AbstractThe fertility requirements of high-yielding, intensively managed sungrown coffee growing under favorable climatic conditions in the Mountain Region of Puerto Rico were studied. About 3,000 pounds of market coffee per acre yearly wore produced when fertilization was adequate. Coffee responded strongly to the apnlinf of 300 pounds of nitrogen and 300 pounds of potassium per acre yearly, in three equal applications. Leaf-nitrogen and -potassium contents of 25 to 3.0 percent were associated with high yields. Coffee did not respond to phosphorus or magnesium applications. The effects of liming on yields and foliar composition of heavily fertilized, high-yielding, sun-grown coffee and on soil condition were determined in experiments at two locations in the Mountain Region of Puerto Rico. Soil types on which liming is likely to be especially critical were studied by analyzing soil samples obtained throughout the Mountain Region. Liming had no significant effect on yields of coffee on either Alonso clay near Adjuntas or Los Guineos clay near Jayuya. Liming increased the calcium content and decreased the manganese content, but had no effect on the N, P, K, or Mg content of the coffee leaves. Liming increased soil pH and exchangeable-base content and sharply decreased the exchangeable-aluminum content of both soils. Both soils had a very low, easily reducible manganese content. Severe symptoms of manganese toxicity in intensively managed coffee plantations on soils with a high manganese content were corrected by liming. The soils of the Coffee Region of Puerto Rico fall into three groups as to likelihood of manganese toxicity becoming a problem with intensively managed coffee: Soils low in easily reducible manganese where toxicity of this element is not a problem; soils high in easily reducible manganese, but high in bases and low in acidity where toxicity of this element is not an immediate problem; and acid soils high in easy reducible manganese where toxicity of this element is likely to be an immediate and serious problem.
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