NOVELTY - Method (M1) of on-farm processing a biomass feedstock into useful industrial chemicals, involves delignifying biomass feedstock to produce a delignified biomass; subjecting delignified biomass to cellulase production; subjecting delignified biomass with cellulase to simultaneous cellulolytic and solventogenic reaction to produce a fermentation broth including useful industrial chemicals and fermentation residues; and collecting and separating useful industrial chemicals from fermentation broth.    USE - For on-farm processing a biomass feedstock into useful industrial chemicals (claimed).    ADVANTAGE - The method integrates well into the existing agricultural paradigm and brings greater profitability to the farmers that grow the biomass material. The method produces useful petrochemical replacements and creates jobs in rural areas. The method includes percolating water or media through the biomass feedstock as it is undergoing cellulolytic and solventogenic reactions, which removes fermentation products and maintains favorable growth conditions for the reaction. The different anaerobic microorganisms are used to complete the cellulase production to perform the cellulolytic reaction and the solventogenic reaction. Thus, effectiveness and efficiency of each reaction can be optimized for optimal processing results. The lignolytic reaction is completed in the same vessel as the simultaneous cellulolytic and the solventogenic reactions. The biomass is not physically processed, after harvesting prior to loading into the reactor. Since the biomass doesn't need to be cut and reduced in size, energy input has been reduced and loading the reactor has been simplified. The present method does not use a liquid fermentation system, where the biomass is suspended in liquid and remains in suspension by stirring. It uses a solid-substrate fermentation system, where the biomass remains fixed in place and water/media is percolated over the biomass. This approach also differs from prior art in that the biomass is not sterilized at any time during the process. Traditionally biomass is sterilized before or after pretreatment-another energy intensive process. by separating the cellulase production and solventogenic reactions into separate steps the best possible microorganisms for each reaction may be selected and the best possible conditions for those microorganisms may be provided to maximize the processing efficiency and produce the maximum amount of the desired industrial product in the shortest possible period of time. The sequential repeating of the (1) delignification, (2) cellulase production and (3) subsequent cellulolytic reaction and solventogenic reaction steps serves to progressively degrade the baled biomass from the outside into the center and the necessity of particle size reduction before treatment is eliminated, allowing the process to use baled biomass saving energy and reactor loading time.