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| Titel |
The Role of Soil Cracking in the Structure Regeneration Process of the Compacted Agricultural Soil |
| VerfasserIn |
Sung Won Yoon, Guy Richard, Hubert Boizard, Jean Roger-Estrade |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041396
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| Zusammenfassung |
| It is of major importance to appreciate the role of crack in soil structure dynamics by climate
factors, especially in the agricultural soils under the reduced tillage systems. The compacted
soils with horizontally oriented soil crack (Φ) can be regarded as an intermediate stage
between compacted (Î) and well structured (Î) soil in their dynamics. The stochastic
Boolean model for this type of crack is presented in this study using the concept of stochastic
geometry. These cracks are assumed to be a line segment with a random length and direction,
and their middle points are assumed to follow the spatial Poisson point process. This
approach was tested on cracks pattern observed on a cropping system experiment in
northern France. . Three cropping systems on a long term experimental station
in a loamy soil are managed to present different degree of compaction levels by
soil moisture contents at the field. The indices indicating relative areas of each
structural feature (ÎsgÎsgnd Φ) proposed by Manichon (1987) and cracks has
been measured for 5 years by the soil morphological description method and image
analysis used in France to characterize the restructuring process on degraded soils
by compaction. In addition, soil morphology, physical, and hydraulic properties
(i.e., the structural void ratio, the shear strength, penetration resistance, and water
infiltration rate) were also compared among these structural types. The results showed
that natural recovery of degraded structural features and physical properties takes
many years under reduced tillage. The structural porosity of soils which was once
compacted is remained very low during the five following years under reduced
tillage. However, the evolution of structure during these 5 years due to climate effect
was also identified. This process typically develops the platy soil structure in the
upper part of the compacted zones, and consequently, the mechanic and hydraulic
properties were also altered. The specified intensity function of the Poisson process
representing crack population and spatial behaviour presented the spatial trend of
clustering behaviour, corresponding to evolution sequence of structural types. Resulted
cracks represented by a line segment show their correlation to climate. The crack
directions of soils with the highest compaction level are significantly horizontal
and different from those with the least compaction, implying the platy structure.
The shear strength of this type of soil decreased quickly, while infiltration rate
and penetration resistance remained rather constant. The infiltration rate which
was almost zero after compaction, increased quickly after several months but the
full recovery took more than one year. These results showed how climate have an
influence on soil structure regeneration in the reduced tillage system of this loamy soil. |
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