1a. Objectives (from AD-416)
1: Develop process-level models to predict management effects on nutrient losses and gaseous emissions from farms. 1.A. Measure and model the crop production and environmental impacts of using new fertilizer technology. 1.B. Develop mechanistic relationships for the partitioning and transfer of volatile organic compounds from silage as affected by silage characteristics, management practices, and the environment. 1.C. Refine and evaluate process-level relationships for simulating ammonia, hydrogen sulfide, and greenhouse gas emissions from farms as influenced by animal, feed, and manure management. 2: Measure and model carbon sequestration potential of farming systems as a means of mitigating the impacts of agriculture on climate. 2.A. Measure the effect of enhanced nutrient availability on the carbon sequestration potential of permanent pastures. 2.B. Develop a sub-model for IFSM that represents belowground partitioning of assimilated carbon, soil respiration, and plant responses to current and elevated carbon dioxide levels. 2.C. Estimate carbon-sequestration potential of humid-temperate farm production systems using remote-sensing and associated models. 3: Refine and apply farm-scale models and analyze watershed data for integrated evaluations of management effects on nutrient losses, gaseous emissions, and the interacting effects on farm performance and profit. 3.A. Develop, evaluate, and release a Dairy Facility Gas Emission Model (DairyGEM) that expands the current DairyGHG model to include ammonia, hydrogen sulfide, and VOC emission predictions in addition to greenhouse gas emissions from dairy farms. 3.B. In support of the Conservation Effects Assessment Project, develop and apply methods for evaluating predictive uncertainty of individual and combined farm management practices. 3.C. In support of the Conservation Effects Assessment Project, publish a historical database collected from our Mahantango Creek experimental watershed to improve access, proper use, and long-term management of the data. 3.D. In support of collaborating projects working on air emissions, carbon sequestration, nutrient management, and bioenergy crop production, expand and use IFSM to evaluate the performance, environmental impact, and profitability of farming systems under historical and projected future climate scenarios.
1b. Approach (from AD-416)
Livestock operations can have a number of adverse impacts on the environment including nutrient leaching to ground water, nutrient runoff in surface water, emission of hazardous compounds to the atmosphere, and increased greenhouse gas emissions. These potential impacts are interrelated, so changes to reduce one environmental problem may increase another. A proper assessment of management changes and mitigation technologies requires a comprehensive approach that integrates all important environmental factors and their interactions along with effects on farm performance and profit. Process-level simulation, evaluated with experimental measurements, will be used to assess the environmental and economic implications of production strategies. This work will focus on further development, evaluation, and application of the Integrated Farm System Model and related software tools. Further development will improve the prediction of ammonia emission, add a component on hydrogen sulfide emission, and develop a component for predicting the emission of volatile organic compounds. An enhanced carbon sequestration component will model belowground plant processes, soil respiration, and crop responses to elevated carbon dioxide. Field and laboratory experimental measurements will help determine model parameters and provide data for model evaluation. The comprehensive models developed will be used to evaluate the effects of alternative technologies, management strategies, and climate on farm performance, environmental impact, and economics. The uncertainty of these complex models will be quantified through multiple simulations of given management practices across the ranges of relevant parameter inputs. The information and software produced will help direct producers and their consultants toward more environmentally and economically sustainable production systems.
3. Progress Report
Activities of 1902-11130-002-00D address the needs of National Program 212 contributing to problem areas 1 (Improving Air Quality) and 2 (Reducing atmospheric greenhouse gas concentrations). Under objective 1A of the project plan, field plots were established in 2010 to compare six nitrogen fertilizer sources. Nitrous oxide emissions were measured weekly or twice weekly throughout the growing season, and corn grain yields were compared. The first year of the study had below average rainfall and nitrous oxide emissions and grain yield were similar regardless of fertilizer source. Year two measurements are ongoing. Under objective 1C, process-based models that predict ammonia and hydrogen sulfide emissions from manure were completed and incorporated in the Integrated Farm System Model (IFSM), a research and educational software tool for evaluating the environmental impact and economics of farming systems. The new model components were evaluated by comparing daily, seasonal, and annual emissions to data measured over a two year period for five dairy barns and two manure storages in the eastern U.S. by the National Air Emissions Monitoring Study. Under objective 2A, the seventh year of eddy covariance CO2 flux data were collected from two cool-season pasture sites at Haller farm near State College, PA. One site received 208 kg N/ha in three applications compared with 29 kg/ha at the other site. The additional N applications led to greater photosynthesis and respiration and substantially increased net ecosystem exchange compared to the low fertility site. Under objective 3A, a new software tool called the Dairy Gas Emission Model (DairyGEM) was completed and released. This new educational tool provides an easy to use but comprehensive model for estimating the emissions of ammonia, hydrogen sulfide, methane, nitrous oxide and carbon dioxide from dairy farms. This software was made available for individual and group use in assessing management effects on whole-farm emissions, the interactions among emissions, and the evaluation of mitigation strategies for reducing emissions. Under objective 3C, a 23 to 40 year historical database of rainfall, streamflow, and water quality for the Mahantango Creek experimental watershed near Harrisburg, PA was compiled, annotated, and made publically available through the USDA-ARS Sustaining the Earth's Watersheds—Agricultural Research Data System (STEWARDS), a digital repository for long-term watershed monitoring data. Under objective 3D, several dairy and crop farms in Southeastern Pennsylvania were modeled with IFSM under current management practices to estimate nitrogen and phosphorus losses. This work provides farm-level baselines for analyzing the impact of potential management changes being developed and promoted to improve air and water quality in the Chesapeake Bay Basin.
1. Assessed the benefits of new manure application methods. In a well managed animal production system, manure nutrients are returned to the soil where they are used to produce feed crops for the animals. During this cycle though, losses occur in the form of gaseous emissions, leaching to groundwater, and runoff in surface water. ARS scientists at University Park, PA, with collaboration from the Pennsylvania State University verified a farm model to appropriately represent several manure application methods and then used the model to assess and compare their long term environmental and economic impacts on farms. Use of a shallow disk injection device for applying manure below the soil surface generally provided the lowest nutrient losses without substantially reducing farm profit. This new information is guiding animal producers and policymakers in the Chesapeake Bay region toward manure application technologies that simultaneously reduce environmental impact and maintain or improve farm profit.