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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Production and Genetic Improvement Research Unit » Research » Research Project #438664

Research Project: Optimizing Nutrient Management for Organically Grown Blueberries East of the Cascade Range

Location: Horticultural Crops Production and Genetic Improvement Research Unit

Project Number: 2072-21000-055-015-G
Project Type: Grant

Start Date: Aug 1, 2020
End Date: Oct 31, 2023

1. Evaluate the effects of commercially available organic nitrogen (N) fertilizer sources applied at low, medium, and high rates on blueberry plant growth, yield, and fruit quality in blueberry systems east of the Cascade Range. 2. Understand N dynamics of organic fertilizers when applied in blueberry systems east of the Cascade Range. 3. Disseminate project information and assess impact.

This experiment was previously established in a mature field of organic-certified ‘Duke’ located in Prosser, Washington, in 2018. The experimental design is a randomized complete block with plots split for different fertilizer rates. Plot size is 3 ft X 36 ft with 12 plants/plot and each treatment is replicated four times. All nitrogen (N) fertilizer sources and rates were selected based on growers’ feedback. Four organic-approved fertilizer N sources were selected, applied annually since 2018, and include: 1) Blood meal (15-0-0; J.R. Simplot, Boise, ID); 2) TRUE 402 fish emulsion (4-0-2; TRUE Organic Products, Inc., Helm, CA); 3) WISErganic (3-2-2; WISErg Cooperation, Redmond, WA); and 4) Combination (40% blood meal and 60% WISErg). Fertilizer rate is split within source at 50, 100, and 150 lbs total N/acre. All treatments received and will continue to receive a uniform rate of phosphorus (P) and potassium (K). Liquid fertilizer applications begin at 5-10% bloom and occur once every 2 weeks. Blood meal will be applied as a slurry (1 blood meal:4 water) 2 weeks before liquid fertilizer applications to allow adequate time to mineralize. All remaining treatment application protocols will be in accordance with what we have done previously and based upon grower feedback so that we can continue generating comparable and representative data for this long-term nutrient management study.