Comparison of Air and Water Permeability between Disturbed and Undisturbed Soils

Abstract

Although soil structure and pore geometry characteristics largely control flow and transport processes in soils, there is a general lack of experiments that study the effects of soil structure and pore‐space characteristics on air and water permeability. Our objective was to determine the dependency of soil permeability on fluid content for both water and air, and compare results for both disturbed (D) and undisturbed (UD) soils. For that purpose, we first measured the water permeability (kw) and air permeability (ka) for several intact UD soil samples. Subsequently, the same samples were crushed and repacked into the same soil cores to create the D equivalent for the same soil material. Measurements showed large differences between D and UD samples, confirming the enormous impact of soil structure and pore‐space characteristics on flow. The permeability of both fluid phases (air and water) was greatly reduced for the D samples, especially for soil air permeability due to its greater dependency on soil aggregation and structure. Soil water retention and permeability data were fitted to Campbell's and Mualem's pore‐size distribution model, respectively. Regardless of soil disturbance, we showed that the tortuosity–connectivity parameter, l, for the water permeability (l1) and air permeability (l2) were different. This is in contrast to the general practice of using the same parameter value for both functions. The relation between l1 and l2 was largely controlled by soil structure and associated macroporosity properties.

Effects of biochar amendment on soil aggregates and hydraulic properties

“…Mohawesh et al (2005) showed that the saturated water content decreased with the increase in bulk density, and as a result the inflection point on the retention curve shifted to a lower matric potential. Tuli et al (2005) reported that the air and water permeabilities of undisturbed soil samples were significantly higher than those of disturbed samples, attributed to the changes of soil structure and macropores. Owing to high surface area and porosity of biochar, its addition to soils should influence soil structure and porosity through changing the bulk surface area, pore size distribution, and soil bulk density (Downie et al, 2009;Major et al, 2010).…”

An Assessment of Lime Filter Drainage Systems

“…Fine-textured clayey soils are of high fertility but often have a low hydraulic conductivity (Forsburg, 2003;Tuli et al, 2005). The infiltration of water into these soils is too slow therefore frequent surface ponding occurs.…”

IMPACTO DO FLORESTAMENTO COM Pinus taeda L. NA POROSIDADE E PERMEABILIDADE DE UM CAMBISSOLO HÚMICO1

“…Alguns estudos têm definido a K a como dependente da estrutura do solo (IVERSEN et al, 2001;TULI et al, 2005;SILVA et al, 2009), influenciada pela Pt, distribuição e geometria do sistema poroso, tortuosidade, conectividade e constrição (MOLDRUP et al, 2003;DORNER;. Mais precisamente, a K a é condicionada em relação ao tamanho e continuidade dos Ma, considerados até mesmo mais importantes do que a quantidade de poros na determinação do fluxo de ar (BALL et al, 1988) e, portanto, sendo comum apresentar-se elevada nas camadas mais superficiais.…”

“…Esse resultado corrobora os de Silva et al (2009), os quais consideram que a K a depende Impacto do florestamento com Pinus taeda... basicamente do conteúdo de água e da densidade do solo, pois ambos influenciam a geometria e a continuidade do sistema poroso. Além disso, esse comportamento vem acompanhado da redução do carbono orgânico total, não favorecendo a estruturação e agregação do solo e, assim, influenciando a redução da aeração (TULI et al, 2005).…”