Immobilization of microbial inoculants for improving soil nutrient bioavailability

As an eco-friendly alternative to chemicals used in agriculture, plant growth-promoting bacteria (PGPB), either isolated or in consortia, have been used as inoculants (as a practice for bioaugmentation) to enhance plant mechanisms, such as nitrogen fixation, growth hormone production, and phosphorus solubilization, which aid in the capture and assimilation of nutrients. To increase the efficiency of microbial inoculants in situ, immobilization strategies are carried out on different carriers from biological matrices, such as chitosan, alginate, zeolites, and agar. Microbial immobilization is an effective approach that mainly provides suitable microenvironment conditions, high biomass, and protection against external damages caused by stressful soil environments. This chapter reports the current advances in microbial inoculant immobilization in different materials to improve crop productivity. The increasing number of bioinoculants for agricultural use endorses the need for the development of new formulations for the sustainable management of successful field applications.