Management Practices for Organic Orchard Nutrition

Non-Technical Summary: Organic fruit production in the South is limited. Previous work has determined that there is an opportunity for local and regional markets for organically produced fruit. However, production is limited due to lack of region and locally specific tested and demonstrated research-based information. Preliminary survey work indicated that two significant horticultural problems facing organic producers are ground cover and weed management, and management of nutrient status of the tree with fertiliers or nutrient sources, and soil and foliar testing protocols. Because sustainable organic production has as a cornerstone principal, the development and management of soil quality and health, and because both nutrient management and ground cover management interact to affect soil quality and health, and thereby tree growth and productivity, a study was initiated. The goal of the study is to develop and demonstrate science based, regionally appropriate organic production systems for apples in the southern region. The specific focus of the study is to develop, demonstrate and communicate the best practices for organic orchard nutrition by studying the interaction of ground cover management and nutrient source on organic orchard growth and productivity. An organic orchard was planted using standard techniques in 2006 and treatments initiated at that time. The effects on tree establishment have been reported. For the study the interaction of ground cover management system and nutrient source were studied with the interaction of treatments as follows. Ground cover management treatments were: 1) municipal green compost (GC), 2) mow-and-blow where the undertree and between row vegetation (primarily planted K31 tall fescue) is periodically mowed and blown under the trees (MB), 3) refuse wood chips (WC), and 4) shredded business paper (SP). The nutrient source treatments were: A) the ground cover provides all nutritional needs (NF), B) composted poultry litter (PL), and C) a certified organic pelletized poultry based fertilizer (CF). The PL and CF nutrient source treatments are applied each spring prior to budbreak based standard foliar [N] as sampled the previous season to be in the range of 1.9 - 2.4% N. After nutrition is applied, ground cover treatments are applied with mulches applied to a depth of 3-6cm. Beginning in the current season of this study, trees will begin to flower and produce a crop. Treatment effects on growth, cropping and economic performance of the orchard systems and make empirical observations of the basis for those outcomes. The incidence of pests and diseases in the organic system will be measured and observed. Soil quality and health will be assessed annually including measurements of soil biodiversity, soil physical properties, and soil chemical properties. From the findings of the study, information will be conveyed in traditional scientific formats (presentations and publications) as well as provided to constituencies through grower group meetings, annual conferences and workshops. Additionally, the orchard will serve as a vehicle for direct education through university classroom experiences and grower field days. <P> Approach: The outcomes of this project will be: 1. Scientific evidence of the long-term effects of ground cover and nutrient management on soil chemistry, physical properties, and biology, and tree growth, yield and physiology 2. Recommendations for best management practices of organic orchard nutrition based upon scientific evidence, validated by practical grower experience. 3. Recommendations for ground cover management in organic orchards in the south 4. Development of economic operating and marketing budgets for organic orchards in the south 5. Trained organic orchard managers through on-farm trials and apprenticeships 6. Informed growers and Extension personnel on successful production practices of organic orchard management. An orchard was established in 2006 using Enterprise/M26 apples planted at 2m x 4m spacing (~600 trees/acre) and trained to a 2-wire minimal trellis system in a modified vertical axis, conical shaped tree to be 4m tall and 1.5m wide at the base. The orchard is managed organically and will be certified in 2008. The interaction of ground cover management system and nutrient source were studied. Ground cover management treatments were: 1) municipal green compost (GC), 2) mow-and-blow where the undertree and between row vegetation (primarily planted K31 tall fescue) is periodically mowed and blown under the trees (MB), 3) refuse wood chips (WC), and 4) shredded business paper (SP). The nutrient source treatments were: A) the ground cover provides all nutritional needs (NF), B) composted poultry litter (PL), and C) a certified organic pelletized poultry based fertilizer (CF). The PL and CF nutrient source treatments are applied each spring prior to budbreak based standard foliar [N] as sampled the previous season to be in the range of 1.9 - 2.4% N. After nutrition is applied, ground cover treatments are applied with mulches applied to a depth of 3-6cm. Tree growth, fruit yield, fruit quality will be measured. Economic inputs and crop value will be recorded and estimated, respectively. The nutrient status of the trees and soil within treatment zones will be monitored periodically during the season. The impact of treatments on the incidence of pests and diseases in the organic system will be measured and observed. Soil quality and health will be assessed annually including measurements of soil biodiversity, soil physical properties, and soil chemical properties. Outreach from the program will be conducted through formal classroom activities, growers workshops and field tours and development of organic production handbook. Project collaborators will attend and present this project at various other producer and scientific meetings and conferences. Information about the project will also be disseminated through the Fruit and Nut Extension newsletter and be made available through the UA Ecological Agriculture website (www.uark.edu/ua/uaecoag/).