There is a decline in crop yield per unit area of land in the sub-Saharan countries leading to threat to food security. This is mainly because of land degradation, climate variability and socioeconomic condition of smallholder farmers. To curb the decline in soil productivity and enhance crop yield, combination of both old and new technologies is been advocated. In this regard a field trial was conducted in 2016 and 2017 to evaluate the effect of poultry manure, Organic NPK® (compost) and NPK fertilizer under soybeans-sorghum mixed cropping. The experiment consisted of three (3) levels of poultry manure (0, 2.0 and 3.5) t/ha, three (3) levels of compost manure (0, 0.2 and 0.4) t/ha and three (3) levels of NPK (0, 30 and 60) KgN/ha. Soybeans was intercropped with sorghum as a nitrogen fixer in selected plots. The experiment was laid in Randomised Complete Block Design and replicated three (3) times. Sole applications of compost manure at 0.4 t/ha had. Soybean as nutrient source marginally enhanced organic matter and nutrients content in the soil. Poultry manure retains the highest concentration of organic matter and nutrients in the soil compared to compost and NPK fertilizer. Higher yields were obtained from application of NPK fertilizer this was however, not sustainable because of depletion in soil organic matter and nutrients content. The incorporation of Nitrogen enhancing cultivars in cropping programmes and use of manure to reduce the quantity of mineral fertilizers is recommended.
Keywords: NPK, Organic manures, Organic NPK®, soil pH, organic matter