Evaluation of water content and water retention capacity of contact lens by optical reflective measurement.

2019 ◽  
Author(s):  
Chia-Lien Ma ◽  
Yu-Hsuan Lin ◽  
Fang-Ci Su ◽  
Kuo-Cheng Huang ◽  
Hsin-Yi Tsai
Keyword(s):  
Water Content ◽  
Contact Lens ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Reflective Measurement

Properties and Management of Allophanic Soils

2003 ◽  
Author(s):  
Anthony S. R. Juo ◽  
Kathrin Franzluebbers
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Water Retention ◽  
Field Capacity ◽  
High Water ◽  
Soil Porosity ◽  
Water Retention Capacity ◽  
Soil Taxonomy ◽  
Retention Capacity ◽  
High Soil

Allophanic soils are dark-colored young soils derived mainly from volcanic ash. These soils typically have a low bulk density (< 0.9 Mg/m3), a high water retention capacity (100% by weight at field capacity), and contain predominantly allophanes, imogolite, halloysite, and amorphous Al silicates in the clay fraction. These soils are found in small, restricted areas with volcanic activity. Worldwide, there are about 120 million ha of allophanic soils, which is about 1% of the Earth's ice-free land surface. In tropical regions, allophanic soils are among the most productive and intensively used agricultural soils. They occur in the Philippines, Indonesia, Papua New Guinea, the Caribbean and South Pacific islands, East Africa, Central America, and the Andean rim of South America. Allophanic soils are primarily Andisols and andic Inceptisols, Entisols, Mollisols, and Alfisols according to the Soil Taxonomy classification. Allophanic soils generally have a dark-colored surface soil, slippery or greasy consistency, a predominantly crumb and granular structure, and a low bulk density ranging from 0.3 to 0.8 Mg/m3. Although allophanic soils are apparently well-drained, they still have a very high water content many days after rain. When the soil is pressed between fingers, it gives a plastic, greasy, but non-sticky sensation of a silty or loamy texture. When dry, the soil loses its greasiness and becomes friable and powdery. The low bulk density of allophanic soils is closely related to the high soil porosity. For example, moderately weathered allophanic soils typically have a total porosity of 78%, with macro-, meso-, and micropores occupying 13%, 33%, and 32%, respectively. Water retained in the mesopores is readily available for plant uptake. Water retained in the micropores is held strongly by soil particles and is not readily available for plant use. The macropores provide soil aeration and facilitate water infiltration. The high water retention capacity is also associated with the high soil porosity. In allophanic soils formed under a humid climate, especially those containing large amounts of allophane, the moisture content at field capacity can be as high as 300%, calculated on a weight basis. Such extremely high values of water content seem misleading.

scholarly journals Improving water retention capacity of an aeolian sandy soil with feldspathic sandstone

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lu Zhang ◽  
Jichang Han
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Sandy Soil ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Mu Us Sandy Land ◽  
Soil Water Characteristic Curves ◽  
High Suction ◽  
Feldspathic Sandstone

Abstract The Mu Us sandy land in China’s Shaanxi Province faces a critical water shortage, with its aeolian sandy soil endangering the regional eco-environment. Here we investigated the effects of feldspathic sandstone on water retention in an aeolian sandy soil from the Mu Us sandy land. Feldspathic sandstone and aeolian sandy soil samples were mixed at different mass ratios of 0:1 (control), 1:5 (T1), 1:2 (T2), and 1:1 (T3). Soil-water characteristic curves were determined over low- to medium-suction (1–1000 kPa) and high-suction (1000–140 000 kPa) ranges, by centrifuge and water vapor equilibrium methods, respectively. Results showed that the addition of feldspathic sandstone modified the loose structure of the aeolian sandy soil mainly consisting of sand grains. The van Genuchten model described well the soil-water characteristic curves of all four experimental soils (R2-values > 0.97). Soil water content by treatment was ranked as T2 > T3 > T1 > control at the same low matric suction (1–5 kPa), but this shifted to T2 > T1 > T3 > control at the same medium- to high-suction (5–140 000 kPa). T2 soil had the largest saturated water content, with a relatively high water supply capacity. This soil (T2) also had the largest field capacity, total available water content, and permanent wilting coefficient, which were respectively 17.82%, 11.64%, and 23.11% higher than those of the control (P-values < 0.05). In conclusion, adding the feldspathic sandstone in an appropriate proportion (e.g., 33%) can considerably improve the water retention capacity of aeolian sandy soil in the study area.

scholarly journals Soil Water Dynamics and Growth of Street and Park Trees

2007 ◽  
Vol 33 (4) ◽  
pp. 231-245
Author(s):  
Christian Nielsen ◽  
Oliver Bühler ◽  
Palle Kristoffersen
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Tree Growth ◽  
Water Loss ◽  
Water Retention ◽  
Tree Planting ◽  
Water Retention Capacity ◽  
Street Trees ◽  
Retention Capacity ◽  
Street Tree

Soil water dynamics were studied in 100 street tree planting pits and in the soil surrounding five park trees. Volumetric soil water content and stem cross-sectional area increment were measured on both park and street trees. Different levels of irrigation were implemented on the 100 street trees. Winter assessments of soil wetness at field capacity showed that the water retention capacity was lower in street planting pits than in the park soil attributable to the rather coarse substrate used in the planting pits. High variability among street tree planting pits in regard to water retention capacity was determined and may be related to poor standardization of the substrates, but may also be affected by varying drainage conditions. The rate of water loss in the street tree planting pits was very high immediately after rainfall or irrigation and decreased exponentially during the first 10 days after water input. This was attributed to rapid drainage. The water loss rate in the park soil was on average slightly higher than in the nonirrigated control street pits but showed a more linear decrease over time. We concluded that the water loss in the park soil during summer was primarily driven by transpiration of trees (above 10 L/day [2.6 gal/day]), which complies with common Danish forest experience. The relationship between water loss and tree growth was reversed in the street tree planting pits. The street trees did consume water for growth, but growth and transpiration of the street trees were not a noticeably driving mechanism in the planting pit hydrology. The large variation in street tree increment is attributed to the variation among street planting pits in their ability to retain water. The faster the water loss rate, the slower the tree growth. Irrigation did not prevent final depletion of the soil water resource in planting pits, but irrigation elevated the water content for limited periods during the growing season and thereby enhanced tree growth. Besides the obvious possibilities for improved water balance by horizontal and vertical expansion of the rooting zone, we also suggest improving the water retention capacity of planting pit soil by adding clay nodules. Options for continuous monitoring of tree vitality and soil water content to optimize maintenance are discussed.

scholarly journals Study of drought tolerance of hybrid material of home plum in southern Russia

2020 ◽  
pp. 94-98
Author(s):  
A. A. Kochubey ◽  
R. Sh. Zaremuk
Keyword(s):  
Drought Tolerance ◽  
Water Content ◽  
Water Retention ◽  
Leaf Tissue ◽  
Stress Factors ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Drought Resistant ◽  
Water Holding ◽  
Hybrid Forms

Relevance. The aim of the research was to determine the physiological characteristics of the manifestation of resistance to stress factors (drought) of new hybrid forms of domestic plum and the allocation of the most drought-resistant in the environmental conditions of southern gardening.Methods. The article presents the results of drought tolerance studies of six promising hybrid forms of home plum (17–1-55, 17–1-69, 17–2-64, 17–2-78, 17–2-81, 17–3-79), concentrated in the genetic collection of SKFNTSVV. The main indicators characterizing the varieties and hybrids of home plum were determined as drought tolerant — the water content of the leaves and the water holding capacity of the leaves under conditions of summer moisture deficiency.Results. The water content of leaf tissue of hybrid forms in the hottest period (second — third decade of July) was heterogeneous. The highest water content in tissues was observed in hybrid seedlings 17–2-64 (63.1%) and 17–2-81 (59.6%). The smallest value was observed in the hybrid 17–3-79 and amounted to 49.7%. According to the data obtained, it was concluded that the studied hybrid forms do not differ in high water content, with the exception of hybrid 17–2-64, in which the water content can be characterized as above average. It was found that the water retention capacity of most hybrid forms is average. The total water content after withering in the studied hybrids was more than 80%. The greatest decrease in the amount of water in the leaves was observed in hybrids 17–1-55 (18.9%), 17–2-64 (18.5%), 17–3-79 (18.4%); the smallest — in hybrids 17–1-69 (13.3%), 17–2-78 (13.6%), which indicates a highwater retention capacity of the last two hybrids. With a general assessment of the hybrid fund of home plum, it was found that most hybrids studied have low hydration of leaf tissue and average water retention capacity. Based on this, two drought-resistant hybrid forms were identified: 17–1-69 and 17–2-78, which, despite the low water content, are distinguished by good water-holding ability in comparison with other hybrids and, as a consequence, the conservation of leaf turgor.

scholarly journals Study of the influence of adaptogens on the water regime of some varieties of the genus Chrysanthemum L. during the introduction into the Bashkir Pre-Urals

2020 ◽  
Vol 202 (11) ◽  
pp. 2-13
Author(s):  
Svetlana Denisova ◽  
Antonina Reut
Keyword(s):  
Water Content ◽  
Water Deficit ◽  
Water Retention ◽  
Water Regime ◽  
Botanical Garden ◽  
Moisture Loss ◽  
Water Retention Capacity ◽  
Total Water Content ◽  
Total Water ◽  
Retention Capacity

Abstract. Purpose. Study of the effect of anti-stress adaptogens on the water regime of some varieties of chrysanthemum in the conditions of the Bashkir Pre-Urals. Methodology and methods. The analysis of indicators of water regime is based on the method of artificial wilting (V. N. Tarenkov, L. N. Ivanova) and the method of saturation of plant samples (V. P. Moiseev, N. P. Reshetskiy). Plants were processed once, and samples were taken in three terms. Calculations were carried out by standard methods using statistical packages of the Microsoft Excel 2003 and the Agros 2.13. Results. The dynamics of indicators of the water regime during the treatment with the preparations “Gumi-20” and “Oberig” is analyzed. An assessment of the total water content, water retention capacity, daily moisture loss and water deficit of ten varieties of chrysanthemum bred by the South-Ural Botanical Garden-Institute of UFRC RAS (SUBGI UFRC RAS) in the period under study is given. Studies have shown that varieties of chrysanthemum in the Bashkir Ural under the same soil-climatic and agrotechnical conditions had the following indicators: total water content ‒ 69.4–86.9 %, water-holding capacity ‒ 25.6–53.8 %, daily moisture loss ‒ 17.2–61.0 %, water deficit ‒ 10.9–13.2 %. The use of anti-stress adaptogens did not have a significant effect on the parameters of the water regime, or their effect was variety-specific. As a result of the correlation-regression analysis, inverse relationships were revealed between the indicators of water deficit and the total water content, as well as between the daily water loss and water retention capacity. Scientific novelty. For the first time, the water regime of varieties of chrysanthemum of the SUBGI UFRC RAS selection was studied, the dependences of the water regime indicators were revealed, and the assessment of the expediency of using anti-stress adaptogens for certain varieties in the conditions of the Bashkir Pre-Urals was given.

scholarly journals Effect of Unimodal and Bimodal Soil Hydraulic Properties on Slope Stability Analysis

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1674
Author(s):  
Hsin-Fu Yeh ◽  
Tsien-Ting Huang ◽  
Jhe-Wei Lee
Keyword(s):  
Hydraulic Conductivity ◽  
Slope Stability ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Seepage Analysis ◽  
Hydraulic Behavior ◽  
Conductivity Function ◽  
The Impact

Rainfall infiltration is the primary triggering factor of slope instability. The process of rainfall infiltration leads to changes in the water content and internal stress of the slope soil, thereby affecting slope stability. The soil water retention curve (SWRC) was used to describe the relationship between soil water content, matric suction, and the water retention characteristics of the soil. This characteristic is essential for estimating the properties of unsaturated soils, such as unsaturated hydraulic conductivity function and shear strength. Thus, SWRC is regarded as important information for depicting the properties of unsaturated soil. The SWRC is primarily affected by the soil pore size distribution (PSD) and has unimodal and bimodal features. The bimodal SWRC is suitable for soils with structural or dual-porous media. This model can describe the structure of micropores and macropores in the soil and allow the hydraulic behavior at different pore scales to be understood. Therefore, this model is more consistent with the properties of onsite soil. Few studies have explored the differences in the impact of unimodal and bimodal models on unsaturated slopes. This study aims to consider unimodal and bimodal SWRC to evaluate the impact of unsaturated slope stability under actual rainfall conditions. A conceptual model of the slope was built based on field data to simulate changes in the hydraulic behavior of the slope. The results of seepage analysis show that the bimodal model has a better water retention capacity than the unimodal model, and therefore, its water storage performance is better. Under the same saturated hydraulic conductivity function, the wetting front of the bimodal model moves down faster. This results in changes in the pressure head, water content, and internal stress of the soil. The results show that the water content and suction stress changes of the bimodal model are higher than those of the unimodal model due to the difference in water retention capacity. Based on the stability of the slope, calculated using the seepage analysis, the results indicate that the potential failure depth of the bimodal model is deeper than that of the unimodal model.

scholarly journals Soil water dynamics in drained and undrained meadows

2021 ◽  
Author(s):  
Jan Vopravil ◽  
Pavel Formánek ◽  
Jaroslava Janků ◽  
Tomáš Khel
Keyword(s):  
Soil Properties ◽  
Water Content ◽  
Water Retention ◽  
Tile Drainage ◽  
Actual Evapotranspiration ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
The Czech Republic ◽  
Saturated Water ◽  
Saturated Water Content

Tile drainage belongs to one of the most important meliorative measures in the Czech Republic. It has been hypothesised that it may improve some soil properties which are influenced by the groundwater and their water regime. In the case of meadows, the used management method may also influence the soil properties. In this study, different physical soil properties (particle and bulk density, total soil porosity, maximum capillary water capacity, minimum air capacity, water retention capacity and saturated water content, volumetric water content and matric potential) at depths of 15, 35 or 40 and 60 cm in differently managed meadows (drained versus undrained) located near the village of Železná in the Czech Republic (mildly cold, humid climatic region) were investigated. The drained meadow is used mainly for grazing (extensively) and the undrained meadow is mown twice a year. In addition, the actual evapotranspiration was estimated for the 2018 vegetation season. The selected physical soil properties were significantly (P &lt; 0.05) different between the experimental meadows, especially at depths of 0–28 versus 0–35 cm (particle and bulk density, total soil porosity, maximum capillary water capacity, water retention capacity and saturated water content) and 28–49 versus 35–45 cm (particle density, water retention capacity and saturated water content). In the case of all the studied soil depths, the volumetric water content and matric potential were significantly (P &lt; 0.05) different between the experimental meadows in the years 2016–2019. The actual evapotranspiration was also significantly different (P &lt; 0.05) between the meadows. The obtained differences in the measured soil properties and estimated actual evapotranspiration were probably influenced by the used tile drainage and also by the type of management of the meadow. It is necessary to obtain more research findings with respect to different types of management in the case of drained meadows and also undrained meadows to understand the role of both treatments (tile drainage, management).

scholarly journals Effect of Particle Size and Solution Leaching on Water Retention Behavior of Ion-Absorbed Rare Earth

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zhong-qun Guo ◽  
Yuan-ming Lai ◽  
Jie-fang Jin ◽  
Jian-rong Zhou ◽  
Zheng Sun ◽  
...  
Keyword(s):  
Particle Size ◽  
Rare Earth ◽  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Soil Mass ◽  
Matric Suction ◽  
Water Retention Capacity ◽  
Retention Behavior ◽  
Retention Capacity

Soil-water characteristic curve reflects water retention behavior of unsaturated soil mass. Particle size and mineral composition can influence water retention behavior of soil mass significantly. To discuss effects of particle size and solution leaching on water retention behavior of ion-absorbed rare earth, soil-water characteristic tests of samples with different particle sizes before and after the solution leaching were carried out by using a pressure plate instrument. Soil-water characteristic curves during drying and wetting were analyzed. A fitting analysis on test data was implemented by the Fredlund&Xing 3 parameter model, the Fredlund&Xing 4 parameter model, and the Van Genuchten model to discuss variation laws of soil-water characteristic parameters in different models. Effects of particle size and solution leaching on water retention behavior of ion-absorbed rare earth as well as action mechanism were investigated. Results demonstrate that given the same matric suction, soil water content decreases gradually with the increase of particle size and content of coarse particles, thus decreasing water retention capacity of soil accordingly. Given the same volumetric water content, matric suction is inversely proportional to particle size. During drying and wetting, the amplitude of variation decreases gradually with the increase of particle size and content of coarse particles. The soil water content after solution leaching is smaller than that before under the same matric suction, indicating that solution leaching can decrease water retention capacity of soil. This is mainly because thickness of the double diffuse layer and pore water pressure are increased as a response to the ion exchange, thus decreasing matric suction.

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