ESTIMATION OF WATER-RETENTION CHARACTERISTICS FROM THE BULK DENSITY AND PARTICLE-SIZE DISTRIBUTION OF SWEDISH SOILS

Soil Science ◽  
1996 ◽  
Vol 161 (12) ◽  
pp. 832-845 ◽  
Author(s):  
Kálmán Rajkai ◽  
Sándor Kabos ◽  
M. Th. Van Genuchten ◽  
Per-Erik Jansson
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Bulk Density ◽  
Size Distribution ◽  
Water Retention ◽  
Retention Characteristics

Impact of Biochar on Water Holding Capacity of Two Chinese Agricultural Soil

2014 ◽  
Vol 941-944 ◽  
pp. 952-955 ◽  
Author(s):  
Dao Yuan Wang ◽  
Deng Hua Yan ◽  
Xin Shan Song ◽  
Hao Wang
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Soil Type ◽  
Agricultural Soil ◽  
Water Retention ◽  
Water Holding Capacity ◽  
Walnut Shell ◽  
Retention Characteristics ◽  
Water Holding

Adding biochar to agricultural soil has been suggested as an approach to enhance soil carbon sequestration. Biochar has also been used as a soil amendment to reduce nutrient leaching, reduce soil acidity and improve water holding capacity. Walnut shells and woody material are waste products of orchards that are cheap, carbon-rich and good feedstock for production of biochar. The effectiveness of biochar as an amendment varies considerably as a function of its feedstock, temperature during pyrolysis, the biochar dose to soil, and mechanical composition. Biochar was produced from pyrolysis of walnut shell at 900 °C and soft wood at 600 to 700 °C. We measured the effect of these different parameters in two types of agricultural soil in Jilin and Beijing, China, a silt clay loam and a sandy loam, on the soils’ particle size distribution and water retention characteristics. Biochars with two different doses were applied to each soil type. Soil field capacity and permanent wilting point were measured using a pressure plate extractor for each combination of biochar and soil type. The results show that the effect of biochar amendment on soil water retention characteristics depend primarily on soil particle size distribution and surface characteristics of biochar. High surface area biochar can help raise the water holding capacity of sandy soil.

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.

scholarly journals Mechanical Container Filling Alters Texture and Water Retention of Peat Growth Media

1994 ◽  
Vol 4 (3) ◽  
pp. 286-288 ◽  
Author(s):  
Juha Heiskanen
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Water Retention ◽  
Fine Particles ◽  
Growth Media ◽  
Matric Potential ◽  
Sphagnum Peat ◽  
Retention Characteristics

Two commercially produced growth media made of light, low humified sphagnum peat, were used to determine how filling into containers affects the particle size distribution and water retention characteristics of peat. It was shown that the filling procedure used broke up the peat particles, resulting in a significant increase in the proportion of particles < 1 mm (g·g-1). Due to the increased proportion of fine particles, the water retention of the peat media increased under wet conditions (-0.1 kPa matric potential), while the air-filled porosity decreased to nearly 0. Also, at matric potentials lower than -0.1 kPa, the reduction in air-filled porosity may restrict aeration and availability of oxygen to roots, thus reducing growth of plants.

Modeling the Production Technology of Fully-Pressed Bi-Metal Powder Materials and Products

2021 ◽  
Vol 316 ◽  
pp. 570-575
Author(s):  
Badrudin G. Gasanov ◽  
Abakar B. Gasanov ◽  
Artem A. Aganov
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Bulk Density ◽  
Size Distribution ◽  
Metal Powder ◽  
Production Technology ◽  
Powder Mixture ◽  
Geometric Parameters ◽  
Powder Materials ◽  
Loading Devices

The features of calculating the thickness of the layers of bimetallic powder products without holes and the type of bushings are shown. The effect of the particle size distribution of the powders, the kinematic and geometric parameters of the loading devices and molds on the mechanism of the expiration of the powder mixture and on the thickness of the layers of the molded product is studied. A technique has been developed for determining the dimensions of the feeder cassette and tooling, depending on the overall dimensions and thicknesses of the working layers, in the production of whole-pressed bimetallic products on press machines with a vertical arrangement of layers. It was found that the thickness of each layer of bimetallic products depends on the geometric parameters of the feeder cassette and tooling, bulk density, particle size distribution and other characteristics of the powders, as well as on the speed of lowering the lower punch ν1 .

Studies on the water retention in arable sandy soil amended with fine size-fractionated sunflower husk biochar 

2021 ◽  
Author(s):  
Łukasz Gluba ◽  
Anna Rafalska-Przysucha ◽  
Kamil Szewczak ◽  
Mateusz Łukowski ◽  
Radosław Szlązak ◽  
...  
Keyword(s):  
Particle Size ◽  
Bulk Density ◽  
Size Distribution ◽  
Sandy Soil ◽  
Water Retention ◽  
Reference Level ◽  
Satellite Monitoring ◽  
Soil Matrix ◽  
Size Fractions ◽  
Biochar Amendment

&lt;p&gt;Biochar application has been reported for improving the physical, chemical, and hydrological properties of soil. However, biochar can be produced from different feedstocks and at different conditions having a direct impact on its properties. Furthermore, the overall effect of improvement depends on the type of soil. That makes biochar amendment difficult to optimize and creates the need for extensive studies of this issue for its better understanding. In these studies, we show that water holding capacity (by means of Available Water Content - AWC) can be significantly improved in arable sandy soil using fine-sized biochar particles.&lt;/p&gt;&lt;p&gt;For our studies, we have used sunflower husk biochar (pyrolyzed at 650&lt;sup&gt;o&lt;/sup&gt;C). Biochar samples were characterized using an elemental analyzer for C, H, N content studies, mercury porosimeter for porosity and specific pore volumes, and vibratory shaker with a stack of sieves for particle size distribution. The examined biochar was sieved in order to obtain four diameter size fractions: &lt;50 &amp;#181;m, 50&amp;#8211;100 &amp;#181;m, 100&amp;#8211;250 &amp;#181;m and &lt;2000 &amp;#181;m and mixed with arable sandy soil for 0.95, 2.24, 4.76 and 9.52 wt.%. The unamended soil sample served as a reference. At first, we have measured the bulk density of the air-dried samples. After then the pressure plate method was used to determine the water retention curves. The results were fitted using the van Genuchten equation. Finally, the AWC for all the measured samples was calculated from a difference between soil water contents for pF=2.2 and pF=4.2.&amp;#160; &lt;/p&gt;&lt;p&gt;The bulk density studies have shown a nonlinear behavior as a function of dose for all fractions of the biochar. The clearest effect is observed for fractions below 100 &amp;#181;m for which the density vs dose characteristics of the samples revealed a maximum for 0.95 wt.% and a decreasing trend for higher biochar contents. The AWC studies shown that the particle size fractions of biochar below 100 &amp;#181;m in diameter cause also the most significant improvement in the water retention, almost doubling the reference level (0.078 m&lt;sup&gt;3 &lt;/sup&gt;m&lt;sup&gt;-3&lt;/sup&gt;) to approximately 0.155 m&lt;sup&gt;3 &lt;/sup&gt;m&lt;sup&gt;-3&lt;/sup&gt; after biochar amendment. The results are explained by the filling of the free volume in the sandy soil matrix by small biochar particles. That leads to a shift of the pore size distribution to smaller radiuses, which in consequence promotes an increase in AWC.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The research was conducted under the project&amp;#160; &quot;Water in soil&amp;#160; -&amp;#160; satellite monitoring and improving the retention using biochar&quot; No. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by the Polish National Centre for Research and Development in the framework of &amp;#8220;Environment, agriculture and forestry&quot; -BIOSTRATEG strategic R&amp;D programme.&lt;/p&gt;

Predicting water retention curves of fine texture soils from particle size distribution

2020 ◽  
Author(s):  
Joseph Pollacco ◽  
Jesús Fernández-Gálvez ◽  
Sam Carrick
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Pore Space ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
Retention Curve ◽  
Soil Particles

&lt;p&gt;Indirect methods for estimating soil hydraulic properties from particle size distribution have been developed due to the difficulty in accurately determining soil hydraulic properties, and the fact that particle size distribution is one piece of basic soil physical information normally available. The similarity of the functions describing the cumulative distribution of particle size and pore size in the soil has been the basis for relating particle size distribution and the water retention function in the soil. Empirical and semi-physical models have been proposed, but these are based on strong assumptions that are not always valid. For example, soil particles are normally assumed to be spherical, with constant density regardless of their size; and the soil pore space has been described by an assembly of capillary tubes, or the pore space in the soil matrix is assumed to be arranged in a similar way regardless of particle size. However, in a natural soil the geometry of the pores may vary with the size of the particles, leading to a variable relation between particle radius and pore radius.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The current work is based on the hypothesis that the geometry of the pore size and the void ratio depends on the size of the soil particles, and that a physically based model can be generalised to predict the water retention curve from particle size distribution. The rearrangement of the soil particles is considered by introducing a mixing function that modulates the cumulative particle size distribution, while the total porosity is constrained by the saturated water content.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The model performance is evaluated by comparing the soil water retention curve derived from laboratory measurements with a mean Nash&amp;#8211;Sutcliffe model efficiency a value of 0.92 and a standard deviation of 0.08. The model is valid for all soil types, not just those with a marginal clay fraction.&lt;/p&gt;

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