Use of carbonate rock and microorganisms as alternative phosphorus supply

Phosphorus (P) fixation reactions in tropical soils are among the main limitations for agriculture, requiring amounts of fertilizers above those required by crops. As P sources are exhaustible and this is an essential element, the search for sustainable strategies for its supply becomes essential. Thus, we evaluated the application of carbonatite rock powder (PR) combined with single superphosphate (SS) associated with inoculation with microorganisms, in the initial development of the corn crop. The experiment was carried out in a greenhouse, under a 6 x 4 factorial scheme, as follows: Six forms of phosphate fertilization (0% P; 100% SS and PR; three proportional combinations of SS+PR), and four inoculations (Ceratobasidium sp.; Tulasnella sp.; Mix of Bacillus megaterium + Bacillus subtilis; no inoculant). The combinations of 75% SS + 25% PR and 50% SS + 50% PR provided increments of up to 87% of dry aerial biomass compared to the control, and 49% with the use of SS alone. The use of PR can be an alternative to reduce soluble sources of P in the initial fertilization of the corn crop. All inoculants, when applied without phosphate fertilization, were efficient to maintain the initial development of corn in a no-tillage soil.