Date of Award

12-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Plant and Environmental Science

Committee Chair/Advisor

Juan Carlos Melgar

Committee Member

Michael Vassalos

Committee Member

Dario Chavez

Abstract

Peach production in the southeastern United States requires optimizing fertilization practices to balance economic sustainability and environmental health. Current guidelines may overlook rootstock-specific nutrient requirements and fail to align with orchard-specific conditions, often resulting in overfertilization, increased costs, and environmental risks. This study, conducted at Clemson University’s Musser Fruit Research Center during 2023 and 2024, aimed to refine fertilization practices through two complementary experiments. The first experiment investigated how three rootstocks, ’MP-29’, Lovell, and Guardian, influence nutrient dynamics of ‘Carored’ peach trees. Nutrient concentrations were measured in various tree organs, including leaves, pruned wood, thinned fruitlets, and harvested fruits, along with the total nutrient loss through harvested fruits. Results showed that trees on Guardian and Lovell rootstocks generally required more nutrients compared to the ‘MP-29’. The second experiment assessed the validity of established nitrogen sufficiency levels by comparing a reduced fertilization approach with standard annual nitrogen applications using mature ‘PF-23’ peach trees grafted onto Guardian rootstock. The reduced fertilization approach included applying nitrogen only when leaf analyses indicated deficiency associated with a significant difference in yield and fruit quality between the two programs. The reduced fertilization approach demonstrated that peach trees could maintain high yields and fruit quality even with leaf nitrogen concentrations below established thresholds, indicating that current sufficiency levels may be overly conservative for certain conditions, such as mature trees with built nutrient reserves grown in clay, nutrient-rich soils. Our study indicates that reducing nitrogen fertilizer applications, even by 20%, could lead to substantial cost savings and environmental benefits for growers, as high yields were maintained with lower N levels, potentially saving 4,008 lb of N and $3,648 over six years for a 100-acre orchard.

Author ORCID Identifier

https://orcid.org/0000-0002-1354-3421

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