基于水稻冠层光谱信息的稻田土壤速效N的Cokriging插值研究

该文以嘉善县陶庄农场内一块3.34 hm²农田为试验区，研究样点土壤养分(土壤全N、全P、有机质、速效N、速效K)与水稻各生长期水稻冠层光谱的关系，并将光谱指数作为协因子，进行土壤养分的Cokriging插值研究。结果表明，正常施肥区各生长期根据TM、SPOT波段组合计算的某些冠层光谱指数，特别是比值光谱指数RSI、归一化光谱指数NDSI，与土壤速效N、有机质等土壤养分具有显著的相关性，可以作为协因子参与这些土壤养分的估算；选择正常施肥区分蘖期TM、SPOT组合中与速效N相关性最高的比值光谱指数TM4/TM3、B3/B2作为协因子，参与土壤速效N的Cokriging插值，与普通Kriging相比，插值精度有一定程度的提高，并且，当采样点越少，或土壤养分与协因子的相关性越高时，插值精度提高更明显。

Investigation of spatial interpolation of available soil nitrogen in paddy field based on rice canopy spectral information

The objectives of the present study are to examine the relationship between soil nutrients, and rice canopy spectral indices, and to interpolate the soil nutrients by the means of Cokriging method which uses soil sample data as the variate and some rice canopy spectral indices as covariate. The area selected for this study was a 3.34 hectare paddy field on Taozhuang Farm in Jiashan county. The soil nutrients analyzed consisted of total N, total P, available K, available N, and organic matter(OM). The results showed that some rice canopy spectral indices calculated according to TM, SPOT bands at the main growing stages, especially spectral indices such as TM4/TM3, B3/B2, were well correlated with some soil nutrients such as available N, OM. The spatial pattern of soil available N in the paddy field was predicted using Cokriging which used soil sample data as the variate and ratio spectral indices TM4/TM3, B3/B2 at the tillering stage as covariate. The Cokriging estimation variances were less than those for ordinary Kriging, furthermore when the amount of soil samples was cut down or the relativity between the variate and covariate was better.