Effects of temperature and dairy cattle excreta characteristics on potential ammonia and greenhouse gas emissions from housing: A laboratory study
2012
Pereira Uzal, José Manuel | Misselbrook, Tom H. | Chadwick, David R. | Coutinho, Joao | Trindade, Henrique
Dairy cattle housing is a significant source of NH₃ 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 NH₃, N₂O, CO₂ and CH₄ emissions. The experiment was conducted using laboratory chambers where constant amounts of urine and faeces were applied to a concrete floor. Potential NH₃ and GHG emissions were measured over 120-h following application at 5, 15, 25 and 35 °C. Increasing temperature promoted a significant increase in NH₃ emissions. At temperatures ≥15 °C, total NH₃ 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 NH₃. The cumulative amount of N₂O released did not vary significantly with temperature and ranged from 1 to 2% of total N deposited. Cumulative CO₂ emissions were ca. 14–58% of total C deposited and the cumulative CH₄ emissions were significantly higher at 25 °C than at all other temperatures. It was concluded that increasing temperature from 5 to 35 °C significantly increased potential NH₃, CO₂ and CH₄ emissions but did not significantly influence N₂O emissions. Also, the diet supplied to lactating cows led to significantly higher NH₃, N₂O and CO₂ emissions relative to heifers and dry cows.
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