Date of Award
5-2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Plant and Environmental Science
Committee Chair/Advisor
Dr. Juan Carlos Melgar
Committee Member
Dr. Guido Schnabel
Committee Member
Dr. William C. Bridges
Committee Member
Dr. Churamani Khanal
Abstract
Peach productivity and sustainability in the southeastern United States are frequently constrained by inherently low soil organic matter (OM), intensive orchard-floor management, and a warm and humid climate that accelerates OM decomposition which makes OM inputs and management central to a long-term orchard sustainability program. This dissertation investigated the effect of different sources of OM amendments (food waste compost, municipal mulch and poultry litter) and application method (incorporated and top-dressed) on soil health, nutritional status, tree performance, fruit quality, and nematode population dynamics in South Carolina peach orchards. The first study evaluated the effect of two rates of food waste compost (FWC) against grower standard (GS) rates of chemical fertilizer on nutrient status and horticultural performance of two 6+ y/o South Carolina peach orchards (a replant – with 20+ years of previous cropping history and a virgin –no prior cropping history). Another study investigated the impact of municipal mulch (M) and poultry litter mixed with mulch (PLM) against the GS rate of chemical fertilizer on the horticultural performance and physiological responses of a 9+ y/o South Carolina peach orchard. In another study, the effect of different sources of OM (FWC, M, PLM and GS) on bacterial spot incidence and bronzing, yield and nutrition of mature peach orchards in South Carolina was evaluated. Finally, the impact of different sources of OM amendments on nematode population distribution across three growing (conventional, organic and research) orchard conditions in South Carolina peach orchards was evaluated. Our result showed that annual application of FWC improved soil chemical properties such as cation exchange capacity (CEC), reduces the bioavailability of copper (Cu) through the formation of stable organo-Cu complexes where Cu binds to the negatively charged OM surface in the soil and maintaining tree performance with reduced or absence of fertilizer inputs, supporting circular nutrient management strategies for peach production. Similarly, the annual application of PLM and M in the second study substantially increased the soil OM content and CEC compared to GS. In general, positive responses to OM amendments, including improved nutrient uptake and growth. Moreover, despite receiving no chemical fertilizers, trees receiving OM amendments maintained productivity comparable to the grower standard during the final year of study. Meanwhile, all OM amendments improved fruit quality by reducing fruit bacterial spot incidence and severity as well as bronzing incidence and severity across all orchards. Our results also demonstrated that soil fumigation provided short-term plant-parasitic nematode suppression by reducing nematode functional diversity and simplified soil food webs in the first growing season across our selected growing regions. In contrast, OM amendments, significantly enhanced total nematode abundance and promoted the populations of beneficial nematodes, thus indicating an enhanced soil food webs. Findings in these studies show that annual application of OM amendments can successfully replace chemical fertilizers without negatively impacting crop productivity while offering valuable insights into the need for specific orchard-based OM amendment programs for sustainable peach production systems in South Carolina peach orchards.
Recommended Citation
Idowu, Ayodeji P., "Nutrient Dynamics and Horticultural Performance of Peach Orchards in Response to Different Soil Amendment Programs in South Carolina" (2026). All Dissertations. 4283.
https://open.clemson.edu/all_dissertations/4283