Objectives: 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. a. Investigate historic, current and potential future land use patterns to determine the suitability of grazing lands for pasture and biofuel production, and to assess potential responses of grazing agriculture to changing climate. b. Characterize potential changes in forage species distribution and dairy cow grazing behavior in response to climate change, and evaluate plant and animal management strategies to mitigate climate change. c. 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. a. Identify management systems that increase soil Carbon (C) sequestration and reduce Nitrogen (N) loss and net Greenhouse Gas (GHG) emissions in bioenergy crop systems across the landscape in the Northeast. b. Evaluate GHG emissions of miscanthus production when grown at the farm scale in Northeast across soils typical of the region and previous land use history. 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. a. Using a comprehensive, systems approach along with existing/new databases and models to identify opportunities and support Livestock GRACEnet, Long Term Agroecosystem Research Network (LTAR) and Climate Hub efforts to improve the environmental performance of dairy systems across the Northeast, Midwest, and West.
Calibration and testing of the Agricultural Policy/Environmental Extender (APEX) model for use in northeastern temperate pastures will continue, in support of Grazing Lands Conservation Effects Assessment Project (CEAP) goals. University Park is leading this CEAP effort to configure the farm-scale model for use with National Resource Inventory pasture data for the continental United States. A consistent and well-documented dataset containing topography and derived variables, historical and projected climate data and derived indices such as CLIMDEX and BIOCLIM, and digital soil mapping products that reduce the positional error in standard Soil Survey Geographic Database (SSURGO) soils maps is being used to map and model forage, biofuels, and crop species distributions under current and potential future climates. These models incorporate field, greenhouse, and survey data (National Resource Inventory, Census of Agriculture and other sources) to better understand shifting patterns of agricultural diversity and productivity for both Long-Term Agroecosystem Network sites and the nation as a whole. To evaluate the environmental effects of growing biomass crops on marginal lands, we will continue to monitor N2O emissions and continuously record soil moisture, temperature, and oxygen concentration across a moisture gradient of perennial grasses switchgrass and miscanthus. The location is an 11 ha watershed in the Mahantango Creek watershed and was formerly Conservation Reserve Enhancement Program (CREP) marginal lands. To better characterize spatial biomass yields across the watershed, we will use structure from motion with a unmanned aerial vehicle (UAV). The moisture gradient will allow us to characterize biomass yield potential across a range of marginal lands from droughty to poorly drained. A life cycle inventory of energy use at the farm scale with over 4,000 acres of miscanthus production will continue. Different establishment strategies are being evaluated to increase production. Spatial yield variation is occurring at both the whole and sub field scales and will be quantified and evaluated. Eddy covariance systems are being used to estimate changes in soil carbon across a soil carbon gradient. Determine if overseeding of annual warm-season grasses into perennial cool-season pastures can help to extend the grazing season during the traditional summer slump found in cool-season perennial, as well as determine the best method of establishment and yield differences of pastures either overseeded or not overseeded. Develop, refine and field test an improved grazing behavior monitor that combines animal grazing patterns, jaw movement, and telemetry into one unit.
This is a bridge project for 8070-21000-008-00D which terminated in November 2017. Objective 1: Biomass estimation in rotationally-grazed pastures is a major challenge. Single- or few-sample surveys, such as NRI (National Resources Inventory) and the farm survey described above cannot adequately describe pasture biomass production. Instead, exclosures or frequent measurements are required to estimate production. Neither of these techniques is possible across large regions, or given the lack of control inherent in working on private lands. Instead, two approaches have been evaluated to obtain biomass estimates: species-specific allometric relationships between biomass and measured height and cover values; and remote sensing estimates using NDVI (normalized difference vegetation index) and other vegetation indices. Seasonal allometric coefficients relating canopy cover to biomass were developed for individual species and for functional groups (grass, large forb, small forb) using data from a grazed, multi-species, experimental pasture in Pennsylvania, and tested on an independent grazed experimental study. The models performed better in autumn than in spring, and performance varied greatly among species. The functional group models were generally more accurate than species-specific models, even for estimating single species. Total grass and forb biomasses were well modeled, with bias less than thirty percent regardless of season. Unlike many allometric models, these were developed and tested on multi-year, grazed, multi-species, pastures, so variability was high, but the results will have broad applicability in grazed, high-fertility, mesic, pastures. Consistent spatial and temporal datasets for soils, climate, and topography for the continental United States are required for multiple projects including LTAR (Long-Term Agroecosystem Research), NRI, and CEAP (Conservation Effects Assessment Project), and forage suitability group development. Considerable effort has been devoted to identifying and calculating derived metrics related to the plant requirements of light, temperature, and water, including climate indices relevant to plant growth, including BIOCLIM, CLIMDEX, and the metrics proposed in the NRCS (Natural Resources Conservation Service) Range and Pasture Handbook. These have been calculated for both current and predicted future climates. Derived topographic variables including slope, aspect, curvature, and topographic convergence have been calculated from the 30m National Elevation Dataset for the continental U.S., and supplemented with both Cropland Data Layer and National Land Cover Data for 2008-2018. Digital soils mapping products at several scales complement standard soils products. The novel behavior recorder halter is currently being beta tested and refined for use on research studies later this summer. This recorder measures the frequency and amplitude of jaw movements of grazing ruminants to quantify bite rate, number and length of meals, ruminating time and resting time. In addition, this unit has a Global Positioning System (GPS) that will pinpoint location of a cow on pasture to monitor movements throughout a pasture or rangeland which can be important for factors such as grazing fragile environments (e.g., riparian areas) or estimating diet selection by combining location and grazing behavior with patches of various forages in a biodiverse pasture. This unit also contains a graphical user interface, which allows the user to remotely download the data onto a computer or smartphone without disturbing the animals. In addition, the unit can send a distress signal if there is a malfunction with the recorder so corrections can be made without losing large amounts of data. Forage plots of cool-season perennials were established at the Rock Springs Research Farm to evaluate interseeding of warm-season grasses to evaluate extension of the grazing season during the summer slump. Warm season grasses will be interseeded in summer 2020. Objective 2: We logged energy use on agricultural machinery from Miscanthus production planted on more than 1000 hectare of land and modeled N2O emissions and changes in soil carbon using DayCent. Although fuel use was higher for land preparation in fields with perennial vegetation, fuel to harvest miscanthus dominated greenhouse gas (GHG) emissions from agriculture machinery for crop management. The N2O emissions and changes in soil carbon were the largest source and sink of GHG emissions associated with Miscanthus production, respectively. In using satellite imagery to estimate crop biomass yields, we found that the Enhanced Vegetation Index (EVI) had a good relationship to field scale yields (R2= 0.5). There was a good relationship between Miscanthus coverage and yield (R2= 0.6), and fuel use for Miscanthus harvest and field yields (R2= 0.7). Soil properties show promise to explain spatial biomass yield variability. In this region, poorly drained soils seem to drive much of the biomass yield variability. We are developing methods to evaluate LiDAR as a tool to quantify forage yields.
1. Riparian grasslands provide economic and water quality benefits. Grassland buffers can improve water quality, but it is typically hard for farmers to capture the economic value without enrollment in government conservation programs. ARS scientists in University Park, Pennsylvania and Pennsylvania State University scientists found that high biomass switchgrass and Miscanthus had similar water quality impacts as the grass mixture enrolled in conservation practices. Although nitrogen didn’t increase yields, it did increase water quality impacts. This finding shows that there are potential economic opportunities for biomass production in riparian buffer grasslands on top of maintaining water quality benefits.
2. Add value to soybean production by pressing oil on-farm. There has been interest in producing biofuel from oil seed crops for use on farms, however little guidance is available on where this may be profitable. ARS scientists in University Park, Pennsylvania and Pennsylvania State University scientists found that the profitability and carbon footprint of processing soybeans on-farm improves as farm location moves towards the coastal Atlantic and Gulf regions where the economic value of the meal is higher. This finding will help farmers determine if pressing their own soybeans may add value to their farm and reduce fuel cost by using the pressed soybean oil in their farm machinery.
3. Double cropping not always profitable. Planting a second crop, such as annual forages, after corn is harvested (known as double cropping) can increase total forage production, decrease livestock feed costs, and have environmental benefits. However, adoption of double cropping has been low in regions with shorter growing seasons. ARS scientists in University Park, Pennsylvania evaluated the cost to produce milk and crops on four dairy farms in northern and western Pennsylvania, a region where double cropping was not common due to the shorter growing season. Double cropping did not result in an economic benefit for three of the four case study farms due to the high cost of production of the annual forage compared with purchasing the forage. Farms considering double cropping should calculate cost of production of their crops and not assume that double cropping will be profitable in every situation.
4. Flaxseed improved fatty acid profile but decreased milk production in grazing cows. Dairy cows grazing pasture have altered milk fatty acid profiles that may have human health benefits. However, these beneficial milk fatty acid profiles are not maintained during the wintertime when hay and silage are fed. ARS scientists in University Park, Pennsylvania evaluated the effect of feeding flaxseed to organic dairy cows fed hay and silage during the wintertime on milk fatty acid profiles. Levels of flaxseed supplementation needed to improve milk fatty acid profiles may also decrease milk production. Increased milk price would be necessary to compensate farmers for increased feed costs and reduced milk production associated with flaxseed supplementation.
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Hafla, A., Soder, K.J., Brito, A., Kersbergen, R., Benson, F., Darby, H., Rubano, M., Dillard, L., Kraft, J., Reis, S. 2018. Impacts of seasonal variation and winter supplementation of ground whole flaxseed on milk fatty acid composition of organic dairy cows in the northeastern United States. Professional Animal Scientist. 34:397-409.
Rau, B.M., Adler, P.R., Dell, C.J., Saha, D., Kemanian, A. 2019. Herbaceous perennial biomass production on frequently saturated marginal soils: Influence on N2O emissions and shallow groundwater. Biomass and Bioenergy. 122:90-98. https://doi.org/10.1016/j.biombioe.2019.01.023.
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