A method and apparatus are provided for applying preservative to agricultural crops during baling. More particularly, a baler has a preservative application system and a crop moisture sensor array. The crop moisture sensor array is in communication with the preservative application system so that the application of preservative to the crop can be controlled in response to a moisture content sensed by the crop moisture sensor array that exceeds both a moisture content threshold value and a threshold value relating to the percentage of crop material having a moisture content above the moisture content threshold value.