2017 ASHS Annual Conference

Washington state is the largest producer of red raspberries (Rubus idaeus) in the country with over 73 million pounds in 2015 the majority of which is concentrated in Northwest Washington particularly in Whatcom County). Washington state also recently emerged as the leader in highbush blueberry (Vaccinium corymbosum L.) Washington state is the largest producer of red raspberries in the country with over 73 million pounds in 2015 the majority of which is concentrated in Northwest Washington particularly in Whatcom County Washington state also recently emerged as the leader in highbush blueberry production with Whatcom County a significant contributor. Additionally, Whatcom County ranks in the top 3% of dairy counties. These production systems have evolved in tandem over time, but have recently lost their nutrient connection due to food safety concerns related to applying manure products to horticultural crops. While anaerobic digester (AD) technology can help mitigate air quality issues while producing renewable energy, the technology has only been adopted on a minority of the dairy farms on which it is potentially profitable. Adoption could be improved with development of commercially viable complementary technologies that help dairy farmers address their pressing nutrient management concerns. As a result, the dairy industry is interested in use of nutrient recovery technologies that physically or chemically convert raw manure into viable fertilizer. The use of such manure derived fertilizers from dairies (supply) to adjacent small fruit operations (demand) in northwestern Washington would assist in managing the overall nutrient balance in the region, but requires the documentation indicating that these products do not pose a food safety risk to a crop that is shipped worldwide. To this end, a trial was initiated in 2016 in ‘Meeker’ red raspberries and ‘Draper’ blueberries comparing two manure-derived fertilizers (ammonium sulfate liquid [8% nitrogen] and phosphorous-rich solid [3-2-1 + micronutrients]) to raw manure, post-AD manure, composted dairy manure, and standard synthetic fertilizers. Horticulture evaluations were paired with soil quality assessments to determine if these products could be substituted for synthetic fertilizers while maintaining productivity and improving soil quality. Soil, leaf, and fruit samples were taken throughout the growing season to determine the potential food safety risks these products pose for use in horticultural crops.