THE EFFECTS OF SURFACE-APPLIED CALCIUM ON SOIL AND MATURE SPARTAN APPLE-TREES

In 1975, hydrated lime and CaSO4 were applied to a Rutland gravelly sandy loam under the canopy of mature apple trees (M. domestica Borkh. ''Spartan'') on M16 at 3000, 6000, 3 .times. 2000 and at 3000, 6000, 3 .times. 4000 kg/ha, respectively. pH and exchangeable Ca, Mg and Mn were measured in the soil sampled in 1979 at 10-cm intervals to a 60-cm depth for each of the check, 6000 kg/ha Ca(OH)2 and 12,000 kg/ha gypsum treatments. The acidity of the surface soil was decreased significantly in the 6000 kg/ha Ca(OH)2 treatment. Negligible soil Ca accumulation occurred below the surface 10-cm depth for any treatment. Soil Mn was decreased from the surface to the 20-cm level in the Ca(OH)2 treatment while soil Mg was decreased from the surface to the 30-cm level in the gypsum treatment. Fruit Ca concentration at harvest, 1975-1979 was not increased by soil Ca treatments. Leaf Mg was often reduced by soil gypsum applications in excess of 3000 kg/ha. Leaf Mn reduction did not occur until the 4th and 5th yr of the experiment in the 6000 and the 3 .times. 2000 kg/ha Ca(OH)2 treatments.