Growth Response of Container-grown Pin Oak and Japanese Maple Seedlings to Sulfur Fertilization

Abstract

Sulfur (S) is essential to the growth of higher plants; however, research on S fertilizer requirements for container-grown nursery tree species has not been established. The purpose of this study was to determine the substrate solution S concentration that maximizes the growth of container-grown pin oak ( Quercus palustris Münchh) (pin oak–K 2 SO 4 experiment) and japanese maple ( Acer palmatum Thunb.) (japanese maple–K 2 SO 4 experiment) in a pine bark (PB) substrate. Both species were fertilized with solutions supplying a range of S concentrations (0, 1, 2, 5, 10, 20, 40, or 80 mg·L –1 ) using K 2 SO 4 . Regression analysis revealed that dry weights of both species were near maximum at the predicted application concentration of 30 mg·L –1 S, which corresponded to about 15 and 7 mg·L –1 S in substrate solution for pin oak and japanese maple, respectively. In a Micromax, FeSO 4 , lime experiment, S was supplied to pin oak via a preplant micronutrient sulfate fertilizer or FeSO 4 in limed or unlimed PB. When the PB pH was relatively low (4.5, unlimed), FeSO 4 and the preplant micronutrient fertilizer were effective in supplying ample S. However, when the PB pH was relatively high (6.1, limed), the preplant micronutrient fertilizer with micronutrients in a sulfate form was more effective in supplying S and micronutrients than FeSO 4 .