Direct green waste land application: How to reduce its impacts on greenhouse gas and volatile organic compound emissions?

摘要

Direct land application as an alternative to green waste (GW) disposal in landfills or composting requires an understanding of its impacts on greenhouse gas (GHG) and volatile organic compound (VOC) emissions. We investigated the effects of two approaches of GW direct land application, surface application and soil incorporation, on carbon dioxide (CO_2), nitrous oxide (N_2O) and methane (CH-4), and VOC emissions for a 12 month period. Five treatments were applied in fall 2013 on fallow land under a Mediterranean climate in California: 30 cm height GW on surface; 15 cm height GW on surface; 15 cm height GW tilled into soil; control + till; control + no till. In addition, a laboratory experiment was conducted to develop a mechanistic understanding of the influence of GW application on soil O_2 consumption and GHG emission. The annual cumulative N_2O, CO_2 and VOC emissions ranged from 1.6 to 5.5 kg N_2O-N ha~(-1), 5.3 to 40.6 Mg CO_2-C ha~(-1) and 0.6 to 9.9 kg VOC ha~(-1), respectively, and were greatly reduced by GW soil incorporation compared to surface application. Application of GW quickly consumed soil O_2 within one day in the lab incubation. These results indicate that to reduce GHG and VOC emissions of GW direct land application, GW incorporation into soil is recommended.