Application of industrial wastes as soil amendment and fertilizers is now a common practice in agriculture. The effect of application of converter sludge, along with organic matter (alfalfa powder), elemental sulfur and sulfuric acid to 3 calcareous soils from central Iran was investigated in an incubation study. Converter sludge used contained 64% iron oxides. Treatments included 0, 2 and 4% pure converter sludge and mixed with organic matter and acidifiers. Results showed that application of 4% pure converter sludge increased soil pH and decreased soil Electrical conductivity (EC) but using a mixture of converter sludge with organic matter or acidifying materials (elemental S and sulfuric acid) decreased soil pH and increased EC. Olsen-P was least affected by the treatments. Application of mixtures of converter sludge with organic matter elemental S and sulfuric acid significantly increased DTPA-extractable Fe and Mn in all 3 calcareous soils with organic matter having the largest effect on DTPA-extractable Fe and elemental S, organic matter and sulfuric acid mixtures having similar effect on DTPA-extractable Mn. Olsen-P and DTPA-extractable Fe and Mn decreased with incubation time for all 3 soils. The rate of decrease was highest for Fe and lowest for P and was different for each soil.
Key words: Calcareous soil, converter sludge, organic matter, elemental sulfur, sulfuric acid.
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