Water flow and salt transport in bare saline‐sodic soils subjected to evaporation and intermittent irrigation with saline/distilled water

2019 ◽  
Vol 30 (10) ◽  
pp. 1204-1218 ◽  
Author(s):  
Dongdong Liu ◽  
Dongli She ◽  
Xingmin Mu
Keyword(s):  
Water Flow ◽  
Salt Transport ◽  
Distilled Water ◽  
Sodic Soils ◽  
Intermittent Irrigation

Water flow and salt transport in cracking clay soils of the Imperial Valley, California

2007 ◽  
Vol 20 (4) ◽  
pp. 361-387 ◽  
Author(s):  
W. W. Wallender ◽  
K. K. Tanji ◽  
J. R. Gilley ◽  
R. W. Hill ◽  
J. M. Lord ◽  
...  
Keyword(s):  
Water Flow ◽  
Salt Transport ◽  
Clay Soils ◽  
Imperial Valley

Water movement in unsaturated soils as influenced by gypsum

Soil Research ◽  
1972 ◽  
Vol 10 (1) ◽  
pp. 25 ◽  
Author(s):  
ML Sharma
Keyword(s):  
Cation Exchange ◽  
Water Flow ◽  
Unsaturated Soils ◽  
Water Movement ◽  
Mean Diffusivity ◽  
Distilled Water ◽  
Exchangeable Sodium ◽  
Flow Properties ◽  
High Concentration ◽  
The Third

Three soils varying in texture and exchangeable sodium were treated either with distilled water or with a gypsum solution of 10 or 30 m-equiv./l. concentration and their water-flow properties, diffusivity (D), capillary conductivity (K), and weighted mean diffusivity (D) determined. Invariably the treatment of soils with gypsum resulted in increased D and K, the increases being more pronounced near saturation and declining with desaturation. The soil with the highest clay content and exchangeable sodium percentage (ESP) responded most. For the three soils, at the end of the third wetting and draining cycle the highest increase in D and K varied from about 3 to 15 times while D increased by a factor of 2 to 7.5. Wetting and draining cycles resulted in decreased D for all soils when distilled water was used, but only for two soils when 10 or 30 m-equiv. solutions were used. In the soil most responding to gypsum D was slightly increased with increasing number of wetting and draining cycles when gypsum solutions were used. This was due probably to rebuilding of structure by cation exchange, which was lost by slaking and dispersion during the first wetting and draining cycle. The electrolyte concentration of flowing solution did not significantly affect the water flow properties provided that the slaking and dispersion were reduced by a solution of high concentration during the process of cation exchange. At the end of the third wetting and draining cycle, 30 m-equiv. solution gave about 1.7 times higher D compared to 10 m-equiv. for the high clay, high exchangeable sodium soil. This was probably because initial structural loss caused by the first wetting and draining with 10 m-equiv. was not fully regained during subsequent wetting and draining.

Conceptual Water Flow and Salt Transport for Flux-Limited and Ponded Infiltration

2011 ◽  
pp. 825-853
Author(s):  
W. W. Wallender ◽  
K. K. Tanji ◽  
B. Clark ◽  
R. W. Hill ◽  
E. C. Stegman ◽  
...  
Keyword(s):  
Water Flow ◽  
Salt Transport

scholarly journals Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function

2003 ◽  
Author(s):  
Lynn M. Dudley ◽  
Uri Shani ◽  
Moshe Shenker
Keyword(s):  
Water Stress ◽  
Water Flow ◽  
Crop Yield ◽  
Response Function ◽  
Deficit Irrigation ◽  
Saline Water ◽  
Piecewise Linear ◽  
Multiplicative Model ◽  
Salt Transport ◽  
Hydrochemical Model

Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.  

Control of salt transport from roots to shoots of wheat in saline soil

2004 ◽  
Vol 31 (11) ◽  
pp. 1115 ◽  
Author(s):  
Shazia Husain ◽  
Susanne von Caemmerer ◽  
Rana Munns
Keyword(s):  
Saline Soil ◽  
Feedback Regulation ◽  
Root Uptake ◽  
Salt Transport ◽  
Salinity Range ◽  
Sodic Soils ◽  
Wheat Genotypes ◽  
Uptake And Transport

Wheat genotypes with 5-fold difference in shoot Na+ concentrations were studied over a salinity range of 1–150 mm NaCl and CaCl2 of 0.5–10 mm to assess their performance in saline and sodic soils. All genotypes had a maximum shoot Na+ concentration at 50 mm external NaCl when the supplemental Ca2+ provided an activity of 1 mm or more. Shoot Na+ concentrations either stayed constant from 50 to 150 mm external NaCl, or decreased in some genotypes at the higher salinity. Calculated rates of root uptake, and root : shoot transport, were at a maximum at 50 mm NaCl in all genotypes, and decreased at higher NaCl in some genotypes, indicating feedback regulation. K+ showed a pattern inverse to that of Na+. Cl– uptake and transport rates increased linearly with increasing salinity, and differed little between genotypes. Increasing external Ca2+ concentration reduced the accumulation of Na+ in the shoot, the effects being greater in the low Na+ genotypes, and greater as the salinity increased, indicating that the plateau in shoot Na+ concentration relied on the maintenance of a minimal Ca2+ activity of 1 mm. Increasing external Ca2+concentration did not reduce the root Na+ concentration, however, suggesting that Ca2+ influenced the loading of Na+ in the xylem.

Biophysical Measurement of Molecular Weight of Foot-and-Mouth Disease RNA Fragments

1974 ◽  
Vol 32 ◽  
pp. 262-263
Author(s):  
Sydney S. Breese ◽  
Howard L. Bachrach
Keyword(s):  
Chemical Properties ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Distilled Water ◽  
Bovine Plasma ◽  
Mouth Disease Virus ◽  
Foot And Mouth ◽  
Carbon Coated ◽  
Rna Fragments ◽  
Physical And Chemical

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.

Freeze-fracture, freeze-etch complementary pairs of virus-infected cells reveal value of etching even when relatively high concentrations of cryoprotectants are used

1978 ◽  
Vol 36 (2) ◽  
pp. 136-137
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe
Keyword(s):  
Plant Tissue ◽  
Phosphate Buffer ◽  
Infected Plant ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Virus Infected Plant ◽  
Infected Cells ◽  
High Concentrations

It has been assumed by many involved in freeze-etch or freeze-fracture studies that it would be useless to etch specimens which were cryoprotected by more than 15% glycerol. We presumed that the amount of cryoprotective material exposed at the surface would serve as a contaminating layer and prevent the visualization of fine details. Recent unexpected freeze-etch results indicated that it would be useful to compare complementary replicas in which one-half of the frozen-fractured specimen would be shadowed and replicated immediately after fracturing whereas the complement would be etched at -98°C for 1 to 10 minutes before being shadowed and replicated.Standard complementary replica holders (Steere, 1973) with hinges removed were used for this study. Specimens consisting of unfixed virus-infected plant tissue infiltrated with 0.05 M phosphate buffer or distilled water were used without cryoprotectant. Some were permitted to settle through gradients to the desired concentrations of different cryoprotectants.

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