INFLUENCE OF ALTERNATE FREEZING AND THAWING ON THE AVAILABILITY OF SOME SOIL MINERALS

Abstract

Twenty-gram portions of Tilly soil of three particle sizes (< 1.68 mm, < 0.250 mm, and < 0.149 mm) were placed in flasks and incubated for over periods of one, three and six weeks at water contents of 80 and 200% of field moisture capacity. They were either frozen and thawed once or repeatedly frozen and thawed. The recycling of freezing and thawing under flooded conditions increased the exchangeable manganese and iron of the soil but decreased the amount of exchangeable calcium and potassium. Increasing the soil moisture content increased the availability of soil manganese and iron. The solubility of potassium and calcium, however, was not affected by soil moisture. In all instances, the availability of certain soil minerals increased with decreasing soil particle size. Significant interactions between moisture level, particle size and freezing and thawing treatments on the mineralization of nutrient elements in the soil is also discussed.