Critical levels of potassium in soil and in coffee tree leaves

Abstract

Two field experiments were conducted, one located on a Red Dusky Latossol (RDL) in the municipality of São Sebastião do Paraíso and the other on a Yellow Red Latossol (YRL), in the municipality of Patrocínio, in the state of Minas Gerais, Brazil, with the objective of determining the response of coffee tree to K doses, critical levels for K in soil and in leaves. In both places, six-year-old coffee trees of the cultivar Catuaí Vermelho, with a plant per hole at spacing of 3.5 x 0.7m were evaluated. Four K doses were applied, corresponding to 0, 100, 200 and 400 kg/ha, as KCl. The treatments followed a randomized block design, with four replicates. Yield of processed coffee grain, soil K content (Mehlich 1) and leaf K content of the third and fourth pair of leaves of the coffee tree were evaluated over four crops (1995 to 1998) in each place. The grains yield of the coffee tree increased with K doses, attaining an optimum crop yield (OPY) of 45.3 sacks/ha with the application of 204.3 kg/ha of K. Potassium critical level in soil associated with OPY was 145.4 mg/dm3 and for leaf potassium content was 17.4 g/kg