Evaluation of Organic and Inorganic Fertilizers on the Yield of Bitter Leaf (Vernonia amygdalina) in Abia State

Bitter leaf (Vernonia amygdalina) is an economically and medicinally important indigenous vegetable crop in South East Nigeria, where it is widely consumed as a food ingredient and medicinal herb. In Abia State, smallholder farmers increasingly face the challenge of declining soil fertility, which reduces vegetable productivity. This study evaluates the effect of organic (poultry manure and compost) and inorganic (NPK 15:15:15) fertilizers on the growth and fresh leaf yield of bitter leaf in Umuahia, Abia State. Five treatment combinations were tested: control (no fertilizer), poultry manure at 5 t/ha, compost at 5 t/ha, NPK at 150 kg/ha, and a combination of poultry manure at 2.5 t/ha and NPK at 75 kg/ha. A randomized complete block design with three replications was used. Plant height, number of leaves per shoot, fresh shoot weight, and leaf area were measured at four-week intervals. Results show that the combined application of poultry manure and NPK produced the highest fresh yield and leaf area index, outperforming either input used alone. The study recommends integrated soil fertility management combining poultry manure and reduced-rate NPK fertilizer for bitter leaf production in Abia State. Keywords: bitter leaf, Vernonia amygdalina, organic fertilizer, NPK fertilizer, Abia State