Whole crop silage (WCRS) production is associated with the greenhouse gas (GHG) emissions because rice cultivation is a major source of methane (CH
4) and nitrous oxide (N
2O). However, few studies addressed the GHG emission from WCRS production system and compared enviromental performance to imported hay (IH) production system. The objectives of this study were to evaluate the GHG emissions of WCRS production system with different mechanized systems at the cases in Chiba using life cycle assessment method and to compare the GHG emissions with IH production systems.
The WCRS production system evaluated were three systems of different harvesting machineries according to the production system at Chiba. Using machineries at three systems were a cutting role baler and self-propelled bale wrapper (CBS), a mower, role baler and self-propelled bale wrapper (MRS) and a mower conditioner, role baler and bale wrapper (MRW). The GHG emissions of IH production system were estimated by the mean of GHG emissions from eight states hay production systems and N
2O emission from the U.S. agricultural land. The GHG emissions assessed were: carbon dioxide (CO
2), CH
4 and N
2O from energy use, chemical use and land use. Two functional units were used to express impact of the WCRS production system: operations of 10 a rice paddy fields and total digestible nutrients (TDN) yield at 10 a rice paddy fields.
GHG emissions at CBS and MRW were similar to 720-860 kg-CO
2eq/10a. Because harvested area was small at MRS, GHG emissions were 1720-1860 kg-CO
2eq/10a. GHG emissions of IH production system were 950-1630 kg-CO
2eq, varied according to hay yields, production area, N
2O emission from land use and CO
2 emission from transportation. Compared with IH production system at mean transportation distance. The GHG emissions at WCRS production system with CBS and MRW were low 330-620 kg-CO
2eq/10a. Besides, bacause large impact of GHG emissions at WCRS production system was caused by CH
4 from paddy fields and CO
2 from machineries production, suitable water control at paddy fields and effective utilization of machineries with adequate land area and intensive machinery use were considered important measures to mitigate GHG emissions from WCRS production systems.
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