Evaluating organic nitrogen fertilizer sources, rates, and timing in northern highbush blueberry grown in high pH soils of eastern Washington

Amit Bhasin

doi:10.7273/000000049

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Evaluating organic nitrogen fertilizer sources, rates, and timing in northern highbush blueberry grown in high pH soils of eastern Washington

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Evaluating organic nitrogen fertilizer sources, rates, and timing in northern highbush blueberry grown in high pH soils of eastern Washington

Amit Bhasin

Washington State University

Master of Science (MS), Washington State University

05/2020

DOI:

https://doi.org/10.7273/000000049

Handle:

https://hdl.handle.net/2376/124312

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Abstract

Northern highbush blueberry (Vaccinium corymbosum L.) prefers acidic soils with high organic matter while growers in eastern Washington utilize amended soils with high native pH and low organic matter content. These edaphic conditions can influence nutrient cycling and plant available forms, which can affect plant growth, development, and fruit production. Furthermore, in eastern Washington, the semi-arid climate provides extended growing conditions after harvest for early-fruiting cultivars. This may require growers to continue nitrogen (N) fertilizer applications postharvest to support vegetative growth that could benefit fruit production in the following years. However, postharvest N applications could be detrimental as it may stimulate excessive vegetative growth, reduce floral bud set, and increase the risk of winter injury. The overall objective of this study was to provide baseline data to guide future nutrient recommendations for eastern Washington organic blueberry growers with an emphasis on N. Two experiments were conducted, and the sub-objectives were: 1) Determine optimal organic N fertilizer sources and rates and 2) Evaluate the impacts of postharvest N applications on fruit bud set and cold hardiness in early-fruiting ‘Duke’ blueberry. In experiment one, treatments included: 1) Blood meal; 2) TRUE 402 fish emulsion; 3) WISErganic; and 4) Combination (40% blood meal and 60% WISErganic). Fertilizer rate was split within source at 57, 112, and 168 kg·ha-1 N. The postharvest N experiment included four treatments varying in timing of N application. No yield and vegetative growth differences were observed across the fertilizer source and rate experiment during the two years in which this study was conducted. Leaf N concentrations increased with higher rates of N application. For postharvest N experiment, fruit bud set was similar across treatments and susceptibility of buds to cold was low across the treatments. While not statistically different, average plant yield in two years tended to increase with later fertilizer application dates. The lack of treatment differences can be attributed to plant age and the short duration of the experiment since blueberry plants can store nutrients in their tissues. Further years of data collection are required to better understand how these perennial plants are responding to these treatments.

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Title: Evaluating organic nitrogen fertilizer sources, rates, and timing in northern highbush blueberry grown in high pH soils of eastern Washington
Creators: Amit Bhasin
Contributors: LISA WASKO DEVETTER (Degree Supervisor) - Washington State University, Horticulture, Department of
Joan R Davenport (Committee Member) - Washington State University, Crop and Soil Sciences, Department of
GWEN-ALYN HOHEISEL (Committee Member) - Washington State University, WSU Extension ANR
Awarding Institution: Washington State University
Academic Unit: Horticulture, Department of
Theses and Dissertations: Master of Science (MS), Washington State University
Publisher: Washington State University
Format: pdf
Number of pages: 166
Identifiers: 99900588363601842
Language: English
Resource Type: Thesis