Abstract

Nutrients are essential for plant growth and development, and soil nutrient ratios play key roles in coffee quality. The objective of this study was to investigate the influence of soil nutrient ratios on the quality of wild Arabica coffee in Ethiopia. Results revealed that the balance between the soil nutrients was well correlated with coffee quality attributes. The balance between magnesium and calcium (Mg:Ca) and the balance between nitrogen and phosphorus (N:P) were found to be very important factors for bean size. Increase in Ca relative to Mg increased bean size, and vice versa. The higher the concentration of available P in relation to soil organic carbon (P:C) or total N (P:N), the better the cup quality of the coffee, and vice versa. The Mg:K ratio, P:N ratio, P:C ratio and P:Zn ratio were very important factors for cup quality. Although the ratio between Mg and K was important for cup quality, it was not apparent for bean size. The ratio between Ca and Mg was of no or little importance for coffee cup quality as opposed to that of bean size. Therefore, coffee growers should make careful decisions depending on the demands of the buyers/consumers and environmental requirements.

Key words: Arabica coffee, bean size, cup quality, coffee forest, nutrient ratios.