Project : USDA ARS

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Research Project: Sustainable Intensification of Crop and Integrated Crop-Livestock Systems at Multiple Scales

Location: Pasture Systems & Watershed Management Research

2021 Annual Report

Objectives
Objective 1: Assess and improve sustainable intensification strategies of crop and integrated crop-livestock systems for farm systems, watersheds, and landscapes. Sub-objective 1A: Quantify long-term sustainabilities of “business as usual” (BAU) and “aspirational” (ASP) dairy and beef production systems through farm simulation and life cycle assessment. Sub-objective 1B: Develop management and placement strategies for improving ecosystem service provisioning through diverse agricultural landscapes that integrate crop and livestock systems. Objective 2: Determine the sensitivity of farm systems, watersheds, and landscapes to climate variability and develop strategies for adapting agriculture to current and projected changes. Sub-objective 2A: Quantify effects of projected climate and potential adaptation strategies on long-term sustainabilities of “business as usual” (BAU) and “aspirational” (ASP) dairy and beef production systems through the use of farm simulation and life cycle assessment. Sub-objective 2B: Characterize the landscape-scale responses and trade-offs of agricultural ecosystem services, given projected climate and potential adaptation scenarios.

Approach
Agriculture faces increasing demands for productivity and efficiency that must be balanced against pressures to continually improve stewardship of natural resources. Climate models from 1950 through 2100 predict increases in temperature and precipitation in the Northeast, further complicating agricultural sustainability planning. Our research focuses on whole farms, watersheds, and landscapes to quantitatively evaluate both long-term sustainabilities and broader environmental impacts of various agricultural production systems under current and predicted climate. We will evaluate alternative production strategies based on economic viability, implementation feasibility, and impacts to ecosystem services and disservices. We are concerned with not only provisioning ecosystem services such as dairy, beef, and crop production but also supporting and regulating services like nutrient cycling and landscape diversity. Disservices from agriculture include greenhouse gas emissions and other nutrient losses to air and water. Our two objectives assess “business as usual” (BAU) and “aspirational” (ASP) agricultural production strategies for sustainable intensification at multiple scales. The (A) sub-objectives are farm-scale in detail and industry-wide in scope. The (B) sub-objectives focus on landscape-scale hydrology and ecology within the Northeast to inform both local and multi-regional research efforts. Objective 1 assesses strategies under recent climate conditions (1980-2005), and corroborates our modeling tools in representing BAU and ASP strategies. To be most valuable, however, developed strategies and tools must be successful under future climate conditions. Objective 2 corroborates our tools under historical climate (1960-1980) and applies them under future mid-century (2040-2060) and late-century (2080-2100) climate projections, assessing ASP strategies that most effectively meet the challenges and opportunities of future climate. We will collaborate with larger USDA-led research networks, including the Long-Term Agroecological Research network (LTAR), Conservation Effects Assessment Project (CEAP), and Dairy Agroecosystems Working Group (DAWG). Such networking provides expertise and data on outcomes from management strategies for cropping and integrated crop-livestock systems that will be used to confirm results of the first objective and provide a basis for extrapolation of future systems for the second. We will analyze data using both simple and complex process-based simulation models, life cycle assessment, and advanced computational techniques. With an emphasis on sustainable intensification in accord with climate predictions, our research will support systems-level understandings of current and potential agricultural systems in the Northeast, and how these can continue to produce food and fuel in the future. Outcomes of this research will support farmers directly through management strategies and decision support tools, and will provide scientifically-valid data to federal and state programs aimed at improving nutrient management, conservation, and resource use efficiency.

Progress Report
Progress was made on both objectives and their subobjectives, all of which fall under National Program Action Plan 216: Agricultural System Competitiveness and Sustainability and contributes to Component 1: Building agroecosystems for intensive, resilient production via GxExM; Component 2: Increasing efficiency for agroecosystem sustainability; and Component 3: Achieving agroecosystem potentials. Under Objective 1, Subobjective 1A, a full life cycle assessment of beef was completed by collaborators at the University of Arkansas with a report submitted to the National Cattlemen’s Beef Association. This provides the most comprehensive full life cycle assessment of U.S. beef available. Representative dairy farms throughout six regions of the U.S. were modeled using the Integrated Farm System Model to provide farm environmental impact data. These data were used to complete a comprehensive cradle to farm-gate life cycle assessment of U.S. dairy farms, and the work was documented in a journal manuscript. Environmental footprints for greenhouse gas emission, fossil energy use, and water consumption represented a relatively small portion of respective national inventories, but the dairy industry’s contribution to ammonia emission appears to be considerably greater. In collaboration with the Southwest Beef Project and Long-Term Agroecosystm Research (LTAR), representative beef cattle operations were modeled throughout the southwest region. Preliminary results were obtained comparing farm-gate life cycle assessments of cattle finishing on rangeland in the Southwest, pastureland in the Northern Plains, and feedlots in the Texas Panhandle. Under Subobjective 1B, high-risk landscape characteristics predicted by the Agricultural Conservation Planning Framework (ACPF) were ground-truthed and overlain with high-risk areas predicted by the Soil and Water Assessment Tool (SWAT). Additionally, nutrient loss predictions between SWAT and the Pennsylvania Phosphorus Index were compared and evaluated. This work feeds into a national effort between ARS and Natural Resources Conservation Service (NRCS) to identify and upgrade tools for conservation planners to organize their mitigation outreach efforts based on local geospatial information and water quality modeling. Spatial maps were developed describing the impact of management on the profitability of double cropping. The economics of double cropping wheat and barley improved with early harvest in the north but decreased in the south. Consistent with historical cropping patterns, double-crop wheat economics improved along a southerly longitudinal gradient and with the addition of straw coproduct. When N fertilizer was applied to rye, rye biomass yield was greater following corn than soybeans and generally increased along a southerly longitudinal gradient. However, cereal rye was only profitable in the southern regions when the rye crop followed corn and no N fertilizer was applied to the rye. Following soybeans, rye was not profitable, with or without N application. Considering the sensitivity of double-crop rotation economics to soybean yields, and that barley has less impact on soybean yields than wheat does in the northern regions, the establishment of a bioenergy or pulp market for biomass could provide significant incentive for widespread planting of winter barley as a double crop in corn-soybean rotations. In conjunction with a LTAR network summary of climate change projections, soil erosion and nutrient losses were modeled for all 18 LTAR regions using the 2018 boundary layers and historical weather data. Additionally, five climate change scenarios were chosen to span the range of projected futures. These analyses provide a broad comparison of climate change-related effects on erosion for agriculture across the U.S. Under Objective 2, Subobjective 2A, previous models of heat stress on cattle informed new strategies to evaluate aspirational dairy systems for Pennsylvania. A representative dairy farm was modeled to compare “business as usual” management strategies with “aspirational” stratagies that used double cropping and subsurface manure injection. Assessments were completed for recent historical climate and projected midcentury climate. Double cropping winter rye and corn silages and subsurface injection of manure reduced soluble P runoff and ammonia volatilization to the atmosphere without significantly increasing total production costs. Adoption of these strategies provided a feasible adaptation and mitigation strategy for future climate by reducing potential increases in soluble P runoff and ammonia emission caused by warmer temperatures and more intense storms while maintaining and potentially reducing total farm production costs. Under Subobjective 2B, cropping rotations were spatially reallocated across a piedmont agricultural watershed to explore the potential for more optimized use of the regions physiographic features in mitigating long-term production-reducing changes in climate. More broadly, the impact of climate variability on storm frequency and volume was assessed over 10 years across 108 subwatersheds within the Chesapeake Bay Nontidal Network. These findings stress the importance of informed design and implementation of best management practices effective in "hot moments" and not just "hot spots" across impaired watersheds to achieve and maintain water quality restoration goals. The "temporal targeting framework" provides a useful and convenient method for watershed planners to create low- and high-flow load targeting tables specific to a watershed and constituent. Modeling of regionally representative farming systems using projected climates was delayed by pandemic-related personnel issues but substantially completed. The same set of climate change projections used for subobjective 1B was used to drive a model of forage production across the northeastern U.S. to develop initial projections of spatial and temporal dynamics in grazing systems. Representative farms were not completed since that required an additional modeling step, but this milestone is anticipated to be completed by the end of the fiscal year.

Accomplishments
1. Environmental impact of U.S. dairy farms. A comprehensive life cycle assessment across six regions of the U.S. provided regional and national estimates of dairy farm impacts. Greenhouse gas emissions, fossil energy use, and blue (ground and surface) water use associated with dairy production were relatively small (less than 3 percent) compared to national inventories. A more significant environmental concern is ammonia emission, where dairy farms may emit as much as 24 percent of the estimated emission from U.S. This analysis also indicates that varied mitigation strategies tailored for individual farms are most effective. This assessment provides a science-based understanding of critical environmental issues facing the dairy industry.

2. Honey bee winter survival. Pollination is a crucial service required by many crops and managed honey bees provide $15 billion in pollination services to U.S. agriculture. Honey production adds another $300 million to the U.S. economy. Bees suffer from many challenges, including insecticides, disease, and overwintering mortality. A multi-year survey of beekeepers in Pennsylvania was used to identify the weather and landscape factors most closely linked to honey bee winter mortality. Summer temperatures that allow for successful growth and collection from flowers were an essential factor. This information contributed to the development of the BeeWinterWise decision support tool (https://beescape.org). This new tool helps beekeepers understand how the current weather at their locations may affect honey bee mortality during the subsequent winter, enabling them to make informed decisions for seasonal hive management.

U.S. DEPARTMENT OF AGRICULTURE

Pasture Systems & Watershed Management Research: University Park, PA