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In this project, we will be addressing the goal of investigating the environmental services provided by organic farming systems that support soil conservation and contribute to climate change mitigation. <P>The Objectives to achieve project goals are: <ol> <LI> Encourage organic transition by developing and establishing organic vegetable cropping systems that maximize soil quality, foster carbon sequestration, and minimize nutrient loss through cover crops, composting, and reduced tillage; <LI> Develop recommendations for methods to enhance ecosystem services and improve soil quality on organic vegetable farms based on results derived from horticultural, soil, gas flux, and soil water data in experimental sites<BR> a. Develop annual and full-rotation carbon (C) budgets from sites <BR>b. Develop relationships between individual/integrative indicators of soil quality and environmental/productivity endpoints; <LI> Determine how product quality and shelf life are affected by different management practices in organic systems and identify relationships among soil properties, crop health, and postharvest quality; <LI> Increase economic returns for organic vegetable growers by reducing costs of production in field operations and labor, decreasing dependence on external sources of applied fertility, lowering energy costs, and obtaining carbon/emission credits; <LI> Develop and offer educational programs on organic vegetable production and postharvest handling for farmers, students, and agricultural professionals to facilitate the transition to organic production.
Non-Technical Summary: The relationship of organic practices with soil properties, crop performance, and resistance to pests has been identified as one of the most important research needs by organic farmers. This multi-disciplinary, multi-state project addresses critical stakeholder needs for improving organic vegetable farming practices to optimize pest management, crop quality, and profitability, while enhancing soil quality to help mitigate global climate change. The long-term goal of the proposed project is to provide organic producers with science-based information they can use to make decisions affecting the sustainability of their operations. This multi-region study will be conducted across two contrasting soil types (low vs. high fertility) and climatic conditions (sub-tropical vs. temperate) to yield widely applicable results. On-farm trials will be conducted with cooperating farmers to strengthen the on-station research and contribute to more effective outreach. Results from this project will be disseminated to a broad audience involving organic producers, researchers, extension agents, policy makers, and students, through a variety of methods including field days, conference and classroom presentations, focus groups, publications, and e-Organics. Potential economic, social and environmental benefits will include an accurate assessment of the effect of compost, cover crops, and reduced tillage, on soil indicators related to soil and water quality, vegetable crop yields, pest status, quality attributes of vegetables, and economic performance. Annual C budgets for each phase of the 3-yr rotation will be used to calculate C budgets for entire rotation, along with a quantification of changes in soil profile C storage and in C distribution within the soil profile. Surface samples will be used to evaluate soil biological, chemical, and physical properties related to soil quality and mathematical relationships will be developed between individual soil quality indicator variables or the integrative index and environmental (i.e., leached NO3-N concentrations and CO2 flux) and productivity (i.e., vegetable yield) endpoints. Stakeholder engagement has been key throughout proposal development, as organic vegetable growers in each state are considered peers with researchers. An advisory panel will be established to provide suggestions and feedback throughout the project, ensuring successful generation of applicable outcomes that place direct benefits in the organic agriculture community. <P> Approach: Research will begin in Fall 2010 on University Experiment Station sites in Iowa and Florida, and on grower-cooperator fields in each state. For each on-station trial, the design will be a split-split-split plot in time. Crop varieties and soil fertility treatments are based on grower recommendations. The main unit treatments will be two crop sequences in rotation, with tillage and soil amendments as sub-treatments. Crop sequence 1 will consist of spring tomato ? fall lettuce; followed by spring yellow squash ? fall broccoli; and spring onions - fall beans. Crop sequence 2 will consist of spring onions - fall beans; followed by spring tomato ? fall lettuce; and spring yellow squash ? fall broccoli. The two, 3-year rotations will include 6 cash crops. The sub-plot treatments will be tillage: (1) till with plastic mulch (2) till without plastic mulch and (3) organic no-till. Sub-sub plots will be organic fertility treatments: (1) composted animal manure alone (no cover crops) and (2) composted animal manure + cover crops. Hairy vetch and rye will be grown as fall cover crops in Iowa while only rye will be planted in FL. In summary, the treatment structure is a 2 x 3 x 2 where the factors are crop sequence, tillage system, and fertility amendment. Treatments will be replicated four times for a total of 48 plots. Hairy vetch and rye will be planted at a rate of 25 lb hairy vetch + 90 lb rye/acre in Fall 2010. In FL, rye will be planted at a rate of 115 lb/acre. Cover crops will be terminated at the appropriate phonological stage in spring 2011 at all locations with the roller/crimper. Cover crop management in the following years may be modified based on the previous year's results. Tomato, broccoli, lettuce, and onions will be planted using transplants, while yellow squash and beans will be direct seeded. The same varieties will be used across locations; organic seeds will be used for all varieties in the organic plots if commercially available. Composted poultry manure will be applied prior to vegetable planting at rates based on N content and availability from the organic amendments, soil test results, and crop needs. Compost will also be side-dressed at the time of vegetable planting in the cover crops treatments. Application rates will be determined based on the above calculations plus estimates of N availability from cover crop decomposition. Total (aboveground + belowground) vegetable and cover crop plant biomass C inputs, vegetable C, compost C, and annual net CO2 flux will be used to construct annual C budgets. Annual C budgets for each phase of the 3-yr rotation will be used to calculate C budgets for entire rotation. Rotation C budgets developed by estimating plant and compost inputs and CO2 losses will be compared to measured changes in soil profile C content. Carbon budgets, gas flux estimates, and nitrate-N leaching below the rooting zone will be conducted at the ISU on-station site only, due to the Iowa location of equipment needed for this component. Aboveground and belowground vegetable plant biomass C inputs will be measured for each crop every year at harvest.