Use of compost and phosphate-solubilizing bacteria affect sugarcane mineral nutrition, phosphorus availability, and the soil bacterial community

The appropriate utilization of phosphorus (P) for fertilization of sugarcane is critical to reduce the economic costs and the environmental impact caused by traditional management practices. Phosphate-solubilizing bacteria (PSB) play an essential role in P cycling and in the P transfer to the plant, thus increasing crop productivity. The goal of this study was to evaluate soil P lability and plant mineral nutrition, as well as changes in the soil bacterial community upon the use of alternative P sources and inoculation with PSB. Different P sources were evaluated, including compost of sugarcane industry wastes, rock phosphate, and triple superphosphate (TSP). Additionally, we carried out soil P fractionations to study its availability. The use of compost as a P source and co-inoculation with Bacillus sp. BACBR04, Bacillus sp. BACBR06, and Rhizobium sp. RIZBR01 increased the content of P in shoot compared with the uninoculated treatments that received only compost or TSP (i.e. soluble P). This treatment also displayed an increase of nitrogen and potassium content in plant tissue. The increase in P content correlated with an increment in soil P availability, as well as with changes in the soil bacterial community and the predicted presence of the phytase gene. These results present a potential new strategy for sugarcane fertilization, using PSB in combination with compost to improve P nutrition and growth in sugarcane with reduced economic and environmental impact.