DEVELOPMENT OF A NEW, MORE ADEQUATE METHOD FOR THE

DETERMINATION OF SOIL ACIDITY

Imre VAGO1, Imre CZINKOTA2, Mark REKASI3, Marianna SIPOS1*, Attila KOVACS2, Laszlo TOLNER2

1University of Debrecen, Faculty of Agricultural and Food Sciences and Environmental Management,

Department of Agricultural Chemistry and Soil Science, Debrecen, Hungary

2University Szent István, Faculty of Agricultural and Environmental Sciences, Department of Soil Science

and Agricultural Chemistry, Gödöllő, Hungary

3Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences,

Budapest, Hungary

ABSTRACT. Soil acidification is a relevant problem in Hungary – just as in other parts of the world. Liming and remediation of acidic soils are essential regarding both environmental and agricultural concerns. The nowadays most applied liming material determination method is not exact enough and does not reflect enough the quality and quantity of different soil acidity forms. The main reason for that is, that with the used hydrolytic acidity measurement method only the amount of protons that are set in rapid reactions till the equation point can be titrated. With the new elaborated „pH-stat” method we measure the amount of KOH and time needed to reach the standard pH-value 6.5 with a longer titration. The enlarged reaction time enables protons, bound on fine inner pores of soils, to dissociate. By the analysis of titration curves the actual and the potential soil acidity can be differentiated. Our measurement results make a more exact calculation of the need amount of liming material possible. The experiments carried out in three sites of acidic soils with maize plants showed that the present Hungarian liming recommendation system results lime overdose that is unnecessary and partly harmful.

Keywords: soil acidity, slow titration, “pH-stat”