Noble strains of rhizobium have been commercially available for agricultural production over the past few decades. These elite rhizobia, however, are often not as successful under adverse edaphic conditions as native strains, primarily due to low tolerance to desiccation. To date, peat has been extensively used as a microbial (rhizobial) carrier material on a large scale to improve and increase the viability of rhizobia. Apart from its global use as a prime carrier material for inoculants, there are multiple issues regarding its use as a microbial carrier. For instance, current peat-based rhizobial inoculants may not provide the strain with sufficient moisture to survive for an extended period under drought conditions. In addition, it is non-renewable, and its production is restricted to only a few areas of the world. It also has a high extraction cost and economically is not cheap. Alternatively, some attempts have been made to find other affordable, locally available in bulk quantity and eco-friendly materials that could be used as the appropriate carrier materials of rhizobia. Hereinto, biochar and biopolymer materials have gained global attraction due to their ease of local availability, ecofriendly nature, and excellent physicochemical characteristics. However, the research in this aspect is still in its infancy and most studies have been conducted outside Australia. For this PhD project, a number of research questions were investigated: a) which types of biochar made from different feedstock will be suitable as rhizobial carrier materials and what are the main reasons for the enhancement of rhizobial growth and survival inside them; b) how different pyrolysis temperature of biochar will affect their various properties leading to a good performance of biochar-based inoculant; c) how different biopolymers as additives in biochar-based inoculant will improve the behavior of materials as rhizobial carriers and what is the best formulation of them; d) how novel superabsorbent biopolymers/biochar inoculant could be created with addition of organic nutrients (mulch hay and eggshells) for excellent rhizobial performance. [...]