中文摘要：

在宏观层面上利用中国1990—2011年的机械化秸秆还田机数量,推算出1990—2011年秸秆还田面积,探讨了20多年来中国秸秆还田情况,并研究了第一次土壤普查、第二次土壤普查和测土配方施肥近60年中国土壤有机碳的变化规律,分析了秸秆还田面积与土壤有机碳含量的关系。结果表明：1990—2011年,中国秸秆还田面积整体上呈上升的趋势,2011年机械化秸秆还田面积是1990年的2.92倍,但与粮食播种面积相比,我国的秸秆还田面积所占的比例很低,2011年机械化秸秆还田面积占粮食作物播种面积的比例（全国均值）只有16.89%。我国31个省（自治区、直辖市）中,有近50%的省份土壤有机碳含量呈现增加的趋势。在区域范围内表现为华北、华东、华中、西北地区土壤有机碳含量增长明显,而西南、华南和东北地区土壤有机碳呈现降低的趋势,尤其是东北地区降幅明显。

英文摘要：

In this paper, on the macro level, the number of mechanical straw returning to field in China in 1990--2011 was used to calculate the area of straw returning to field in 1990--2011, the situation of returning straw to field in China in the past 20 years was discussed, the changes of soil organic carbon in China in the past 60 years were studied by using the first soil survey, the second soil survey and soil testing and formula fertilization, and the relationship between straw mulching ar- ea and soil organic carbon content in the past 20 years was analyzed. The results showed that, during 1990--2011, the whole area of straw returning to field in China showed an upward trend, and the 2011 mechanical straw returning to field area was 2.92 times that of 1990, but compared with the total grain sewing area, the proportion of straw returning to field in our country was very low, in 2011, the proportion of mechanical straw returning to field area and grain sewing area was only 16. 89%. Among 31 provinces （autonomous regions and municipalities directly under the central government） of China, soil organic carbon content of nearly 50% provinces showed an increasing trend. In North China, East China, Central China and Northwest China, soil organic carbon content increased significantly, in Southwest China, South China and Northeast China, soil organic carbon presented a decreasing trend, and in the Northeast China the content fell significantly.