Productivity of onion (Allium cepa L.) as influenced by composted poultry manure and fishpond waste in an aquaponics-based food system

Abstract

Sustainable intensification of food production with aquaponics-based food systems requires conscious efforts of soil amelioration with the rich organic outflows to realize the closed nature of such integrated systems. This study assessed the effects of composted poultry manure and fishpond waste on the growth and yield of onion (Allium cepa L.) for sustainable production by smallholder farmers. A randomized complete block design on-station study was conducted in an aquaponics-based system at the CSIR-Crops Research Institute, Kumasi, in the 2016 minor season. The onion cultivar “Boko red” was grown under three treatments; 0 application (absolute control), 12 t/ha composted poultry manure, and 6 t/ha composted poultry manure plus 25 l/hill of pond water derived based on the crop nutrient requirements. Growth parameters (plant height and the number of leaves) were taken weekly from four weeks after transplanting, as well as yield parameters (total dry matter and total bulb weight). Among the treatments, the highest mean yield (25381 kg/ha) was attained with composted poultry manure and pond water combined. This shows the potential usage of organic waste as alternate sources of fertilizers for vegetable production, in integrated aquaculture systems. Organic waste such as poultry manure, droppings of small ruminants, fishpond waste, crop residues etc., are freely and abundantly available in integrated aquaculture systems, and can substitute inorganic fertilizers with considerably benefit to farmers by increasing yield.