APPLICATION OF LIME AND WOOD ASH TO DECREASE ACIDIFICATION OF FOREST SOILS

Liming and wood ash application are measures to decrease acidification of forests soils. The assessment of lime requirement can be based on that base saturation which indicates a low risk of acid toxicity. Beca use of a wide spread Mg deficiency in Central European forests, Mg con taining lime is normally applied. Ash from untreated wood is applied t o decrease soil acidity as well as to improve K and P nutrition. In wo od ash, K is the most soluble nutrient, follwed by Ca and Mg. The over all dissolution rate of lime applied to the forest floor is about It h a(-1) a(-1). After liming, soil solution alkalinity and Mg concentrati ons increase markedly, while changes of Ca, H ions and Al concentratio ns are less pronounced. After the application of wood ash, K concentra tions increase due to the high K content and the high solubility of K in wood ash, After the application of a sufficiently high dosage of li me to the forest floor, the decrease of acidity in deeper soil layers may need decades because of the low solubility of lime. Nitrification and nitrate leaching induced by lime or wood ash may reduce their acid buffering efficiency.