Effect of Organic Matter and Moisture Level on Extractable Soil Manganese

Abstract

Studies on the optimum amounts of plant residue additives, incubation time, and moisture level for maximum release of extractable Mn were performed with four soil types using greenhouse and controlled environment facilities. Addition of decomposing ryegrass or alfalfa residues to flooded soils significantly increased extractable Mn in three of the four soil types, but no effect was obtained with any soil having a low moisture content. Organic matter decomposition and flooding tended to shift soil pH toward neutrality, lessening the effect of pH on the release of extractable Mn.