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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: IMPROVED MEASUREMENT, MONITORING, AND MITIGATION OF NITROUS OXIDE EMISSIONS AND RELATED N LOSSES FROM INTENSIVELY FERTILIZED AGRO-ECOSYSTEMS

Location: Soil and Water Management Research

2009 Annual Report


1a.Objectives (from AD-416)
This project will integrate research, education, and extension activities to address the Measurement/Monitoring and Mitigation Priorities of the Air Quality Program via the following inter-related objectives: 1. Develop improved methods and protocols for monitoring direct and indirect N2O emissions from fertilized soils including a mobile on-site Nitrogen Emissions Laboratory; 2. Quantify the effectiveness of alternative agricultural management practices for mitigating N2O emissions and related N losses using the above protocols; and 3. Disseminate information obtained from the above activities to non-scientific stakeholders that encourages improved management practices to reduce impacts on air quality. Outputs from the project include: Objective 1. Error analysis tools including chamber dynamics models will be developed that allow scientists engaged in N2O, NH3, and other trace gas research to evaluate and improve methods. Documentation of method protocols and description of the NEL in the scientific literature will encourage the development of similar procedures and facilitate on-field collaboration with farmers and commodity groups. Target date to completion: Week 32. Objective 2. The experimental data will generate improved estimates of time-integrated total N2O emissions for specific site management regimes including potential mitigation strategies. These data will be useful to farmers, fertilizer and agricultural equipment manufacturers, local conservation officials, state and federal environmental officials, and policy makers. The monitoring efforts will also provide unique data sets of interest to scientists and will provide improved understanding of process controls over key mechanisms of N loss, which in turn will allow testing and refinement of process models of N2O emissions from agricultural systems. Target date to completion: Week 48. Objective 3. Results will be used to generate information tools that will be disseminated via formal programs of the University of Minnesota Extension Service and via the web, including: A. A series of educational bulletins written in concise, layman's terms which will provide an overview of the environmental impacts of off-site N losses, (ii) the capabilities of the mobile, on-site Nitrogen Emissions Laboratory (NEL), and (iii) the basic principles of fertilizer N management, with focus on minimizing gaseous N emissions as well as overall N losses. Target date to completion: Week 48. B. A web-based nutrient management calculator for agricultural producers will be developed. The calculator will be based upon current University of Minnesota Extension Service recommendations and supplemented with information regarding N gas emissions and losses generated from this study. Users will be prompted to input basic information including crop, soil type, location, other management factors such as irrigation, rotation, and method, timing and chemical form of fertilizer applications. Target date to completion: Week 48.


1b.Approach (from AD-416)
Objective 1: Methods for determining soil-to-atmosphere fluxes of N2O and NH3 will be evaluated and improved using laboratory and field tests and by comparison of data to chamber dynamics models. A comprehensive monitoring system for quantifying direct and indirect sources of N2O emissions will be established by integrating existing capabilities with newly developed methods. A mobile on-site Nitrogen Emissions Laboratory (NEL) which can be efficiently moved from site to site will be enhanced and implemented. Objective 2: The methods and protocols established in Objective 1 will be applied to field experiment studies at multiple contrasting site locations where specific practices for reducing total N2O emissions will be compared with conventional management. Use of the same measurement methods across all sites will also increase the validity of the data. The treatments described below have been identified after consultation with Stakeholder Advisory Board members. Additional treatment details (e.g. N application rates and timing) as well as additional possible treatments (e.g. use of manure-based fertilizers) will be determined after further consultation with the Board prior to initiating experiments at each site. Objective 3: A key aim of the project is to disseminate practical information to agricultural producers, industry, conservation officials and others who will ultimately benefit from the research. In addition to input that the Stakeholder Advisory Board has already had on this proposal, their input will continue through meetings and interactions to assist in the development of information tools. Technology transfer will also be expedited by University of Minnesota professors with substantial experience in Extension service and collaboration with farmers and commodity groups. We will also involve the graduate student in these interactions in order to provide extension experience which often is lacking or difficult to incorporate into graduate studies. To assist in the development of information products described below and to identify other potential issues to be addressed, a survey of current N management practices and information needs among agricultural producers across the state of Minnesota will be conducted. University of Minnesota Extension Service personnel with expertise in surveys will design and conduct the survey. Initial input into the survey design will be provided by the Advisory Board. The survey will help to identify potential users of the information, to generate mailing lists, and to assess preferences for web-based versus printed material. The survey will also collect information such as: current N fertilizer management practices with respect to application rates (lbs/acre), timing (fall or spring, single or multiple applications), method (surface or subsurface), and chemical form; impacts of increased fertilizer costs on practices; general concerns about N management and losses; interest in information regarding methods for minimizing N losses.


3.Progress Report

A field experiment in a coarse-textured soil used for corn production was designed with input from fertilizer manufacturing companies (Agrium and Agrotain) and an agricultural equipment manufacturer (John Deere). The experiment is designed to concurrently measure both direct and indirect N2O emissions under irrigated and dryland management and under varying nitrogen fertilizer management, including the use of a novel anhydrous ammonia application method, and a no-fertilizer control. Replicated plots (n=4) were established using a split plot design with irrigation and fertilizer management as the main plot and sub-plot treatments, respectively. Measurements were made of soil-to-atmosphere emissions of nitrous oxide, nitric oxide, and leaching of nitrate below the rooting depth over the entire growing season. Ancillary measurements were also made of soil inorganic nitrogen, soil moisture and temperature, and plant populations over the course of the growing season, as well as grain yields at end of season. An on-site, mobile laboratory and automated trace gas flux measuring system was also developed and installed at the experimental site. Preliminary automated measurements were made of soil nitrous oxide and carbon dioxide fluxes. A mathematical model describing the dynamics of trace gas production, transformation, and transport into gas-flux measurement chambers was developed further to account for transport driven by pressure gradients, and dilution of chamber gas concentrations arising from water vapor efflux and air temperature increases during chamber deployment. The model was used to evaluate the conditions favoring negative nitrous oxide flux, i.e., soil N2O uptake, and also to evaluate potential methodological artifacts causing ostensible soil N2O uptake. A preliminary chamber-based method for measuring soil-to-atmosphere emissions of ammonia (i.e., ammonia volatilization) was developed by coupling a chamber to a high-sensitivity, real-time ammonia analyzer. The method was tested in agricultural fields treated with varying forms of nitrogen fertilizer.


Last Modified: 10/1/2014
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