Modeling the Relationship between Soil Bulk Density and the Water Retention Curve

2006 ◽  
Vol 5 (2) ◽  
pp. 554-563 ◽  
Author(s):  
S. Assouline
Keyword(s):  
Bulk Density ◽  
Water Retention ◽  
Soil Bulk Density ◽  
Water Retention Curve ◽  
Retention Curve ◽  
The Relationship

scholarly journals Gamma-ray beam attenuation as an auxiliary technique for the evaluation of the soil water retention curve

1998 ◽  
Vol 55 (3) ◽  
pp. 498-502 ◽  
Author(s):  
O.O.S. BACCHI ◽  
K. REICHARDT ◽  
J.C.M. OLIVEIRA ◽  
D.R. NIELSEN
Keyword(s):  
Soil Moisture ◽  
Bulk Density ◽  
Water Retention ◽  
Gamma Ray ◽  
Soil Bulk Density ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Beam Attenuation

The soil water retention curve is fundamental for the hydraulic characterization of a soil and has many applications in agricultural research as well as in practical agriculture. A new procedure for soil moisture and soil bulk density evaluation inside closed pressure chambers through gamma-ray beam attenuation is presented. The proposed procedure presents several advantages in relation to the traditional process: avoids the need of continuous sample manipulation; minimizes the problem of hysteresis; allows a more precise evaluation of soil moisture by taking into account changes of soil bulk density due to swelling or shrinking on addition or removal of water; allows frequent evaluation of soil moisture without the need of opening the pressure chamber; allows a more precise judgement of equilibrium; reduces drastically the time of the determination of the retention curve and allows easy automation of data acquisition by a computer.

scholarly journals Evaluation of Water Retention Curves by Regression and Machine Learning Methods

2021 ◽  
Vol 1203 (3) ◽  
pp. 032088
Author(s):  
Milan Cisty ◽  
Barbora Povazanova
Keyword(s):  
Bulk Density ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Support Vector ◽  
Data Set ◽  
Retention Curve ◽  
Vector Machines ◽  
The One

Abstract The paper presents two methods that simplify the estimation of the water retention curves. The case study is evaluated for the soils of Záhorská lowland in the paper. These methods are based on the supposed dependence of the soil water content on the percentage content of the 1st, 2nd, 3rd and 4th Kopecký grain categories, and the dry bulk density. The representative set of the drying branch of water retention curves was measured using soil samples from the Záhorská lowland region in a laboratory. Particle size distribution and dry bulk density were also determined. In this paper support vector machines and multiple linear regression is compared to estimate the pedotransfer functions that can be used for the prediction of the drying branch of the water retention curve. Both methods were verified on other data set of measured water retention curves than the one which was used for building the models with a close agreement to measured results.

Evaluation of soil physical quality of irrigated agroecosystems in a semi-arid region of North-eastern Brazil

Soil Research ◽  
2012 ◽  
Vol 50 (6) ◽  
pp. 455 ◽  
Author(s):  
V. P. Pereira ◽  
M. E. Ortiz-Escobar ◽  
G. C. Rocha ◽  
R. N. Assis Junior ◽  
T. S. Oliveira
Keyword(s):  
Bulk Density ◽  
Soil Bulk Density ◽  
Natural Vegetation ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Physical Quality ◽  
Soil Physical Quality ◽  
Eastern Brazil ◽  
North Eastern

Concern about soil physical quality has grown in recent years, particularly in view of serious problems caused by intensive soil use. We hypothesised that improper soil management in irrigated areas damages the structure of sensitive soils in some regions in North-eastern Brazil. The aim of the study was to evaluate the physical quality of irrigated soils planted with annual and perennial crops, compared with soils under natural vegetation in Ceará State, Brazil. Measurements were made of least limiting water range (LLWR), the S index, and relative density. Undisturbed soil samples were collected at two depths (5–10 and 20–25 cm) in four cultivated areas (banana, guava, pasture, and maize/bean in succession) and two natural vegetation areas (NV1, NV2) adjacent to the cultivated areas. All sites were in the Jaguaribe-Apodi Irrigated District, Limoeiro do Norte, Ceará, Brazil. The LLWR was determined using the water retention curve, soil resistance to penetration, and soil bulk density, which are parameters needed to obtain the upper and lower limits of LLWR. The S index was obtained from the water retention curve. The relative density was obtained from the relationship between bulk density and maximum density obtained from the Proctor test. The S index varied as a function of soil management. The variation in LLWR differed between the studied areas as a function of soil bulk density. The relative densities for NV1 and NV2 were lower than for cultivated areas, showing that intensive soil use has caused compaction. The studied parameters seem to be good indicators of soil physical quality, and it was noticed that soils under cultivation suffer an alteration of their structure relative to soils under natural vegetation.

scholarly journals Corn crop performance in an Ultisol compacted by tractor traffic

2018 ◽  
Vol 53 (4) ◽  
pp. 464-477 ◽  
Author(s):  
Moacir Tuzzin de Moraes ◽  
Renato Levien ◽  
Carlos Ricardo Trein ◽  
João de Andrade Bonetti ◽  
Henrique Debiasi
Keyword(s):  
Grain Yield ◽  
Bulk Density ◽  
Field Capacity ◽  
Penetration Resistance ◽  
Soil Bulk Density ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Soil Penetration Resistance ◽  
Corn Crop ◽  
Corn Grain

Abstract: The objective of this work was to determine whether compaction by tractor traffic in areas managed under controlled traffic can be limiting to corn crop, under different tillage systems, in a Typic Paleudult of medium texture. Two experiments were carried out, one in the field over two crop seasons and another in a greenhouse. The treatments consisted of minimum tillage with chiselling; no-tillage subjected to one, three, or six passes of a tractor weighing 3.8 Mg; and an area without traffic. Evaluations were performed for soil physico-hydraulic parameters (soil bulk density, penetration resistance, and water retention curve), root and shoot growth, and grain yield. The agricultural traffic increased bulk density, soil penetration resistance, and water content at field capacity. The highest values for soil penetration resistance (1,600 kPa) and bulk density (1.67 g cm-3) in the trafficked soil were not limiting to corn development and increased grain yield for both crop seasons. Tractor traffic of up to six passes is beneficial to corn cultivation, and it increases water availability and corn grain yield.

scholarly journals An unfrozen water retention curve for capturing soil density and specific surface effects

2020 ◽  
Vol 195 ◽  
pp. 02018
Author(s):  
Jiwen Zhang ◽  
Qingyi Mu ◽  
Hongjian Liao ◽  
Jie Cao
Keyword(s):  
Wide Temperature Range ◽  
Water Retention ◽  
Water Retention Curve ◽  
Unfrozen Water ◽  
Retention Curve ◽  
New Model ◽  
Temperature Range ◽  
Unfrozen Water Content ◽  
Proposed Model ◽  
The Relationship

Unfrozen water retention curve (UWRC) defines the relationship between temperature and unfrozen water content in frozen soils. Although many models have been proposed for the UWRC, these existing models cannot predict UWRC well over a wide temperatures range. In this study, a new UWRC model is proposed with explicit considerations of both capillarity and adsorption. In this model, capillarity is considered dominating when the freezing of soil pore water at higher temperatures (above -2oC), whereas the effects of adsorption pronounce at temperatures below -2oC. Moreover, effects of void ratio on the freezing of capillary water are incorporated. The proposed model was applied to predict UWRCs of silt and clay at different initial void ratios over a wide temperature range (from -50 to 0oC). Predicted results by this new model are compared with predictions by three well-known existing models. The new model can capture the density effects on UWRC. Moreover, the new model can predict better UWRC over a wide temperature range since it explicitly considers both effects of capillarity and adsorption.

Deriving point and parametric pedotransfer functions of some gypsiferous soils

Soil Research ◽  
2008 ◽  
Vol 46 (3) ◽  
pp. 219 ◽  
Author(s):  
Mehdi Homaee ◽  
Ahmad Farrokhian Firouzi
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Bulk Density ◽  
Size Distribution ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Geometric Standard Deviation ◽  
Retention Curve ◽  
Gypsum Content

Parametric description of the soil water retention curve as well as the hydraulic conductivity curve is needed for modelling water movement and solute transport in the vadose zone. The objective of this study was to derive pedotransfer functions (PTFs) to predict the water retention curve and the van Genuchten and the van Genuchten–Mualem parameters of some gypsiferous soils. Consequently, 185 gypsiferous soil samples were collected and their physical properties were measured. The particle size distribution was determined in 2 steps: (i) with gypsum, by covering the particles with barium sulphate; (ii) without gypsum, using the hydrometry method. The easily obtainable variables were grouped as (1) particle size distribution, bulk density, and gypsum content; and (2) bulk density, gypsum content, geometric mean, and geometric standard deviation of the particle diameter. Stepwise multiple linear regression method was used to derive the PTFs. Two types of parametric and point functions were derived using these variables. The first group of variables predicted water retention and the van Genuchten and van Genuchten–Mualem parameters better than the second group. The gypsum content appeared to be the second dominant parameter for predicting water retention at 0, −330, −1000, −3000, −5000, and −15 000 cm. The derived PTFs were compared with the Rosetta database as independent dataset. The validity test indicated that in order to predict the hydraulic properties of gypsiferous soils the derived PTFs are more accurate than what can be obtained from the Rosetta database. Removal of gypsum increased the water retention at pressure heads of 0, –100, –330, –1000, –3000, –5000, and –15 000 cm (P < 0.01). The results also indicated that hydraulic parameters were different for the same soil with and without gypsum.

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