Millimeter-scale spatial variability in soil water sorptivity

PD Hallett*, N Nunan, JT Douglas, IM Young

*Corresponding author for this work

Research output: Contribution to journalArticle

88 Citations (Scopus)

Abstract

Recent evidence suggests that reduced water infiltration may be linked to small scale microbial and/or chemical processes that cause subcritical water repellency. We measured water sorptivity on the surface of a large intact block of soil (0.9 m wide, 1.3 m long, 0.25 m deep) taken from a grassland site and examined the effects of surface elevation and water repellency on water sorptivity at the millimeter scale. The soil block was partially dried to 0.22 mm(3) mm(-1), appeared to wet readily, and is not severely water repellent at any water content. Water sorptivity varied from 0.1 to 0.8 mm S-1/2 across the sampling grid with a coefficient of variation (CV) of 0.57. Water repellency, determined by comparing water and ethanol sorptivities, also varied considerably (CV = 0.47). Geostatistical analyses of water sorptivity and repellency measurements found little evidence of spatial autocorrelation, suggesting a high degree of local variability. These data were compared to larger scale measurements obtained with conventional infiltrometers under tension conditions (40 mm contact radius), and ponded conditions (37 and 55 mm radius rings) where macropores influence infiltration heterogeneity. Larger scale tension infiltrometer measurements were less variable with a CV of 0.22, whereas ponded infiltrometer measurements were more variable, CV > 0.50, presumably because of the influence of macropore flow. Data collected on surface elevation showed that ponded infiltration but not tension infiltration was influenced by surface topography. The results suggested that repellency can induce levels of spatial variability in water transport at small scales comparable to what macropores induce at larger scales.

Original languageEnglish
Pages (from-to)352-358
Number of pages7
JournalSoil Science Society of America Journal
Volume68
Issue number2
DOIs
Publication statusPublished - Mar 2004

Keywords

  • range
  • transport
  • field
  • intrinsic sorptivity
  • macroporosity
  • rates
  • growth
  • steady-state infiltration

Cite this

Millimeter-scale spatial variability in soil water sorptivity. / Hallett, PD; Nunan, N; Douglas, JT; Young, IM.

In: Soil Science Society of America Journal, Vol. 68, No. 2, 03.2004, p. 352-358.

Research output: Contribution to journalArticle

Hallett, PD ; Nunan, N ; Douglas, JT ; Young, IM. / Millimeter-scale spatial variability in soil water sorptivity. In: Soil Science Society of America Journal. 2004 ; Vol. 68, No. 2. pp. 352-358.
@article{eaa8a72be6fd4b30964e0dfa5c7f4bfa,
title = "Millimeter-scale spatial variability in soil water sorptivity",
abstract = "Recent evidence suggests that reduced water infiltration may be linked to small scale microbial and/or chemical processes that cause subcritical water repellency. We measured water sorptivity on the surface of a large intact block of soil (0.9 m wide, 1.3 m long, 0.25 m deep) taken from a grassland site and examined the effects of surface elevation and water repellency on water sorptivity at the millimeter scale. The soil block was partially dried to 0.22 mm(3) mm(-1), appeared to wet readily, and is not severely water repellent at any water content. Water sorptivity varied from 0.1 to 0.8 mm S-1/2 across the sampling grid with a coefficient of variation (CV) of 0.57. Water repellency, determined by comparing water and ethanol sorptivities, also varied considerably (CV = 0.47). Geostatistical analyses of water sorptivity and repellency measurements found little evidence of spatial autocorrelation, suggesting a high degree of local variability. These data were compared to larger scale measurements obtained with conventional infiltrometers under tension conditions (40 mm contact radius), and ponded conditions (37 and 55 mm radius rings) where macropores influence infiltration heterogeneity. Larger scale tension infiltrometer measurements were less variable with a CV of 0.22, whereas ponded infiltrometer measurements were more variable, CV > 0.50, presumably because of the influence of macropore flow. Data collected on surface elevation showed that ponded infiltration but not tension infiltration was influenced by surface topography. The results suggested that repellency can induce levels of spatial variability in water transport at small scales comparable to what macropores induce at larger scales.",
keywords = "range, transport, field, intrinsic sorptivity, macroporosity, rates, growth, steady-state infiltration",
author = "PD Hallett and N Nunan and JT Douglas and IM Young",
year = "2004",
month = "3",
doi = "10.2136/sssaj2004.3520",
language = "English",
volume = "68",
pages = "352--358",
journal = "Soil Science Society of America Journal",
issn = "0361-5995",
publisher = "Soil Science Society of America",
number = "2",

}

TY - JOUR

T1 - Millimeter-scale spatial variability in soil water sorptivity

AU - Hallett, PD

AU - Nunan, N

AU - Douglas, JT

AU - Young, IM

PY - 2004/3

Y1 - 2004/3

N2 - Recent evidence suggests that reduced water infiltration may be linked to small scale microbial and/or chemical processes that cause subcritical water repellency. We measured water sorptivity on the surface of a large intact block of soil (0.9 m wide, 1.3 m long, 0.25 m deep) taken from a grassland site and examined the effects of surface elevation and water repellency on water sorptivity at the millimeter scale. The soil block was partially dried to 0.22 mm(3) mm(-1), appeared to wet readily, and is not severely water repellent at any water content. Water sorptivity varied from 0.1 to 0.8 mm S-1/2 across the sampling grid with a coefficient of variation (CV) of 0.57. Water repellency, determined by comparing water and ethanol sorptivities, also varied considerably (CV = 0.47). Geostatistical analyses of water sorptivity and repellency measurements found little evidence of spatial autocorrelation, suggesting a high degree of local variability. These data were compared to larger scale measurements obtained with conventional infiltrometers under tension conditions (40 mm contact radius), and ponded conditions (37 and 55 mm radius rings) where macropores influence infiltration heterogeneity. Larger scale tension infiltrometer measurements were less variable with a CV of 0.22, whereas ponded infiltrometer measurements were more variable, CV > 0.50, presumably because of the influence of macropore flow. Data collected on surface elevation showed that ponded infiltration but not tension infiltration was influenced by surface topography. The results suggested that repellency can induce levels of spatial variability in water transport at small scales comparable to what macropores induce at larger scales.

AB - Recent evidence suggests that reduced water infiltration may be linked to small scale microbial and/or chemical processes that cause subcritical water repellency. We measured water sorptivity on the surface of a large intact block of soil (0.9 m wide, 1.3 m long, 0.25 m deep) taken from a grassland site and examined the effects of surface elevation and water repellency on water sorptivity at the millimeter scale. The soil block was partially dried to 0.22 mm(3) mm(-1), appeared to wet readily, and is not severely water repellent at any water content. Water sorptivity varied from 0.1 to 0.8 mm S-1/2 across the sampling grid with a coefficient of variation (CV) of 0.57. Water repellency, determined by comparing water and ethanol sorptivities, also varied considerably (CV = 0.47). Geostatistical analyses of water sorptivity and repellency measurements found little evidence of spatial autocorrelation, suggesting a high degree of local variability. These data were compared to larger scale measurements obtained with conventional infiltrometers under tension conditions (40 mm contact radius), and ponded conditions (37 and 55 mm radius rings) where macropores influence infiltration heterogeneity. Larger scale tension infiltrometer measurements were less variable with a CV of 0.22, whereas ponded infiltrometer measurements were more variable, CV > 0.50, presumably because of the influence of macropore flow. Data collected on surface elevation showed that ponded infiltration but not tension infiltration was influenced by surface topography. The results suggested that repellency can induce levels of spatial variability in water transport at small scales comparable to what macropores induce at larger scales.

KW - range

KW - transport

KW - field

KW - intrinsic sorptivity

KW - macroporosity

KW - rates

KW - growth

KW - steady-state infiltration

U2 - 10.2136/sssaj2004.3520

DO - 10.2136/sssaj2004.3520

M3 - Article

VL - 68

SP - 352

EP - 358

JO - Soil Science Society of America Journal

JF - Soil Science Society of America Journal

SN - 0361-5995

IS - 2

ER -