江汉平原农田土壤全氮的多尺度空间结构与成因分析

研究不同尺度的土壤氮素空间变异特征有利于科学表征氮素在连续尺度空间上的变异,从而为制定合理的耕作施肥方案、提高氮肥利用率、降低环境风险提供科学依据.选取江汉平原后湖农场为样区,以土壤全氮为例,分析该区域1 000m和200m两个嵌套采样尺度数据样本,应用经典统计学、地统计学方法和GIS技术,进行空间结构拟合分析,并探讨不同尺度上氮素空间结构形成的影响因素.结果表明:1)不同尺度上空间变异特征差异明显,随着尺度的减小空间相关性变弱;同一尺度,由于受成土因素的影响,不同区域的变程、结构方差等特征函数也不尽相同.2)经土壤氮素空间分布影响因素的方差分析(ANOVA),土地利用方式对土壤全氮的大尺度空间结构无显著性影响,而小尺度上则影响显著;土壤类型对大、小尺度土壤氮素的空间分异均有显著性影响,随尺度增大显著性增强.因此,研究全氮含量变化影响因素的机理时,1 000m采样间距以下全氮含量变化研究需考虑土壤类型可能会带来农场土壤全氮显著性差异的影响,而200m以下采样间距则需同时考虑土地利用和土壤类型给土壤全氮含量带来的显著差异性.

Multi-scale spatial structure and cause analysis of spatial variation of soil total nitrogen in farmland of Jianghan Plain

The research on different scale spatial variability of soil nitrogen feature is conducive to scientific characterization of nitrogen in the continuous spatial variation, which offers a scientific basis for the reasonable formulation on the cultivation fertilization scheme, the improvement of nitrogen fertilizer utilization and the reduction of environmental risk. The study was on the Houhu Farm areas in the Jianghan Plain, taking the variation of soil total nitrogen（TN） as a case, analyzed the data samples from two nested sampling scale （1 000 m and 200 m） in the region. With classical statistics, geo statistical methods and GIS, the characteristics of spatial variation on two scales were obtained respectively, and the influencing factors of nitrogen space structure on different scales were discussed. The results showed that： （1） There were obvious differences spatial variability on different scale, and the spatial correlation became weak with the scale decreasing; on the same scale, the total nitrogen fitting models were different because of the soil-forming factors. （2） By analyzing of the spatial distribution of soil nitrogen factors, ANOVA analysis showed that there existed significant differences in TN between land uses on small-scale（200 m）, but also existed significant differences in TN between soil types on 1 000 m and 200 m sample scales.