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2008 BIOAg Research Symposium Proceedings

CSANR’s BIOAg Program hosted an annual BIOAg Research Symposium for BIOAg related research, Extension and Education projects in Pullman in October of 2008. More than 35 posters of research, Extension and education projects were displayed.

Organic Waste

Compost Research and Extension for Biologically Intensive and Organic Agriculture
Carpenter-Boggs, L., Crosby, C., Price, C., Bonds, N.

The goals of the BIOAg compost program are to:

  1. Expand the use of composting for safe, sustainable waste management.
  2. Increase the use and effectiveness of compost as an agricultural soil amendment and nutrient source.
  3. Improve our understanding of composts and extracts as a resource for plant disease management.

Antibiotics in Animal Manure – Implications to Sustainable Agriculture
Ullman, J.L.

Antibiotics present a challenge to organic farms that use manure as a soil amendment, because these compounds can remain bioactive in agricultural systems, and can be taken up by crops and vegetables. This is an important environmental and economic consideration for organic producers as antibiotics can impart direct human and environmental health threats, promote antibiotic-resistant bacteria and impair soil and plant productivity necessary for sustainable agriculture. Concern over these pharmaceuticals has recently led to increased research efforts, but significant knowledge gaps remain. Antibiotic removal prior to manure land application would be preferable since the persistence and availability of these compounds varies considerably, but studies on management practices remain sparse and conflicting.
Therefore, this project will initiate a characterization of antibiotics in relation to manure management practices in Washington State. Our rationale is to provide organic producers with empirical information on manure-borne antibiotics to facilitate educated decisions for maintaining a safe and marketable organic product, while protecting the environment. This will be accomplished by an integrated approach. A reconnaissance of antibiotics and antibiotic-resistance in manure management practices will be conducted to identify prevalent drugs and insight into treatment methods. Antibiotics will be selected based on this reconnaissance for future experiments on fate and transport processes, including associated microbial interactions. These results will be linked to field conditions through composting and anaerobic digestion treatment effectiveness studies. Information gained will be incorporated into state, regional and national extension activities, as well as a new WSU graduate-level course.

Renewable Fertilizer from Nutrient Extraction of Anaerobically Digested Dairy Manure
Jiang, A.; Zhang, T., Frear, C., Chen, S.*

The high price of fossil-fuel based fertilizer has caused financial hardship to many Washington farmers and end consumers and continues to be a major factor in negative lifecycle, energy and carbon assessments. WSU has developed a patented integrated nutrient recovery system to work in series with commercial dairy anaerobic digesters (AD). The importance of this technology is that although the biological AD process is effective in mineralizing a considerable portion of organic carbon to collectable methane and therefore power, it has little treatment effect on the N, P and K; resulting in effluents that still have high levels of nutrient loading to limited dairy farmland. The goal of this technology is to create a scenario where nutrients are collected in concentrated form for easier transport from the farm, at which point the product(s) can be marketed as sustainable or even organic fertilizer for both added value to the dairy producer and cost savings to the end consumer. WSU is partnering with WSDA to evaluate the capabilities of the process at pilot-scale however no resources have been developed via that grant to assess the fertilizer value and its resulting marketability. Thus, proposal objectives are to: (1) evaluate the fertilizer value for the pilot-study product(s) using field studies with grass and corn; (2) develop a preliminary market feasibility report by integrating mass/energy balances, estimated process and capital/business costs, transport costs, and consumer demand, competition and price point structures; and (3) accomplish outreach for what has been learned to potential suppliers and customers.


Breeding Wheat for Enhanced Soil Fertility
Piaskowski, J.*, Garland-Campbell, K.

When associated with plant roots, arbuscular mycorrhizal (AM) fungi improve phosphorus (P) uptake in plants and are especially important in low-input systems where inorganic nutrients are limited. Genetic variation for plant response to AM fungi has not been widely investigated for wheat. Our objective is to evaluate a diverse panel of wheat genotypes including representatives from the US, the Caucasus, and from related wild species for the ability to associate with AM fungi. Four low P soils-collected in Eastern Washington-were pasteurized, mixed with sand to provide low P planting medium, inoculated with a commercial AM fungi inoculant, and planted with wheat. Data collected will include above-ground and below-ground biomass, leaf P content, and AM fungal colonization. Expected results are genotypes with optimal ability to extract and use P when associated with AM fungi in low-input systems.

Optimizing Nitrogen Fixation in Pulses
Abi-Ghanem, R.; Carpenter-Boggs, L.; McPhee, K.

There is a huge demand for N for agriculture, incl. an increasing demand for organic N for organic agriculture. Natural gas for the Haber-Bosch process is increasingly limited, esp. in North America. This study is using non-radioactive isotope studies to increase our potential to biologically fix nitrogen in the grain legumes (pea, chickpea, and lentil) by 1) identifying varieties of these crops that are better hosts for the N-fixing bacteria (which then can be used to breed even better hosts), and 2) Identifying strains of Rhizobia and Mesorhizobia that are more effective N-fixers (that should be favored in inoculants). We are finding that there is a variation in 15N/14N ratio (and therefore N-fixation) among rhizobia strains as well as lentil varieties. Some varieties are better N-fixation hosts and should be used as breeding lines. Likewise, particular rhizobia strains should be selected for future inoculation.

Winter Canola as a Rotation Crop in the Low and Intermediate Precipitation Zones
Schillinger, W.*; Kennedy, A.; Paulitz, T.; Young, D.; Jirava, R., Johnson, H.; Smith, T.

Multiple-year experiments are being conducted in the low (Ritzville) and intermediate (Davenport) precipitation regions of eastern Washington to document the rotation benefits of winter canola in wheat-based cropping systems. Some growers have reported that wheat following winter canola has less disease and weed pressure and produces considerably higher grain yield compared to monoculture cereals in either a 2-year winter wheat – summer fallow rotation or 3-year winter wheat – spring wheat – spring barley rotation. Additionally, it has been observed that water runoff from frozen agricultural soils does not occur from winter canola stubble; presumably because the deep tap root provides open channels for water to penetrate through the frozen surface soil layer. The present study is required because the boost in winter wheat grain yield and the soil physical, biological, or pathology factors that may account for increased grain yields by having winter canola in the crop rotation have yet been documented.

Transitioning to Dryland Organic Crop Production in Eastern Washington
Fuerst*, P, Koenig, R, Burke, I, Painter, K, Pittmann, D, and Gallagher, R

Certified organic crop production in eastern Washington presents many challenges in the areas of weed control and soil fertility and, perhaps for these reasons, there are very few certified dryland organic growers in our region. The purpose of the Organic Transitions Study at the Boyd Farm near Pullman was to evaluate the trade-offs among weed management, soil quality, and farm economics that occur during the three-year transition followed by two years of certified organic wheat production. Although intensive tillage is a proven strategy for weed management, our plots have never been plowed because of the highly erosive nature of our soils. A reduced tillage system, consisting of rotary harrow (pre-plant), rotary hoe (in-crop), and undercutter or sweep (post-harvest and sometimes pre-plant) was utilized for weed management. Timely use of the rotary hoe has been relatively effective against most annual weeds except wild oats. Field bindweed is our worst perennial weed, and we are utilizing competitive crops and post-harvest undercutter for management.
We report the following general observations: (1) spring pea harvested for grain was a failure in all regards; (2) winter pea green manure was highly competitive with weeds and contributed to soil N and subsequent wheat yields; (3) winter wheat was more competitive with our weed spectrum and was more profitable than spring wheat; (4) alfalfa-clover forage provided income during the transition while suppressing weeds, building soil N, and improving subsequent wheat yields; (5) commercially-produced organic fertilizer added substantially to costs while adding small quantities of nutrients.
Four new organic cropping systems were established for the 2008 crop year. Plots were severely depleted of N following two years of wheat, and poultry manure was applied to four cropping systems in the fall of 2007. One unexpected consequence of applying manure was the stimulation of vast numbers of wild oats in this year’s spring wheat and barley, precluding any grain harvest; these spring crops were cut for hay in early July. Winter peas were thinned by the extended winter conditions and were undercut to control weeds in early June of this year, precluding the intended harvest for hay. Winter triticale was grown for the first time on these plots this past year and was exceptionally competitive.
We conclude that weeds have been the single most critical issue faced in our minimum tillage organic systems. A weed management plan is strongly recommended for anyone contemplating dryland organic crop production in our region. Such a plan should include choosing crops that compete well against the weed species present and timely practices before, during, and after each crop.

Effectiveness and economic impact of weed control systems in organic garlic production
Fluegel, S*; Fluegel, J; Hastain E; Bailey, C.

Demand for organic gourmet garlic (Allium sativum L.) is growing and the supply cannot keep up with the demand. Unfortunately, organic hardneck garlic is extremely labor intensive. The most labor intensive aspect of growing hardneck garlic is weeding. Garlic is a 9 month crop and must compete with winter, spring and summer annuals. Since weed control is dependent on effective integrated farming systems not single components, this study will examine the effectiveness of a combination of pre-planting and post-planting weed reduction techniques. A split plot randomized block design will compare the interaction of solarization and stale seedbed technique with hand and flame weeding. Additionally, an economic analysis will be conducted using cost of labor, cost of materials and value of crop for each weeding technique combination.


Land EKG: Ecosystem Service Monitoring for Range Managers
Nelson, D.; Robinette, M.; Orchard, C; Carpenter-Boggs, L.

The 3-day Land EKGä Rangeland Monitoring Coordinator Workshop held August 21-23, 2008 was a joint effort of the BIOAg program and the WSU Rangeland Stewardship Team. It was designed to build capacity in participants to learn and apply the rangeland monitoring system and to assist ranchers in implementing this system on their own rangeland. It was conducted on several Washington ranches in the Ellensburg area and the field forms were tailored to match native soils, plants, climate and issues of the local area. The objective of the workshop was to provide the necessary background and hands-on skills to establish and evaluate rangeland sites and perform the Land EKGä documentation. Further exercises taught how monitoring information can be used to direct management to make sustainable and profitable decisions.

Mixed crop-livestock farming systems for the inland Northwest, U.S.
Bramwell, S.

Current farming practices have degraded the natural resource base and are not sustainable. Integrating livestock into organic farming systems can have economic and environmental benefits, but still present some agronomic challenges. One particularly troublesome management period is the transition from a perennial pasture (soil-building and livestock phase) into a grain crop (cash flow phase). This work has aimed to:

  1. Determine the impact of tillage on grain yields following grazed alfalfa pasture
  2. Determine the impact of tillage on soil nitrogen release
  3. Identify potential nitrogen leaching when transitioning from a perennial to an annual.

We have found that very intensive disruption is necessary to take out existing alfalfa; reducing disturbance intensity left alfalfa crowns that greatly reduced grain yield. Grain yield in the organic moldboard plow treatment yielded 82 percent of County average. Profitability of the whole integrated rotation is 10 percent more than if non-integrated with a livestock phase, due primarily to the cost of alternative sources of organic fertility. We saw very little potential for N leaching in these plots.

Sustainability Impact Assessment

Trade-offs between Bio-energy and Soil Carbon Sequestration on the Palouse: Evaluating Sustainable Options
Kruger, C., Huggins, D., Kok, H.

Crop residues can be removed from the field and used as biofuel feedstock. If left in the field, these residues help to maintain soil carbon, fertility, and reduce erosion. Removing them therefore will have soil health consequences, and the value of the potential energy output must be balanced with the value of the nutrients and other benefits provided to the soil. Optimum management of these residue resources can be improved by mapping soil quality and erosion potential.

Gender and Certified Organic Production in Washington State
Goldberger, Jessica

The face of U.S. agriculture is changing. Men have historically controlled agricultural land, labor, capital, and decision-making. Today, women make up a growing proportion of principal farm operators, especially in “alternative” agriculture. This research investigates the “gendered” nature of certified organic production in Washington State. Understanding the experiences and perspectives of female and male farmers will help land-grant universities, such as Washington State University, and other service providers better serve the needs of all organic producers.


Analysis of Local Food Distribution of a BIOAg Producer Group
Sáez, H*; Soontag, V; Flaxman, A; Crosby, T.

Produce transportation and distribution remains an obstacle for farmers in regional food systems. Characterized by small and medium-sized producers, regional networks lack the production volumes and capacity for logistics coordination necessary to reduce average costs of transportation and delivery transactions. This raises fuel use and emissions, increases costs, and reduces the profitability and viability of BioAg producers. Producer groups are banding together to solve this problem in accordance to local conditions but they lack the information and frameworks necessary to find optimal solutions. Mathematical models are emerging that shed light on these issues but because regional food systems defy industrial production and delivery systems, little attention has been paid to the issue of coordinating transportation for multiple, spatially dispersed, small and medium-sized producers. This project seeks to advance a solution by developing a mathematical framework. Using algorithmic game theory, we hope to develop a usable decision-making protocol to help farmer groups choose transportation arrangements that
1) minimize fuel consumption,
2) reduce delivery costs, and
3) increase access to regional markets.
We are conducting a case study of Growing Washington, a farmers’ group in Whatcom, Skagit, and King counties. Using the data from this and similar case studies across the nation, we hope to develop a game theoretical model that sheds light on the points at which a combination of variables – including distance, volumes, participants, delivery sites, and frequency of delivery – dictate changes in systems of transportation in order to increase efficiency, reduce environmental impact, and increase profitability.


Building Sustainability Through Building the People Network
Munts, P.*

WSU Spokane County Extension’s Small Farms Program offers the Cultivating Success Small Farming and Ranching course in Spokane this fall. This 10-12 week course, designed to be offered during the evenings through county extension offices and on-campus, combines classroom and on-farm experience to give students lessons in technical aspects of farming along with practical whole farm management skills. Guest speakers range from soil, forage, and horticultural scientists to local successful producers. Students tour local farm and market operations, meet key community agricultural leaders, and build a network of resources and connections. In addition to this, students learn how to obtain critical production and marketing information through electronic resources.
The final product is a whole farm plan that students will use to evaluate their farming goals and resources from environmental, economic, and social dimensions. Course topics include: Sustainability Concepts, Whole Farm Planning, Resource Evaluation, Marketing, Enterprise Assessment, Sustainable Crop and Livestock Production , Ecological Soils Management, Integrated Pest & Weed Management, Intensive Grazing Management, and Irrigation, Equipment & Facilities. Students learn how to apply successful whole farm management principles that focus on environmentally sustainable practices, marketplace profitability, trend identification, and feasibility assessment. This course is designed for beginning farmers, transitioning farmers, and agricultural professionals.

Cultivating Success: Community-based Education for Sustainable Agriculture
Ostrom, M; Perillo, C;

The vision of the Cultivating Success program is to increase producer and consumer understanding, value, and support of sustainable local farming systems in Washington and Idaho through educational and experiential opportunities. Partners in this program strive to create strong communities with infrastructures that provide the resources and skills needed to produce local and sustainable food and agricultural products for the residents of the Pacific and Inland Northwest.

  • The Cultivating Success™ Program offers a series of courses that provide beginning and existing farmers with the planning and decision-making tools, production skills and support necessary to develop a sustainable small acreage farm.
  • Cultivating Success™ connects the student with the farmers and exposes them to real world situations through a community-based, experiential approach.
  • Whether you are an academic student or community member – Cultivating Success™ provides educational opportunities for anyone interested in the knowledge and skills you need to be a successful small acreage farmer or rancher.
  • Courses are offered in various locations Washington and Idaho, to audiences that include academic students, new and experienced farmers, immigrant farmers, and agricultural professionals.

WSU Organic Farm
Sullivan, J.*; Jaeckel, J.; Reganold, J.

The Organic Farm is committed to education, research, and extension. As a teaching farm the primary goal is to pass on the skills necessary to grow organic fruits and vegetables in an intensive small-scale environment. The farm is available to the WSU scientific community to conduct organic research projects. In addition, the farm operates a 100 member CSA (Community Supported Agriculture) enterprise and strives to provide fresh produce to local food banks and non-profits.

Graduate Certificate in Sustainable Agriculture
Carpenter-Boggs, L.; Templin, H.; Pan, W.; Andrews, P.; Snyder, W.

The Graduate Certificate in Sustainable Agriculture provides post-baccalaureate students with an interdisciplinary understanding of practices and current issues in sustainable agriculture, along with the science that makes it work.

The Graduate Certificate in Sustainable Agriculture requires a minimum of 9 graded credits.

Certificate Core (Required courses = 6 credits)
AFS 501: Current Research in Organic and Sustainable Agriculture (3)
AFS 545: Field Analysis of Sustainable Food Systems (3)

Scientific Breadth Component (Elective course(s) = 3 credits)
The Scientific Breadth Component ensures that students gain knowledge of a relevant discipline outside their primary degree department. Students must complete at least 3 graded credits in disciplines other than the home department. The course(s) must be clearly and directly relevant to the practice or understanding of sustainable agriculture.

Short Course in Biodynamic Agriculture
Lia, B.; Sehmsdorf, H.; Murray, T.

This Short Course will introduce students to proven BD approaches to soil, crop and animal husbandry, and position them for transition to BD practices through lectures, experiential exercises, and hands-on learning on the farm.
The Short Course will consist of

  • lectures,
  • hands-on activities,
  • homework, and
  • a farm tour

Crop Breeding for Organic Systems
Colley, M.; Jones, S.

The development and use of crop genetics ideally suited to organic and sustainable farming systems is a key component of a whole-farm management approach addressing pest, fertility, climatic stress, and public demand for enhanced flavor and nutrition in crop plants. Few sustainable agriculture education programs include instruction on plant breeding or variety evaluation and most university-based breeding programs lack courses on plant improvement in or for organic systems. A team of classically trained plant breeders with experience in organic systems research will develop and co-teach a new on-line Extension course on the fundamentals of organic plant variety improvement with a focus on participatory, on-farm methodologies.

Demonstration Improvements and Educational Aids for the Aeschliman Learning Site
Kok, H.

John Aeschliman receives numerous tour groups on his BioAg learning site each year. He delivers an introduction to the farm and farming philosophy, followed by a field visit. Practical hands-on demonstrations are performed, including demonstration of a soil pit, a Giddings soil probe, and a ‘fire-hose’ demonstration, illustrating improved infiltration under direct seed farming systems. This project will provide John tools to improve the quality and ease of his educational capacity. Production of a narrated slide set, giving the history of the farm, and explaining John’s farming philosophy, is underway, with the help of the Spokane County Conservation District. The presentation will be on the web, and available on DVD for John to hand out. We can probably make mini-DVDs that would double as business cards for John. Interviews with John have been completed, high quality photos have been produced. The final product will be reviewed by John, the Learning Site coordinators and Russ Evans with PNDSA. Production of an A-frame rain simulator, with pump and battery, will take place this winter.

G&L Farm, BIOAg Demonstration & Learning Site
Beckley, G. & L.; Carpenter-Boggs, L.; Robinette, M.; Nelson, D.

Gregg Beckley is trying significantly new BIOAG ideas to transition from unprofitable conventional dry-land wheat production and CRP in a 12-14 inch precipitation zone to a sustainable value-added pasture-based program producing grass-fed natural, or organic, beef that is profitable, protects and enhances the environment (i.e., soil, water, vegetation and wildlife habitat) and improves his quality of life.
Gregg has made up his mind to make the transition out of conventional dry-and wheat production and CRP to something that will be sustainable. He is prepared to make the necessary investment to make this happen. This will not be a short-term process as the first land to come out of CRP contract will be in 2010. He is planning to construct fencing and a water distribution system for the cattle grazing operation. The production of ready-to-eat grass-fed beef will be the end result of a production chain with many phases including cow-calf production, calf growing, grass-finishing, processing, fabrication into retail cuts, packaging, distribution and marketing. This will involve collaboration with other producers to put all these phases together. In addition to investing his own money, he is seeking funding from several sources that include EQIP, the Ruckelshaus Policy Consensus Center’s Agriculture Pilots program, Centennial Clean Water Act, etc. The farm would serve as a replicable model of a major collaborative effort in eastern Washington.

Pest Management / Plant Protection

Successful Biological Control of Cereal Leaf Beetle in Washington State
Roberts, D*; Miller, T; Pike, K; Miller, S; Klaus, M

The cereal leaf beetle (Oulema melanopus) has been a pest of cereals and grasses in the USA since 1962, but it is new to Washington state since 1999. Cereal leaf beetle (CLB) has a wide host range in the grass family and may cause up to 75% yield loss, especially in spring cereals. The biological controls are two tiny wasp species that parasitize the egg or larvae, respectively, of CLB. Elsewhere in the U.S. these biocontrols have reduced grain losses by CLB to less than 1%. The wasps are harmless to people, pets, livestock, plants, and other insects.
The Washington State Department of Agriculture released the first biocontrols in 2000. Since 2003 a multi-agency group led by WSU Extension has expanded the program. We believe biocontrol has the potential to manage CLB populations in Washington, but the active cooperation of farmers in minimizing insecticide applications is necessary to achieve that goal.
By 2008, parasitism levels in CLB of the larval parasitoid, Tetrastichus julis, were greater than 90% in all commercial grain fields sampled in the dryland, eastern portion of the state. Insecticide treatments should not be needed to manage CLB in these areas. The parasitoid was also established in the irrigated Columbia Basin where wheat is a rotation crop of secondary importance. In a few areas where the biocontrol has not yet reached 75% parasitism, farmers may need to tolerate some yield loss to enable the wasp to reach population equilibrium with CLB.

Compost teas as potential biocontrol agents for control of Xanthomonas campestris
Crosby,C*; Carpenter-Boggs, Lynne

Compost tea, an aerated mixture of mature compost and microbe stimulating additives, inhibits growth of seed-born cabbage pathogen Xanthomonas campestris pv. campestris (Xcc) in laboratory studies. Production of small molecular weight diffusible signal factor was blocked by compost tea treatment. The effect was not observed using sterilized compost teas. Signal factors are critical in the epiphytic survival of the pathogen, and invasion of the host plant. Inhibition of this signal factor indicates compost tea has potential as biological control agent for Xcc.

Conservation Biology of Syrphids, Predator of Woolly Apple Aphid in Central Washington
Gontijo, L.*; Beers, E.; Snyder, W.

Woolly apple aphid, Eriosoma lanigerum Hausman has become a pest of increasing importance in Washington apple orchards for the past few years. The problem is especially critical in organic orchards, where few approved pesticides are available. However, there is a good potential for biological control of this pest, both in conventional and organic orchards. A preliminary survey of predators has indicated that syrphids (Diptera: Syrphidae) are likely to be the most common predator found in aphid colonies. One approach to enhance biological control is the conservation of natural enemies. This may be achieved by altering crop systems to provide necessary resources for beneficial insects. Syrphid larvae are known to prey upon aphids whereas the adults feed on nectar and pollen. Engineering the orchard ecosystem to include plants that attract and sustain adult syrphids should therefore augment biological control. In this study we investigated the attractiveness of 6 flowering plant species to syrphid adults. The plant species tested were: sweet alyssum Lobularia maritima, buckwheat Fagopyrum esculentum, mustard Brassica juncea, cosmos Cosmos sulphureus, zinnia Zinnia hybrida and marigold Calendula officinalis. Sweet alyssum was observed to attract significantly more syrphid flies than all the other plant species. In the presence of honeybees, Apis spp., syrphid flies were observed to spend great amount of time trying to dislodge the former from the flowers. Nonetheless, not correlation was detected between the number of syrphid flies and honeybees.

Identification of Root Disease-Causing Organisms and Their Management in Washington Raspberries
Gigot, J*; Zasada, I; Walters, T

Over 90% of the nation’s processed raspberries are grown in Washington State. Unfortunately, the lifespan of Washington raspberry plantings has decreased and a replant disorder similar to that observed in other perennial crops has developed. Phytophthora rubi is the most common cause of raspberry root rot and the plant-parasitic nematode Pratylenchus penetrans can result in reduced raspberry vigor. The roles of other soilborne organisms are unclear. In order to design effective soilborne pest management systems it is essential to know the target organisms and how to manage them. Currently, whole field pre-plant fumigation is practiced to manage this problem; a management practice that is expensive, chemically intensive and subject to increased regulation. We propose to address raspberry root disease by 1) initiating a survey of soilborne pests of raspberry and 2) evaluating root disease management options that reduce the need for broadcast pre-plant fumigation. In the survey we will work with extension personnel and growers to identify declining plantings and new plantings showing raspberry root rot and replant disease symptoms in Washington. We will use selective media, existing molecular techniques and soil extractions to identify fungal and nematode pathogens of raspberry. Toward developing alternative management options we will test brassicaceous seed meal amendments and drip fumigation with and without soil solarization in a controlled field experiment. This research directly addresses the reduced toxic input, sustainable farming and crossover priority areas for the 2008 WSU BIOAg Program.

Brassica juncea seed meal as a fumigant in organic greenhouse production
Higgins, S; Carpenter-Boggs, L.; Mazzola, M.; Paulitz T.; Smith, J; Crosby, C.

A growing body of evidence indicates that the seed meal of several Brassicaceous species may serve as effective biofumigants against soil-borne pathogens. Our objective was to examine Brassica juncea seed meal (BSM) for its potential as a biofumigant for organically-certified greenhouse potting mix. We hypothesized that the effectiveness of BSM as a fumigant would depend on how much time elapsed after incorporating it into a Pythium-contaminated potting mix. Spinach was the test crop.
After initial seeding, spinach emergence was consistently higher, and mortality was consistently lower, in the +BSM pots than in the control pots. In the control pots, Pythium was stimulated later in the incubation. In the +BSM pots, Pythium was not detectable by dilution plating after the initial seeding. The high emergence of spinach in BSM-amended potting mix, relative to emergence in the control mix, indicated that the pathogenicity of the +BSM potting mix had been reduced.

Evaluating Soils Receiving Multiple Green Manures for Suppression of Verticillium dahliae
McGuire*, A.; Johnson, D.

Farmers are using mustard green manures on over 20,000 acres each year in the Columbia Basin, mainly before potatoes. Although this practice has the potential to replace the use of the fumigant metam sodium for control of Verticillium dahliae, only a small number of farmers are doing so. They lack any way of estimating the effect of the green manures on their soil’s ability to suppress this or other soilborne pathogens. This project will evaluate the soil changes that have resulted from multiple mustard green manure crops (up to eight over the past 16 years) on one farmer’s fields where metam sodium has been successfully eliminated. We will evaluate the soil’s suppression ability and attempt to correlate it with other soil measurements with the goals of giving farmers a way to rate the suppression ability of their own soils following green manures and giving researchers direction in determining the mechanism behind the suppression.

Where are the bugs? How soil type and management affect soil food webs and their spatial structure.
Collins, D*; Cogger, C; Kennedy, A; Forge, T; Collins, H; Bary, A; and Rossi, R.

Agricultural landscapes are shaped by geological history, climate, alluvial processes, and present and historical management. Soil properties often change over short distances, complicating efforts to describe soil quality on field or farm scales. We sampled 81 points across a 25-ha area to evaluate farm-scale variation of soil communities and their relation to edaphic properties at Full Circle Farm, Carnation, WA. Nitrogen mineralization was positively correlated with microbial biomass (r2=0.59), and negatively correlated with bulk density (r2=0.42) and nematode maturity index (r2=0.33). Nematode abundance was not strongly linearly correlated with any edaphic or management practices; the strongest correlation was with pH (r2=0.22). However, a regression tree model for nematode abundance explained 61% of the farm-scale variation and indicated that recently tilled fields formed a homogeneous group with relatively low nematode density. We examined field-scale distribution by sampling 42 points in each of two 0.09-ha fields with contrasting soil texture. Field-scale spatial analyses indicated nematodes, bacterial to fungal biomass ratio, and collembolans were autocorrelated (i.e. places close to one another tended to have similar values) in the sandier, but not in the clay-rich field. Microbial biomass was autocorrelated in the clay-rich field. We conclude soil physical and chemical properties can have significant, but inconsistent effects on biological variation, and mapping inherent soil quality parameters should precede monitoring soil communities.

Forecasting late blight epidemics
Inglis, D.*

This project proposes to develop a disease forecasting model for late blight on organic potatoes in western Washington. Such a model could be applicable to conventional potatoes grown in the region as well. We will follow-up on 10 yr of historical data on naturally-occurring late blight epidemics and corresponding weather, recently recovered and compiled at WSU-NWREC. Four potential predictors obtained from our preliminary work, and others not yet identified, will be formulated into empirical models, statistically analyzed, and cross-validated across years and regions (northwestern and eastern Washington) for potato late blight forecasting purposes, with the advice of a WSU statistician. Initial planning on making the model accessible to the public via WSU’s AgWeatherNet will be done in concert with posting eastern Washing-ton’s existing late blight model on the same site. Organic and other potato growers will be educated on integrated late blight control practices for which disease forecasting is essential.


Comparing tillage and mulching for organic orchard performance
Wiman, M., Kirby, E., Granatstein, D.*, Mullinix, K.

Weed control and nitrogen nutrition remain two major challenges for the rapidly expanding organic tree fruit sector in the state. Tillage has been the most common weed control practice, often with significant financial cost, and soil quality degradation that conflicts with the National Organic Standards. We compared novel tillage, mulch, and cover crop techniques to understand the economic and environmental trade-offs. Trial 1 compared wood chip mulch, tillage tools, and tillage frequency in an established orchard, and Trial 2 investigated the effects of tillage, wood chip mulch, ‘living mulch’ cover crops, and the Swiss ‘Sandwich’ system in a newly planted orchard. In Trial 1, tillage initially controlled, then stimulated annual weeds; with no clear impact on soil quality. Wood chip mulch provided excellent weed control that lasted three years, increased tree growth, and enhanced fruit yield and size, with the additional fruit value exceeding the estimated cost of mulch application. However in Trial 2, wood chip mulch did not provide satisfactory weed control but did lead to tree growth and fruit yield that were similar to tilled plots. Tillage provided satisfactory weed control, but by Year 2, the unsupported trees had significantly greater leaning, possibly indicating root pruning. Living mulch species, especially bentgrass and trefoil, provided excellent weed control, but were too competitive with trees in Year 1. By Year 2, the trees with living mulch grew satisfactorily, but still less than other treatments, and had lower fruit yield in Year 3.

Organic Fertility Management Alters Development and Phytonutrients of Tomato
Andrews, P; Davies, N; Vega-Villa, K; Collier, M; Feng, X.

A greenhouse study on the effects of organic (ORG) and conventional (CON) fertility management on plant growth and phytochemicals in three cultivars of tomatoes with differing genetic potentials for fruit size was completed. ORG fertility management delayed plant development. ORG plants compensated by producing larger leaves adjacent to fruiting trusses, which resulted in equal yields and mean fruit size for ORG and CON plants. Phytochemical constituents were only negatively correlated with fruit size, so that phenolic concentrations and antioxidant activities most often declined as fruit size increased. This demonstrates reduced “nutrient density” for certain antioxidant phenolic compounds. Only the medium-sized First Lady cultivar grown organically was able to overcome the negative effects of fruit size on phenolic concentration.

Effects of Ground Cover Management Strategies on Yield and Nitrogen Supply in Organic Apple Production Systems
TerAvest, D*; Reganold, J

Biological weed and fertility management in organic orchards was studied using a number of treatments, including wood chip mulch, living ground covers, and the wonder weeder (shallow tillage tool). Ground cover management strategies had a significant impact on yield and nitrogen supply in a young organic apple orchard. Living mulches increased organic N supply but resulted in low apple yields. A wood chip mulch resulted in good apple yields, tree growth and N supply. Other treatments resulted in good yields but low organic N supply.

Influence of processing on phytonutrient content of organic and conventional raspberries and blueberries
Sablani, S. S., Andrews, P. K., Davies, N., Saez, H., Walters, T. W., Symaladevi, R. M. and Mohekar, P. R.

The phytonutrients of conventionally and organically grown blueberries and raspberries were measured.

The influence of industrial processing methods i.e. air drying, freeze-drying, canning, freezing and fruit juice concentrate preparation on phytonutrient concentration was determined.

The long-term goal of the research is to improve the shelf life and nutrient retention in organically grown berries by increasing our understanding of the mechanisms of nutrient destruction in processing methods.