Effects of temperature and dairy cattle excreta characteristics on potential ammonia and greenhouse gas emissions from housing: a laboratory study.

摘要

Dairy cattle housing is a significant source of NH 3 and GHG emissions to atmosphere. However, the climate, temperature in particular, and the characteristics of the excreta of the housed cattle, may have a strong influence on the magnitude of such emissions. The objectives were to assess the effects of temperature and excreta characteristics of heifers, dry cows and lactating cows on potential NH 3, N 2O, CO 2 and CH 4 emissions. The experiment was conducted using laboratory chambers where constant amounts of urine and faeces were applied to a concrete floor. Potential NH 3 and GHG emissions were measured over 120-h following application at 5, 15, 25 and 35degreesC. Increasing temperature promoted a significant increase in NH 3 emissions. At temperatures 鈮?5degreesC, total NH 3 emissions accounted for more than 100% of the urea-N content of the urine for the three dairy cattle types, indicating that other organic N compounds of urine and faeces are an important source of NH 3. The cumulative amount of N 2O released did not vary significantly with temperature and ranged from 1 to 2% of total N deposited. Cumulative CO 2 emissions were ca. 14-58% of total C deposited and the cumulative CH 4 emissions were significantly higher at 25degreesC than at all other temperatures. It was concluded that increasing temperature from 5 to 35degreesC significantly increased potential NH 3, CO 2 and CH 4 emissions but did not significantly influence N 2O emissions. Also, the diet supplied to lactating cows led to significantly higher NH 3, N 2O and CO 2 emissions relative to heifers and dry cows.