Use of LD (Linz-Donawitz) Slag as a Liming Material in the Basque Country (Spain): Effect on Chemical Composition of Pastures

LD (Lintz-Donawit:i:) slag is an iron industry by-product generated at a rate of 10 million I/year in Europe. Its chemical composition (45% Cao and 8% Mg2O) seemed to indicate that a good way of re­utilisation of this waste would be Its use as a corrector of pH for acid soils. The slag effect on chemical composition and yield has been studied in grasslands in the Basque Country during a 2-year field trial. Two different pastures have been considered, Derio (pH 4.75), a resown loliwn pere1me-Trifoli11m repens pasture, and Abadiano (pH 5.45), a natural prairie. Previous studies have shown that slag addition increases pasture yield on very acid soils (Derio), significantly increases soil pH and decreases exchangeable aluminium, This work addresses how chemical composition was affected. When the level of applied slag increased so did the herbage content of Ca and Mg. Mn concentrations in herbage decreased when LD slag doses were higher, although at Derio the large Mn amounts added (LD slag 3.4%) caused toxicity problems the first year due to low pH. Fe variation was less clear but decreased from year to year and from high rates to low rates.