title: Greenhouse gas emissions from passive composting of manure and digestate with crop residues and biochar on small-scale livestock farms in Vietnam.
abstract: This study investigated the effects of different mixing ratios of crop residues and biochar with liquid digestate from anaerobically treated pig manure on CH₄, CO₂, and N₂O emissions over 84 days in a system of passive aeration composting, resembling typical Vietnamese solid manure storage conditions. Two treatments with solid manure were included for comparison. The results showed that C losses through CH4 and CO₂emissions accounted for 0.06-0.28% and 1.9-26.7%, respectively, of initial total C. CH4 losses accounted for just 0.4-4.0% of total C losses. Total N losses accounted for 27.1-40% of initial total N in which N₂O emissions corresponded to 0.01-0.57% of initial total N, and hence accounted for only 0.1-1.8% of total N losses. It is assumed that the remainder was either the result of denitrification losses to N₂or ammonia volatilization. The composting of biochar (B) or crop residue with digestate (D) showed significantly lower CH4 and N₂O emissions compared with composting manure (M) (p < .05). The composting of digestate with biochar showed significantly lower CO₂and CH₄emissions and significantly higher N₂O emissions compared to the composting of digestate with rice straw (RS) (p < .05). The combined composting of digestate with biochar and rice straw (D + B + RS5:0.3:1) showed significantly reduced N₂O emissions compared with composting digestate with biochar with alone (p < .05). Composting sugar cane bagasse (SC) with digestate (D + SC) significantly reduced CH₄and N₂O emissions compared with the composting of rice straw with digestate (D + RS3.5:1 and D + RS5:1) (p < .05).
authors.affiliation: a Institute for Agricultural Environment, Vietnamese Academy of Agriculture Sciences , Hanoi , Vietnam.|b Department of Plant and Environmental Sciences, Faculty of Science , University of Copenhagen , Copenhagen , Denmark.
authors.forename: Quynh Duong
authors.initials: QD
authors.lastname: Vu
authors.affiliation: b Department of Plant and Environmental Sciences, Faculty of Science , University of Copenhagen , Copenhagen , Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: de Neergaard
authors.affiliation: c Soils and Fertilizers Research Institute, Vietnamese Academy of Agriculture Sciences , Hanoi , Vietnam.
authors.forename: Toan Duc
authors.initials: TD
authors.lastname: Tran
authors.affiliation: c Soils and Fertilizers Research Institute, Vietnamese Academy of Agriculture Sciences , Hanoi , Vietnam.
authors.forename: Huong Thi Thu
authors.initials: HT
authors.lastname: Hoang
authors.affiliation: d National Institute of Animal Sciences , Hanoi , Vietnam.
authors.forename: Van Thi Khanh
authors.initials: VT
authors.lastname: Vu
authors.affiliation: b Department of Plant and Environmental Sciences, Faculty of Science , University of Copenhagen , Copenhagen , Denmark.
authors.forename: Lars Stoumann
authors.initials: LS
authors.lastname: Jensen
mesh_terms: D000383:Agriculture / Q000379:methods*; D000393:Air Pollutants / Q000032:analysis*; D000818:Animals; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis; D002482:Cellulose; D002606:Charcoal; D057232:Global Warming; D008372:Manure; D008697:Methane / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D012275:Oryza; D012987:Soil; D013552:Swine; D014744:Vietnam; D014866:Waste Products
chemical_list: D000393:Air Pollutants; D008372:Manure; D012987:Soil; D014866:Waste Products; C540010:biochar; D002245:Carbon Dioxide; D002606:Charcoal; D002244:Carbon; D002482:Cellulose; C027433:bagasse; D009609:Nitrous Oxide; D009584:Nitrogen; D008697:Methane
keywords: GHG emissions; biochar; composting; crop residue; digestate