Effects of Soil pH, Phosphorus Rates, Deep Tillage Practices, and Clay Additions on Peach Tree Performance in Deep Sandy Soils of North Carolina

Abstract

Abstract Effects of soil pH, tillage practices, P application, and the addition of clay at the planting site on tree size, fruit yield, fruit size, and tree longevity of peaches [Prunus persica (L.) Batsch] for 20 growing seasons are reported. Because of widespread tree death, ‘Loring’ trees were removed after 9 years and the orchard replanted to ‘Winblo’. Soil pH below 5.6 resulted in poor tree growth, low fruit yield, and small fruit size compared to trees grown in soils at higher pH. In the final 10 years of the experiment, marked improvement in tree size, fruit yield, fruit size, and longevity were evident as soil pH increased. The effect of 3 tillage practices—normal plow to a depth of 20 cm, normal plow to a depth of 20 cm plus a 75-cm-diameter ⨯ 122-cm-deep hole at the planting site, and deep plowing to a depth of 58 cm—varied with cultivar. Both methods of soil profile modification (which penetrated the A2 horizon) resulted in increased yield and tree size compared to normal plowing to 20 cm with ‘Loring’ during the first 9 years. During the final 10 years, fruit yield was lower and tree death greater in the deep-plow plots, but there were no differences in fruit yield, tree size, or tree longevity between the other tillage treatments. Phosphorus rates (0, 15, and 30 kg/ha annually) or clay additions did not influence tree size, fruit yield, or tree survival. Results of this study lend strong support for the maintenance of soil pH above 5.6 and good evidence that increase in tree growth, fruit yield, and tree longevity is further enhanced when soil pH is maintained above 6.0.