AGRONOMIC AND NUTRITIONAL EFFECTS OF LINZ-DONAWITZ SLAG APPLICATION TO 2 PASTURES IN NORTHERN SPAIN

Most grassland soils in western European countries are acidic in their natural state and require a liming material to bring them to their op timum pH. A study was conducted to determine whether Linz-Donawitz (LD ) slag, a by-product of the iron and steelmaking industry, could be us ed as a dolomitic agent for pastures. Six rates of slag (0, 1, 1.5, 3, 5, and 7.5 t ha(-1)), with and without fertilizer, were investigated for their effects on soil properties, pasture yield and botanical comp osition, and herbage mineral concentrations. The three-year study was conducted on a newly established pasture of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), and white clover (Tri folium repens L.), and on a resident pasture dominated by Yorkshire fo g (Holcus lanatus L.) and browntop (Agrostis tenuis Sibth.). Applicati on of slag increased soil pH (0.15 and 0.11 units per ton of slag appl ied at Derio and Abadiano, respectively) and decreased Al percentage o f the soil complex to levels not considered harmful to plant growth. E xchangeable Ca increased markedly and exchangeable Mg slightly. In gen eral, herbage Ca and Mg concentrations increased accordingly to their increase in the soil, while Fe, Mn, Cu, and Zn decreased with increasi ng rates of slag. LD slag appears to be a useful liming material for c orrecting soil acidity in pasture soils. and for increasing Ca and Mg, and decreasing Mn concentrations, in herbage.