Movement of Calcium and Magnesium in Ultisols from Dolomitic Limestone
1984
Messick, D. L. | Alley, M. M. | Zelazny, L. W.
Root growth and crop yield are limited on many soils by acid subsoil and toxic concentrations of Al and Mn, and deficiencies of Ca and Mg. Calcium and magnesium movement and neutralization of acidity below the zone of limestone incorporation were investigated on seven acid Virginia soils. Dolomitic limestone treatments of 0, 4.5, 9.0, and 13.4 Mg ha⁻¹ on the Coastal Plains and 0, 4.5, 9.0, 13.4, and 18.0 Mg ha⁻¹ on Piedmont and Valley soils were surface-applied and incorporated (0–20 cm). Four years after limestone application, soil samples were collected at depth increments of 0 to 10, 10 to 20, 20 to 25, 25 to 30, 30 to 40, 40 to 50, and 50 to 60 cm. Samples were analyzed for exchangeable Ca, Mg, and Al, and pH. Calcium and magnesium movement and depth of neutralization decreased with increasing soil clay content. Liming increased cation retention in horizons that received direct lime application apparently due to increased pH-dependent CEC. Depth of neutralization was lime rate dependent with greater neutralization of acidity at higher limestone rates. Magnesium movement was detected at greater depths than Ca in all soils, but neutralization of acidity did not accompany movement of either Ca or Mg. This demonstrated that the cation moved as a neutral salt or that pH change was not measurable.
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