Improvement in the physical quality of genotype G1 arabica coffee beans as a result of applying rice husk ash and KCl fertilizer

Abstract

Arabica Gayo coffee has earned global acclaim for its exceptional flavor profile. Its exports primarily consist of green coffee beans, making the physical quality a crucial criterion. Several factors are considered in assessing the physical quality of coffee beans, including shape (normal, single, and damaged) beans as well as size. Therefore, this study aimed to find out the improvement in the genotype G1 arabica coffee beans physical quality through the potassium from rice husk ash and KCI fertilizer. A total of 132 genotype G1 arabica coffee were selected randomly with specific criteria including eight years of age, a 2.5 m x 2.5 m planting distance, well-pruned, grown under shade from lamtoro trees with slightly dense density, and adequately maintained. Moreover, a non-factorial randomized block design was used. The treatments comprised a control, and the potassium application at doses of 29, 58, 87, 116, and 145 kg K2O ha-1 from KCl fertilizer (containing 58% K2O) and rice husk ash (containing 2% K2O), totaling 11 treatment units. Each unit was replicated four times and consisted of three coffee trees, resulting in a total of 132. The research results showed that the potassium fertilizer application from both KCl and rice husk ash increased the 100 beans weight (water content 14-18%), the normal beans percentage, single beans, small and medium beans size, but can reduce the damaged beans percentage and large beans size. The application of 250 kg ha-1 KCl, equivalent to 156.25 g of KCl per coffee trees was found to be the best potassium fertilizer dose for improving all the quality variables of genotype G1 Arabica coffee beans.