Effect of N and NPK fertilizers on early field performance of narrow-leaved ash, Fraxinus angustifolia.

The effect of fertilization in the first growing season on early survival and growth of narrow-leaved ash (NLA) (Fraxinus angustifolia ssp. oxycarpa) was evaluated throughout the first 3 years of growth in Adapazari, Turkey. A randomized complete block design with four replications was established to investigate fertilization effects. Granular N urea [46%, (NH2)2CO, NH2-N] and NPK (15/15/15%; NH3-N, P2O5, K2O) fertilizers were applied in mid-May of the first growing season. Fertilization treatments per tree were control, 67 g NPK (equal to 10/10/10 g N/P2O5 /K2O tree(-1)), 133 g NPK (20/20/20 g N/P2O5 /K2O tree(-1)), 33 g urea N (15 g N tree(-1)) and 54 g urea N (25 g N tree(-1)). After three growing seasons under these fertilizer treatments, 98% of trees were still viable. Compared to the control treatment, fertilization had a large and positive effect on diameter and height growth during the first 3 years of growth. However, since there were no significant differences among the fertilized plots in terms of tree diameter and height growth, addition of P and K to the fertilizer regime was not beneficial. The results show that N fertilization in the first growing season has the potential to improve early field growth of narrow-leaved ash.