Progress 12/01/02 to 11/30/07
Outputs
A key principle of organic farming is to maintain active communities of beneficial soil organisms that can regulate soil ecosystem processes necessary for successful crop production. A basic assumption of this "living soil" concept is that significant interactions exist between soil organisms and important soil processes and properties and that farm inputs can fundamentally alter those relationships. In a manuscript to be submitted to "Ecological Applications", (we investigated the validity of that assumption using field and laboratory studies of a range of soil organisms, properties and processes) using conventional, integrated and organic apple production practices to represent a range of farming practices. Consistent with other studies, our data confirm that organic management does result in qualitative and/or quantitative shifts in soil micro-, meso-and macro-biological communities and improved soil quality in general. Unlike other studies, however, we used
correlation analysis to establish empirical relationships between soil organisms, properties and processes. Our results support the idea that the soil biota, the "living soil", have direct positive impacts on important soil properties and processes.
Impacts
With our work on evaluating the effects of organic, conventional, and integrated apple production systems on soil health, crop quality, financial performance, environmental quality, and energy efficiency, we continue to gain an understanding of how agricultural practices affect these sustainability indicators and agroecosystem processes. Experience gained from our study is contributing to improvements in the production practices of organic and integrated apple growers in the Pacific Northwest and in the ability of conventional apple growers to convert to organic production methods or adopt integrated management approaches. Our study adds valuable information to the knowledge base of alternative apple production systems and may help expand economic opportunities for farmers and promote reduced use of agrochemicals. Results from our research are already being, and will continue to be, disseminated through peer-reviewed journals, at scientific meetings, through extension
publications, at meetings with growers and agricultural consultants, during field days, and in farm magazines.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
Conventional agriculture has improved in crop yield but at large costs to the environment, particularly off-site pollution from mineral N fertilizers. In response to environmental concerns, organic agriculture has become an increasingly popular option. One component of organic agriculture that remains in question is whether it can reduce agricultural N losses to groundwater and the atmosphere relative to conventional agriculture. In our long-term study of apple production systems, we found reduced N pollution from the organic and integrated farming systems compared with the conventional farming system. We evaluated differences in denitrification potential and a suite of other soil biological and chemical properties in soil samples taken from organic, integrated, and conventional treatments in an experimental apple orchard. Organically farmed soils exhibited higher potential denitrification rates, greater denitrification efficiency, higher organic matter, and greater
microbial activity than conventionally farmed soils. The observed differences in denitrifier function were then assessed under field conditions after fertilization. N2O emissions were not significantly different among treatments; however, N2 emissions were highest in organic plots. Annual nitrate leaching was 4.4 -5.6 times higher in conventional plots than in organic plots, with the integrated plots in between. This study demonstrates that organic and integrated fertilization practices support more active and efficient denitrifier communities, shift the balance of N2 emissions and nitrate losses, and reduce environmentally damaging nitrate losses. Although this study specifically examines a perennial orchard system, the ecological and biogeochemical processes we evaluated are present in all agroecosystems, and the reductions in nitrate loss in this study could also be achievable in other cropping systems.
Impacts
With our work on evaluating the effects of organic, conventional, and integrated apple production systems on soil health, crop quality, financial performance, environmental quality, and energy efficiency, we continue to gain an understanding of how agricultural practices affect these sustainability indicators and agroecosystem processes. Experience gained from our study is contributing to improvements in the production practices of organic and integrated apple growers in the Pacific Northwest and in the ability of conventional apple growers to convert to organic production methods or adopt integrated management approaches. Our study adds valuable information to the knowledge base of alternative apple production systems and may help expand economic opportunities for farmers and promote reduced use of agrochemicals. Results from our research are already being, and will continue to be, disseminated through peer-reviewed journals, at scientific meetings, through extension
publications, at meetings with growers and agricultural consultants, during field days, and in farm magazines. Other scientists as well as undergraduate and graduate students conducting related research work of their own are using our research site at Enterprise Orchards in Zillah, WA.
Publications
- Peck, G., P.K.Andrews, J.P.Reganold, and J.K.Fellman. 2006. Apple orchard productivity and fruit quality under organic, conventional, and integrated management. HortScience : A Publication of the American Society for Horticultural Science. 41(1):99-107.
- Kramer, S.B., J.P.Reganold, J.D.Glover, B.Bohannan, and H.A.Mooney. 2006. Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils. Proceedings of the National Academy of Sciences of the United States of America. 103:4522-4527.
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Progress 01/01/05 to 12/31/05
Outputs
In years nine (2002) and ten (2003) of this study, we compared the orchard productivity and fruit quality of Galaxy Gala apples in the organic (ORG), conventional (CON), and integrated (INT) plots. Due to problems with fruit russeting and market demand for newer cultivars, every other tree was top-grafted in 1999 from Golden Delicious to Galaxy Gala, with the remaining half grafted in 2000; the rootstock remained EMLA.9, with Golden Delicious as an interstock for each tree. Measurements of crop yield, yield efficiency, crop load, average fruit weight, tree growth, color grades and weight distributions of marketable fruit, percentages of unmarketable fruits, classifications of unmarketable fruit, as well as leaf, fruit, and soil mineral concentrations were used to evaluate orchard productivity. Apple fruit quality was assessed at harvest and after refrigerated (0-1 degree C) storage for three months in regular atmosphere (ambient oxygen levels) and for three and six
months in controlled atmosphere (1.5-2% oxygen). Fruit internal ethylene concentrations and evolution, fruit respiration, flesh firmness, soluble solids concentration (SSC), titratable acidity (TA), purgeable volatile production, sensory panels, and total antioxidant activity (TAA) were used to evaluate fruit quality. ORG crop yields were two-thirds of the CON and about half of the INT yields in 2002, but about one-third greater than either system in 2003. High ORG yields in 2003 resulted in smaller ORG fruit. Inconsistent ORG yields were probably the result of several factors, including unsatisfactory crop load management, higher pest and weed pressures, lower leaf and fruit tissue nitrogen, and deficient leaf tissue zinc concentrations. Despite production difficulties, ORG apples had 6-10 N higher flesh firmness than CON, and 4-7 N higher than INT apples, for similar-sized fruit. Consumer panels tended to rate ORG and INT apples to have equal or better overall acceptability,
firmness, and texture than CON apples. Neither laboratory measurements nor sensory evaluations detected differences in SSC, TA, or the SSC:TA ratio. Consumers were unable to discern the higher concentrations of flavor volatiles found in CON apples. For a 200 g fruit, ORG apples contained 10-15% more TAA than CON apples and 8-25% more TAA than INT apples. Across most parameters measured in this study, the CON and INT farm management systems were more similar to each other than either was to the ORG system. Despite limited technologies and products for organic apple production, the ORG apples in our study showed improvements in some fruit quality attributes that could aid their marketability. To further understand the contributions by specific antioxidants to the higher TAA of the organic apples at harvest and after controlled-atmosphere storage, we are currently analyzing specific polyphenols (quercetin, phloretin/phloridzin, ellagic acid, naringenin/naringin, and kaempferol) in these
fruit by HPLC. In addition, we plan to measure the ascorbic acid concentrations of these apples.
Impacts
With our work on evaluating the effects of organic, conventional, and integrated apple production systems on soil health, crop quality, financial performance, environmental quality, and energy efficiency, we continue to gain an understanding of how agricultural practices affect these sustainability indicators and agroecosystem processes. Experience gained from our study is contributing to improvements in the production practices of organic and integrated apple growers in the Pacific Northwest and in the ability of conventional apple growers to convert to organic production methods or adopt integrated management approaches. Our study adds valuable information to the knowledge base of alternative apple production systems and may help expand economic opportunities for farmers and promote reduced use of agrochemicals. Results from our research are already being, and will continue to be, disseminated through peer-reviewed journals, at scientific meetings, through extension
publications, and to growers and agricultural consultants at meetings, during field days, and in industry publications. Our research site at Enterprise Orchards in Zillah, WA, is being studied by other scientists as well as undergraduate and graduate students to conduct related research work of their own.
Publications
- Peck, G. M., C. Richter, P. K. Andrews, and J. P. Reganold. 2005. Internationalization of the organic fruit market: The case of Washington State's organic apple exports to the European Union. Renewable Agriculture and Food Systems. 20:101-112.
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Progress 01/01/04 to 12/31/04
Outputs
From our work with apples this past decade, we have learned much about the effects of organic, conventional, and integrated apple production systems on soil health, crop quality, financial performance, and environmental quality. This year we published on these topics in journals, book chapters, and proceedings. In one of our published studies, we examined the broader issues and complexities of the international marketing of organic fruit, using organic apple production in Washington State and market opportunities for this organic fruit in the European Union (EU) as a case study. Some organic commodities, such as apples, are heavily concentrated in the United States (US), with Washington State being the leading US producer of organic apples. In 2003, there was an all-time high of 4047 ha of certified organic apple orchard in Washington State, a more than ten-fold increase since 1989. But this growth has not occurred without difficulties. Washington States organic apple
growers have encountered international supply and demand pressures forcing them to seek new markets, such as the EU. We found that, as a result of the expansion of organic apple plantings in Washington State, there has been a decrease in the price premiums that traditionally offset the greater costs of organic production and motivated many Washington growers to certify their apple orchards. We also found that increased demand for organic fruits in the EU has been outpacing supply, making EU member states the most important export market for Washingtons organic apples. In an attempt to mitigate trade barriers, the USDA and the EU have unified standards within their borders, but these two bodies have so far not agreed to accept each others organic codes unequivocally. This puts the burden of proof upon US organic apple growers to illustrate that they not only meet USDA standards, but also EU standards. Growers and marketers may have to interact with as many as six different regulatory
bodies in order to export organic produce from the US to the EU. This study shows that while the EU market remains a promising destination for US organic apples, organic growers and marketers must plan ahead and thoroughly understand the multitude of regulations involved in the international trade of organic fruits.
Impacts
Many growers who think organic certification is a good business move but lack the commitment to its core values may find the additional challenges that organic systems present difficult and are therefore unlikely to remain in the organic market long. Nevertheless, food safety scares, public distrust of genetically modified crops, and possible health benefits from eating organic produce will all help to increase organic food sales. In the end, as organic food continues to expand its market share, farmers will have more management options and economic opportunities, consumers will have more choices in the marketplace, and society will likely accrue greater environmental benefits. With our work on evaluating the effects of organic, conventional, and integrated apple production systems on soil quality, horticultural performance, and other agroecosystem components, we continue to gain an understanding of how agricultural practices affect these components and agroecosystem
processes. Experience gained from our study is contributing to improvements in the production practices of organic and integrated apple growers in the Pacific Northwest and in the ability of conventional apple growers to convert to organic production methods or adopt integrated management approaches. Our study adds valuable information to the knowledge base of alternative apple production systems and may help expand economic opportunities for farmers and promote reduced use of agrochemicals.
Publications
- Andrews, P.K. and J.P. Reganold. 2004. Research networking to evaluate the sustainability of horticultural production systems. Acta Horticulturae. 638:359-368.
- Reganold, J. P. 2004. Organic agriculture as a form of sustainable agriculture. In R. M. Goodman (ed) Encyclopedia of Plant and Crop Science. Marcel Dekker, Inc., New York, NY. pp. 846-849.
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Progress 01/01/03 to 12/31/03
Outputs
The organic, conventional, and integrated Gala apple production systems all received ground-applied nitrogen fertilizers in Spring 2003. The organic system had 35-37% higher yields than the conventional and integrated systems. However, average fruit size for the organic system was smaller (171 g) than conventional (188 g) or integrated (195 g) fruit. Additionally, pack-out data showed that organic fruit was heavily distributed toward smaller fruit sizes. All three systems used lime-sulfur and oil for blossom thinning; however, the conventional and integrated systems also received a post-bloom chemical thinning, which likely reduced their yields but increased their fruit size relative to organic fruit. This over-cropping and small fruit size may also be a result of a light crop from the organic trees the previous year, a pattern called biennial bearing. At harvest and after a seven-day shelf-life test at 20oC, organic and integrated fruit were firmer but less sweet
than conventional fruit. The lower sugar in the organic fruit is opposite to our previous results; however, the excess crop load and nitrogen from the blood meal fertilizer application may have caused the maturity of organic fruit to be delayed, and hence, conversion of starch to sugars. We also evaluated pest and predatory mite population densities on leaves and found that the organic plots had higher densities of the pest Panonychus ulmi (European red spider mite), but lower densities of specialist predatory mites that feed on P. ulmi than did the conventional and integrated systems. However, the organic plots had higher population densities of generalist mites, which feed on both pollen and several mite and insect pests. Since soil enzymes and microbial assays may serve as quick soil quality tests to compare different management systems, B-glucosidase, L-asparaginase, microbial biomass C and N, denitrification potential, nitrification potential, and nematode functional diversity
were assayed in all three systems in 2002 and 2003. Soils under organic management consistently had the highest levels of enzyme activities, microbial biomass C and N, denitrification potential, nitrification potential, and nematode functional diversity. The relative rate of N2O emissions and mineralizable N were lowest in organically managed soils. Our results show a strong correlation between enzyme activities and total N, organic matter content, microbial biomass N, denitrifier activity, and nitrifier activity. These data suggest that organically managed orchards support a more active microbial population, potentially facilitating internal nutrient cycling and nutrient retention.
Impacts
While inadequate thinning in organic systems may result in higher yields, it also may result in many fruit falling below commercially acceptable size. Hand thinning may be more critical in organic systems as a final step in crop load management than in conventional and integrated systems because those systems have more chemical thinning options. This year the grower cooperator was unable to provide the necessary labor for extra hand thinning in the organic plots because of poor overall farm performance. Therefore, labor shortages have greater negative economic impacts to organic horticultural production systems, because they are more dependent on labor than are conventional systems. Differences in pest and predatory mite populations will also impact the efficacy of pest control measures among production systems. We are gaining an understanding of how agricultural practices affect agroecosystem components (such as soil quality, horticultural performance, and pest and
disease severity) and processes. Experience gained from our study is contributing to improvements in the production practices of organic and integrated apple growers in the Pacific Northwest and in the ability of conventional apple growers to convert to organic production methods or adopt integrated management approaches. Our study adds valuable information to the knowledge base of alternative apple production systems and may help expand economic opportunities for farmers and promote reduced use of agrochemicals.
Publications
- No publications reported this period
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