Spatial Variability of Field-measured Soil-water Characteristics1
- P. J. Greminger,
- Y. K. Sud and
- D. R. Nielsen2
One hundred neutron access pipes were placed 1-m apart along a 100-m transect together with tensiometers located at soil depths of 0.3 and 0.6 m. After ponding the experimental site with water for at least 4 d, the site was allowed to drain and covered with 0.3 m of straw to reduce evaporation. Measurements of soil-water content θ and soil-water pressure head (h) initially made at 2-h intervals were made less frequently as redistribution proceeded. The (θ,h|t)—observations were fitted to the five-parameter van Genuchten model. Spatial autocorrelations and cross-correlations of θ, h, and percentage sand manifested significant coefficients for distances as great as 10 m. The practical significance of this research is that it addresses the impact of the separation distance between a tensiometer and a neutron meter access tube on the precision of the measured soil-water characteristic curve. Greater precision is obtained for separation distances < 10 m.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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