VARIABILITY OF SOME SIWA OASIS SOILS USING PRINCIPAL COMPONENT ANALYSIS | ||||
| Journal of Soil Sciences and Agricultural Engineering | ||||
| Article 3, Volume 28, Issue 1, January 2003, Page 629-640 PDF (2.91 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jssae.2003.243971 | ||||
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| Author | ||||
| A. B. EI-Menshaway, | ||||
| Dept. of Soil and Water Sci., Fac. of Agric., EI-Shatby, Univ.of AI~x. | ||||
| Abstract | ||||
| A survey of some Siwa oasis area soils was carried out in 2001-2002. Measurements of topsoil properties were made at 36 grid system (350x350m.) sites. The results have been statistically and geostatistically analyzed to assess the degree and nature of spatial variability and spatial dependence in the soil properties. Classical statistical analysis showed that the coefficients of variation (C.V.) were 2.09, 2.07,1.54,1.50,1.47,1.43,1.40,1.18,1.13,1.06,0.90, 0.78, 0.76 and 0.73 for K+, S04-, cr, Na", EC, HCO'3, gravel, Mg++, ca", V.F.S., SAR, CaC03, fine sand and very coarse sand, respectively. Principal component analysis (PCA) was carried out to reduce data redundancy and interpretation. The first sex PC's were selected as each of them explained more than 4.55% of the total variance. These six PC's explained 80.26% of the total variance. This is confirmed by the coefficient of variation (C.V.). Geostatistical analysis showed that the semi-variogram model was Spherical for depth and CaC03%, Gaussian for EC and SAR, and Exponential for O. M. and tatol sand. The only variables that showed the EC, SAR, depth and total sand has the highest nugget variances of 2460,324, 167 and 122.1 which indicate their strong spatial dependence and high inherited variability. The maximum interpolation distances for CaC03, depth EC, SAR, O.M and total sand, are 540.1, 531.0, 275.3, 124.4, 619 and 616 m., respectively. Highly variable soil properties were used to produce kriging maps, using Punctual kriging method. The information taken from the semi-variogram model for each property was used in drawing the isarithmic maps for these properties, indicating their spatial distribution. | ||||
| Keywords | ||||
| Siwa oasis; Geostatistical; Principal component analysis; spatial variability; coefficient of variation; semi-variogram; nugget; kriging | ||||
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