In the last part of this paper, some issues to be further researched were put forward, including the turnover model of som, its components, and its relationship with global carbon cycle.

最后提出应加强对土壤有机质周转模型、有机质组分，尤其是活性有机质以及有机质与全球碳循环关系的研究。

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The group said it had reduced carbon emissions relative to the turnover of its UK businesses by 5.6% in the two years to 30 April 2011 as a result of a package of measures designed to make the group more sustainable.

BBC: Perth firm Stagecoach in greener fuel move