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

Imre Vágo *, László Tolner **, Imre Czinkota **, Márk Rékási *** and Imre Kádár ***

*Faculty of Agricultural Science, University of Debrecen, Böszörményi Street 138, H-4032, Hungary, Email: vago@agr.unideb.hu

**Faculty of Agriculture and Environmental Sciences, Szent István University, Gödöllő, Páter K. Street 1, Hungary, E-mail: Tolner.Laszlo@gmail.com, Imre.Czinkota@gmail.com

***Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Budapest, Herman Otto Street 15. E-mail: Rekasi@rissac.hu, kadar@rissac.hu

Abstract: 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 CaCO3 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 the new method can characterise quantitatively soil acidity thus it can give the basis for the lime requirement calculation.

Key Words: Soil acidity, slow titration, brown forest soil, long-term field experiment