Search results for "Water retention curve"
showing 10 items of 17 documents
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Testing the shape-similarity hypothesis between partide-size distribution and water retention for sicilian soils
2012
Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD) but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH) method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD) method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1) or estimated by a logistical model with parameters gathered from literature (procedure AP2). For both SH and LD data, procedure AP2 …
Influence of biochar on the physical, chemical and retention properties of an amended sandy soil
2017
Soil porosity plays an important role in soil-water retention and water availability to crops, potentially affecting both agricultural practices and environmental sustainability. The pore structure controls fluid flow and transport through the soil, as well as the relationship between the properties of individual minerals and plants. Moreover, the anthropogenic pressure on soil properties has produced numerous sites with extensive desertification process close to residential areas. Biochar (biologically derived charcoal) is produced by pyrolysis of biomasses under low oxygen conditions, and it can be applied for recycling organic waste in soils and increase soil fertility, improving soil st…
Testing the shape-similarity hypothesis between particle-size distribution and water retention for Sicilian soils
2012
Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particlesize distribution (PSD) but limited experimental PSD data are generally determined by the conventional sieve-hydrometer (SH) method. Detailed PSDs can be obtained by fitting a continuous model to SH data or performing measurements by the laser diffraction (LD) method. The AP model was applied to 40 Sicilian soils for which the PSD was measured by both the SH and LD methods. The scale factor was set equal to 1.38 (procedure AP1) or estimated by a logistical model with parameters gathered from literature (procedure AP2). For both SH and LD data, procedure AP2 …
A Comparative Study of Soil Suction Measurement Using Two Different High-Range Psychrometers
2007
An extensive experimental study was performed to compare the measurement capabilities within different ranges of two total suction measurement equipment: SMI transistor psychrometers and a chilled-mirror dew-point psychrometer (WP4 Dewpoint PotentiaMeter). The equipment were used in a systematic way to determine the relative humidity of the environment surrounding different compacted clayey soils along drying paths and covering a wide total suction range (0.1 to 70 MPa). The equipment description and the calibration protocols followed are presented, as well as suggestions regarding the improvement of their performance. The water retention curves of two different compacted clayey soils are p…
A test of the Beerkan Estimation of Soil Transfer parameters (BEST) procedure
2014
Abstract The Beerkan Estimation of Soil Transfer parameters (BEST) procedure is attractive for a simple soil hydraulic characterization but testing the ability of this procedure to estimate soil properties is necessary. The BEST predictions were compared with soil water retention and hydraulic conductivity data measured in the laboratory and the field, respectively, at ten Sicilian field sites. Provided that BEST yielded physically possible scale parameters of the soil characteristic curves in most of the four replicated infiltration runs at a site, the measured water retention was satisfactorily predicted (i.e., not statistically significant differences between measurements and predictions…
Soil moisture influences sorptivity and water repellency of topsoil aggregates in native grasslands
2017
Abstract Water repellency is associated to coating of soil particles by hydrophobic substances, usually of organic origin, affecting water dynamics in soil matrix. We analyzed the effect of water repellency on water sorptivity of topsoil aggregates of six soil types under three initial moisture conditions (10 kPa, 100 kPa, and air-dried). Undisturbed soil samples were collected to evaluate sorptivity in the 0–5 cm soil layer at different locations in Pampa Biome in southern Brazil. Disturbed soil samples were also collected for soil particle size distribution, particle density and organic matter content. Sorptivity test was conducted in a tension micro-infiltrometer, using distilled water a…
Appendix – Additional Measurements
2016
This appendix deals with the determination of different soil physical and hydraulic characteristics used in the analysis and/or interpretation of the infiltration experiments. The core method and the excavation method for measurement of soil bulk density are initially presented. Determination of soil water content by the thermo-gravimetric and the Time Domain Reflectometry methods is then illustrated. Subsequently, field measurement of soil water matric potential by tensiometers is discussed. Laboratory determination of the soil water retention curve by tensiometric and pressiometric techniques is also described. Finally, different methods to test water stability of soil aggregates are illu…
Artificial Neural Networks for Predicting the Water Retention Curve of Sicilian Agricultural Soils
2018
Modeling soil-water regime and solute transport in the vadose zone is strategic for estimating agricultural productivity and optimizing irrigation water management. Direct measurements of soil hydraulic properties, i.e., the water retention curve and the hydraulic conductivity function, are often expensive and time-consuming, and represent a major obstacle to the application of simulation models. As a result, there is a great interest in developing pedotransfer functions (PTFs) that predict the soil hydraulic properties from more easily measured and/or routinely surveyed soil data, such as particle size distribution, bulk density (&rho
A simplified approach to estimate water retention for Sicilian soils by the Arya-Paris model
2014
Application of the Arya and Paris (AP) model to estimate the soil water retention curve requires a detailed description of the particle-size distribution (PSD) because the scale factor a, relating the pore length of an ideal soil to that of the natural one, depends on the particle size distribution parameters. For a dataset of 140 Sicilian soils that were grouped in five texture groups, the logistic and linear models were applied to evaluate a, and the water retention values predicted by the AP model were compared with the measured ones. Using the parameters proposed by Arya et al. (1999), the two models yielded similar unsystematic root mean error of estimate (RMSEu). Therefore, their pote…