Evaporation from porous media as influenced by osmotic potential

2020 ◽  
Author(s):  
Adil Salman ◽  
Deep Joshi ◽  
Mahyar Naseri ◽  
Wolfgang Durner
Keyword(s):  
Porous Media ◽  
Water Potential ◽  
Osmotic Potential ◽  
Soil Surface ◽  
Natural Soil ◽  
Total Water ◽  
Matric Potential ◽  
Model Calculations ◽  
Two Stages ◽  
Saline Solutions

<p>The measurement of the water potential is important to characterize solute transport in soil and water uptake by plants. Many researchers have characterized the matric potential and its impact on evaporation from porous media. However, only few studies have been carried out to characterize the effect of the osmotic potential. In this study, we investigated the simultaneous influences of the osmotic and matric potentials on the evaporation from soil. Our hypothesis was that both potential components affect the two stages of evaporation and that the osmotic potential in direct vicinity of the soil surface is a controlling variable. To meet our objective, we performed evaporation experiments on columns filled with pure quartz sand and natural soil materials with different textures, under climate-controlled laboratory conditions. The soils were initially saturated with different concentrations of saline solutions and evaporation from each column was measured daily. Our results show that the osmotic potential reduced the amount of evaporated water from the investigated porous media. The amount of reduction due to the osmotic potential is compared with model calculations that consider the total water potential at the soil surface.</p>

Corrigenda - Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

scholarly journals Linear Relationship of a Soil Total Water Potential Function and Relative Yield—A Technique to Control Salinity and Water Stress on Golf Courses and Other Irrigated Fields

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1916
Author(s):  
Jose Beltrao ◽  
Gulom Bekmirzaev ◽  
Jiftah Ben Asher ◽  
Manuel Costa ◽  
Thomas Panagopoulos
Keyword(s):  
Water Potential ◽  
Crop Yields ◽  
Relative Yield ◽  
Golf Courses ◽  
Simple Relationship ◽  
Total Water ◽  
Trickle Irrigation ◽  
Matric Potential ◽  
Retention Model ◽  
Relationship Of

A simple empirical approach is proposed for the determination of crop relative yield (%) through the soil total water potential (kPa). Recurring to decimal logarithms, from analytical exponential expressions, a linear simple relationship of soil total water potential Ψt (matric Ψm + potential Ψo) function and crop relative yield was studied and developed. The combination of the salinity model, the soil water retention model and the matric potential approach were used to reach this objective. The representation of turfgrass crop relative yield (%) versus a function of soil total water potential f(Ψt) values was shown through a log-normal graph (y = a + mx); the log scale axis “y” (ordinates) defines relative yield Yr, being two the origin ordinate “a” and “m” the slope; the normal decimal scale axis “x” (abscissa) is the function of soil total water potential f(Ψt). Hence, it is possible, using only two experimental points, to define a simple linear relation between a function of soil total water potential and crop relative yield, for a soil matric potential value lower than −20 kPa. This approach was first tested on golf courses (perennial turfgrass fields), but it was further decided to extend it to other annual crop fields, focused on the model generalization. The experimental plots were established, respectively, in Algarve, Alentejo and Oeiras (Portugal) and in the North Negev (Israel). Sprinkler and trickle irrigation systems, under randomized blocks and/or water and salt gradient techniques, were used for water application with a precise irrigation water and salt distribution. Results indicated that there is a high agreement between the experimental and the prediction values (R2 = 0.92). Moreover, the precision of this very simple and easy tool applied to turfgrass fields and other irrigated soils, including their crop yields, under several different sites and climatic conditions, can contribute to its generalization.

Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1 ◽  
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

The Components of Leaf Water Potential I. Osmotic and Matric Potentials

1967 ◽  
Vol 20 (2) ◽  
pp. 329 ◽  
Author(s):  
J Warren Wilson ◽  
CW Rose
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Matric Potential ◽  
Tissue Matrix

Osmotic potential ('IT) resulting from solutes should be distinguished from matric potential (T) resulting from adsorption by the tissue matrix. The usual methods of measuring so�called "osmotic potential" actually give not only 'IT but also part or all of T.

The importance of liquid-seed contact during the germination of Medicago tribuloides Desr.

1963 ◽  
Vol 14 (5) ◽  
pp. 646 ◽  
Author(s):  
RH Sedgley
Keyword(s):  
Seed Germination ◽  
Water Potential ◽  
Liquid Water ◽  
Total Water ◽  
Matric Potential ◽  
Small Pressure ◽  
Plate Apparatus

At a given matric potential, rates of uptake of water and rates of seed germination on a suction plate apparatus were increased by improving the degree of contact between liquid water and seed. The conclusion of Collis-George and Sands (1962) that small matric potentials, as such, influence the rate of seed germination is critically reviewed in the light of the present investigation. The rate of germination of seeds was not influenced by small pressure potentials, which like matric potentials are a non-osmotic component of the total water potential.

The response of Evapotranspiration to osmotic potential in small-scale lab lysimeters

2021 ◽  
Author(s):  
Adil Salman ◽  
Wolfgang Durner ◽  
Deep C. Joshi ◽  
Mahyar Naseri
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Osmotic Potential ◽  
Soil Water Potential ◽  
Matric Potential ◽  
Soil Material ◽  
Total Soil ◽  
Evapotranspiration Rate ◽  
Soil Osmotic Potential ◽  
Total Soil Water Potential

<p>Drought and climatic change are among the main environmental stressors for the water and soil qualities. Soil water potential is the major soil-related factor controlling water availability to plants and their evapotranspiration. It consists of two main components: matric and osmotic potential. Although the effect of matric potential on plant evapotranspiration has been extensively studied under various conditions, there is still a lack of quantitative studies on the effects of osmotic potential on evapotranspiration.</p><p>In our study, we investigated the influence of soil osmotic potential on the evapotranspiration rate and cumulative evapotranspiration of grass planted in small laboratory lysimeters. A sandy loam soil material was packed in four lysimeters with a volume of 6000 cm<sup>3</sup> and equal bulk density. The soil material was air dried, freed from roots and passed through a 2 mm sieve. Each lysimeter was equipped with soil sensors at two different depths to monitor soil moisture, bulk electrical conductivity, temperature, and matric potential. To obtain continuous mass balance measurements, each lysimeter was placed on a balance connected to the computer. Grass seeds were planted in each lysimeter at the same density and irrigated with distilled water until plant height was 12 cm. Irrigation water of two different qualities (EC= 0 and 4.79 dS/m) was then applied to produce different levels (0 and -0.17 MPa) of osmotic potential. The volumetric water content was adjusted to a value between 15 and 20 % in each lysimeter during the grass growth period. When the volumetric water content reached 15 %, irrigation water was added to the lysimeters to increase it to 20 %. Data were collected to calculate changes in osmotic potential relative to changes in total soil water potential. In addition, the relationship between osmotic potential and evapotranspiration rate during the growing season was determined.</p><p>Our results indicate a controlling role of soil osmotic potential on total soil water potential. This role results a significant reductions in evapotranspiration in response to increases in osmotic potential, in addition to effects on plant health. Osmotic potential has a significant function on total soil water potential when the soil becomes dry and poor water qualities are used in irrigation.</p>

scholarly journals Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 666
Author(s):  
Guilin Han ◽  
Anton Eisenhauer ◽  
Jie Zeng ◽  
Man Liu
Keyword(s):  
Soil Depth ◽  
Isotope Composition ◽  
Soil Surface ◽  
Natural Soil ◽  
Calcium Isotope ◽  
Karst Forest ◽  
Content Ratio ◽  
The Difference ◽  
Preferential Uptake ◽  
Vital Factor

In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ44/40Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ44/40Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ44/40Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ44/40Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (40Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems.

Embryo dormancy responses to temperature in capeweed (Arctotheca calendula) seeds

2002 ◽  
Vol 12 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Amanda J. Ellery
Keyword(s):  
Soil Temperature ◽  
Water Potential ◽  
Low Temperatures ◽  
Seasonal Changes ◽  
Temperature Fluctuation ◽  
Soil Surface ◽  
Seed Collection ◽  
Embryo Dormancy ◽  
Response To Temperature ◽  
Dormancy Cycles

Changes in embryo dormancy of capeweed [Arctotheca calendula (L.) Levyns.] seeds in response to temperature were investigated to determine the nature of seasonal dormancy cycles. Primary embryo dormancy persisted for 2–3 months after seed collection and was then rapidly relieved when seeds were maintained at temperatures simulating summer soil surface temperatures. Embryo dormancy was also rapidly relieved in seeds maintained at constant temperatures, indicating that a daily temperature fluctuation was not necessary for the relief of embryo dormancy in capeweed. Dormancy relief was maximal at 40°C. Secondary dormancy was induced when seeds were maintained at low temperatures and a water potential of –1.5 MPa, suggesting that the onset of winter may postpone germination until a subsequent autumn. These results indicate that the dormancy cycles observed in capeweed seeds maintained on the soil surface are probably driven by seasonal changes in soil temperature.

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