Comparison of effects of different vermicompost types on growth, nodule formation, and yield response of soybean

While there is a general understanding of the benefits of vermicompost, more specific research is needed to compare the effects of various feedstock-derived vermicompost on soybean growth, nodule formation, and yield response. An experiment was conducted in a glasshouse at the College of Agriculture, Hawassa University in 2023 to evaluate the effect of different types of vermicompost on the growth, nodule formation, yield related parameters and yield of soybean. Twelve vermicompost types, along with a control, were arranged in a completely randomized block design with six replications. Three replications were used for destructive sampling, while the remaining replications were used for yield and related parameters. The soybean variety Nyala, released by the Hawassa Agricultural Research Center in 2014, was used for the study. Results indicated that regardless of the type of vermicompost used, its application significantly improved the growth and yield and related parameters of soybean compared to plants without vermicompost. Vermicompost from different sources increased the leaf area per plant by 7 to 62% compared to those without vermicompost. Among the vermicompost types used, the one prepared from common bean straw + coffee husk resulted in the highest aboveground biomass and grain yield, surpassing plants without vermicompost by 28% and 60%, respectively. Overall, the various vermicompost types used increased aboveground biomass and grain yield per plant in a range of 5% to 30% and 18% to 60%, respectively, compared to the control. On the other hand, root nodule number per plant, effective nodule per plant, fresh, and dry weight were significantly reduced under vermicompost application compared to the control. Based on the grain yield results, it is advisable to use vermicompost made from a mixture of common bean straw and coffee husk for optimal soybean growth and yield. Conducting field experiments across various locations is essential to provide a solid recommendation.