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Sampling Strategies for Mapping Soil Phosphorus and Soil Potassium Distributions in Cool Temperate Grassland 总被引:1,自引:0,他引:1
Unlike the situation for arable soils, virtually nothing is known about the spatial dependencies of soil properties in cool temperate grassland or about what the optimal sampling strategies ought to be for mapping soil nutrient distributions in such situations. The aim of this study was to investigate the spatial variability in plant-available (soil) phosphorus and potassium in a grass silage field in Northern Ireland and devise optimal sampling strategies for mapping their distributions. Soil samples were collected from the field at 25 m intervals in a regular rectangular grid to provide a database of soil properties. Different data combinations were subsequently abstracted from this database for comparison purposes, and ordinary kriging used to produce interpolated soil maps. Soil potassium displayed greater spatial variability than soil phosphorus. In keeping with this observation, the results of three separate statistical procedures demonstrated that the optimal sample size for estimating the true population means was about twice as large for soil potassium as for soil phosphorus. Optimal sampling strategies, however, related not just to sample size but to sample combination and field shape as well. 相似文献
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Radar soundings of the subsurface of Mars 总被引:2,自引:0,他引:2
Picardi G Plaut JJ Biccari D Bombaci O Calabrese D Cartacci M Cicchetti A Clifford SM Edenhofer P Farrell WM Federico C Frigeri A Gurnett DA Hagfors T Heggy E Herique A Huff RL Ivanov AB Johnson WT Jordan RL Kirchner DL Kofman W Leuschen CJ Nielsen E Orosei R Pettinelli E Phillips RJ Plettemeier D Safaeinili A Seu R Stofan ER Vannaroni G Watters TR Zampolini E 《Science (New York, N.Y.)》2005,310(5756):1925-1928
The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick. 相似文献
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