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Abstract
Ground limestone (CaCO3) was applied at 0, 25, 50, 75, or 100 g/9.5-liter pot using a 1 peat : 1 perlite : 1 vermiculite (by volume) medium having an initial pH of 4.52 and an electrical conductivity (EC) of 0.2 dS·m–1. Muskmelon (Cucumis melo var. reticulatus) were grown for 56 days in the medium that had been fertilized. Irrigations were applied as the crop grew, with the levels used consisting of 0%, 20%, 40%, or 60% in excess of the amount required to bring all pots to saturation. The water had a pH of 7.44 to 7.95 and an EC from 1.5 to 1.8 dS·m–1. Measurements were taken at each irrigation. Leachate pH increased with increasing rate of limestone application, but the rate of increase with increasing limestone rate declined, with maximum benefit occurring at 75 g/pot. Irrigtation level did not affect leachate pH, which indicates a buffering capacity of the medium that was not readily diluted. Increasing limestone application decreased leachate EC, which suggests retention of the salts from the irrigation water. This retention resulted in a net accumulation of salts in the medium that could not be completely offset by the increased leaching produced as irrigation levels increased.