The method of preparation of carbamide containing biocomposite fertilizer with the increase water resistance, including the impregnation of a support from aspen bark by urea water solution and the subsequent deposition of the urea nitrate, was proposed. The influence of conditions of a biocomposite fertilizer obtaining on its resistance to nitrogen leaching by water was studied. It was shown that the urea transformation to nitrate form on a support surface allow decrease nitrogen leaching from biocomposite fertilizer in average twice.