Content and Change of Available Iron in Tobacco-growing Soil from Xiangxi Autonomous Prefecture

In order to understand the distribution of available iron contents in tobacco growing soils of Xiangxi,distribution frequency of available iron contents among different counties,soil types,altitudes were analyzed by both classic statistics and geostatistics with 488 soil samples.The results were as follows:(1) Available iron contents in the tobacco soils were little higher with a mean of 83.20 mg / kg,amplitude of 10.04 ～ 328.89 mg / kg and variation coefficient of 82.31%.About 27.10% of the soil samples of available iron contents were suitable for tobacco cultivation.(2) There were no significant differences among the different counties for the contents of available iron,and the order of available iron content in soil for different counties was Luxi Fenghuang Huayuan Guzhang Yongshun Longshan Baojing.(3) There were extremely significant differences among different soil types for the contents of available iron,and the order of available iron content in soil for different soil types was red ash soil lime soil red soil yellow soil paddy field yellow brown soil.(4) There were no significant differences among the different altitudes for the contents of available iron,and its content in average of 61.68 ～ 91.84 mg / kg in five groups.(5) Kriging interpolation map indicated that the spatial distributions of available iron were plaques shape distribution and its main area are exist in the northern and southern that available iron content is 89.9 ～ 184.0 mg / kg.