Improving productivity of arabica coffee genotype G1 through potassium fertilization

Abstract

Abstract One of the determinants of coffee productivity is the availability of nutrients in the soil, with potassium being among the essential nutrients required to enhance productivity. Therefore, this study aimed to determine the optimal potassium fertilizer dosage needed to increase the productivity of Arabica coffee plants of the G1 genotype. This study was conducted in the experimental garden of Syiah Kuala University in Bener Meriah Regency, Aceh Province, Indonesia using a Non-Factorial Randomized Block Design (RBD). A total of 132 Arabica coffee trees of genotype G1 were randomly selected based on specific criteria, such as 8 years of age, planted with a spacing of 2.5 x 2.5 m, pruned properly, grown under moderately dense shade of Leucaena trees, and well-maintained. The treatments included a control group without potassium fertilizer and multiple groups receiving potassium fertilizers at 29, 58, 87, 116, and 145 kg K2O per hectare. These potassium sources were derived from potassium chloride (KCl) fertilizer containing 58% K2O and Rice Husk Ash containing 2% K2O, respectively. This resulted in 11 treatment units, each comprising 3 coffee trees replicated 4 times, for a total of 44 treatment units. The results showed that potassium fertilization from KCl and Rice Husk Ash had a significant effect on the increased productivity of Arabica coffee genotype G1. The effect was observed based on the number of productive branches per tree, clusters per branch, fruits per cluster, fruits per tree, the weight of red cherries per tree, parchment coffee per tree, green beans per tree, and the green beans yield at 14% moisture content. The optimal potassium fertilizer dosage was 145 kg K2O per hectare, equivalent to 250 kg KCl or 156.25 g KCl per tree. Additionally, it was observed that potassium sourced from KCl was more effective than potassium from Rice Husk Ash due to the longer time the latter takes to improve the productivity of Arabica coffee.