Effects of different fertilizer rates on the growth and yield of soybean

Abstract

The experiment was carried out during the 2024 cropping season at the Teaching and Research Farm of Akwa Ibom State University, Obio Akpa, located in Oruk Anam Local Government Area of Akwa Ibom State, Nigeria. To evaluate the effect of different rates of poultry manure on growth performance, yield and proximate composition of soybean.Randomized Complete Block Design (RCBD) was used, arranged in a split-plot with three replications. The main plot treatments consisted of eight soybean varieties, namely Sc-Sentinel, Sc-Signal, TGX 1448-2E, TGX 20103-01F, TGX 1951-13F, TGX 2020-4E, Sc-SOL1, and TGX 1951-4, while the subplot treatments comprised poultry manure fertilizer applied at 0, 1, 2, and 3 t/ha. Data on growth indices, yield, and proximate seed composition were collected and analyzed using analysis of variance (ANOVA). Significant means were separated using the Least Significant Difference (LSD) at 5% probability level. Results revealed notable varietal differences in vegetative growth, especially leaf area development. Variety Sc-Signal gave the largest leaf areas values at 3 and 4 weeks after planting, recording 49.45, 58.13, 78.67, and 86.43 cm². TGX 2020-4E also recorded large leaf areas with the values of 47.11, 54.60, 74.90, and 82.33 cm² across the same growth stages. In contrast, Sc-Sentinel consistently produced the smallest leaf areas, ranging from 37.89 to 69.41 cm². Yield performance followed a similar trend. Sc-Signal produced the highest seed yield (2.627 t/ha), closely followed by TGX 2020-4E (2.505 t/ha). The lowest yield was observed in Sc-Sentinel with 1.873 t/ha. Poultry manure aplication significantly enhanced productivity, with 3 t/ha poultry manure yielding 2.704 t/ha, though this was not statistically different from the 2 t/ha application (2.699 t/ha). The control treatment, which received no fertilization, yielded only 0.936 t/ha. The study concluded that Sc-Signal and TGX 2020-4E are superior varieties for cultivation under the study conditions, and the application of 2 t/ha poultry manure is optimal for maximizing soybean yield.