduced by nitrogen application at any time except in late summer. Objective 2: Improve establishment, harvest management, and storage method to reduce nitrogen input, increase the profitability of crop rotations, increase the recovery of dry matter and nonstructural carbohydrates, improve the energy density of baled hay, and mitigate the negative effects of rainfall on ensiling, storage, and feeding characteristics of rain-damaged silages. Yield, chemical composition, and digestibility data of leaf and stem samples were compiled for a study of biomass alfalfa planted in Wisconsin and Minnesota at low to high plant density by conventional row seeding vs. precision-spaced seeding methods. Overall, planting method and plant density had little effect on the yield and chemical composition of biomass alfalfa managed 3 years under a 3-cut harvest schedule. Initial studies demonstrated that foliar applications of prohexadione (PHD) increased plant survival of interseeded alfalfa by up to 300% during establishment in corn. Subsequent studies identified suitable rates, timing, and adjuvants for PHD applied to glyphosate-resistant alfalfa. Because of its effectiveness, an agrichemical company is moving forward with registration of PHD for use on interseeded alfalfa. Several non-GMO alfalfa varieties had 2- to 40-fold greater survival than glyphosate-resistant varieties, both with and without PHD treatment. To facilitate interseeding of non-GMO alfalfa, encapsulated acetochlor and bromoxynil were identified as effective herbicides for weed control. When successfully established, first year yield of interseeded alfalfa was two-fold greater than conventionally spring-seeded alfalfa. Alfalfa interseeding initially reduced silage corn yield by up to 15%, but increasing nitrogen fertilizer rates largely eliminated yield depression. Alfalfa seeding rate had no effect on silage corn yield, but higher seeding rates improved alfalfa plant density. Rain simulator studies indicated alfalfa interseeding reduced runoff of soil and nutrients by 40 to 80% during and after silage corn production compared to conventional systems where alfalfa was spring seeded after corn. Producers frequently who preserve forages as baled silage ask questions about potential damage to their crop when wrapping in plastic is delayed by inclement weather or when bale wrappers are temporarily unavailable. Our objectives were to test a prototype bale wrap containing an oxygen-limiting barrier against an identical commercially available bale wrap manufactured without the oxygen barrier after wrapping time delays of 0, 1, 2, or 3 d. Inclusion of an oxygen barrier had no effect, but wrapping delays of one or more days usually impaired silage fermentation and nutritive value. This information will help forage growers produce baled silage that is of good quality with methods that are economically sustainable. We tested different dairy-slurry application strategies on growing alfalfa, but they had little effect on silage fermentation products or the nutritive value of alfalfa silages. Counts of clostridial bacteria suggested application of slurry to alfalfa stubble would be preferred over delayed application to growing alfalfa. Furthermore, crop damage from salt burn, wheel traffic, or smothering was less likely when dairy slurry was applied immediately after harvest. Visual observations of plots suggested delayed application of slurry onto alfalfa regrowth should only be considered as a last resort, such as when manure-storage reservoirs are full. Should this be absolutely necessary, producers should apply manure to older alfalfa fields, rather than risk damage to recently established stands, which could easily reduce their productive life. Objective 3: Improve pasture grass and legume production systems through increases in establishment capacity, persistence, productivity, resilience to climate extremes, and quality. Demonstrated field tolerance of 2,4-D resistant red clover bred for cool humid northern U.S. climates. Based on this work, multiple seed companies have requested further information about this germplasm and selection techniques. Successfully modeled random mating expectation in insect mediated forage legume polycrosses to help reduce inbreeding depression in forage legume polycrosses. Developed and demonstrated the use of paternity testing in autotetraploid alfalfa to facilitate its implementation by multiple breeding companies. Measured alfalfa selfing rates in a Western U.S. seed production field and both developed and demonstrated a DNA assay to rapidly assess selfing rates. This work is expected to increase alfalfa yields by eliminating excessive inbreeding in alfalfa seed production fields. Measured the depressed performance of self-pollinated alfalfa progeny in a commercial alfalfa breeding nursery and demonstrated the inefficiency of allowing such plants into the breeding nursery a hitherto undocumented problem that should be addressed. Demonstrated that birdsfoot trefoil selection carried out in a grass sod improved the performance of birdsfoot trefoil progeny derived from that selection when grown in mixtures with grasses. This work provides evidence that forage legumes intended for use in forage mixtures should undergo selection in a similar environment. Developed and released red clover variety ‘FF 9615’, tested under the experimental name DFRC1, which is now commercially available; this variety is higher yielding and more persistent than other commercially available red clover varieties. Released birdsfoot trefoil variety ‘Witt’, which is now commercially available. WITT was licensed by Allied See. It is currently being marketed and sold by Allied Seed based on PVP. PVP was granted in 2013 on this variety. Objective 4: Improve profitability, conversion efficiency, and adaptability to climatic variation in forage and bioenergy crops. Conducted field experiments to evaluate high-lignin vs. low-lignin and high-ferulate vs. low-ferulate genotypes of three species (orchardgrass, reed canarygrass, and smooth bromegrass). Differential lignin concentration of leaves and stems had little or no impact on any measure of agricultural fitness. Conversely, reduced etherified ferulate concentration reduced agricultural fitness in all three species, manifested as increased leaf:stem ratio, reduced forage yield, slower recovery following defoliation, and reduced persistence under frequent defoliation. These results confirm observations from previous studies indicating that reduced lignin concentration is a "safe" selection goal, but the goal of reduced ferulate cross-linking with the cell walls of cool-season grasses has too severe of a negative impact on agricultural fitness to overcome the benefits of improved digestibility. Biomimetic cell wall model studies assessed 21 structurally diverse alternative monomers for forming lignin and for lessening the inhibitory effects of lignin on cell wall digestibility. Several monomers that impaired lignification generally improved digestibility, this presumably would diminish the functional value of lignin in plants. Monomers designed to moderately alter hydrophobicity or introduce readily cleaved acetal, amide, or ester functionalities into the polymer often readily formed lignin, but most failed to improve digestibility. Fortunately, several alternative monomers containing multiple ester-linked catechol or pyrogallol units were identified as desirable bioengineering targets because they efficiently formed lignin and improved digestibility, presumably because they blocked cross-linking of lignin to structural polysaccharides via quinone-methide intermediates and ferulate esters and they promoted lignin fragmentation during chemical pretreatment. Heterosis was rare to non-existent in a population of 64 upland x lowland hybrids of switchgrass. There was some evidence for mid-parent heterosis in a few crosses, but no evidence for high-parent heterosis. This study showed that random selection of parents from the two switchgrass ecotypes, upland and lowland, cannot be expected to automatically result in high-parent heterosis. Rather, heterotic effects that have been observed in field studies of switchgrass derive from lowland x upland hybridization, following by intercrossing of F1 individuals to create random-mating populations, and intensive selection for progeny with the desired traits of the two divergent parents. Extensive field evaluations have documented several populations derived in this manner possess the late-flowering trait and high biomass yield of the lowland parent combined with the cold tolerance of the upland parent.