Understanding the Impacts of Nutrient Leaching in Peach (Prunus persica L.) Crop Production

Abstract

Nutrient leaching has been a long-standing concern due to its potential detrimental effects on the environment, human health, and aquatic ecosystems. This issue is becoming increasingly pressing, considering the new challenges of climate variability and extreme weather events. This study evaluated nutrient leaching among three different young peach cultivars and assessed their growth performance and physiological traits, highlighting nutrient management as a critical determinant of peach production, using the recommended fertilization rate. Three peach cultivars (Prunus persica (L.) Batsch), early mid-season ‘Crimson Joy’, mid-season ‘Liberty Joy’, and late season ‘Rich Joy’ grafted onto ' Guardian® ' rootstock., were planted at Auburn University's Research and Extension Center in Chilton, Clanton, Alabama using a Randomized Complete Block Design (RCBD) with four blocks. Each block consisted of nine peach trees, totaling 36 trees. Two different seasons of data were collected and analyzed (2024 and 2025). The literature review presented in Chapter One summarizes current knowledge on nutrient leaching in southeastern U.S. peach production, focusing on nitrogen as the most leached nutrient and a key in plant metabolism. It explores how soil hydrology, orchard practices, and peach physiology interact to influence nutrient mobility, and evaluates strategies to reduce losses while maintaining yield and fruit quality, considering agronomic, environmental, and policy implications. More elaboration of these descriptions is expanded in the next chapters. Chapter Two covers nutrient leaching evaluation in sandy soil with different young peach (Prunus persica (L.) Batsch) cultivars. A soil sampling method was used to compare the nutrient levels at selected depths. The soil depths were 25.4 cm and 50.8 cm within and 76.2 cm and 101.6 cm below the peach tree root zone. The collected soil samples were analyzed for macro and micro-nutrients including ammonium nitrogen (NH4-N (mg/kg)), nitrate nitrogen (NO3-N (mg/kg)), organic matter and soil pH. Soil analysis conducted before fertilizer application across two seasons revealed decreasing pH values with increase in soil depth, alongside consistently low organic matter levels (<2%). After fertilizer application, NH4-N was highest at the upper soil depth (25.4 cm) during initial measurements, with concentrations influenced by sampling days after transplanting (DAT), cultivar, depth, and their interactions. NO3-N varied significantly over time and depth, with notable concentrations detected below the root zone, showing complex interactions involving sampling DAT and depth in the first season, and sampling DAT, cultivar, and depth in the second season. Soil pH fluctuated over time and depth, with significant interactions between cultivar and depth in the first season, and significant variation by sampling date and depth in the second season. Chapter Three focused on evaluation of growth performance and physiological traits in young peach (Prunus persica (L.) Batsch) trees of different ripening seasons. Trees were assessed by measuring monthly plant height, leaf chlorophyll content, stomatal conductance, trunk cross-sectional area and annual leaf nitrogen analysis. ‘Rich Joy’ exhibited the greatest height, while ‘Crimson Joy’ had the largest TCSA. Stomatal conductance differed significantly among cultivars at 60 DAT in the first season, with ‘Crimson Joy’ showing significance compared to other cultivars, and ‘Liberty Joy’ showed higher SPAD values in the second season. In both seasons, foliar nitrogen concentrations were within the optimal range for all cultivars, with higher mean values observed in ‘Crimson Joy’ and ‘Liberty Joy’ in the first and second seasons respectively; however, no significant differences were detected. This study underscores the importance of integrating soil management with peach growth and physiology through sustainable practices such as precise fertilization and organic amendments to enhance nutrient retention, lower production costs, and protect the environment. This study closes with conclusions and recommendations in Chapter Four.