Water repellency and distribution of hydrophilic and hydrophobic compounds in soil aggregates from different tillage systems

E. Urbanek*, P. Hallett, D. Feeney, R. Horn

*Corresponding author for this work

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

Water repellency properties of individual soil aggregates offer increased reduction of carbon (C) mineralization within soils. These studies explore the spatial distributions of C and groupings of C-H and C = O compounds at multiple soil depths, on surfaces and within multiple sized soil aggregates. Measurements were conducted on soil aggregates, sampled from three horizons in a silty loam Anthrosol under long term grassland pastures and short term conservation tillage wheat and in a silty loam Luvisol subjected to long term conventional tillage of maize. Soil aggregates were fractionated into seven size classes by dry sieving and single aggregates were mechanically separated into external, transitional and interior regions by soil aggregate erosion (SAE) chambers. Soil materials from different aggregate-size classes and aggregate layers were evaluated for total C and nitrogen (N) contents. Functional hydrophobic and hydrophilic groups in each of these soils were identified by DRIFT spectrometry. Water repellency was identified on the surfaces of different size-class aggregates and each of their interior regions by the ethanol/water sorptivity method.

Total organic C contents within individual aggregates and size classes varied considerably and were influenced by soil depths and management practices. Whole microaggregates had greater C contents than macroaggregates. Total organic C content was highly correlated to hydrophobic (CH) groups (R-2=0.78), but not hydrophilic groups. External surfaces of aggregates from no tilled soils of wheat and grass exhibited the largest gradients of hydrophobic C-H groups when compared to their interiors. More hydrophilic C = O groups were observed in maize and grassland biomes where plant biomass was greater. Although highly variable, the largest gradients of C = O groups were measured in the Ap and Ah horizons of maize and grasslands. Water repellency indices were greater in aggregate sizes ranging from 8 to 5 mm for agricultural soil management systems and were similar for most aggregate sizes measured for grasslands. Soil aggregate water repellency appears to be controlled by the uniform distribution of these compounds at surfaces of all soil aggregate-size fractions and possibly by the concentrations of hydrophobic compounds on surfaces of aggregates at multiple soil depths. Further inquires into the mechanisms controlling soil wetting require more than a quantification of total organic C. These studies demonstrated spatial interactions between the locations and quantities of hydrophobic and hydrophobic compounds distributed among soil aggregate-size fractions located within the soil profile. (C) 2007 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)147-155
Number of pages9
JournalGeoderma
Volume140
Issue number1-2
Early online date10 May 2007
DOIs
Publication statusPublished - 15 Jun 2007

Keywords

  • soil organic carbon
  • management
  • organic-matter
  • water repellency
  • fractions
  • sandy soils
  • aggregates
  • hydrophobic and hydrophilic groups
  • transport
  • coatings
  • arable soils
  • stability
  • hydrophobicity
  • sorptivity
  • wettability

Cite this

Water repellency and distribution of hydrophilic and hydrophobic compounds in soil aggregates from different tillage systems. / Urbanek, E.; Hallett, P.; Feeney, D.; Horn, R.

In: Geoderma, Vol. 140, No. 1-2, 15.06.2007, p. 147-155.

Research output: Contribution to journalArticle

@article{cd187d7a47a7441c96055be5c54618d3,
title = "Water repellency and distribution of hydrophilic and hydrophobic compounds in soil aggregates from different tillage systems",
abstract = "Water repellency properties of individual soil aggregates offer increased reduction of carbon (C) mineralization within soils. These studies explore the spatial distributions of C and groupings of C-H and C = O compounds at multiple soil depths, on surfaces and within multiple sized soil aggregates. Measurements were conducted on soil aggregates, sampled from three horizons in a silty loam Anthrosol under long term grassland pastures and short term conservation tillage wheat and in a silty loam Luvisol subjected to long term conventional tillage of maize. Soil aggregates were fractionated into seven size classes by dry sieving and single aggregates were mechanically separated into external, transitional and interior regions by soil aggregate erosion (SAE) chambers. Soil materials from different aggregate-size classes and aggregate layers were evaluated for total C and nitrogen (N) contents. Functional hydrophobic and hydrophilic groups in each of these soils were identified by DRIFT spectrometry. Water repellency was identified on the surfaces of different size-class aggregates and each of their interior regions by the ethanol/water sorptivity method.Total organic C contents within individual aggregates and size classes varied considerably and were influenced by soil depths and management practices. Whole microaggregates had greater C contents than macroaggregates. Total organic C content was highly correlated to hydrophobic (CH) groups (R-2=0.78), but not hydrophilic groups. External surfaces of aggregates from no tilled soils of wheat and grass exhibited the largest gradients of hydrophobic C-H groups when compared to their interiors. More hydrophilic C = O groups were observed in maize and grassland biomes where plant biomass was greater. Although highly variable, the largest gradients of C = O groups were measured in the Ap and Ah horizons of maize and grasslands. Water repellency indices were greater in aggregate sizes ranging from 8 to 5 mm for agricultural soil management systems and were similar for most aggregate sizes measured for grasslands. Soil aggregate water repellency appears to be controlled by the uniform distribution of these compounds at surfaces of all soil aggregate-size fractions and possibly by the concentrations of hydrophobic compounds on surfaces of aggregates at multiple soil depths. Further inquires into the mechanisms controlling soil wetting require more than a quantification of total organic C. These studies demonstrated spatial interactions between the locations and quantities of hydrophobic and hydrophobic compounds distributed among soil aggregate-size fractions located within the soil profile. (C) 2007 Elsevier B.V. All rights reserved.",
keywords = "soil organic carbon, management, organic-matter, water repellency, fractions, sandy soils, aggregates, hydrophobic and hydrophilic groups, transport, coatings, arable soils, stability, hydrophobicity, sorptivity, wettability",
author = "E. Urbanek and P. Hallett and D. Feeney and R. Horn",
year = "2007",
month = "6",
day = "15",
doi = "10.1016/j.geoderma.2007.04.001",
language = "English",
volume = "140",
pages = "147--155",
journal = "Geoderma",
issn = "0016-7061",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - Water repellency and distribution of hydrophilic and hydrophobic compounds in soil aggregates from different tillage systems

AU - Urbanek, E.

AU - Hallett, P.

AU - Feeney, D.

AU - Horn, R.

PY - 2007/6/15

Y1 - 2007/6/15

N2 - Water repellency properties of individual soil aggregates offer increased reduction of carbon (C) mineralization within soils. These studies explore the spatial distributions of C and groupings of C-H and C = O compounds at multiple soil depths, on surfaces and within multiple sized soil aggregates. Measurements were conducted on soil aggregates, sampled from three horizons in a silty loam Anthrosol under long term grassland pastures and short term conservation tillage wheat and in a silty loam Luvisol subjected to long term conventional tillage of maize. Soil aggregates were fractionated into seven size classes by dry sieving and single aggregates were mechanically separated into external, transitional and interior regions by soil aggregate erosion (SAE) chambers. Soil materials from different aggregate-size classes and aggregate layers were evaluated for total C and nitrogen (N) contents. Functional hydrophobic and hydrophilic groups in each of these soils were identified by DRIFT spectrometry. Water repellency was identified on the surfaces of different size-class aggregates and each of their interior regions by the ethanol/water sorptivity method.Total organic C contents within individual aggregates and size classes varied considerably and were influenced by soil depths and management practices. Whole microaggregates had greater C contents than macroaggregates. Total organic C content was highly correlated to hydrophobic (CH) groups (R-2=0.78), but not hydrophilic groups. External surfaces of aggregates from no tilled soils of wheat and grass exhibited the largest gradients of hydrophobic C-H groups when compared to their interiors. More hydrophilic C = O groups were observed in maize and grassland biomes where plant biomass was greater. Although highly variable, the largest gradients of C = O groups were measured in the Ap and Ah horizons of maize and grasslands. Water repellency indices were greater in aggregate sizes ranging from 8 to 5 mm for agricultural soil management systems and were similar for most aggregate sizes measured for grasslands. Soil aggregate water repellency appears to be controlled by the uniform distribution of these compounds at surfaces of all soil aggregate-size fractions and possibly by the concentrations of hydrophobic compounds on surfaces of aggregates at multiple soil depths. Further inquires into the mechanisms controlling soil wetting require more than a quantification of total organic C. These studies demonstrated spatial interactions between the locations and quantities of hydrophobic and hydrophobic compounds distributed among soil aggregate-size fractions located within the soil profile. (C) 2007 Elsevier B.V. All rights reserved.

AB - Water repellency properties of individual soil aggregates offer increased reduction of carbon (C) mineralization within soils. These studies explore the spatial distributions of C and groupings of C-H and C = O compounds at multiple soil depths, on surfaces and within multiple sized soil aggregates. Measurements were conducted on soil aggregates, sampled from three horizons in a silty loam Anthrosol under long term grassland pastures and short term conservation tillage wheat and in a silty loam Luvisol subjected to long term conventional tillage of maize. Soil aggregates were fractionated into seven size classes by dry sieving and single aggregates were mechanically separated into external, transitional and interior regions by soil aggregate erosion (SAE) chambers. Soil materials from different aggregate-size classes and aggregate layers were evaluated for total C and nitrogen (N) contents. Functional hydrophobic and hydrophilic groups in each of these soils were identified by DRIFT spectrometry. Water repellency was identified on the surfaces of different size-class aggregates and each of their interior regions by the ethanol/water sorptivity method.Total organic C contents within individual aggregates and size classes varied considerably and were influenced by soil depths and management practices. Whole microaggregates had greater C contents than macroaggregates. Total organic C content was highly correlated to hydrophobic (CH) groups (R-2=0.78), but not hydrophilic groups. External surfaces of aggregates from no tilled soils of wheat and grass exhibited the largest gradients of hydrophobic C-H groups when compared to their interiors. More hydrophilic C = O groups were observed in maize and grassland biomes where plant biomass was greater. Although highly variable, the largest gradients of C = O groups were measured in the Ap and Ah horizons of maize and grasslands. Water repellency indices were greater in aggregate sizes ranging from 8 to 5 mm for agricultural soil management systems and were similar for most aggregate sizes measured for grasslands. Soil aggregate water repellency appears to be controlled by the uniform distribution of these compounds at surfaces of all soil aggregate-size fractions and possibly by the concentrations of hydrophobic compounds on surfaces of aggregates at multiple soil depths. Further inquires into the mechanisms controlling soil wetting require more than a quantification of total organic C. These studies demonstrated spatial interactions between the locations and quantities of hydrophobic and hydrophobic compounds distributed among soil aggregate-size fractions located within the soil profile. (C) 2007 Elsevier B.V. All rights reserved.

KW - soil organic carbon

KW - management

KW - organic-matter

KW - water repellency

KW - fractions

KW - sandy soils

KW - aggregates

KW - hydrophobic and hydrophilic groups

KW - transport

KW - coatings

KW - arable soils

KW - stability

KW - hydrophobicity

KW - sorptivity

KW - wettability

U2 - 10.1016/j.geoderma.2007.04.001

DO - 10.1016/j.geoderma.2007.04.001

M3 - Article

VL - 140

SP - 147

EP - 155

JO - Geoderma

JF - Geoderma

SN - 0016-7061

IS - 1-2

ER -