Nutrient Uptake in Fertilized Plantations of American Sycamore

Abstract

AbstractAnnual applications of ammonium nitrate (169 kg/ha elemental N), alone and in combination with concentrated superphosphate (112 kg/ha elemental P), increased biomass of 4‐ and 5‐year‐old American sycamore (Platanus occidentalis L.) by approximately 45 and 205% on a bottomland and a terrace site, respectively, in the Ohio River Valley region of western Kentucky. Growth response and nutrient contents of trees fertilized with N and P were not significantly different from those receiving N only. After 5 years, N fertilization has increased elemental content of aboveground tree components by 189% for N, 48% for P, 90% for K, 93% for Ca, and 106% for Mg. Initial spacing of the seedlings in these closely‐spaced (0.3 by 0.9 m, 0.9 by 0.9 m, 1.8 by 0.9 m) trials did not have a significant effect on nutrient contents. Recovery of added N, as indicated by increased above ground tree contents after 5 years, represented 11 and 14% of the quantity added in fertilizer applications on the bottomland and terrace, respectively. After 5 years, levels of available P in soils receiving annual P fertilization had increased by 140 kg/ha, representing about 25% of the total P added. After 5 years exchangeable Ca had decreased in the bottomland soils and exchangeable K, Ca, and Mg had decreased in the less fertile terrace soil.