1a. Objectives (from AD-416):
1: Identify, through experimentation and plant growth and habitat modeling, pasture-based dairy and livestock production systems and management practices that improve food security by enhancing productivity, improving long-term environmental sustainability, and increasing flexibility to adapt to changing environmental and climatic conditions. We will initially delineate current land-use practices for grazing lands in the eastern US and investigate how land use might change in the future (sub-objective 1.A). Primary land use practices to be considered are pasture-based animal agriculture and bioenergy feedstock production systems. Sub-objective 1B will characterize potential changes in forage species distribution and dairy cow grazing behavior in response to climate change (adaptation), and evaluate plant and animal management strategies to mitigate climate change. Sub-objective 1.C will identify conservation practices and animal management strategies that improve nutrient utilization efficiency and reduce sediment and nutrients movement off-farm. 2: Develop best management practices and identify management systems that improve productivity and environmental sustainability of bioenergy production as part of multifunctional agricultural systems. Objective 2 focuses on bioenergy cropping systems and will identify management systems that increase soil C sequestration and reduce N loss and net GHG emissions (sub-objective 2.A) and evaluate the effects of miscanthus production at the commercial scale on C sequestration and GHG intensity (sub-objective 2.B). Sub-objective 2B will also include a life-cycle inventory assessment to profile the energy and GHG emissions associated with miscanthus production. Objective 3. Improve dairy industry production capacity and environmental sustainability to meet the demands of existing and emerging markets, and improve dairy industry resilience to abiotic and biotic stressors while maintaining producer economic viability. Using a comprehensive, systems approach along with existing/new databases and models to identify opportunities and support Livestock GRACEnet, LTAR and Climate Hub efforts to improve the environmental performance of dairy systems across the Northeast, Midwest, and West. The following research focus areas will be prioritized: a) Improve nutrient use efficiency across dairy production, emphasizing the conservation of nitrogen and phosphorus in local and regional crop production and reduction of off-farm nitrogen and phosphorus losses, especially through novel/greater use of forage crops and innovative practices. b) Improve carbon sequestration and reduce greenhouse gas emissions from dairy cattle, production facilities and land application of manure. c) Improve the understanding of pathogen transport and control through water and/or bioaerosol pathways.
1b. Approach (from AD-416):
This research will provide the necessary information for developing decision-support tools that bring together diverse forage production systems, innovative animal management strategies and novel biofuel production practices to build multifunctional farms and landscapes. The purpose is to provide guidance on optimizing the placement and management of pasture and bioenergy crops in ways that are appropriate to the landscape context and that will increase productivity and enhance ecosystem services of farming enterprises. We will initially delineate current land-use practices for grazing lands in the eastern US and investigate the production and environmental consequences of potential future management changes. Primary land-use practices to be considered are pasture-based animal agriculture and bioenergy feedstock production systems. We will provide information on plant and animal adaptation to climate change and on the effectiveness of greenhouse gas (GHG) mitigation strategies for grazing animals, pasturelands, and biofuel feedstock production systems. We will provide farm scale life cycle inventory (LCI) data on miscanthus and identify water quality and GHG impacts of switchgrass and miscanthus production on marginal lands We will also assess the effects of grazing management and manure application strategies on nutrient movement and water quality as part of the pasture component of the national Grazing Lands Conservation Effects Assessment Project (CEAP). Results will fill gaps in our knowledge of management practices that increase resilience to climate change, improve conservation of soil and water resources, and reduce GHG emissions. Successful completion of this project will 1) increase farm productivity, 2) improve adaptation to climate change and 3) provide targeted conservation practices to enhance ecosystem services.
3. Progress Report:
For sub-objective 1.A.1, species distribution models, climatic models of agricultural land uses, and landscape classification have been combined to create an ecologically-based grouping of agricultural land uses including pasture, and to characterize the agricultural potential of the entire continental U.S. For sub-objective 1.A.2, potential agricultural suitability models have been developed for the continental U.S., and are being combined with food and bioenergy production models to evaluate the trade-offs between land use for food and for fuel under current and potential future climates. For sub-objective 1.B.1, topoclimatic models for forage species production have been used with predicted future climates to develop regional and national estimates of changes in pasture communities. Sub-objective 1.B.2 has been complete. For sub-objective 1.B.3, a manuscript was published comparing forage yield and carbon sequestration between two- and five-species pasture mixtures. Management of cropping system plots continued. The perennial grasses switchgrass and reed canarygrass at the Penn State University Hawbecker farm were harvested in August 2015, November 2015, and April 2016, collecting biomass yield data; other management practices were completed as appropriate during growing season. For sub-objective 1.B.4, a continuous culture fermenter study that evaluated the effects of alternative forages on ruminal fermentation and methane output of a pasture-based diet was published in the Journal of Dairy Science in 2016. The results of this study showed that beet pulp improved protein digestibility but impaired fiber digestibility and had higher methane output than supplementing with barley. For sub-objective 1.C.1, improving the fatty acid profile of milk may have human health benefits. We looked at the effect of feeding increasing amounts of flaxseed to organic dairy cows on milk fatty acid profile and milk yield. Increasing flaxseed supplementation increased beneficial fatty acids such as omega-3 and conjugated linoleic acid, but also decreased the daily amount of milk produced, which would result in decreased farm income unless a substantial premium was paid by milk processors for these increased fatty acids in milk. For sub-objective 1.C.2, manure was applied to Penn State University Rock Springs farm site in fall 2015 and twice in spring 2016. The initial manure application at Paul farm in Northumberland County, Pennsylvania, occurred in spring 2016. Nitrous oxide emissions, yield and nutrient runoff were monitored following each application and ammonia emissions monitored following the second manure application at Penn State University Rock Springs farm in 2016. A talk describing initial results will be presented at the annual American Society of Agronomy Meeting in November 2016. For sub-objective 1.C.3, the relationship between grazing management practice and runoff water quality in beef-grazed pastures was quantified. Results show that neither cumulative runoff depths nor trends in runoff depths across seasons differed among treatments. Runoff quantity was most highly correlated to antecedent moisture conditions throughout the season, and did not vary significantly across stocking methods or with soil compaction or dry matter yield. In summary, analyses of the response variables suggested that the variability within treatments likely muted any treatment effect on the response variables. For sub-objective 2.A.1, water quality and soil N2O emissions data were collected regularly at the Mattern watershed in Klingerstown, Pennsylvania. Biomass yield was determined at the end of the growing season. For sub-objective 2.A.2, biomass yield data were collected and life cycle assessment was initiated. For sub-objective 2.B.2, fuel use was measured during miscanthus harvest.
1. Can pasture meet nutritional needs of dairy cows? Little research has evaluated the nutritional content of pastures relative to nutrient needs of grazing dairy cows. ARS scientists at University Park, Pennsylvania conducted a study to determine how frequently pastures in the northeastern U.S. met nutrient requirements of lactating dairy cows and to describe a sample of the feeding strategies accompanying grazing on these farms. Nutritional quality of pastures was generally high, with energy as the most limiting dietary component, which can be corrected with energy supplementation. High quality pasture and diverse supplementation strategies allow farmers to use resources such as pasture and homegrown forages and grains to meet goals of milk production for their farm. Previous research has confirmed that some degree of supplementation of grazing dairy cows will result in a profitable increase in milk production, however it is important to recognize that markets currently exist that pay premiums for value-added milk products (such as grass-fed milk) which may negate the economic benefits of supplementation.
2. Increasing species richness improves pasture yield and carbon sequestration. Pasture management options are needed that both increase forage production and provide ecosystem services such as increased soil carbon sequestration. One possible management practice could be to increase the number of plant species sown in a pasture. Over the nine years of this study, ARS researchers in University Park, Pennsylvania found that a five-species mixture had 31% greater forage yield than a two-species mixture. Yield benefits from the five-species mixture were greatest in years with high rainfall and were greater than average the last two years of the study, suggesting that the effects were long-lived. The five-species mixture also sequestered three times as much soil organic carbon as the two-species mixture. This study showed that increasing the number of sown species can have multiple, long-term benefits for temperate pastures.
3. Zero net greenhouse gas (GHG) emissions from Great Plains agriculture is possible. The Great Plains is an important agricultural production region supplying food for the global marketplace. Understanding the historical change in GHG emissions with climate and technology, can help identify solutions for the future reductions in GHG emissions. In collaboration with Colorado State University, University of Colorado, and University of Michigan, ARS researchers in University Park, Pennsylvania found that the largest sources of GHG emissions prior to 1930 was from plowout of native grasslands, whereas after 1930, it was GHG emissions from agriculture production. In contrast with cool and wet weather, hot and dry weather decreased soil carbon, thereby increasing GHG emissions. Increased adoption of no tillage and slow release nitrogen fertilizers would reduce GHG emissions, potentially achieving zero net GHG emissions if adoption is high enough, without reducing agricultural production.
4. Flaxseed improves fatty acid profile of milk but decreased milk production. Increasing flaxseed supplementation to dairy cows increased beneficial fatty acids such as omega-3 and conjugated linoleic acid, but also decreased the daily amount of milk produced, which would result in decreased farm income unless a substantial premium was paid by milk processors for these increased fatty acids in milk.
5. Beet pulp increased methane output of pasture-based diet. Due to its sugar content, beet pulp may provide a better source of energy to grazing dairy cows than barley grain, which contains starch. ARS researchers in University Park, Pennsylvania looked at supplementing a pasture diet with either barley grain or beet pulp at two levels of supplementation. Feeding beet pulp improved protein digestibility, but decreased fiber digestibility of the diets compared to supplementation with barley grain. However, methane output was greater for diets supplemented with beet pulp, which may have negative environmental impacts and must be weighed against potential benefits. More research is needed to evaluate the economic and environmental sustainably of supplementing pasture diets with alternative energy sources such as beet pulp.
6. Landscape strategies to minimize greenhouse gas emissions. Multiple factors can affect the carbon footprint of biofuels, such as soil type, land use, and management intensity, however there are few examples of available data to calibrate across this range of factors. In collaboration with Colorado State University, ARS researchers in University Park, Pennsylvania found that switchgrass yields and greenhouse gas emissions varied greatly across a landscape large enough to supply a biorefinery in response to variations in soil type, land use history, and management intensity, providing the bioorefinery significant opportunities to minimize the carbon footprint of their feedstock. These results demonstrate the value of this modeling approach to identify strategies to mitigate greenhouse gas emissions and minimize the carbon footprint of the bioenergy feedstock production.
5. Significant Activities that Support Special Target Populations:
Scientists in University Park, Pennsylvania have participated in activities targeting small farmers including: 1) education of organic and grazing-based farmers on forage, grazing, and livestock management by participation in the Northeast Pasture Consortium, Pennsylvania Project GRASS, and the Grazing Lands Coalition (GLC); 2) conducting on-farm research funded by OREI on flax as a supplement for grazing dairy cattle on organic dairies and on the benefits of grass cultivar diversity within perennial ryegrass-white clover mixtures; and 3) providing climate change adaptation strategies to northeast farmers though the USDA Northeast Climate Hub.
Skinner, R.H., Goslee, S.C. 2016. Defoliation effects on pasture photosynthesis and respiration. Crop Science. 56:2045-2053. doi:10.2135/cropsci2015.12.0733.
Resende, T.L., Kraft, J., Soder, K.J., Pereira, A.B., Woitschach, D.E., Reis, R.B., Brito, A.F. 2015. Incremental amounts of ground flaxseed decreases milk production but increases n-3 fatty acids and conjugated linoleic acids in dairy cows fed high-forage diets. Journal of Dairy Science. 98:4785-4799.
Soder, K.J., Brito, A., Hafla, A.N., Rubano, M.D. 2016. Effect of starchy or fibrous carbohydrate supplementation of orchardgrass on ruminal fermentation and methane output in continuous culture. Journal of Dairy Science. 99:4464-4475.
Tracy, B., Albrecht, K., Flores, J., Hall, M., Islam, M., Jones, G., Lamp, W., Macadam, J., Skinner, R.H., Teutsch, C. 2016. Evaluation of alfalfa-tall fescue mixtures across multiple environments. Crop Science. 56:2026-2034. doi:10.2135/cropsci2015.09.0553.
Field, J., Marx, E., Easter, M., Adler, P.R., Paustian, K. 2016. Ecosystem model parameterization and adaptation for sustainable cellulosic biofuel landscape design. Global Change Biology Bioenergy. doi: 10.1111/gcbb.12316.
Egan Jr, J.F., Goslee, S.C., Orr, A.N. 2015. Tradeoffs between production and perennial forages in dairy farming systems vary among counties in the Northeastern United States. Agricultural Systems. 139:14-28.
Rauschert, E., Shea, K., Goslee, S.C. 2015. Plant community associations of the invasive thistles. AoB Plants. doi: 10.1093/aobpla/plv065.
Parton, W.J., Gutmann, M.P., Merchant, E.R., Hartman, M.D., Adler, P.R., Mcneal, F.M., Lutz, S. 2015. Measuring and mitigating agricultural greenhouse gas production in the U.S. Great Plains 1870-2000. Proceedings of the National Academy of Sciences. 112(34):E4681-E4688.
Skinner, R.H., Dell, C.J. 2016. Yield and soil carbon sequestration in grazed pastures sown with two or five forage species. Crop Science. 56:2035-2044.