HIGH TEMPERATURE COMPOSTING OF CATTLE FEEDLOT MANURE KILLS WEED SEED

Abstract

The temperature and exposure period required to kill seed of johnsongrass, (Sorghum halepense); pigweed,(mixture of Amaranthus sp. primarily hybridus and Palmeri); kochia, (Kochia scoparia (L.) Schrad); barnyardgrass,(Echinochloa crus-galli (L.) Beauv); sorghum, (Sorghum bicolor L. Moench DeKalb 42Y), and field bindweed,(Convolvulus arvensis L.) buried in compost during laboratory experiments or compost manufacturing process wasdetermined. When buried in compost, seed of all species except field bindweed were killed with three days or more exposureat 49C (120F). It required seven days of exposure at 83C (180F) to kill all field bindweed seed in compost. In dry air,rather than compost, all species survived 60C (140F) for 30 days. All seed except field bindweed were killed in dry air by72C (160F) for three days. It took seven days of exposure at 83C (180F) to reduce viability of field bindweed from about30 to 7% in dry air. At 83C (180F) viability was reduced only to 5% with 30-day exposure. Seed of all species except fieldbindweed were killed in a three-day composting process where temperature was maintained at 72C (160F) or higher. Fieldbindweed seed were killed with a 12-day exposure in an outside storage pile of compost. Compost manufactured at thislocation is probably free of viable weed seed and would be suitable for lawns, nurseries, and agricultural land.