A field study was conducted to evaluate the combined effects of poultry manure (PM) and NPK 15:15:15 fertilizer on soil properties, growth and yield of Celosia argentea L. in the rainforest region of Southern Nigeria. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. The treatments consisted of three rates of NPK (0, 150, 300 kg/ha) and three rates of poultry manure (PM) (0, 8, 16 t/ha) applied in combination, resulting in nine levels of fertilizer. Celosia was harvested 8 weeks after planting (WAP). Results indicated that the combined application of PM and NPK significantly (P < 0.05) enhanced soil chemical properties after harvesting Celosia argentae. The highest rates (16 t/ha PM + 300 kg/ha NPK) increased soil organic carbon (22.57 g/kg), total nitrogen (0.85 g/kg), available phosphorus (25.38 mg/kg), and exchangeable bases (K, Ca, Mg, Na) compared to the control. Plant growth and yield were also significantly (P < 0.05) improved. The combination of 16 t/ha PM + 300 kg/ha NPK resulted in the highest plant height (74.83 cm at 8 weeks after planting, WAP) and the highest marketable yield of 4.98 t/ha. While the number of leaves and stem girth showed less consistent significant (P < 0.05) differences, the overall trend favored the combined fertilizer rates. The study concludes that the combined application of PM (16 t/ha) and NPK (300 kg/ha) is highly effective in improving soil fertility and enhancing the productivity of Celosia argentea, offering a sustainable alternative to sole mineral fertilization.
Edmond et al. (2026) studied this question.