Alternative sources of potassium in coffee plants for better soil fertility, productivity, and beverage quality

Fontes alternativas de potássio em cafeeiros para melhoria da fertilidade do solo, da produtividade e da qualidade de bebida

Abstract:

The objective of this work was to evaluate alternative sources of potassium for improving soil fertility and coffee productivity and beverage quality. The experiment was conducted in a coffee (Coffea arabica) crop, planted in an Oxisol area, in the municipality of Patrocínio, in the state of Minas Gerais, Brazil. The treatments consisted of the K sources TK47 and Super Greensand (SG) - both based on glauconite silicate mineral -, at the following doses: 0 kg ha^-1 K₂O (control); 42, 84, 168, and 336 kg ha^-1 K₂O from TK47; 618 kg ha^-1 K₂O from KCl; and 168 kg ha^-1 K₂O from SG. A randomized complete block design was used, with four replicates in each treatment. The experimental units consisted of three rows with ten plants each, using the eight central plants as the useful plot. Potassium fertilization with TK47 increased soil fertility, correcting soil acidity and elevating K⁺, P, and Ca²⁺ contents, effective cation exchange capacity, and Zn²⁺ and Fe²⁺ levels in the soil. Fertilization with 336 kg ha^-1 K₂O from TK47, in a single dose, provides grain yield and polyphenol oxidase activity similar to those of fertilization with 618 kg ha^-1 K₂O from KCl, in a split-dose, but a better sensory analysis of the resultant beverage.

Index terms:
Coffea arabica; alternative fertilizers; coffee mineral nutrition; glauconite; potassium gradual solubilization; residual effect