Spatial Variation of Infiltration Rate and Related Soil Properties in a Central Gezira Clay Soil. II. Geostatistical Methods

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Mustafa, M.A.
Ibrahim, A.S.A
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Faculty of Agriculture, University of Khartoum, Shambat, Sudan
The spatial variation of steady-state infiltration rate (IR), clay content, ECe, CaCO3, SAR and pH (paste) at 5-m regular intervals, along two 500-m long transects (S-N, W-E) crossed in the middle were studied in two sites (Kubur and Talha) using geostatistical techniques. The data of the two transects were pooled for each site. An average and a 2-dimentional IR semi-variograms were computed for Kubur site. The former semi-variogram gave a better accountability to a spherical model than the latter. Thus, average semi-variograms were computed for all other soil properties. All average semi-variograms fitted the spherical model except that of clay content at Kubur site, which fitted a linear model. The parameters of the two models are provided and may be used in kriging. All semi-variograms exhibited nugget variances, indicating micro-scale spatial variability. The ranges for CaCO3, ECe, clay content, pH (paste), IR and SAR were 116, 58, 56, 53, 50 and 31 m, respectively. The cross semi-variogram for IR versus clay content, ECe, SAR, or CaCO3 are presented for both sites. The cross semi-variogram in Talha site showed that IR decreased with increase of clay content, and the relationship decreased with increase in lag distance. Other cross semi-variograms indicated lack of relationship between IR and the other soil properties.
Page(s): 9 (2),183-200, 16 Ref.