AbstractVariable liming and heavy fertilization of a Cialitos clay (ultisol) over a 7-year period markedly affected soil properties and yields of subsequently planted sugarcane. A total of 3,680 pounds of N, 480 pounds of P, and 2,870 pounds of K had been applied per acre to all plots over this period. Cane yields increased from less than 1 ton per acre, when no lime had been applied, to over 40 tons when a total of 20 tons of limestone had been applied per acre over the previous 7-year period. Yields increased with increasing exchangeable base content in the upper 6 inches of soil from less than 10 tons per acre when exchangeable bases dropped below 3 meq., to over 40 tons when exchangeable bases exceeded 8 meq./l00 g. of soil (58-percent base saturation). Cane yields increased with decreasing exchangeable Al from less than 10 tons, when exchangeable Al exceeded 8 meq., to over 40 when exchange able Al was less than 2 meq./100 g. of soil. Yields increased with increasing soil pH, but the presence of free salts in this heavily fertilized soil made pH an unreliable criterion for determining the need for liming. Applying 8 tons of limestone per acre to the surface of a very acid Cialitos clay before planting increased cane yields from an average of 12.4 to 34.5 tons per acre, and decreased exchangeable Al from 7.3 to 0.5 meq. per 100 g. of soil. The foliar composition at 9 months of age, and the sucrose content of the sugarcane were not affected by the soil factors studied, or by lime applications, and remained unchanged, at satisfactory levels, in plots yielding from almost 0 to over 40 tons of cane per acre. A survey showed that in many sugarcane soils of the Humid Region exchangeable aluminum exceeded levels that depressed cane yields on Cialitos clay in this experiment.
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