Abstract

FILGUEIRA, Roberto R; SORACCO, Cg; SARLI, Go  and  FOURNIER, Ll. Estimation of soil hydraulic properties by field measurement and use of steady- and transient-flow models. Cienc. suelo [online]. 2006, vol.24, n.1, pp.39-48. ISSN 1850-2067.

Soil management influences physical properties of the soil, mainly hydraulic functions. Their measurement have been one of the research preferences in Soil Physics. Tension disc infiltrometer has become a valuable instrument for the in situ measurement of soil surface hydraulic properties. Methods of analysis of the information obtained with this instrument have generally relied on the restrictive assumptions of steady-state infiltration at large times, but today approximate analytical expressions for three-dimension unsteady, unconfined flow out of a disc infiltrometer, are also available. In our study field tension infiltrometer measurements were run on a clay loam soil with different agricultural practices to determine sorptivity and saturated hydraulic conductivity, using steady- and unsteady-state water flow models. From steady state flow model, results obtained for sorptivity (S₀) ranged from 26.8 to 58.5 mm h^-1/2 and saturated hydraulic conductivity (K₀) ranged from 41.7 to 78.2 mm h^-1, for conventional tillage and praire site, meanwhile S₀ ranged form 23.9 to 51.2 mm h^-1/2 and K₀ between 19.0 and 45.7 mm h^-1 for the compacted site. Mean values of sorptivity were not statistically different between sites, meanwhile saturated hydraulic conductivity means were not different for conventional tillage and praire sites, but both means were different from the compacted site mean. From unsteady state flow model sorptivity values ranged from 10.9 to 36.6 mm h^-1/2 and K₀ values ranged between 58.6 and 189.3 mm h^-1 for conventional tillage management and natural prairie sites. For the compacted site S₀ values ranged from 15.8 to 33.9 mm h^-1/2 and for K₀ values from 13.6 to 71.5 mm h^-1. Mean values of sorptivity were not statistically different between sites, meanwhile saturated hydraulic conductivity means were not different for conventional tillage and praire sites, but both means were different from the compacted site mean.

Keywords : Sorptivity; Hydraulic conductivity; Steady flow model; Transient flow model.

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