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Spatial variability of some nutrient constituents of an Alfisol from loess I. Classical statistical analysis
Author(s) -
Dahiya I. S.,
Kersebaum K. C.,
Richter J.
Publication year - 1984
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19841470607
Subject(s) - loess , alfisol , mathematics , spatial variability , soil science , mineralogy , statistics , environmental science , chemistry , soil water , geology , geomorphology
Classical statistical techniques were used to evaluate the lateral and vertical variability of some nutrient constituents, viz. NO 3 , extractable K and Mg, and organic C, of a loess soil field. In all 50 sites at a 30m × 30m grid were selected within a 10 ha field situated about 25 km west of Hannover. Samples were taken at 0–30, 30–60 and 60–90 cm depths. Analysis based on cumulative probability density function showed that all properties except K in the 30–60 and 60–90 cm depths were normally distributed. K in these depths was lognormally distributed. Mean values of NO 3 increased with depth, that of K decreased and that of Mg remained nearly constant. Comparison of coeffizients of variation (CV – % variation) indicated that organic C was least variable laterally (CV = 8.7) and K the most (CV = 43.8 for 30–60 cm depth). The CV of NO 3 and Mg increased slightly with depth indicating less drastic vertical variation. The number of observations required to yield an estimate of the mean value within a prescribed accuracy and precision is shown to depend upon the nature and extent of the spatial variability of a parameter. Thus, estimated number of samples was smaller for lower CV values and vice versa. The optimum number of samples for a given property is determined by the depth in which the largest estimated number of samples is required to be taken.