Soil water characteristic curve measurement without bulk density changes and its implications in the estimation of soil hydraulic properties

Geoderma ◽  
2011 ◽  
Vol 167-168 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaoli Fu ◽  
Mingan Shao ◽  
Dianqing Lu ◽  
Huimin Wang
Keyword(s):  
Bulk Density ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Characteristic Curve ◽  
Soil Hydraulic Properties ◽  
Soil Water Characteristic Curve ◽  
Soil Hydraulic

Root effects on soil water and hydraulic properties

Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
Horst Gerke ◽  
Rolf Kuchenbuch
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Root Effects

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

The Development of a One-Parameter Model for the Soil-Water Characteristic Curve in Loess Gully Regions

2012 ◽  
Vol 256-259 ◽  
pp. 488-493
Author(s):  
Xiao Yu Song ◽  
Huai You Li ◽  
Wen Juan Shi
Keyword(s):  
Soil Water ◽  
Hydraulic Properties ◽  
Characteristic Curve ◽  
Soil Samples ◽  
Soil Hydraulic Properties ◽  
Logarithmic Model ◽  
Soil Water Characteristic Curve ◽  
Soil Water Characteristic Curves ◽  
Best Fit ◽  
Gardner Model

It is important to understand soil hydraulic properties in order to predict the movement of water and solutes such as pollutants. To this end, 55 soil samples were collected from different areas of the Nanxiaohegou basin and used to generate soil-water characteristic curves. These were then fitted using the power-, exponential-, and logarithmic versions of the Gardner model; the logarithmic model yielded the best fit overall. The logarithmic model was further simplified to yield a one-parameter model for estimating the soil-water characteristic curve within the basin, and it was demonstrated that the value of the single parameter is dependent on the topography and usage of the land.

The hydrology of Vertosols used for cotton production: II. Pedotransfer functions to predict hydraulic properties

Soil Research ◽  
2006 ◽  
Vol 44 (5) ◽  
pp. 479 ◽  
Author(s):  
R. W. Vervoort ◽  
B. Minasny ◽  
S. R. Cattle
Keyword(s):  
Linear Regression ◽  
Bulk Density ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Characteristic Curve ◽  
Total Carbon ◽  
Pedotransfer Functions ◽  
Cotton Production ◽  
Total Carbon Content ◽  
Soil Water Characteristic Curve

Using a range of earlier published results and a recently published dataset, pedotransfer functions (PTFs) were developed to predict some hydraulic properties of Vertosols. A fitting approach using neural networks was employed with good results to predict the soil water characteristic curve. The developed functions are complex due to the large numbers of parameters, but moisture contents are predicted to within 5%. Other PTFs to predict the moisture content at the drained upper limit (DUL) and lower limit (LL), and bulk density in the normal shrinkage curve, were developed using multiple linear regression. The PTFs to predict the soil water characteristic curve, DUL and LL, and the bulk density in the normal shrinkage zone were mainly based on total clay, sand, and silt contents and bulk density, with minor contributions of ECEC and total carbon content. PTFs for unsaturated hydraulic conductivities were also developed using multi-linear regression and were mainly dependent on silt contents and ESP values. The mean error in these predictions was 2.76 mm/h, which is reasonable for predictions at the field and farm scale where inherent soil variability can cause larger variation. The developed PTFs can be used to predict parameters needed in crop modelling tools such as OZCOT to simulate cotton development on Vertosols. Some further examples of the use of the PTFs for management of irrigation are given.

EFFECT OF CHANGING BULK DENSITY DURING WATER DESORPTION MEASUREMENT ON SOIL HYDRAULIC PROPERTIES

Soil Science ◽  
2004 ◽  
Vol 169 (5) ◽  
pp. 319-329 ◽  
Author(s):  
Dianqing Lu ◽  
Mingan Shao ◽  
Robert Horton ◽  
Chunping Liu
Keyword(s):  
Bulk Density ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Water Desorption ◽  
Soil Hydraulic

scholarly journals Inverse estimation of soil hydraulic properties and water repellency following artificially induced drought stress

2018 ◽  
Vol 66 (2) ◽  
pp. 170-180 ◽  
Author(s):  
Vilim Filipović ◽  
Thomas Weninger ◽  
Lana Filipović ◽  
Andreas Schwen ◽  
Keith L. Bristow ◽  
...  
Keyword(s):  
Soil Water ◽  
Inverse Modeling ◽  
Hydraulic Properties ◽  
Global Climate ◽  
Water Repellency ◽  
Irrigation Event ◽  
Water Infiltration ◽  
Soil Hydraulic Properties ◽  
Soil Water Repellency ◽  
Soil Hydraulic

AbstractGlobal climate change is projected to continue and result in prolonged and more intense droughts, which can increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, withR2and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (Ks) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.

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