The Influence of Potassium on the Yield and Sucrose Content of Sugarcane

Abstract

The results of over 200 field experiments with potash fertilizers on sugarcane conducted by the Agricultural Experiment Station of the University of Puerto Rico over a wide range of cane varieties and soils of Puerto Rico were analyzed with respect to the influence of the potash on cane yields and sucrose content. The results indicated that potash increased yields mainly on the red and yellow podzolic soils of the humid area and in a planosal of the semi-arid area. The irrigated cane areas showed slight if any response to potash. The use of potash increased sucrose concentrations in the cane only if cane yields were also increased. Increases of 10% or more in cane tonnage were needed for increases in sucrose. When potassium fertilizer significantly influenced sucrose concentration, this was accomplished mainly by raising the polarization value of the cane juice. Percent Brix and extraction were not appreciably influenced. The use of foliar diagnosis proved to be of great value in determining when to apply potash fertilizers to cane. Leaf values of 2.00% or more on a dry-weight basis indicated no expected potash responses for all soils and cane varieties in Puerto Rico. In humid areas, leaf values below 1.80% indicated that a response to potash fertilizers could be expected.