the primary goal in harvesting and ensiling a crop is to preserve as nearly as possible the quantity and quality of the crop at the time of cutting.Crops are typically placed in a silo at moisture concentrations at which plant enzymes are still active and a wide variety of microorganisms can grow. As a result,preservation of the crop in the silo depends on maintaining both an anaerobic environment and a sufficiently low pH. The anaerobic environment inhibits aerobic spoilage microorganisms and provides the conditions for a natural lactic acid bacterial fermentation of sugars to lactic acid and other products. this fermentation lowers crop pH in order to reduce plant enzyme activity and prevent the growth of undesirable anaerobic bacteria