The invention relates to a solid inoculum carried in a superabsorbent agro-pellet with a variable volume, operating in a natural mini fermenter preloaded with an anhydrous nutritive medium, encouraging rapid regrowth of the viable micro-organisms and the continuous multiplication thereof. The liquid inoculum incorporated into the carrier at a low density of microbial cells is preferably comprised between 1/500e and 1/10e of the density recommended by the norm for a liquid inoculum of the same strain. The bioaugmentation of the microbial population is between 104 and 106 additional microbial cells. The solid inoculum according to the invention allows the preservation of the microorganisms and the handling thereof in advantageous conditions. It is not exposed to soil leaching caused by water. Said inoculum is used for the biological treatment of crops for the development and/or the preservation thereof from parasite attacks.
