东北黑土农田养分时空演变分析

通过东北黑土农田的广泛采样、化验分析,目前黑土农田有机质含量平均为33.9 g kg-1,全氮1.91 g kg-1,速效磷24.85 mg kg-1,速效钾159.95 mg kg-1。1979年~2002年期间黑土农田土壤有机质下降了3.76 g kg-1~4.14 g kg-1,平均每年下降0.16 g kg-1~0.18 g kg-1;而土壤速效磷含量大幅度上升,已是原来1979年的2倍以上,23年里土壤速效磷上升了12.66 mg kg-1~14.66 mg kg-1,平均每年上升0.55 mg kg-1~0.64 mg kg-1。认为土壤速效磷是过去的20多年里人为生产活动改变最大的肥力因子,其他土壤养分指标的空间分布有较明显的地带性,存在显著的空间变异,尤其是土壤有机质、全氮、碱解氮与地理纬度高程度相关,受气候等自然因素影响较大。

Analysis for Temporal and Spatial Changes of Black Soil Cropland in the Northeast Area of China

Through large scale sampling and assaying on Phaeozems(black soil) in the Northeast of China,the results indicated that in the black soil the average content of soil organic matter(SOM) was 33.9 g kg-1,total nitrogen (TN) 1.91 g kg-1,available phosphorus(AP) 24.85 mg kg-1,and available potassium(AK) 159.95 mg kg-1.From 1979 to 2002,the content of SOM in the black soil dropped as much as 3.76 to 4.14 g kg-1 and the decreasing rate was 0.16 to 0.18 g kg-1 yr-1.On the other hand,the content of AP increased 12.66 to 14.66 mg kg-1 during the past 23 years,more than double of that in 1980,and the increasing rate was 0.55 to 0.64 mg kg-1 annually.It was AP that had been changed most by human production activities during the past 23 years.What must be underlined was that SOM,TN and available nitrogen(AN) were significantly correlated with geographic latitude,and the changes were mainly affected by climatic and other natural factors.