An apparatus, method and system for applying a biologically active or chemical substance to a relatively large volume harvested or pre-harvested crop includes relatively small container of a mixture biologically active or chemical substance and water in fluid communication with fluid conduit. A pump moves mixture from the bottle through the conduit. A source of pressurized air is in fluid communication with the conduit to aerate the mixture. The aerated mixture is expelled through a nozzle at distal end of the conduit. In one aspect, the controller can monitor speed of the pump by monitoring operating voltage of the pump. Speed of the pump can be adjusted to adjust application rate. In one aspect, a process combines a flow of air through an orifice with the metering of a low volume of additive, such as an aid to preservation, to a crop as it is being cut or harvested to provide for even distribution of the additive to the crop.