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Geostatistical analysis of cyst nematodes in soil
Author(s) -
WEBSTER R.,
BOAG B.
Publication year - 1992
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1992.tb00162.x
Subject(s) - topsoil , transect , geostatistics , range (aeronautics) , globodera rostochiensis , sampling (signal processing) , variogram , spatial variability , environmental science , soil science , ecology , mathematics , biology , physical geography , statistics , geography , soil water , kriging , nematode , materials science , filter (signal processing) , computer science , composite material , computer vision
SUMMARY The numbers of cyst nematodes that live in agricultural soil vary both in time and space with important consequences when devising procedures for inspection and strategies for their control. We have examined the distributions of two species, Globodera rostochiensis and Hererodera avenue , in fields in the east of Scotland by counting their live cysts in the topsoil. Nested sampling and analysis showed that most of the spatial variation occurs within distances of 5 m to 50 m. Experimental variograms computed from transects and grid surveys appeared to be isotropic and bounded with a range of approximately 60 m. Both species are strongly aggregated. H. avenue occurred in large patches. Indicators for cyst counts of 1, 4 and 10 were created from the data. The experimental auto and cross variograms of these indicators were computed and models fitted to them. All of these variograms had the same spherical form as that of the original counts but shorter ranges, and the cross variograms had more structure, suggesting a border effect. Biologically, the distribution can be explained by the nematodes being spread by cultivation from initial fortuitous foci of infestation or control by nematophagous fungi or both.