Organic amendment composition and sowing depth in coffee Arabica: Effects on seedling growth biometrics

Abstract

There is a significant production of coffee in the Gedeo zone, southern Ethiopia, which has could generate a huge amount of coffee husk wastes that have polluted the environment. However, organically enriching the soil is an effective method to enhance the development and productivity of coffee. Thus, this study aims to understand the effects of the interaction between sowing depth and organic amending practices. Three sowing depths and sixteen different organic amendment compositions were tested in a complete randomized design with three replications. Coffee seedling growth biometrics was measured, and R-program was used to calculate the statistical difference at a 5 % significance level. The organic amendment composition with 3:2:1 (topsoil: forest soil: sand) sown at a depth of 2 cm had statistically higher values of seedling stem height, leaf length, and taproot length by 82.82 %, 93.35 %, and 85.41 % than in the topsoil at a depth of 3 cm. Likewise, the main effect of organic amendment with 3:2:1 (topsoil: forest soil: sand) in internode length, number of nodes per seedling stem, number of true leaves per seedling, and leaf width were also higher by 70.42 %, 63.16 %, 92.23 % and 91.80 % than seedlings grown in topsoil solely. Interestingly, the days of 50 % emergence in 3:2:1 (ratio of topsoil: forest soil: sand) organic amendment composition were earlier by 62.11 days than using topsoil. This could be because of the accessibility of a significant quantity of organic carbon, primary macronutrients, alkaline nature of the growth media in addition to having low bulk and particle densities in the forest soil that could increase coffee seedling growth biometrics by improving soil porosity, aeration and nutrient uptake capacity, producing important soil microbes and neutralizing organic acids in comparison with the topsoil.