Comparison of methods for soil acidity measurement in Nyirlugos (Hungary) long-term field expriment

摘要

Soil acidification and the amelioration of acidic soils is a world wide problem. Acid soils occupy approximately 30% of the world's ice free land area. The knowledge of the exact value of soil acidity is important because of lime requirement estimation, thus the amelioration and protection of soils. In Hungary and in some other countries the CaCO_3 amount needed to ameliorate acid soils is calculated by considering their hydrolytic acidity (y1). In the measurement suggested by Kappen (1929) the acidity of the equilibrium solution of the soil's Ca-acetate extract is quantified. The amount of acidity titrated in the equilibrium solution depends on the acidity of the soil and on the suspension pH. To determine the total releasable surface acidity the soil must be continuously percolated or the soil/extractant ratio must be changed. For the elimination of this principle error of Kappen's method the soil acidity can be determined by the pH-stat titration of the soil suspension. Our results show that thenew method can characterise quantitatively soil acidity thus it can give the basis for the lime requirement calculation.