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Crop Plant Nutrition and Insect Response in Organic Field Crop Production: Linking Farmer Observation to University Research and Extension


This project is designed to develop and disseminate practical research-based information on how soil fertility and resulting crop plant nutrition contribute to insect pest suppression and the integrated pest management (IPM) paradigm and its application in organic agriculture. Our long-term GOALS are to: <OL> <LI>More clearly define the role of soil fertility, crop plant nutrition and insect response in organic agriculture systems, resulting in practical insect IPM recommendations in Wisconsin and across the U.S.; <LI> Improve organic grain and forage crop farm net revenue and profitability because of increased farmer capacity to make decisions about allocating scarce off-farm resources (i.e., soil fertility amendments) in the most effective ways; <LI> Utilize soil-plant-insect interactions for crop protection to enhance environmental sustainability of organic agriculture. </OL>Project OBJECTIVES are to: <OL> <LI>Evaluate two different organic fertility systems in a certified organic grain/forage crop long-term experiment by comparing soil and crop plant nutrient status with pest and beneficial insect response;<LI>Conduct simple experiments on working organic farms to test hypotheses from the long-term experiment and grower observations on their farms that integrate organic fertility practices with other National Organic Program-compliant insect pest suppression tactics; <LI> Develop a multi-institutional partnership between Wisconsin organic farmers, UW Madison, Cooperative Extension, and two-year campuses of the UW Colleges system to achieve full integration of research, extension, and education project goals. </OL>EXPECTED OUTPUTS from the project include:<uL> <LI> Controlled Long-Term Experiment (LTE) research comparing organic fertility systems for effects on soil chemistry of plant nutrients and insect response; <LI> Conduct greenhouse studies using modified LTE field soil (precise Ca, Mg cation calibration) and elucidate crop plant and insect response mechanisms; <LI> Perform on-farm research on factors most important to practical crop nutrient and insect IPM application; <LI> Develop extension resources and decision support tools that enhance IPM paradigm for organic agriculture.

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Non-Technical Summary: This project addresses a lack of research on soil test calibration data and plant tissue analyses specifically comparing different organic fertility management approaches with each other, and for potentially corresponding crop plant-mediated pest and beneficial insect population response. The two organic fertility systems chosen by farmer stakeholders for consideration in this project test the general hypothesis that insect pest populations are less variable and stabilize at lower densities under organic fertility systems affording crop plant tissue a regulated and balanced nutrient supply. Conceptually, our project combines 1) on-farm observation and data collection; 2) a controlled long-term experiment systems trial and 3) greenhouse/laboratory reductionist approaches. These components reinforce each other to deliver practical research based information on the role of organic crop plant nutrition in insect IPM. The intent of this project is not to convince farmers to use one fertility approach over the other, but rather to involve farmers in shaping the research direction so they can use the results in whole farm planning and Land-grant University research/extension personnel can offer improved systems based programs to address insect pest suppression in organic crops. Only by understanding both the ecological complexity and reductionist mechanisms behind organic grower observations of plant-insect interactions can researchers help apply this knowledge in new situations. Knowledge gained from this project will improve organic farmer ability to document soil and crop nutrient management as an IPM strategy when developing an organic system plan (OSP), and working with technical service providers under the USDA NRCS Environmental Quality Incentives Program (EQIP). Under National Organic Program Standard 205.206, soil and crop nutrient management are required to prevent crop pest insects, weeds and diseases. Our project will identify pest and natural enemy insect response indicators that can be used to document changes in effectiveness of organic fertility systems as an underlying IPM strategy in organic agriculture. Expected OUTCOMES/IMPACTS: Organic grain and forage crop producers will gain awareness of soil test analytical method nuances and impacts on interpreting results, improved attitude toward land-grant university approach to organic fertility systems research, and increased knowledge of principles of crop plant mineral nutrition and insect response for key field and forage crop pest complexes (short term). Organic producers will improve insect IPM success through alignment of their existing organic fertility approaches with pest management goals, and applying new IPM research knowledge base to organic fertility input cost decision -making. (medium term). Organic grain and forage crop farm net revenue and profitability will improve because of increased farmer capacity to make decisions about allocating scarce resources (soil fertility amendments) in the most effective ways, and utilizing soil-plant-insect interactions for crop protection will enhance environmental sustainability of organic agriculture (long term). <P> Approach: This integrated research/extension/education project investigates two organic fertility practices in a four-year grain crop/forage legume rotation. Under the Standard Organic Fertility system, nitrogen and other crop nutrients are supplied by livestock manure and 2 years of alfalfa hay in the rotation. The Soil Balance system incorporates a more intensive off-farm input approach with annual "cation-balancing" application of gypsum as a calcium soil amendment. A 30-acre certified organic long-term experiment systems trial, and on-farm research with cooperating growers in southern and north central Wisconsin achieve the OREI high priority goal to conduct advanced on-farm research and development that emphasizes observation of, experimentation with, and innovation for working organic farms. Project outcomes will more clearly define how organic crop plant nutrition and insect response mechanisms contribute to pest suppression through plant mediated effects and beneficial insect functional response. Extension deliverables will offer IPM recommendations for crop-pest associations of economic concern to organic field crop growers regionally and nationally. These include soybean: soybean aphid, corn: Lepidoptera ear and stalk boring caterpillar pests, and alfalfa: potato leafhopper. This integrated project focuses on plant-insect interactions (soil chemistry and plant nutrition), through field studies conducted within the context of a large scale, long-term systems trial. Processes in soil and plants that are potentially relevant to pest and beneficial insect response mechanisms are not likely to occur within a short time frame of 2-3 years. Because systems research field trials often yield significant results in later project stages, our methods include shorter-term, controlled greenhouse and laboratory experiments targeting processes relevant to our overall hypotheses. A greenhouse trial involving the creation of "artificial" base saturation ratios represents one such test of the same hypotheses from the long-term field experiment under more tightly controlled conditions. Project PD consults regularly with the University of Wisconsin Madison CALS statistical consulting service on all aspect of project analysis, particularly multivariate methods which are a useful approach to dealing with overall complexity of long-term systems trials. Principle component analysis will be used to reveal the internal structure of data from the long-term experiment and on-farm research location replicates, in a way which best explains the variance and identifies explanatory patterns in data of high dimension (e.g., ecological complexity). Additionally, this project is building a multi-institutional integrated education/research partnership providing organic agriculture classroom curriculum credits and mentored on-farm research internships to undergraduates at small sized freshman/sophomore campuses of the UW Colleges system who are seldom offered integrated education/research opportunities in organic agriculture due to a smaller student body (less than or equal to 1,000) and distance (greater than 100 miles) from the UW Madison campus.

Cullen, Eileen
University of Wisconsin - Madison
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