陕南丘陵区县域农田土壤养分的空间分布格局

Spatial distribution of soil nutrients in hilly region of Southern Shaanxi

【目的】研究陕西南部丘陵区土壤养分的空间分布情况,为区域精准农业的发展提供科学依据和实践指导。【方法】2010-2011年,以陕西省镇安县为研究区,在19个镇采集农田0~20cm土层土样2 283个,采用地统计学并结合"GIS"技术,构建不同土壤养分的最优半方差模型,进行普通Kriging插值分析,对该地区土壤养分的空间特征进行评析。【结果】镇安县农田土壤有机质、全氮、速效氮、速效磷和速效钾,均呈中等变异强度。在空间结构上,土壤速效磷属于弱的空间相关性,有机质、速效氮和全氮表现为中等强度的空间相关性,速效钾具有强的空间相关性。总体来看,农田土壤养分空间呈中间低、四周高的分布格局。农田土壤有机质和全氮平均含量分别为18.27,1.09g/kg,速效氮、速效磷、速效钾平均含量分别为97.47,16.27,122.09mg/kg。与20世纪80年代相比,2011年镇安县土壤有机质、全氮、速效氮、速效磷、速效钾的增幅分别为40.54%,17.20%,57.21%,125.97%和47.10%。镇安县土壤碳氮比平均为9.84,速效氮磷比平均为4.00。【结论】镇安县农田土壤有机质、全氮和速效磷含量处于中等水平,速效氮和速效钾含量处于中等偏上水平。土壤碳氮比较全国农田偏低,速效氮磷比整体上偏高,比例严重失调。因此,镇安县的农田应科学、合理施肥,以提高肥料利用率。

【Objective】The study explored the spatial variability of soil nutrients in farmlands in hilly region of Southern Shaanxi to provide scientific guidance for development of precision agriculture.【Method】This paper took Zhen'an County in Southern Shaanxi as the study area and collected 2 283 soil samples from 0-20 cm top soil of farmlands in 19 towns during 2010-2011.Combination of geostatistics with geographical information system(GIS)was applied to construct best semi-variance models and conduct ordinary Kriging interpolation analysis for spatial analysis of soil nutrients in this region.【Result】The spatial variability of soil organic matter(SOM),total nitrogen(TN),available nitrogen(AN),available phosphorus(AP)and available potassium(AK)in farmlands of Zhen'an County was moderate.AP had weak spatial correlation,SOM,AN and TN had moderate spatial correlation,while AK had strong spatial correlation.Spatially,soil nutrients were lower in central while higher in surrounding.Average contents of SOM,TN,AN,AP,and AK were 18.27,1.09g/kg,97.47,16.27,and 122.09 mg/kg,respectively.They increased by 40.54%,17.20%,57.21%,125.97%,and 47.10%from 1980 sto 2011.The mean ratio of C to N was 9.84 and that of N to P was 4.00.【Conclusion】The contents of SOM,TN and AK were in moderatelevel,while AN and AK were higher than middle level.The mean ratio of soil nutrients was imbalance.Therefore,it is necessary to guide farmers to fertilize rationally and improve fertilizer utilization.