Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218
Performing Department
Horticulture
Non Technical Summary
Wisconsin's vegetable processing industry has a unique opportunity to remain vital and competitive through expansion into organic production. Despite the existence of a substantial organic market, a number of production challenges face vegetable growers and processors attempting to take full advantage of this opportunity. Production systems that adhere to organic regulations while managing nutrients and weeds must be developed and refined for commercial scale acreages necessary to supply organic vegetable processing plants with adequate raw product volume. If effective management recommendations were available, growers could decrease the risk of expanding their certified organic acreages, thus allowing the industry to grow. As such, the goal of this project is to develop weed and nutrient management systems that are optimized for organic wholesale processing vegetable production. Weed management remains a significant challenge to organic vegetable production and has been particularly challenging for large scale organic processing vegetable growers (personal communication, MWFPA). Inadequate weed management especially in sweet corn in organic systems leads to weed escapes, weed seed production and reduced yields compared to conventional check plots. Due to slow initial sweet corn growth, weeds emerging in crop rows can easily escape mechanical management practices and compete with the crop for nutrients, especially nitrogen. Weed escapes produce viable seed by the time of sweet corn harvest, potentially contributing to future management problems. Fertility management can alter crop-weed interference and weed seed production. Improved soil fertility affects crop-weed interactions, often giving weeds an advantage. Weeds tend to be more competitive than many crops at higher soil fertility levels, accumulating higher levels of N, P, K, Ca, and Mg in their tissues. Nitrogen fertilizer can affect weed germination and establishment. Many weeds are high-N consumers, thus limiting N for crop growth. However, the converse may occur as well. For example, giant foxtail caused yield reductions in field corn when fertilized with nitrogen at standard rates, but competitive effects were eliminated by adding excess nitrogen fertilizer. In addition, synthetic N increased weed emergence, growth rate, and competitive ability in some cases, while crop growth was favored in others. No studies have documented these interactions under organic fertility management. Fertility management practices in organic production differ from conventional management influencing crop-weed interference. Soil fertility practices in organic systems include short-term cover cropping, spreading compost or manure, crop rotation, and applying various OMRI approved fertilizers to meet plant nutrient requirements. OMRI approved fertilizers, compost, manure, or green manures are rarely applied in plant available forms and must be mineralized. Previous research has shown that organic fertility management changed soil physical, biological and chemical properties that in turn altered weed species diversity, weed emergence, growth, seed longevity, and crop impact.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
This Integrated Project has the ultimate goal of establishing an organic processing vegetable industry in the Midwest that is economically viable, environmentally sound, and internationally known for quality. Short-term goals to achieve this outcome include a) identifying nutrient and weed management practices to optimize returns and environmental efficiency for organic production of processing sweet corn, b) execution of appropriate extension and outreach to farmers to faciliate adoption of the best management practices determined as a result of this research. Intermediate-term goals include adoption of these practices in the vegetable processing system to improve competitiveness and regional environmental quality and to build awareness of organic opportunities and project findings among growers, processors, students, extension educators, and agricultural professionals. Objectives: 1) Determine the effects of nutrient management strategies on sweet corn yields in organic processing vegetable systems. 2) Determine the effects of weed management strategies on nitrogen cycling in organic sweet corn production systems. Results will be used to improve nutrient and weed management in organic processing vegetables. Agronomic information will demonstrate management system performance with respect to yields gained, total amount of N applied, and the efficiency of the system. The interaction of nitrogen source and availability, crop demand at the time of availability, and weed seed production and nitrogen uptake is critical in developing realistic management programs for commercial organic sweet corn production. Some growers choose to oversupply nitrogen to overcome potential for weed interference and negative effects on crop yield. This may be a risk-mitigation strategy leading to excess nitrogen and potential for environmental loss. Conversely, increased nitrogen uptake by weeds and resulting biomass production will increase residue incorporation into soils and improve soil organic matter and other quality factors. This will be tested under separate funding. The data will be published in peer-reviewed journals and extension articles. We expect increased organic processing vegetable production, growing farmer confidence in using organic practices with spillovers to other crops, greater awareness and knowledge of organic practices and opportunities among farmers, processors, and other ag professionals, plus inclusion of organic practices and sustainability in course curricula and extension education. In addition, we expect improved management of weeds in sweet corn with less negative effects on yield and quality and improved soil quality and productivity. Timeline of Activities: April-Sept 2011: Complete first year; field research Sept. -Dec. 2011: Complete data analysis; February 2012: Present at Organic Farming Conference; April 2012: Repeat field experiment; Sept.-Dec. 2012: Complete data analysis; Jan - Sept 2013: Write extension publication; Write and submit peer reviewed journal article
Project Methods
Objective 1. The experiment will be conducted on organic certified land at the UW Hancock Agricultural research station. Each sub-sub-plot will measure 10 by 24 meters. The field will be arranged in a split-split-block design, where cropping system (control, plant, or animal input-based) is the main factor, the weed management program (intense or nearly weed free) or intermediate (moderate weed pressure) is the subfactor, and fertility rate is the sub-sub-factor. The plant-based cropping system will use spring planted and tilled field pea as a green manure. The animal-based cropping system will use pelleted, composted poultry manure. Intense weed management regime (2 rotary hoeings + 3 cultivations, plus in-row hand hoeing) and moderate management regime (1 rotary hoeing + 2 cultivations). Fertility rates will include: 0, 75, 150, and 225 kg/ha nitrogen in the form of OMRI-approved 11-0-0 fertilizer. Previous research has shown similar yields between OMRI approved 11-0-0 and urea when applied at similar rates at Hancock Ag Research Station. Insect management will be scheduled as needed and in compliance with organic certification. Organic sweet corn will be selected in consultation with vegetable processing and seed companies. Data analysis. Data will be analyzed using ANCOVA and regression. Cropping system and weed management intensity will be discreet factors and fertility rate will be a continuous variable in describing weed biomass, density, and species diversity. Regression analysis will be used to characterize the relationship between weed biomass, density, and species diversity with weed seed production and nitrogen uptake. Regression analysis will also be used to predict sweet corn yield and recovery in response to nitrogen fertility, weed biomass, density, and nitrogen uptake. Nutrient use efficiency will be analyzed with ANOVA. A harvest index (yield/AGB) and N recovery index (total N in yield/total N in AGB) will be calculated. Nitrogen use efficiency indices will be calculated as follows: (1) Agronomic Efficiency: AE = (Yt - Y0)/N (2) Crop Recovery Efficiency: CRCE = (AGB-Nt - AGB-N0)/N (3) Crop Removal Efficiency: CRME = (YNt - YN0)/N Objective 2. As part of the outreach component of this project, we will hold field days that will be broadly advertised though grower and Extension groups. Based on our past meetings, we expect about 150 attendees per tour. These tours will be crucial for building awareness and encouraging farmers to adopt organic practices for processing vegetables. They will inform farmers about management practices and build social networks with other farmers who can provide training and assistance. Obviously, 150 farmers will not adopt organic practices for processing vegetables after one farm tour. However, Lohr and Salomonsson (2000) identified lack of production information and training in management systems as persistent barriers to adoption of organic practices. Lohr and Park (2003) recommended on-farm experiments and educational activities as we propose to improve Extension's effectiveness for organic farmers.