Aquaculture systems generate large amounts of waste, which may constitute a lucrative alternative for horticultural crop fertigation. With the ever-increasing global water scarcity, dual use of water for crop and fish production has the potential to optimize water use, dispose of aquaculture wastes, provide additional nutrients to crops, and reduce inorganic fertilizer usage. Therefore, the need to increase sustainable food production and match the food security demands under climate change impacts generates the force for developing circular water-energy-nutrient systems of integrated aqua-agriculture. In the light of this, a recirculating aquaponics system has been established at the Aquaculture Research and Development Centre, in Uganda to investigate the effect of fish effluent on growth performance and yield of crops.
This greenhouse study was conducted to determine the effects of fish effluents on the growth performance and yield of tomatoes (Anja F1). Approximately 120 seedlings were transplanted in potting bags and placed 50cm apart. These comprised of three treatments in triplicate, the control with tomatoes irrigated with underground water, one receiving water from Nile Tilapia tanks and another from African catfish tanks. One-way ANOVA test was conducted to identify the significant differences amongst the treatment means, and Tukey’s HSD test was used to determine the source of variation. Results showed that tomatoes yields recorded a significant difference between the treatment means; irrigation of Anja F1 tomato variety with C. gariepinus effluent significantly (P< 0.05) increased the yield with respect to clusters per plant, number of fruits per cluster and number of fruits per plant. This research underscores the urgent need for adaptive management strategies to mitigate the adverse effects of using organic fertilizers. Therefore, the use of Clarias gariepinus effluent can be a viable alternative for smallholder farmers, for whom inorganic fertilizers are often expensive to afford or inaccessible.