Development of Pelletized Bioformulation from Bacillus subtilis Using Agricultural Waste Materials and Evaluation of Its Effects on Lettuce Growth

Abstract

Currently, large amounts of chemical fertilizers are used to increase agricultural productivity, resulting in the accumulation of chemical residues in the environment and the deterioration of soil quality. Therefore, environmentally friendly bioformulations have been developed as alternative agricultural inputs. This research aimed to develop a pelletized bioformulation from Bacillus subtilis by immobilizing the bacteria on carrier materials derived from agricultural wastes, including rubberwood sawdust and finely ground corncobs. The study also investigated the properties of the bioformulation and evaluated its practical efficiency in plant cultivation using a factorial experiment in a completely randomized design (CRD). The results showed that the bacterial survival rate was 6.3 × 10⁶ cfu/g, and the optimal coating ratio of corncob-derived hydrogel was 1:1. No toxic chemical residues from any of the seven chemical groups were detected, and the cell survival rate was 46.44 ± 2.78%. In addition, the bioformulation exhibited suitable physical properties and essential nutrient contents. The bioformulation was tested on three types of lettuce, namely green leaf lettuce, romaine lettuce, and red leaf lettuce, by comparing the use of organic fertilizer alone with organic fertilizer supplemented with the bioformulation. The results demonstrated that the bioformulation significantly promoted plant growth. MANOVA and one-way ANOVA analyses revealed that plant type, fertilizer formulation, and the interaction between these two factors significantly affected shoot length and plant weight.