关键词: 土地质量, 地球化学调查, 采样密度对比研究, 浙中盆地

Abstract: Abstract: A research on the technique of 1∶50,000 land quality geochemical survey at a hillybasin area in central Zhejiang Province was carried out at 2014. The experimental procedure was as follows：(1)using the upper limit of sampling density of 1∶50,000 land quality geochemical survey, the average sampling density is 164 samples per km2, Kriging interpolation method is used for the patch assignment (hereinafter referred to as interpolation);(2)to reach the target of precise land management, use the land plots as sampling units. The average sampling density is 1795 samples per km2.Then use the measuring results in the patch assignment (hereinafter referred to as measured). Several parameters, including element content, geochemical grade of soil environment, geochemical grade of soil nutrient and geochemical comprehensive grade of soil quality were compared respectively in 16 samples per km2 and 180 samples per km2. The study showed that: (1) by studying the relative deviation (RD) between interpolation and measured value of 15 elements which are crucial in the land quality assessment, we found that the RD qualified rate pass 90%, 80% to 90%, under 80% were separately 9,4 and 2; (2) the difference between interpolation and measured value in single geochemical grade of soil environment and comprehensive geochemical grade of soil environment are quite small, while it was more distinct in geochemical grade of soil nutrient; (3) the proportions of number and area change between interpolation and measured value for the first and second grade patches are 118% and 74%.The comprehensive geochemical grade of soil quality has changed in about 40% of the patches. In the experiment plot, the RD between interpolation and measured value were mainly caused by the spatial difference of N, P, K. The research shows that, the results of 1∶50,000 land quality geochemical survey, in a word, according to the land quality geochemical assessment requirements, can provide the scientific reference for land utilization and fertilization. But not well enough for precise land management.

Key words: land quality, geochemical survey, study of the sample density, basin in central Zhejiang