Development of multifunctional biofertilizer formulation from indigenous microorganisms and evaluation of their N2-fixing capabilities on chinese cabbage using 15N tracer technique

Biofertilizer is an alternative to chemical fertilizers to increase soil fertility and crop production in sustainable farming. Most biofertilizer products consist of a single function micro-organism such as N2 fixing bacteria. This paper discusses the development of multifunctional biofertilizer products, based on indigenous micro-organisms that have all the desired characteristics, including plant growth promoting, phosphate solubilising and antagonistic towards pathogens, and optimisation of the micro-organisms present in the modified "Natural Farming" compost. Composting through the "Natural Farming" method is a simple and cheap method to turn empty fruit bunches (EFB) of oil palm into compost. Indigenous micro-organisms in each stage of composting were isolated and screened for the abilities to solubilise phosphate and produce indole-3-acetic acid (IAA). These indigenous micro-organisms were developed into biofertilizer products. Effects of these products on plant growth of Chinese cabbage and contribution of N2 to the plants were evaluated using the 15N isotopic tracer technique in a greenhouse trial. Fertilizer treatment using a combination of microbial strains (T7) was found to significantly enhance the growth of Chinese cabbage. All the plants receiving biofertilizer microorganisms showed N2-fixing effects as compared to the control (T9). The isolated indigenous micro-organisms may enhance plant growth through N2 fixation, solubilising insoluble inorganic phosphate compounds or hydrolyse organic phosphate to inorganic P or stimulation of plant growth through hormonal action such as produce IAA. Combination of microbial strains could be a good multifunctional biofertilizer for sustainable agriculture