干旱区绿洲农田土壤微量元素有效态含量空间分布特征

采用地统计学和GIS相结合的方法，对甘肃省张掖山丹县和民乐县农田耕层土壤中有效态Fe，Cu，Zn，Mn，Ni和Co含量的空间变异特征、分布规律及影响因素进行了研究. 结果表明,研究区有效态Fe和Zn含量较缺乏，6种微量元素均属中等变异强度. 有效态Cu，Zn和Ni含量的最适半方差模型为球状模型，Fe和Co为指数模型，Mn为高斯模型；有效态Fe，Cu，Mn，Ni和Co含量具有强烈空间相关性，有效态Zn含量具有中等空间相关性；6种微量元素有效态含量的变程大小顺序为Fe＞Ni＞Zn＞Co＞Mn＞Cu. 有效态Fe和Ni含量呈明显的带状分布，总体上为由南向北递减，有效态Mn和Co含量呈岛状分布；有效态Fe和Zn含量处于中等及偏低水平，而有效态Cu，Mn和Ni含量处于中等及丰富水平. 此外，土壤有机质含量对研究区主要微量元素(Cu除外)有效态含量的影响最大. 

Spatial Distribution Characteristics of Available Microelement Contents in Oasis Cropland Soils of Arid Areas

The method of geostatistics combined with GIS was applied to study the spatial variability characteristics,distribution laws and influencing factors of available Fe,Cu,Zn,Mn,Ni and Co contents in farmland topsoils from the Shandan and Minle Counties of Zhangye City,Gansu Province.The results showed that the soils relatively lacked available Fe and Zn concentrations,and the six microelements all belonged to moderate variability level.Better theoretical semivariogram models of available microelements were the spherical model for Cu,Zn and Ni,the exponential model for Fe and Co,and the Gaussian model for Mn.Available concentrations of Fe,Cu,Mn,Ni and Co had strong spatial correlations.The contents of available Zn had a moderate spatial correlation.The variation range of the six microelements available contents followed the order Fe > Ni > Zn > Co > Mn > Cu.The contents of available Fe and Ni presented clear continuous zonal distribution,and a decreasing trend was found from south to north.The distributions of Mn and Co presented an island shape.The contents of available Fe and Zn were moderate or poor in the soils,while the contents of available Cu,Mn and Ni were moderate or rich in the soils.Moreover,the contents of available microelements,except for Cu,were mostly influenced by organic matter in the study area.