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Deterioration mechanism of stone and earthen walls in historical village of Hokkaido
Published in J. Carmeliet, H. Hens, G. Vermeir, Research in Building Physics, 2020
T. Ishizaki, M. Takami, J. Grunewald, R. Plagge, H. Fechner
The soil water retention curve is an important physical parameter of water retention and water migration in the earthen wall. The relationship between the water potential and water content was obtained using water potential measuring apparatus (WP4, Decagon Device, Inc.). Figure 8 shows the relationship between the water potential and water content of the soil for earthen wall. The water potential decreased with decreasing water content.
A conceptual model for water-limited evapotranspiration taking into account root depth, root density, and vulnerability to xylem cavitation
Published in N. Khalili, A.R. Russell, A. Khoshghalb, Unsaturated Soils: Research & Applications, 2020
Alessia Amabile, Brunella Balzano, Marco Caruso, Alessandro Tarantino
When a plant loses water to the atmosphere, the potential of water in the leaf drops at the sites of evaporation. A gradient in water potential is formed that drives water from the soil through the plant. Stomata do not usually respond to the reduction in water potential necessary to maintain the transpiration stream, unless water supply to the leaves is limited by the hydraulic conductivities of bulk soil, soil-root interface, or xylem. These progressively decrease as evapotranspiration takes place. Then stomata begin to close rapidly to limit the water loss in the leaf in response to the limited water supply.
Energy Concept and Thermodynamics of Water in Soil
Published in Shingo Iwata, Toshio Tabuchi, Benno P. Warkentin, Soil-Water Interactions, 2020
Shingo Iwata, Toshio Tabuchi, Benno P. Warkentin
Various concepts were proposed in the decade after 1935 to satisfy this demand. They include pF by Schofield (1935), water potential by Veihmeyer and Edlefsen (1937), osmotic potential and pressure potential by Day (1947), and soil moisture stress, the sum of water suction and osmotic pressure, by Wadleigh and Ayers (1945). Although these concepts have different names, they are all expressions of chemical potential (total potential) of water in soil relative to free water at the same temperature. pF is the base 10 logarithm of the absolute value of chemical potential expressed in a gravitational system of units, assuming that solutes are negligible. Water potential is the chemical potential of water. Pressure potential and osmotic potential are equivalent to the decrement of chemical potential due to surface tension effects and/or electric and van der Waals force fields, and due to solutes. Water suction and osmotic pressure are, respectively, equal to the value of pressure potential and osmotic potential divided by the partial volume of water in soil.
Triple Probe Heat Pulse (TPHP) Soil Moisture Content and Temperature Monitoring Digital System Using Nanomaterials based Sensor Elements for Precision Agriculture
Published in IETE Journal of Research, 2022
The soil moisture content is the amount of water present in the soil in a different context of definition. Soil moisture can be defined in two different contexts [8] as the soil water content and the soil water potential. Soil water content is the amount of water that can be evaporated from the soil by heating it between 100°C and 110°C, but usually at 105°C, until there is no further weight loss. This is the actual soil water definition that can be used by plants in agriculture. This is actually the standard method of determining the soil water content called the gravimetric method. Soil water potential describes the energy status of the soil water and is used for water transport analysis, water storage estimates, and soil–plant–water relationships. A difference in water potential between two soil locations indicates a tendency for water flow, from high to low potential. But in this case, there is no direct moisture volume or mass determination rather potential in terms of pressure.
Regulatory role of folic acid in biomass production and physiological activities of Coriandrum sativum L. under irrigation regimes
Published in International Journal of Phytoremediation, 2022
Muhammad Tajammal Khan, Shakil Ahmed, Anis Ali Shah
Two completely expanded young leaves were used to measure leaf water potential (Ψw) and relative water content (RWC) from 10:30 a.m. to 12:00 p.m. Water potential was measured by using Pressure Chamber (CHAS OIVN, England). Leaf disks (5 mm in diameter) were taken having fresh weight (Wf) 0.5 g from each treatment and put into test tubes containing distilled H2O for 4 h at 4 °C to determine the relative water content (RWC). The saturated leaves were weighed (Wt) and then dried for 72 h at 65 °C for dry weight. RWC was estimated by using the given formula of (González and González-Vilar 2001).
A theoretical analysis of the potential effect of negative pressure in wood drying based on a CT-scanner study
Published in Drying Technology, 2022
Steve Riley, Jonathan Harrington, Diego Elustondo
Nevertheless, it was pointed out during the peer review process that such patchy M patterns could be caused by non-uniformities in drying conditions or irregularities in the wood fiber. It is difficult to withdraw general conclusions from 12 samples, and CT-scanners studies are very expensive and time consuming to justify expanding and replicating the experiments. However, regardless of whether the interpretation of the measured data is accurate or not, there is still the theoretical possibility that M gradients between wet and dry zones do not necessarily drive moisture in the direction of the gradients. The basis for this claim are two theoretical concepts that are widely accepted in the scientific literature:Conditions spontaneously tend to thermodynamics equilibrium: Thermodynamics equilibrium is the basic principle to predict the direction of spontaneous mass transfer. A rigorous description of the theory of thermodynamics equilibrium is presented in Appendix B. In short, equilibrium is reached when all states of water in wood have the same water potential. If there are differences in water potential, then moisture will be exchanged spontaneously to equalize those differences. Since water potential depends on variables such as pressure, temperature, M, solutes concentration, and height (see Appendix B), then gradients of those variables are the measurable driving forces pointing in the direction of thermodynamics equilibrium.Water inside cell lumens can be at negative pressure: Negative pressure reduces water potential with respect to normal water (see Equation (7) in Appendix B), and the existence of negative pressure in cell lumen water is well documented in the literature. It is usually explained through the theory capillary effect.[21] More generically, the existence of negative pressure can be explained by the theory of metastable liquids,[22] which considers it a state of matter that has been stretched beyond normal state. The advantage of using the theory of metastable liquids is that it assumes that all thermodynamics properties of stretched water can be estimated with standard equations of state.[23]