Response of Granulated Polyhalite on Yield and Quality of Coffee (Coffea arabica)

Potassium (K), magnesium (Mg), calcium (Ca) and sulfur (S) are necessary for coffee production. To supply coffee requirements, approximately 50% of Colombian coffee growers use bulk blends of fertilizers. However, the fertilizer sources available are few and are usually not compatible with other granulated sources, causing low fertilization efficiency. To evaluate the effect of granulated polyhalite (GPoly4), a multimineral source of K, Mg, Ca and S, on coffee yield and coffee quality, an experiment was carried out on Colombian coffee growing in the experimental soil Typic Melanudand, containing 0.40, 0.50 and 0.40 cmol(P+) kg?1 of K, Ca, and Mg, respectively. The response of six treatments viz. NPK-GPoly4, NPK-CaNO3- CaSO4-MgO, NPK-MgSO4, NPK-CaNO3-MgSO4, NPK-CaNO3-MgO, and NPK (control), on yield and coffee quality were studied. Applications of NPK-GPoly4 and its nutritional equivalent, using NPK-CaNO3-MgO, increased coffee cherry yield. The nutrient content in coffee leaves and soil explained the results. The coffee bean had good quality, and the quality parameters of the coffee drink i.e. acidity, body and balance were much improved than the desired levels in all of the treatments. According to the results, GPoly4 must be considered as an alternate source to supply K, Ca, Mg and S to coffee in Colombia.