陕西典型麦田区土壤全氮的空间异质性及其影响因素

为制定合理施肥方案,确保农业资源的可持续利用,采用地统计学方法结合GIS技术研究陕西蒲城县农业区麦田土壤中全氮(TN)的空间结构和分布特征。结果表明:蒲城县土壤全氮含量范围在0.42—1.32 g·kg^-1之间,变异系数为21.0%,属于中等变异强度,表明土壤全氮含量分布不均匀;486个原始全氮含量样点剔除特异值后,符合正态分布;半变异函数的最佳理论模型符合指数模型,函数块金值为5.83×10^-3,偏基台值为7.26×10^-3,块金值/基台值为0.46,说明全氮具有中等强度的空间相关性;普通Kriging插值结果显示,该县全氮含量呈现出由西南到东北逐渐下降的趋势,除分布于西南方向的荆姚镇和原仁乡有一些斑块状样区(11.5%)处于中等含氮水平以外,其余88.5%的调查样区土壤全氮含量均处于不同程度的缺乏状态,这与农户对西南灌区氮肥的投入多于东北山原区密切相关。该县相关部门要重视氮肥的投入,提高该县整体氮肥含量,同时针对“西南多氮东北少氮”的实际情况,实行因地施肥与精准分区管理。

Spatial heterogeneity and the influencing factors of soil total nitrogen in typical wheat fields of Shanxi province,China

In order to make reasonable fertilization scheme and guarantee the sustainable utilization of agricultural resources,the spatial structure and distribution characteristics of soil total nitrogen(TN)were studied by geostatistic and geographic information system(GlS)techniques in the wheat fields of Pucheng county.These results are as following:the content ranges of soil TN in the wheat fields of Pucheng county were 0.42-1.32 g·kg^-1,and the variance coefficient was 21%belonged to middle intensity,which suggested that the distribution of total TN was unequal.After 486 sample points were got rid of distinguished values,it was the normal distribution in the sample area.The best theoretical model of hemivariate function was accorded with index model,and the Nugget was 4.56×10^-3,and the Partial Sill was 8.68×10^-3,and the ratio of Nugget and Sill was 0.46,which suggested that TN belonged to moderate variability.The ordinary Kriging interpolation result showed that TN gradually declined from southwest to northeast in the cultivated lands of Pucheng county,and 88.5% of the sampling areas was TN deficiency except for a few patch(11.5%)distributed in southwest of Pucheng county,which was closely related to nitrogen application in southwestern irrigation areas than in northeastern arid areas.Therefore,the local relevant departments should focus on nitrogen investment and improve nitrogen level in the whole regional soil.More importantly,implement precision management should be adopted due to different nitrogen levels in different areas.