Effect of Soil Management and Calcium Nitrate Fertilization on the Availability of Soil Nitrate and Cations in an Eastern Apple Orchard

Abstract

Abstract Four annual applications of Ca(NO3)2 were made to ‘Golden Delicious’ and ‘Delicious’ apple trees beginning in the second leaf at rates of 0.5 to 8 times the recommended rate (45 g/tree per year of age) in each of three soil management systems: cultivated, herbicide, and mowed sod. Soil samples were collected in Mar. and July 1983 (fifth leaf) to a 120-cm depth at the tree drip line. July samples were analyzed for available Ca, Mg, K, Mn, percentage of base saturation, NO3-N, and soil pH (0.01 m CaCl2); March samples only for NO3-N. The sod system had the highest soil pH, Ca level, and percentage of base saturation; the herbicide had the lowest, and the cultivated treatment was intermediate. The rate of Ca(NO3)2 had no measurable effect on these values except in the surface pH levels (030 cm), where sod was unaffected but the cultivated and herbicide systems had a significant reduction in pH with increasing levels of Ca(NO3)2. Soil Mn availability and leaf Mn increased with increasing Ca(NO3)2 levels in association with the decreasing pH levels. Available soil Mg and leaf Mg decreased with increasing Ca(NO3)2 due to Ca displacement of soil Mg on the cation exchange complex. Leaf Ca was unaffected by Ca(NO3)2 rate or the soil management system. During the growing season (Mar.-July 1983), the herbicide system accumulated significantly more of the applied Ca(NO3)2 than the cultivated or sod systems. No yield response and minimal leaf NO3 response suggested differences in NO3 accumulation were due to variation in leaching due to the soil management systems.