20年来部分黑土耕层有机质和全氮含量的变化

Changes in Organic Matter and Total Nitrogen of Black Soils in Jilin Province over the Past Two Decades

黑土有机质含量的变化一直倍受社会关注。根据第二次全国土壤普查的采样记录,2001年在吉林省黑土区采集了27个土壤样品,分析测定了耕层土壤(深度与第二次土普数据相同)的有机质和全氮含量。与第二次土普查数据对比发现,过去20年间,吉林省黑土土壤有机质和全氮含量有增有减,但平均水平无明显变化。与已有的研究对比分析,高产玉米生产条件下的根系碳输入量可能抵消矿化损失的有机质量,使水土流失不严重区域的黑土土壤有机质水平维持平衡,有机质含量下降的土壤可能是水土流失的结果。而在水土流失不严重地区土壤有机质则可能增加。

Black soils are main agricultural soils in Northeast China and the organic matter content of these soils has been one of the hot research topics for many years. By referencing the data and sampling locations in the Second National Soil Surveys of Jilin Province conducted in the 1980s, we re-sampled 27 black soils along the Jing-Ha (Beijing-Harbin) railway in central Jilin. The contents of soil organic matter and total nitrogen of those soils were determined and compared in pair with the data measured 20 years ago on an equivalent depth. We found that 2-decades intensive farming affected differently the contents of soil organic matter and total nitrogen, with increasing for some soils and decreasing for others. However, there was no significant difference in overall average of soil organic matter. By comparing the results with other studies, we believe that the present corn dominated production has balanced soil organic matter level of black soils through roots alone in areas where soil erosion was not a problem. However, the soils that organic matter decreased during the past two decades might be subject to severe soil erosion. During the same time, some black soils gained organic matter.