Effects of HCl acid and lime amendments on soil pH and extractable Ca and Mg in a sandy soil
Shuman, L.M.; Boswell, F.C.; Ohki, K.; Parker, M.B.; Wilson, D.O.
Communications in Soil Science and Plant Analysis 14(6): 481-495
The response of a coarse-textured soil to lime and HCl was examined in a field experiment where Mn treatments on soybeans were the primary objective. Three treatments included HCl, control and lime. Acid (742 liters/ha of 3N HCl) was added at the beginning of the experiment, while dolomitic lime treatments were added each year (2240, 2740 and 2900 kg/ha). The lime and acid were applied to the soil surface and incorporated to a depth of 10 to 13 cm. Soil samples were taken every 2 to 3 months at 3 depths (0-15, 15-30 and 30-45 cm) and analyzed for pH and extractable Ca and Mg. Acid treatment decreased the pH by 0.2 units at the 0 to 30 cm depth, an effect which lasted throughout the 3 year study. The pH of the surface soil was little affected by lime in the first year, but rose to a peak of 7.2 after the second lime treatment, before falling to initial levels. Calcium values were lowered only slightly by the acid treatment, while lime additions caused steady increases in soil Ca. Magnesium values increased several months after each of the first and second lime applications, and decreased in the acid treatments after the first year. Lime raised the subsoil (30 to 45 cm) pH after 4 to 6 months. Seasonal variations in pH were very wide, with the untreated soil pH varying from 6.1 to 6.8. The high pH level of 7.0 was not maintained for an entire season until the third year of the experiment.