COMPARATIVE STUDIES OF THE EFFICIENCY OF LIME REFUSE FROM SUGAR BEET FACTORIES AS AN AGRICULTURAL LIMING MATERIAL

Lime refuse from several sugar beet extraction factories was used in a field assay to study its behaviour as an amendment material for an acid soil (plinthic Palexerult). A finely pulverized dolomitic lime was used as a reference. A total of 6.3 t/ha of dolomitic lime and 7.4 t/ha of sugar factory lime scum were employed. Two years after its incorporation into the soil the effects of the lime scum on the change cations were similar to those caused by the dolomitic lime. Throughout six years and six crops it was observed how, in the plots amended with lime refuse, a slightly higher pH was maintained than that measured in the plots without lime, and with fewer fluctuations. Once the maximum pH value was reached in the treated plots, the rate of the pH decline was similar to the acidification process undergone by the soil in the con- trol plots and fitted the regression: pHw = - 0.000435* daa + 6.93 where daa are the days after the application of the amendment. The recycling of sugar beet factory lime refuse as a liming material for acid soils was seen to be a valuable and efficient alternative to traditional limes and dolomites.