Abstract
Manure application to land and deposition of urine and dung by grazing animals are major sources of ammonia (NH3 ) and nitrous oxide (N2 O) emissions. Using data on NH3 and N2 O emissions following land-applied manures and excreta deposited during grazing, emission factors (EFs) disaggregated by climate zone were developed, and the effects of mitigation strategies were evaluated. The NH3 data represent emissions from cattle and swine manures in temperate wet climates, and the N2 O data include cattle, sheep, and swine manure emissions in temperate wet/dry and tropical wet/dry climates. The NH3 EFs for broadcast cattle solid manure and slurry were 0.03 and 0.24 kg NH3 -N kg-1 total N (TN), respectively, whereas the NH3 EF of broadcast swine slurry was 0.29. Emissions from both cattle and swine slurry were reduced between 46 and 62% with low-emissions application methods. Land application of cattle and swine manure in wet climates had EFs of 0.005 and 0.011 kg N2 O-N kg-1 TN, respectively, whereas in dry climates the EF for cattle manure was 0.0031. The N2 O EFs for cattle urine and dung in wet climates were 0.0095 and 0.002 kg N2 O-N kg-1 TN, respectively, which were three times greater than for dry climates. The N2 O EFs for sheep urine and dung in wet climates were 0.0043 and 0.0005, respectively. The use of nitrification inhibitors reduced emissions in swine manure, cattle urine/dung, and sheep urine by 45-63%. These enhanced EFs can improve national inventories; however, more data from poorly represented regions (e.g., Asia, Africa, South America) are needed.
Highlights
Manure application to land and livestock deposition of urine and dung on pasture and rangelands are major sources of ammonia (NH3) and nitrous oxide (N2O) emissions from agriculture (Sajeev et al, 2018)
Our analysis showed that cattle solid manure broadcast on to soils in temperate wet climates has an NH3 emission factor (EF) value of 0.030 kg NH3–N kg–1 N applied, which is significantly lower than 0.242 kg NH3–N kg–1 N applied as determined for cattle slurry under the same climatic conditions (Table 2)
Using the DATAMAN database, we have developed disaggregated NH3 EFs for cattle and swine manures applied to land in wet climates and N2O EF for cattle, sheep, and swine manure emissions in wet and dry climates
Summary
Manure application to land and livestock deposition of urine and dung on pasture and rangelands are major sources of ammonia (NH3) and nitrous oxide (N2O) emissions from agriculture (Sajeev et al, 2018). Nitrous oxide is a potent greenhouse gas (GHG); livestock systems contribute over 32% of total global N2O emissions (Uwizeye et al, 2020). Ammonia emissions represent significant losses of nitrogen (N) from agricultural systems and contribute to secondary particulate formation and ecosystem degradation (Behera et al, 2013; Hafner et al, 2018; Sigurdarson et al, 2018). Livestock production represents 60% of global NH3 emissions (Uwizeye et al, 2020), largely derived from manure management (Webb et al, 2005). Whereas some studies have reported that soil injection of slurry often increases N2O emissions, other studies have reported similar N2O emissions between broadcast and manure injection (Chadwick et al, 2011; Webb et al, 2010), suggesting that the effects of manure application method on N2O emissions depend on the climate conditions that favor (or not) soil denitrification process (Chadwick et al, 2011)
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