Influence of wood ash on soil chemical composition and biochemical parameters of young Scots pine

Short-term effects of different doses (0.25 and 0.5 kg m) of wood ash fertilization in a field experiment in a 20-year-old Scots pine stand on a nutrient-poor sandy soil (Arenosol) was studied in North Estonia. Soil chemical properties, nutrient accumulation, soluble carbohydrates, starch, hemicellulose, cellulose, and lignin were used as biochemical indicators for the assessment of the state of trees from 2000 until 2005. Changes in the soil upper horizon (30 cm) showed an increase in the pH and in the concentrations of K, Ca, B, Mg, and other elements, except N, after treatment. Statistical relationships were found between the doses of wood ash used in the treatment and the mineral composition of the soil. Changes in soil properties brought about changes in nutrient accumulation into trees and the needle diagnosis showed an essential increase in the K, Mg, Fe, Mn, and Zn concentrations in needles. No statistically significant changes were observed in the concentrations of soluble carbohydrate (tendency to decrease), starch (tendency to increase), and structural carbohydrates, but a somewhat higher accumulation of cellulose and lignin was registered in the needles of Scots pine. The effect of wood ash on carbohydrate metabolism and lignin synthesis seemed to depend on the seasonal development stage of needles and climatic conditions.