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We propose a project to investigate the effects of various cover crops, specifically their residue quality and termination time on nitrous oxide emissions, nitrogen availability patterns and carbon accumulation in major Midwest field crop systems under organic and conventional management. Our overall hypothesis is that cover crop use in organic and conventional systems, when managed effectively, can improve nitrogen synchrony, decrease nitrous oxide emissions, and better sequester carbon dioxide compared to non-cover crop systems. <P> Our goals are to 1) determine the potential of cover crops as management options for improving nitrogen synchrony with cash crops, 2) evaluate the impact of cover crops on nitrous oxide emissions and carbon accumulation, and 3) improve farmer knowledge of cover crop use in relation to N use efficiency, greenhouse gas mitigation and economic potential through decision tools and communications.<P> We have assembled a multidisciplinary research team to meet four specific objectives: 1. Quantify the effect of cover crop use on nitrous oxide emissions, nitrogen availability patterns and carbon accumulation for a model corn-soybean-wheat rotation under organic and conventional agricultural management. 2. Use these data to develop recommendations and tools for improving nitrogen synchrony, reducing greenhouse gas footprints and improving farm economics. 3. Extend recommendations through publications and decision tools to farmers, researchers and educators using workshops, field days, websites and stakeholder networks. 4. Expose data to others for testing and refining process-based greenhouse gas simulation models.<P> Important secondary objectives of this research will be to help position U.S. farmers for participation in future markets for carbon/greenhouse gas credits and contribute knowledge required to reduce all forms of reactive nitrogen in the environment.
Non-Technical Summary: <BR>Nitrogen is an essential nutrient for food production. Nitrogen moves in the environment where it can be lost to the air as a gas and to water by moving through the soil or over the soil surface. Because of this, it is difficult for crops to use all the nitrogen that was applied. This loss is primarily the result of the timing between the supply of nitrogen and crop demand for that nitrogen. Of particular environmental concern are the emissions of nitrous oxide--a greenhouse gas from agricultural soils that can contribute to global warming and ozone destruction. Lost nitrogen also represents a significant economic loss to farmers. Any practice that improves the timing between soil nitrogen release and crop growth will decrease nitrogen loss, protect the environment and improve farm profits. Cover crops are grown when cash crops such as corn and soybeans are not growing. Cover crops can be a useful management tool for reducing negative environmental impacts. The timing of nitrogen use can be improved by cover crops. Cover crops also benefit farming by recycling nutrients, reducing erosion, improving soil, supporting soil organisms, and suppressing weeds and insects. Cover crops are important to organic farming and the transition of land from conventional to organic farming. Conventional farmers are also showing increased interest in cover crops. We propose a study to investigate the effects of various cover crops on nitrous oxide emissions, nitrogen availability and carbon accumulation in major Midwest farming systems under organic and conventional management. Four cover crops will be studied: annual ryegrass, red clover, oilseed radish and a commercially available cover crop mix. Our goals are to determine the potential of cover crops as a farm management option for improving nitrogen timing with cash crops, evaluate the impact of cover crops on nitrous oxide emissions, and improve farmer knowledge of cover crop benefits to nitrogen use and farm economics. Results from this project will improve the tools and information farmers use to make decisions that can reduce nitrogen loss to the air and water. <P> Approach: <BR> 1. Quantify the effect of cover crop use on nitrous oxide emissions, nitrogen (N) availability patterns and carbon (C) accumulation for a model corn-soybean-wheat rotation under organic agriculture (OA) and conventional agriculture (CA) management. 1.1. The research design is a randomized split-split-block experiment with four replications for two management practices-OA and CA. The no cover crop control will be a corn-soybean rotation. Each block consists of 14 treatments with nine split for termination date. Treatments are: corn/no cover; soybeans/no cover; four corn with rye cover; four soybeans followed by wheat; and wheat followed by annual ryegrass cover, red clover cover, oilseed radish cover and a commercially available cover crop mix. 1.2. Soil samples will be collected and analyzed for total C and N, inorganic N, cellulose and lignin fractions and water content. 1.3. Above ground plant cover crop and weed biomass will be analyzed for total C and N, and cellulose and lignin fractions. 1.4. Gas samples for nitrous oxide and methane and carbon dioxide analysis will be collected using a two-part chamber system and analyzed using gas chromatography. 2. Develop recommendations and tools for improving N synchrony, reducing greenhouse gas (GHG) footprints and improving farm economics. 2.1. Enhance the MSU Greenhouse Gas Calculator and the Midwest Cover Crops Council (MCCC) Decision Tools by adding cover crops and GHG emissions, respectively. 2.3. An economic assessment of converting to OA will be carried out using the three-year field plot trials against conventional outcomes. A 15-year soil quality transition from CA to OA will be modeled under each management scenario to develop a time-trend response on yields and C uptake. 3. Extend the recommendations through publications and decision tools to farmers and educators using workshops, field days, websites and stakeholder networks. 3.1. One field day and two workshops per year will provide an opportunity for farmers, researchers and Extension educators to observe research plots and presentations by research personnel to increase knowledge and awareness of agricultural issues associated with GHG emissions, N availability and C accumulation and present practices using cover crops as a management option for addressing these issues. 3.3. This project's progress and findings will be shared through the annual MCCC workshop/meeting. Periodic updates from this project will be posted on the MCCC, New Agricultural Network and MSU Michigan Cover Crop websites. Project findings will be incorporated into numerous publications, peer-reviewed articles, Extension bulletins and fact sheets. 3.4. Surveys will be used to assess knowledge gain and changes in attitude, behavior and cover crop adoption rates. 4. Expose data to others to test and refine process-based, field-scale GHG simulation models. 4.1. Data generated by the project will be permanently archived for public access on the KBS LTER Data Catalog. 4.2. Data from this research will be useful in developing and refining methodologies and offset projects that could increase the potential for farmer participation in C and environmental markets.