Cheese whey (60 000 mg COD I-I) was applied at a rate of 20 l/m(2) (4 lbs/ft(2)) to growing alfalfa (Fortress variety) on silt loam calcareous soil. Selected sites were covered with a collection tent to collect gases generated. Large amounts of carbon monoxide (>535 ppm) and relatively small amounts of methane (less than or equal to 37 . 1 ppm) were emitted from the soil. These results indicate a concern for whey disposal on agricultural ground and the resultant production of CO.