Thesis
NITROGEN SUPPLY FROM SOIL ORGANIC MATTER: PREDICTORS AND IMPLICATIONS FOR NUTRIENT MANAGEMENT
Washington State University
Master of Science (MS), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000002446
Handle:
https://hdl.handle.net/2376/121728
Abstract
Northern highbush blueberry (Vaccinium corymbosum L.) is a globally important specialty crop, and maintaining high productivity in blueberry systems depends in part on proper N management. Nitrogen can be provided by applying fertilizers or through mineralization of soil organic matter (SOM); however, the amount of N released through mineralization of SOM is difficult to predict and is not always considered in development of N fertility programs. This thesis covers the knowledge gap of N mineralization in high organic matter soils and how N release from SOM might impact northern highbush blueberry plants. Two experiments were conducted to: (1) identify N application rates that maximize fruit quality and yield and understand how optimal N rates change across soils with different SOM contents and (2) identify soil properties that are predictors of N mineralization from SOM that work in high organic matter soils and are cost-efficient, rapid, and scalable to commercial grower service laboratories. The first experiment had three N fertilizer treatments, including low (33-50 kg N ha-1), medium (67-84 kg N ha-1), and high (102-118 kg N ha-1) rates of N, that were applied for 2 years in 4 mature, commercial ‘Duke’ blueberry fields that were located in northwest Washington representing a range of soil organic carbon (SOC) contents 3-28%. Results suggested there was substantial N mineralization throughout the growing season at sites with higher SOM; however, higher N rates were not required to maximize fruit yield and quality at sites with lower SOM. Even the lowest N rates within this study appeared to be sufficient for production. The second experiment studied 10 soils collected from commercial blueberry fields in northwest Washington with varying levels of SOC (3-43%). These soils were incubated for 6 months, and several potential predictors of net N mineralization were evaluated. Findings from the second study suggested that soil total N is a reasonable predictor of potentially mineralizable N in high organic matter soils. As total N analysis is already available from most commercial grower service laboratories, growers may be able to adjust N application rates based on the test with little cost or additional time.
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Details
- Title
- NITROGEN SUPPLY FROM SOIL ORGANIC MATTER: PREDICTORS AND IMPLICATIONS FOR NUTRIENT MANAGEMENT
- Creators
- Cheyenne Sloan
- Contributors
- Gabriel T LaHue (Advisor)Lisa W DeVetter (Advisor)Deirdre E Griffin LaHue (Committee Member)David R Bryla (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 70
- Identifiers
- 99900606855101842
- Language
- English
- Resource Type
- Thesis