Particle-size and organic matter effects on structure and water retention of soils

Biologia ◽  
2015 ◽  
Vol 70 (11) ◽  
Author(s):  
Kálmán Rajkai ◽  
Brigitta Tóth ◽  
Gyöngyi Barna ◽  
Hilda Hernádi ◽  
Mihály Kocsis ◽  
...  

AbstractWater storage and flow in soils are highly dependent on soil structure, which strongly determines soil porosity. However pore size distribution can be derived from soil water retention curve (SWRC). Structural characteristics of cultivated arable fields (693 soil profiles, 1773 samples) and soils covered by treated forest stands (137 soil profiles, 405 samples) were selected from the MARTHA Hungarian soil physical database, and evaluated for expressing organic matter effects on soil structure and water retention. For this purpose the normalized pore size distribution curves were determined for the selected soils, plus the modal suction (MS) corresponding to the most frequent pore size class of the soil. Skewness of soils’ pore size distribution curves are found different. The quasi-normal distribution of sandy soils are transformed into distorted in clayey soils. A general growing trend of MS with the ever finer soil texture was shown. Sandy soils have the lowest average MS values, i.e. the highest most frequent equivalent pore diameter. Silty clay and clay soil textures are characterized by the highest MS values. A slight effect of land use and organic matter content is also observable in different MS values of soils under forest vegetation (’forest’) and cultivated arable land (‘plough fields’). MS values of the two land uses were compared statistically. The results of the analyses show that certain soil group’s MS are significantly different under forest vegetation and cultivation. However this difference can be explained only partly and indirectly by the organic matter of different plant coverage in the land use types.

2008 ◽  
Vol 3 (Special Issue No. 1) ◽  
pp. S7-S20 ◽  
Author(s):  
M. Kutílek ◽  
L. Jendele

Products of biological processes are the dominant factor of soil structure formation in A horizons, while in B horizons their role is less expressed. Soil structure influences dominantly the structural domain of the pore system in bimodal soils thus affecting soil hydraulic functions. The form of soil hydraulic functions depends upon the pore size distribution and generally upon configuration of the soil pore system. We used the functions derived for the lognormal pore size distribution and modified them to bi-modal soils. The derived equations were tested by experimental data of catalogued soils. The procedure leads to the separation of two mutually different domains of structural and matrix pores. The value of the pressure head (potential) separating the two domains is not constant and varies in a broad range. For each domain we obtained its water retention function and unsaturated hydraulic conductivity function. The separation of hydraulic functions for the two domains is a key problem in the solution of preferential flow and in controlling lateral flow between the structural and matrix domains. Water retention function is fully physically based while the conductivity function still keeps fitting parameters, too. Their simple relationship to tortuosity and pores connectivity was not confirmed. Since they differ substantially for matrix and structural domains, we suppose that there exists a great difference in configuration of porous systems in structural and matrix domains. The use of uniform fitting conductivity parameters for the whole range of pores is not justifiable.


Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 339 ◽  
Author(s):  
Pavel Dlapa ◽  
Dávid Hriník ◽  
Andrej Hrabovský ◽  
Ivan Šimkovic ◽  
Hubert Žarnovičan ◽  
...  

Soil hydraulic properties are very sensitive to land-use in regions susceptible to physical degradation. Intensive agricultural practices often lead to soil compaction and erosion in the investigated area. The main goal of this paper was to evaluate the impact of land-use on the pore size distribution and water retention in loamy soils. The soil water retention curve (SWRC) combined the total porosity and the water retention of the undisturbed sample at 3, 10, 31, 100, 310, and 1000 hPa suctions and the disturbed sample at 1.5 MPa. The triple-exponential model approximated the curve’s course, and its derivative defined the distinct macro-, structural, and textural pore maxima, with characteristic suctions corresponding to SWRC inflection points. The soil organic carbon content had the greatest influence on the content of all three pore classes. The water retention properties followed the hierarchical pore size distribution in the four research plots and decreased in the identical orchard > forest > grassland > arable soil order. These results show that the orchard and forest areas are the most appropriate land uses with respect to porosity and water retention, while the grassland has not fully recovered after its conversion from arable soil and remains relatively poor, and the arable soil properties are the worst.


Author(s):  
Gabriele Della Vecchia ◽  
Anne-Catherine Dieudonné ◽  
Cristina Jommi ◽  
Robert Charlier

2013 ◽  
Vol 50 (4) ◽  
pp. 435-450 ◽  
Author(s):  
Christopher T.S. Beckett ◽  
Charles E. Augarde

Several models have been suggested to link a soil's pore-size distribution to its retention properties. This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties. Mechanisms are suggested for the determination of both the main drying and wetting paths, which incorporate an adsorbed water phase and retention hysteresis. Predicted results are then compared with measured retention data to validate the model and to provide a foundation for discussing the validity and limitations of using pore-size distributions to predict retention properties.


2019 ◽  
Vol 18 (1) ◽  
pp. 0 ◽  
Author(s):  
Mehdi Rahmati ◽  
Andreas Pohlmeier ◽  
Sara Mola Ali Abasiyan ◽  
Lutz Weihermüller ◽  
Harry Vereecken

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1113
Author(s):  
Stefan Julich ◽  
Janis Kreiselmeier ◽  
Simon Scheibler ◽  
Rainer Petzold ◽  
Kai Schwärzel ◽  
...  

Tree species, e.g., shallow vs. deep rooting tree species, have a distinct impact on hydrological properties and pore size distribution of soils. In our study, we determined the soil hydrologic properties and pore size distribution at three forest stands and one pasture as reference on soils with stagnant water conditions. All sites are located in the Wermsdorf Forest, where historical studies have demonstrated severe silvicultural problems associated with stagnant water in the soil. The studied stands represent different stages of forest management with a young 25-year-old oak (Sessile Oak (Quercus petraea) and Red oak (Q. robur)) plantation, a 170-year-old oak stand and a 95-year-old Norway Spruce (Picea abies) stand in second rotation. We determined the infiltration rates under saturated and near-saturated conditions with a hood-infiltrometer at the topsoil as well as the saturated hydraulic conductivity and water retention characteristic from undisturbed soil samples taken from the surface and 30 cm depth. We used the bi-modal Kosugi function to calculate the water retention characteristic and applied the normalized Young-Laplace equation to determine the pore size distribution of the soil samples. Our results show that the soils of the old stands have higher amounts of transmission pores, which lead to higher infiltration rates and conductance of water into the subsoil. Moreover, the air capacity under the old oak was highest at the surface and at 30 cm depth. There was also an observable difference between the spruce and oak regarding their contrasting root system architecture. Under the oak, higher hydraulic conductivities and air capacities were observed, which may indicate a higher and wider connected macropore system. Our results confirm other findings that higher infiltration rates due to higher abundance of macropores can be found in older forest stands. Our results also demonstrate that an adapted forest management is important, especially at sites affected by stagnant water conditions. However, more measurements are needed to expand the existing data base of soil hydraulic properties of forest soils in temperate climates.


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