The effect of fertilization on early growth of konara oak and Japanese zelkova seedlings planted in a harvested pitch pine plantation

We determined a suitable amount of fertilizer for konara oak (Quercus serrata) and Japanese zelkova (Zelkova serrata) planted in a harvested pitch pine (Pinus rigida) plantation. Two-year-old bare-root seedlings of konara oak and one-year-old containerized seedlings of Japanese zelkova were planted in April 2011. Three plots were established for each tree species to evaluate each of three fertilization applications. Solid compound fertilizer (N:P:K = 3:4:1) was applied yearly in three amounts (control: no fertilization, F1: 180 kg ha⁻¹, and F2: 360 kg ha⁻¹), every May from 2011 to 2013. We measured the root collar diameter and height, and analyzed the compartmental N and P concentrations. Compartmental N concentrations of konara oak and Japanese zelkova were not consistent based on amount of fertilization. However, the compartmental P concentrations of konara oak and Japanese zelkova were significantly different in the order of F2, F1, and control. Although the differences in growth of konara oak appeared after 3 years of fertilization, Japanese zelkova showed differences after only 2 years of fertilization owing to differences in seedling type. Growth of konara oak was affected by fertilization at F1 and F2 in 2013. However, growth of Japanese zelkova was affected only at F2. Nutrient demand of Japanese zelkova appeard to be higher than that of konara oak, at least during the early growing period. Results from this study could be practically used in harvested pitch pine plantations to determine appropriate fertilization regimes.