In Portugal, chestnut wood demand has increased in the last decades. Since chestnut plantations are usually established in low fertility soils, addition of N, P and K as fertilizers usually have a benefic effect in increasing wood productivity. The study aims to evaluate the effects of fertilization on growth of chestnut tree (Castanea sativa Mill.) cultivated for wood purposes. An experimental essay was established in a 3-year old chestnut tree stand with a planting spacing of 3.5 × 3.0 m. Four treatments were applied to randomized blocks with three repetitions: control (C), addition of phosphorus (P), addition of phosphorus and potassium (PK) and addition of nitrogen, phosphorus, and potassium (NPK). The chemical properties of the soil and the concentration of nutrients in the leaves were evaluated after the treatment, and measurements of tree diameter and stem height were made for a monitoring period of 4 years. Treatments did not affect soil properties or leaf nutrient concentrations. On the counterpart, the effect of the fertilizers was noticed for tree dimensions and growth. Gains of NPK in relation to the control were observed for the height variable, over the years. Seven years after application of the treatments, differences were also noticed for the diameter and the volume index variables. The NPK treatment has presented a significant effect on tree growth compared to the control, with noticeable gains in the stem height.
Nitrogen; Phosphorus; Potassium fertilizers; Tree growth