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
the degree to which crop quantity and quality is preserved in the silo is affected by the crop, the harvesting process , weather during harvest, and silo management. Once the farmer makes a decision to harvest a crop. the crop's characterisitics primarily determine the resources for a satisfactory fermentation in the silo. however, those resources can be modified by harvest and ensiling management and weather conditions during harvest. Exposure of the crop to air during storage i mainly a factor of silo management, including how well and how rapidly the silo is filled, how well the silo is sealed, maintenance of the seal during storage, and the manner and rate of silage removal from the silo.
Even if one gets a satisfactory fermentation and does an excellent job of keeping the crop anaerobic , substantial losses of nutrients may still occur. Soluble nutrients may be lost in silage juice that seep from the base of silo. Silage effluent and its characteristics are a function of the crop's moisture concentration and how the crop is chopped and ensiled