华北地区典型农田土壤有机质和养分的空间异质性

Spatial heterogeneity of soil organic matter and nutrients in typical farmland in the North China Plain

华北平原是我国重要的粮食生产基地,研究华北平原土壤有机质及养分的丰缺状况对于区域农业生态系统的可持续性发展具有重要意义。本研究选取华北平原典型农田,通过设置北线、中线、南线3条研究线路,在省域尺度上研究土壤有机质和养分的空间异质性及其平衡状况。结果表明,研究区域内土壤有机质、全氮、碱解氮、有效磷、速效钾平均含量分别为14.0±3.5 g/kg、0.98±0.28 g/kg、76.6±21.6 mg/kg、18.6±9.9 mg/kg,136.1±42.7 mg/kg,除全氮和有效磷外,有机质及其余养分在不同线路间无显著差异。有效磷在靠近黄河、土壤pH值较高的南线上显著偏低。土壤有机质及养分均为中等程度变异,有效磷的变异系数(47.8%)显著高于有机质及其余土壤养分(24.3%～31.6%)。土壤碳氮比介于4.2～14.3间,平均为8.6,低于全国平均水平。土壤有机质和各养分均较1980年有所增加,主要原因可能是华北平原长期以来投入了大量的有机、无机肥。华北平原农田配方施肥应该考虑增施有机肥、减少氮素化肥的投入。

The North China Plain is an important base of grain production in China.Study of soil organic matter(SOM)and nutrients in the North China Plain is of great importance for the sustainable development of the regional agriculture.In this study,three sampling lines(north,middle,and south)were selected in typical farmland of the North China Plain,and SOM and main nutrients were analyzed on a provincial scale.Average contents of SOM,total nitrogen(TN),available nitrogen(AN),available phosphorus(AP),and available potassium(AK)in the study area were 14.0±3.5 g/kg,0.98±0.28 g/kg,76.6±21.6 mg/kg,18.6±9.9 mg/kg and 136.1±42.7 mg/kg,respectively.There were significant differences between different lines for TN and AP,with the lowest AP found along the south line that revealed highest soil pH.Soil organic matter and nutrients showed some fluctuations in the east-west direction,but with no obvious changing trend.The coefficient of variation of AP(47.8%)was significantly higher than those(24.3%~31.6%)of SOM and other nutrients.Soil C∶N ratio ranged from 4.2 to 14.3,with an average of 8.6,which was lower than the national average level.The present levels of SOM and nutrient were modest higher than those in the 1980s,which might be due to increased rates of organic and chemical fertilization.This study suggests that there is a need to use more organic or combined organic-chemical fertilizers in the North China Plain.