Short-term effects of wood ash on the soil and the lignin concentration and growth of Pinus sylvestris L.

Short-term effects of different doses of wood-ash application (0.25 kg m−2; 0.5 kg m−2; control without treatment) on soil chemical properties, tree growth and lignin concentration was investigated in a young Scots pine (Pinus sylvestris) forest stand in northern Estonia from 2000 until 2003. Changes in the soil upper horizon (30 cm) showed an increase of pH and concentration of available K, Ca and P and a decrease of N after treatment. Later, from the second year after treatment, a decrease of P was found if compared to the control. The changes in the Mg concentration were very small at the beginning of the experiments, but an increase in the Mg concentration in soil was established a year after the treatment. Statistically significant stimulation of lignification in shoots was found after wood-ash treatment, but the pattern of seasonal changes in the rate of lignin concentration in needles and shoots was similar to control. It was found that the increase of Klason lignin as a result of wood-ash application correlated negatively with N and positively with K, Mg and Ca in soil. The diameter increment of pines had a negative correlation with lignin concentrations in shoots and needles. The increment of stem biomass, diameter and height was stimulated, but not significantly, by the wood-ash dose of 0.25 kg m−2.