CONVENTIONAL AND SUSPENSION LIMESTONE INFLUENCE ON SOIL CHEMICAL-PROPERTIES AND CORN AND SOYBEAN YIELDS

Conventional and suspension limestone materials prepared from identical limestone rock were evaluated to compare their reaction rates for neutralizing soil acidity. Measurement of the limestone materials influence on 5N NH4OAc extractable Ca and Mg and N KCl exchangeable Al, soil pH, and crop yields were utilized to study reaction rates. Field plots were established on a Goldsboro sandy loam (Aquic Paleudults) and an Emporia loamy sand (Typic Hapludults) in the Coastal Plain region. Corn was the indicator crop for the Goldsboro soil, while soybeans were grown on the Emporia soil. Treatments ranged 0-13.94 and 0-4.48 metric tons/ha on the Goldsboro and Emporia soils, respectively. Initially, extractable soil Ca and Mg increased and exchangeable Al decreased more rapidly with suspension limestone applications than with conventional treatments. Regardless of material lime rates of 2.24 metric tons/ha and greater increased surface soil pH 2 wk after limestone application on both soils. Sixteen weeks after lime treatment, increases in extractable Ca and Mg and soil pH, and decreases in exchangeable Al were approximately equal for both materials. Yield responses varied with lime treatments at both locations.