The fermentation of (usually chopped-up) agricultural vegetation in order to preserve it. It is carried out for 1-2 weeks, using either indigenous microorganisms (e.g., Lactobacillus spp.) or introduced microorganisms (to speed up the process, yield product containing more nutrients for livestock, etc.), in the absence of oxygen (to prevent the growth of aerobic mold fungi). When indigenous microorganisms are used, Lactobacillus spp. become the dominant microorganisms present, and heat is generated by the microorganisms within the vegetative mass (optimum temperature is 25-30°C, which is 77-86°F). Lactic acid is produced by the microorganisms, which inhibits the growth of bacteria that would normally putrefy the vegetation.