Reusing Coffee Processing Wastewater and Human Urine as a Nutrient Source: Effect on Cabbage Cultivation

Abstract

Coffee processing wastewater (CPWW) and human urine (HU) are among the high volume and nutrient-rich wastes which can be recycled to increase crop/vegetable productivity. The aim of this study was to evaluate the fertilizing potential of the mixture of these wastes on cabbage cultivation and compare the effect of the optimum mixture with a synthetic fertilizer. Nine triplicate treatments: T0 (rainwater), T1 (CPWW), a blend of HU and CPWW in different ratios as T2 (1:1), T3 (1:2), T4 (1:3), T5 (2:1), T6 (3:1), T7 (urine only) and T8 (4 g Urea + 10 g NPK (19:19:19)) were laid as completely randomized design in a greenhouse with triplicates. It was found that the weight of cabbage head under T3, T4, and T8 were 1.79 ± 0.15, 1.42 ± 0.09, and 1.88 ± 0.10, respectively. A significant difference was observed for the height (F = 21.56, p = 0.00005), area of leaves (F = 8.38, p = 0.0002), circumference (F = 14.22, p = 0.00008), and weight (F = 10.69, p = 0.00005) of cabbage under T3 (1:2 ratio of HU and CPWW treatment) with most of the other combinations. However, the growth and yield parameters under T3 were comparable to the treatment that received the synthetic fertilizer. About 60% of the variation in yield (as the fresh weight of cabbage) among the treatments can be explained by the variation in the nutrient and pH in fertilizer application of which phosphorus was the main factor (50%). Generally, T3 was the optimum combination that could substitute the effect of synthetic fertilizer for cabbage cultivation after careful investigation of its effect on soil characteristics.