Carbon, Nitrogen Balances and Greenhouse Gas Emission during Cattle Feedlot Manure Composting
- Xiying Hao *,
- Chi Chang and
- Francis J. Larney
Carbon and N losses reduce the agronomic value of compost and contribute to greenhouse gas (GHG) emissions. This study investigated GHG emissions during composting of straw-bedded manure (SBM) and wood chip-bedded manure (WBM). For SBM, dry matter (DM) loss was 301 kg Mg−1, total carbon (TC) loss was 174 kg Mg−1, and total nitrogen (TN) loss was 8.3 kg Mg−1 These correspond to 30.1% of initial DM, 52.8% of initial TC, and 41.6% of initial TN. For WBM, DM loss was 268 kg Mg−1, TC loss was 154 kg Mg−1, and TN loss was 1.40 kg Mg−1, corresponding to 26.5, 34.5, and 11.8% of initial amounts. Most C was lost as CO2 with CH4 accounting for <6%. However, the net contribution to greenhouse gas emissions was greater for CH4 since it is 21 times more effective at trapping heat than CO2 Nitrous oxide (N2O) emissions were 0.077 kg N Mg−1 for SBM and 0.084 kg N Mg−1 for WBM, accounting for 1 to 6% of total N loss. Total GHG emissions as CO2–C equivalent were not significantly different between SBM (368.4 ± 18.5 kg Mg−1) and WBM (349.2 ± 24.3 kg Mg−1). However, emission of 368.4 kg C Mg−1 (CO2–C equivalent) was greater than the initial TC content (330.5 kg Mg−1) of SBM, raising the question of the net benefits of composting on C sequestration. Further study is needed to evaluate the impact of composting on overall GHG emissions and C sequestration and to fully investigate livestock manure management options.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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