Two field experiments were conducted on two experimental EPAMIG Farms (Minas Gerias State), in order to evaluate the nutritional coffee status by the nutritional balance index (NBI) supplied by DRIS in response to potassium fertilization. The experimental design was a split plot scheme of randomized blocks, carried out on a Red Latosol distroferric (RLdf) of São Sebastião do Paraíso and a Yellow Red Latosol distrofic (YRLd) of Patrocínio. Three K sources were applied in the plots: potassium chloride (KCl), potassium sulfate (K2SO4), and potassium nitrate (KNO3), and four K doses (0, 100, 200, and 400 kg ha-1) in the subplots, with four repetitions. Yield and leaf nutrient contents were observed from 1995 to 1998 for the calculation of DRIS for a diagnosis of the nutritional state of the coffee plant, and of the grain quality (measured by polyphenyloxidase enzyme activity). The response to potassium fertilization was consistently evaluated by the nutritional state diagnosis of the coffee tree with DRIS, as grain yields were more intensely influenced by the nutrient excess of the applied sources than the coffee beverage quality.
coffee; potassium; source; dose; yield; quality; NBI
