It is important for CNG farmers to have an adequate buffer to protect their fields from potential sources of contamination. The appropriate size of the buffer depends on the context, including factors like prevailing wind patterns, the elevation and slope of the land, and what the neighboring land uses are. Typically, we look for a minimum distance of 20 feet to crops like a fertilized hayfield, field corn and soybeans, while a buffer of 50 feet is required for crops such as sweet corn. A buffer may need to be somewhat larger if for example the growing area is located downhill or downwind, or it may need to be quite a bit larger if you are located next to crops that are sprayed aerially.