Respiration in broiler litter slurry that was surface applied to soil was examined for the purpose of determining the feasibility of enriching closed crop canopies with carbon dioxide. An estimated flux density of 1.11g CO2 m(-2) h(-1) was calculated to be required from a ground source to obtain a maximum average increase in photosynthate of 23% for C-3 plants. Litter as received from the farm, was stored at 24 degrees C for 72 days in a closed container (approximating conditions for deep stack storage). The stored litter was made into a slurry and stored at 24 degrees C in a closed container for 23 days (approximating conditions in a manure storage pond). When stored slurry, inoculated 10% by volume with fresh litter slurry aged for seven days, was applied to soil at the rate of 0.13 ml cm(-2) (12,890 l ha(-1)) an average flux density of 5.32 g CO2 m(-2) h(-1) was measured.