there is a little more to it than that, lol but yes the molasses is feeding simple micro organisms in the soil. The simple micobes have a very short half life, and are in turn eaten by more complex microbes. Creating a mini eco system. However, these micro organisms do not feed the roots. Plants can not absorb nutrients directly from the soil, they must be chelated first. This is accomplished by mycorrhizal fungi. But myco are not among the microbes created by using molasses.