Advances in formulation development technologies

Abstract

The increasing need for environmentally friendly agricultural applications is motivating the use of fertilizers based on beneficial microorganisms called biofertilizers. These biofertilizers could be defined as formulations containing one or more beneficial and efficient microbial strains (or species) loaded on economically safe and easy-to-use carrier material. Productions of biofertilizers require integration of physical, chemical, and biological parameters to increase the populations and survival of these microorganisms. The most common biofertilizers are nitrogen fixers; phosphate solubilizers; potassium mobilizers; sulfur oxidizers; Pseudomonas fluorescens, which is known as the most common plant-growth-promoting rhizobacteria (PGPR); and mycorrhizae. Productions of efficient biofertilizers require selection of good microbial strain(s), selection of good carrier, and using a suitable formulation process. Selected strains must be effective and competitive against soil indigenous populations. Good carriers must be characterized by their ability to deliver the right number of viable cells in good physiological condition and at the right time. The formulation process refers to the laboratory or industrial process for unifying the carrier with the bacterial strain. There are different formulation technologies that were utilized during the last decades at which four basic dispersal types from microbial inoculant were produced (powder, granule, slurry, and liquid). High-quality microbial inoculants should meet farmers' and manufacturers' requirements, which include the following: contains large population of one or several strains; has consistent and reproducible efficacy under different field conditions; free from significant contamination and opportunistic pathogens for humans, animals, and plants; has an extended shelf life and resistance to mishandling by the farmers.