This document specifies a method for the determination of the lime requirement of acid soils to target pH levels at requested time of maintenance as determined by reaction with 0,1 mol/l ammonium acetate pH 5,5. Due to general soil buffering systems, the method is applicable to all soils which are acid enough to dissociate hydrogen ions from the soil colloid system to depress the pH of the buffer solution. NOTE 1 – The method originates from research in Canada and Norway, see [1] and [2]. NOTE 2 – Annex A gives regression equations to predict the maintenance of a range of pH levels at different times after liming in mineral and organic soils in Europe.