Document Type

Honors Thesis

Major

Ecology and Environmental Sciences

Advisor(s)

Lily Calderwood

Committee Members

Ivan Fernandez, Margaret Killinger

Graduation Year

May 2024

Publication Date

Spring 2024

Abstract

Maine is home to one of the largest commercially grown crops in the Northeast: lowbush (wild) blueberry. This native crop is managed by 485 landowners, with parcels ranging in sizes as small as 20 acres to as large as thousands of acres throughout the state (Calderwood et. al, 2020). Although the plants may be considered “wild”, growers still need to apply fertilizers to maintain a consistent yield and quality crop for their income (Calderwood et. al, 2023). There have been many more fertility studies conducted on highbush blueberry (Vaccinium corymbosum) compared to lowbush blueberry (Vaccinium angustifolium). Due to the differences between species and the vastly different production systems, research must be conducted on lowbush blueberry fertilizer type and timing. In this project, we aimed to determine if the existing highbush blueberry nitrogen recommendation improves lowbush blueberry plant productivity in the crop year. Nitrogen is the most important macronutrient for plant growth and development. Based on the crop year fertility samples collected in 2021 and 2022, nitrogen was above the optimum range at bloom, but declined through fruit ripening to harvest. Currently, growers only take foliar samples in the prune year at tip dieback (July) and only apply granular fertilizer in the following prune year, two years after the sample was taken. For this study, during the growing season of 2023 in a crop field, four treatments were applied to an irrigated site where the 2022 baseline foliar nutrient test indicated that only nitrogen was required. Granular ammonium sulfate was applied at T5 bud (pre-bloom) and pinhead stages (post-bloom). The preliminary data from this one-year study suggests that a pre-bloom application timing could improve nitrogen levels in lowbush blueberry leaves during the crop year.

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