2008 Annual Report 1a.Objectives (from AD-416) The overall goal of this research is to develop and apply software tools in comprehensive evaluations of the impacts and interactions of dairy farm management on air and water quality while maintaining or enhancing farm profitability. Specific objectives are:. 1)Develop process-based relationships that predict emissions of ammonia, hydrogen sulfide, volatile organic compounds, and greenhouse gases from animal, feed, and manure sources on dairy farms,. 2)Quantify carbon sequestration potential of temperate grasslands and develop a remote sensing tool to estimate carbon dioxide fluxes from small, rotationally-grazed pastures,. 3)Validate models and quantify uncertainties of model predictions at multiple scales by comparing predictions to measured water, soil, and management effects of conservation practices (CEAP objective 3, ARS Model Validation, Evaluation, and Uncertainty Analysis), and. 4)Determine precision and accuracy of analytical data among watersheds in support of the five overall CEAP objectives (CEAP objective 6, ARS Data Quality Assurance). 1b.Approach (from AD-416) Research will be conducted to evaluate and reduce the impact of dairy farms on air and water quality. Air quality work will focus on quantifying gaseous emissions from dairy farms and the carbon sequestration that can be achieved in temperate pasture systems. Mathematical relationships will be derived that describe the biological, chemical, and physical processes involved in the formation, release, and transfer of the major gaseous compounds found in dairy facilities. These relationships will be derived based upon theoretical or scientific understanding of the processes where rates will be controlled by the characteristics of the feed or manure and the surrounding environment. Parameters for these relationships will be determined using experimental emissions data collected at University Park and in other laboratories across the country and in Europe. As these individual models are developed and validated, they will be integrated in a simulation model that predicts emissions throughout the year for each of the important gaseous compounds as a function of the feed, manure, and animal management used on the farm. A methodology will be developed for estimating carbon dioxide fluxes on intensively managed pastures from remotely sensed indices. This development will include a methodology for scaling the resolution size of available satellite images to the relatively small size of intensively managed pastures. Carbon dioxide fluxes will be quantified for switchgrass fields and perennial grass pastures using Eddy Covariance data collection. Water quality work will continue to focus on CEAP project goals. This will include a comprehensive evaluation of the environmental and economic impacts of BMPs such as manure application methods and precision feeding and forage management practices on northeastern dairy farms. BMP selection optimization will be applied to the Wallkill watershed, NJ, a watershed with high stakeholder involvement and concern for improved nonpoint source pollution control. Parameter and overall model uncertainty associated with watershed environmental impact assessments of conservation practices will be quantified. The CEAP inter-laboratory quality assurance/quality control program will be expanded and improved to assess environmental matrix effects and better address accuracy and precision of laboratory results at ranges of concentrations that are typical of water quality monitoring values. These assessments of air and water quality impacts at the farm and watershed level will lead to more profitable and environmentally friendly farm production systems. 3.Progress Report Ammonia volatilization from manure was found to be closely related to the pH at the manure surface, and this surface pH was found to be dependent upon the rate at which carbon dioxide was formed and emitted from the surface. This is an important discovery, but the new insight has complicated and slowed our process-based modeling of ammonia emissions from manure. Further experiments substantiated this pH effect, and manuscripts documenting this work were prepared. Preliminary work was begun to measure the volatile compounds emitted from silage. Silage samples were isolated, gas emissions were measured, and the samples were analyzed to quantify their chemical composition. A simulation model was completed that predicts greenhouse gas emissions and the carbon footprint of dairy production systems. This model was integrated with a whole-farm simulation model (Integrated Farm System Model or IFSM) and a simpler educational and decision aid tool called DairyGHG. Documentation of the model and both software tools was completed and the tools were made available for public use through our Internet site. Daily photosynthetically active radiation (PAR) was measured at the eddy covariance site, and drought effects on gross photosynthesis were estimated using a moisture stress multiplier from IFSM obtained through simulations using weather and management data for the site. Multiplying remotely sensed NDVI by daily PAR and the moisture stress multiplier greatly improved seasonal relationships between measured and estimated gross primary productivity. Long-term eddy covariance estimates of net ecosystem exchange were continued on two pastures providing the sixth year of data collection at the Penn State University Haller Farm and the fourth year on a producer owned switchgrass field in southwestern Pennsylvania. Because of a change in producer priorities, this will be the final year of data collection from the switchgrass field. Farm management strategies for helping New York dairy producers cope with rising corn prices were simulated using IFSM. Environmentally sound strategies found to maintain or improve farm profit were the use of no-till management and winter cover crops on existing and expanded corn land and the use of precision feeding and forage management. A manuscript was prepared documenting this work. Farm-level modeling was begun to determine cost-effective control of nutrient losses within Wallkill Watershed, NJ. Various potential management scenarios were defined, but progress of the project was slowed due to difficulty in arranging time with farmers to obtain data. Initial methods for measuring model and parameter uncertainty for the Soil and Water Assessment Tool were modified based on feedback from other researchers. These methods were tested and compared with measured data uncertainties on several ARS watersheds. This research addresses NP 203 program component 3 "Malodorous Compounds," NP 204 program component 1 "Carbon cycle and carbon storage," and the NP 207 program vision of "Integrated agricultural systems that are competitive, profitable, sustainable, and environmentally compatible." 4.Accomplishments 1. Grass-based dairy production of organic milk in Pennsylvania: To improve profitability, some small dairy farms in Pennsylvania are transitioning to greater use of managed pastures and organic production. Computer simulation of four Pennsylvania farms was used to evaluate the economic and environmental impacts of these practices. Grass-based systems using managed rotational grazing with animals maintained outdoors all year had lower erosion and phosphorus losses, lower production costs, and greater profit compared to systems using crop production, supplemental grazing, and winter confinement. The economic benefit of using organic practices was highly dependent upon the price difference between organic and conventional milk. Potential economic and environmental benefits are encouraging producers on small dairy farms to consider grass-based and organic dairy production practices. Addresses the NP 207 program vision of "Integrated agricultural systems that are competitive, profitable, sustainable, and environmentally compatible." 2. Simulating pasture photosynthesis: Accurate representation of carbon sequestration in global climate change. Models are now needed to evaluate how climate and management affect the net pasture carbon balance including carbon uptake through photosynthesis and loss through respiration. Daily measurements of gross canopy photosynthesis were used to validate the photosynthetic component of the pasture growth subroutine of the Integrated Farm System Model. The model did an excellent job of predicting annual photosynthesis and yield. Predictions of annual photosynthesis were particularly good, differing from observed values by an average of 7% in the three years simulated. Refinement of this model to accurately simulate physiological parameters such as gross photosynthesis assures users that the true dynamics of carbon assimilation and pasture growth are appropriately represented. This research addresses NP 204 program component 1: "Carbon cycle and carbon storage." 3. Carbon sequestration in mature pastures: Converting annual cropland to perennial pasture has the potential to increase soil carbon sequestration but more information is needed on the carbon sequestration potential of land that has been in pasture for several years. Four years of monitoring daily carbon fluxes from two central Pennsylvania fields that had been managed as perennial pastures for at least 35 years revealed that these pastures were small carbon sinks when only physiological processes such as photosynthesis and respiration were considered. However, when a complete carbon budget was calculated including the removal of harvested forage and application of manure, the pastures became net carbon sources to the atmosphere. Mature pastures in the northeastern USA may not help slow the increase in atmospheric carbon dioxide but may actually contribute to its increase. This research addresses NP 204 program component 1: "Carbon cycle and carbon storage." 5.Significant Activities that Support Special Target Populations All accomplishments support the special target population of small farms. Although these research results can be applied to farms of all sizes, the analyses of grass-based production and precision feed management predominately address the needs of small dairy farms. Farm evaluations in all studies represent farms with gross annual receipts under $250,000, which are typical of this region. 6.Technology Transfer Number of New Commercial Licenses Executed 4 Number of Web Sites Managed 1 Review Publications Corson, M.S., Rotz, C.A., Skinner, R.H., Sanderson, M.A. 2007. Adaptation and evaluation of the integrated farm system model to simulate temperate multiple-species pastures. Agricultural Systems. 94(2):502-508. Rotz, C.A., Kamphuis, G.H., Karsten, H.D., Weaver, R.D. 2007. Organic dairy production systems in Pennsylvania: a case study evaluation. Journal of Dairy Science. 90:3961-3979. Sedorovich, D.M., Rotz, C.A., Vadas, P.A., Harmel, R.D. 2007. Predicting management effects on phosphorus loss from farming systems. Transactions of the American Society of Agricultural Engineers. 50(4):1443-1453. Rotz, C.A., Karsten, H.D., Weaver, R.D. 2008. Grass-Based Dairy Production Provides a Viable Option for Producing Organic Milk in Pennsylvania. Online. Forage and Grazinglands. doi:10.1049/FG-2008-1212-01-RS. Skinner, R.H., Corson, M.S., Gilmanov, T.G. 2008. Simulating Gross Primary Productivity of Humid-Temperate Pastures. Agronomy Journal. 100:801-807. Garcia, A.M., Veith, T.L., Kleinman, P.J.A., Rotz, C.A., Saporito, L.S. 2008. Assessing manure management strategies through small-plot research and whole-farm modeling. Journal of Soil and Water Conservation. 63(4):204-211. Skinner, R.H. 2007. Winter carbon dioxide fluxes in humid-temperate pastures. Agricultural and Forest Meteorology. 144(1-2):32-43. Veith, T.L., Sharpley, A.N., Arnold, J.G. 2008. Modeling a Small, Northeastern Watershed with Detailed Field-Level Data. Transactions of the ASABE. 51(2):471-483. Skinner, R.H. 2008. High biomass removal limits carbon sequestration potential of mature temperate pastures. Journal of Environmental Quality. 37:1319-1326. Ghebremichael, L.T., Veith, T.L., Hamlett, J.M., Gburek, W. 2008. Precision feeding and forage management effects on phosphorus loss modeled at a watershed scale. Journal of Soil and Water Conservation. 63(5):28-291.