Agricultural Development in Tropical Acidic Soils: Potential and Limits of Phosphate-Solubilizing Bacteria

Abstract

Acidic soils of the tropical regions of the world represent the largest pool of potential land for future agriculture development. Unfortunately, most are poorly fertile due to a combination of factors including soil acidity, high aluminum concentration, and extremely low availability of soluble forms of phosphorus (P). The potential use of P-solubilizing bacteria (PSB) as biofertilizers represents one of the most attractive and cost-effective measures for increasing crop productivity in acidic soils. PSB are natural colonizers of the rhizosphere, able to mobilize P efficiently from the soil inorganic pool, mainly by producing and excreting organic acids. Therefore, an enormous amount of work has been conducted towards the isolation, identification, and characterization of thousands of PSB. Although the ability of PSB to promote plant growth has been demonstrated in vitro and in the greenhouse, results of field tests have been rather discouraging. Besides, few studies have been conducted in acidic soils. Thus, much remains to be done to fully exploit the enormous potential of PSB for crop production improvement in acidic soils.