Effect of watertable depth on evaporation and salt accumulation from saline groundwater

Soil Research ◽  
2005 ◽  
Vol 43 (5) ◽  
pp. 565 ◽  
Author(s):  
D. A. Rose ◽  
F. Konukcu ◽  
J. W. Gowing
Keyword(s):  
Transition Zone ◽  
Soil Profile ◽  
Arid Regions ◽  
Capillary Flow ◽  
Sandy Loam ◽  
Upward Movement ◽  
Evaporation Front ◽  
Evaporative Demand ◽  
Saline Groundwater ◽  
Rate Of Evaporation

When the evaporative demand is greater than the ability of the soil to conduct water in the liquid phase, the soil profile above a watertable exhibits a liquid−vapour discontinuity, known as the evaporation front, that affects the depth of salinisation and the rate of evaporation. We conducted experiments on a sandy loam with shallow saline watertables under high isothermal evaporative demand (24 mm/day), monitoring rates of evaporation from the soil and upward movement of groundwater, and observing profiles of soil water and salinity over periods of up to 78 days. Three zones were distinguished in the soil profile: a zone of liquid flow above the watertable, a zone of vapour flow close to the surface, and an intermediate transition zone in which mixed liquid−vapour flow occurred. The vapour-flow zone above the evaporation front appeared after a few days and progressed downward to depths of 40, 60, and 120 mm, while eventual steady-state rates of evaporation were 1.3, 1.1, and 0.3 mm/day for watertable depths of 300, 450, and 700 mm, respectively. Salts mainly accumulated in the transition zone, suggesting that the depth of the evaporation front should be a criterion to locate and prevent salinisation as a result of capillary flow from a watertable in arid regions.

Determination of water content in drying soils: incorporating transition from liquid phase to vapour phase

Soil Research ◽  
2004 ◽  
Vol 42 (1) ◽  
pp. 1 ◽  
Author(s):  
F. Konukcu ◽  
A. Istanbulluoglu ◽  
I. Kocaman
Keyword(s):  
Water Content ◽  
Transition Zone ◽  
Sandy Loam ◽  
Vapour Phase ◽  
Coarse Sand ◽  
Arid Environments ◽  
Evaporation Front ◽  
Matric Potential ◽  
Silty Loam

In arid and semi-arid environments, soil profiles often exhibit a liquid–vapour displacement known as evaporation front characterised by a critical matric potential (ψme) or water content (θe) located somewhere inside the unsaturated zone above a watertable (WT). The objective of this study was to determine the θe including the range of water content (θ) in the transition zone from liquid to vapour both theoretically and experimentally for different soil textures under saline and non-saline WTs. Characteristic shapes of water content and salt concentration profiles were the criteria to obtain θe experimentally, and the θ–diffusivity relationship was used to compute the θe and θ range in the transition zone. Measured θe values of 0.05 and 0.12 m3/m3 under non-saline WT and 0.07 and 0.15 m3/m3 under saline WT were in agreement with the computed values of 0.05 and 0.10 m3/m3 for sandy loam and clay loam soils, respectively. The model calculates roughly the same θe for saline and non-saline conditions. Besides experimental soils, θe and range of θ in the transition zone were calculated for silty loam and coarse sand. The lighter the soil texture, the smaller is θe and the steeper the transition zone. The results were further compared with those calculated by different authors.

scholarly journals Towards Sustainable Use of Potassium in Pineapple Waste

2004 ◽  
Vol 4 ◽  
pp. 1007-1013 ◽  
Author(s):  
Osumanu H. Ahmed ◽  
M.H.A. Husni ◽  
A.R. Anuar ◽  
M.M. Hanafi
Keyword(s):  
Arid Regions ◽  
Crop Residues ◽  
Sandy Loam ◽  
Sustainable Use ◽  
Foliar Spray ◽  
Sustainable Food ◽  
Standard Procedures ◽  
Agricultural Use ◽  
The Arid Regions ◽  
Pineapple Leaves

Due to the 1997/98 haze problem in South-East Asia and the increasing need for sustainable food production and development, the usual management of crop residues (including pineapple wastes) through burning is prohibited. As a result, the need for alternative uses of pineapple wastes in pineapple production has been emphasized. This study investigated an environmentally friendly means of recycling pineapple leaves for agricultural use. Pineapple leaves were shredded and composted in a composting drum for 30 days. Part of the shredded leaves was ashed in a muffle furnace for 4 h. Humic acid (HA), K-fulvate, and K in HA and compost were analyzed using standard procedures. An ash to water ratio of 1:7 was used to extract 0.1 molar (M) KOH from the shredded leaves. The 0.1 M KOH contained 50% K and was able to extract 20% HA from the composted pineapple leaves. Percent K in the fulvate using 0.1 M KOH was 43. Besides serving as a foliar spray (supplement soil application K fertilizers), source of K for freshwater fish (e.g., tilapia), the HA produced can be used as a soil conditioner. Studies show that between 0.05–0–01 g of HA per kg soil retards runoff by 36% in sandy and sandy loam soils. The K-fulvate can be used as a fluid fertilizer. In addition, the pH of 2 of the K-fulvate suggests it could be used to dissolve phosphate rocks, particularly those in the arid regions where high soil pH does not facilitate the dissolution of these important rocks that serve as one of the sources of phosphorus fertilizer in agriculture.

Influence of size of rainfall events on water-driven processes. II. Soil nitrogen mineralisation in a semi-arid environment

2003 ◽  
Vol 54 (4) ◽  
pp. 353 ◽  
Author(s):  
Victor O. Sadras ◽  
Jeffrey A. Baldock
Keyword(s):  
Soil Nitrogen ◽  
Sandy Loam ◽  
Variable Temperature ◽  
Weather Data ◽  
Annual Rainfall ◽  
Substantial Part ◽  
Nitrogen Mineralisation ◽  
Evaporative Demand ◽  
Fixed Temperature ◽  
Rainfall Events

Power laws describe the relationships between the number N (s) and the size s of daily rainfall events, i.e. N (s) ~ s–τ, with higher τ corresponding to sites or seasons with greater frequency of small rainfall events. This paper tested the hypothesis that the rate of soil nitrogen mineralisation increases with increasing exponent τ, as affected by both spatial and temporal sources of variation. Rates of nitrogen mineralisation in an uncropped sandy loam soil were calculated using a simulation model with detailed nitrogen and water balances, and long-term weather data for 6 Australian locations in a range of annual rainfall from 260 to 360 mm. Daily rates of mineralisation were calculated using actual rainfall, and variable or fixed temperature and evaporative demand. The annual pattern of mineralisation rate, calculated as a function of rainfall and variable temperature and evaporative demand, was bimodal with peaks in April and November. These peaks disappeared and differences among locations were reduced when the effects of temperature and evaporative demand were removed. Under constant temperature and evaporative demand, mineralisation rates between April and November were 68% greater than rates between December and March. In the former period, characterised by a high frequency of small rainfall events, monthly mineralisation rate was a direct function of the amount of rainfall. In contrast, mineralisation was independent of the amount of rainfall during the period of larger, less frequent rainfall events from December to March. Parameter τ accounted for 75% of the variation in mineralisation rate in the period December–March and it also accounted for a substantial part of the variation between periods.

Chromium(VI) leaching from large undisturbed soil lysimeters following application of a simulated copper-chromium-arsenic (CCA) timber preservative

Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 351 ◽  
Author(s):  
P. L. Carey ◽  
V. J. Bidwell ◽  
R. G. McLaren
Keyword(s):  
Organic Matter ◽  
Soil Profile ◽  
Sandy Loam ◽  
Soil Analysis ◽  
Rainfall Simulation ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
First Order ◽  
Copper Chromium ◽  
Soil Lysimeters

Copper, chromium, and arsenic (CCA) solutions are commonly used in New Zealand as a means of preserving softwood timbers such as Pinus radiata. With stock working solutions of CCA salts in timber treatment plants frequently 10% w/v or more, there exists a potential for spillage and leaching of these compounds to groundwater. High concentrations of Cr(VI) (up to 52 mg Cr/L) were found in the leachates of large undisturbed soil lysimeters where a Templeton sandy loam (Immature Pallic) had received surface applications of a simulated copper, chromium, and arsenic (CCA) timber preservative. Leaching was produced by using a combination of natural and imposed rainfall simulation over the lysimeters for a period of 102 days after CCA application. An average of 26% of the applied chromium was collected in the leachates after 102 days. Of the mean 74% of Cr(VI) still retained within the soil profile after leaching ended, almost half was located in the top 100 mm of the profile. No copper or arsenic was detected in any of the lysimeter leachates, with soil analysis indicating that these elements had been retained within the soil profile. In an incubation study, soil cores sampled from the same Templeton sandy loam and split into alternate 50-mm segments (to 450 mm) were stored at 10˚C for 102 days after addition of an identical CCA solution. These were periodically extracted for available chromium. Results showed that the reduction of dichromate/chromate anions (Cr2O72–/CrO42–) to the strongly sorbed chromic cation (Cr3+) was largely first-order and greatest in surface layers where soil organic matter contents were largest. After 102 days, <1% of the added Cr(VI) was still extractable in the 0–50 mm soil cores whilst ≈60% of Cr(VI) in the 400–450 mm cores (or deeper) was still extractable after the same period. A linear systems model comprising a series of conceptual mixing cells was used to describe the individual and mean Cr(VI) leaching breakthrough curves (BTCs). This State-Space Mixing Cell model proved effective in simulating the Cr(VI) leaching using first-order kinetics to quantify rate-limited local solute adsorption coupled to advective-dispersive transport. The solute mass involved in the model process was ≈30%. The bulk of the remaining 70% of applied dichromate was assumed to have undergone reduction to the non-mobile chromium cation. This study shows that there exists a significant potential for Cr(VI) to be a serious threat to groundwater in the event of a large uncontained spillage of a concentrated CCA solution. This potential can be significantly lessened if the Cr(VI) is reduced after retention in an organic matter rich layer.

Factors Affecting Johnsongrass Rhizome Production and Germination

Weed Science ◽  
1972 ◽  
Vol 20 (1) ◽  
pp. 41-45 ◽  
Author(s):  
C. G. McWhorter
Keyword(s):  
Soil Profile ◽  
Clay Soil ◽  
Sandy Loam ◽  
Sorghum Halepense ◽  
Percentage Germination ◽  
Factors Affecting ◽  
Opposite Trend ◽  
Rhizome Buds

Approximately 80% of the johnsongrass(Sorghum halepense(L.) Pers.) rhizomes produced in clay soil were in the top 7.5 cm, but 80% of the rhizomes in sandy loam occurred in the top 12.5 cm. Distribution of rhizomes within the top 20 cm of soil was more uniform in sandy loam than in clay; yet, 5% of the rhizomes produced in clay occurred deeper than 20 cm, but only 1% of the rhizomes in sandy loam occurred deeper than 20 cm. Incorporation ofa,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-/7-toluidine (trifluralin) in soil at 0.84 kg/ha reduced rhizome production approximately 50% throughout the soil profile but reduced rhizome production most in the top 6 cm. More plants emerged from rhizomes when planted in sandy loam than in clay. More plants emerged from short rhizomes (76 mm) than from long rhizomes (152 mm) when planted at depths to 7.6 cm, but the opposite trend was obtained when rhizomes were planted deeper. Percentage germination of rhizome buds increased as rhizomes were cut into smaller pieces. Exposure of rhizomes to temperatures of 50 to 60 C killed buds within 1 to 3 days. Rhizomes usually survived temperatures of −3 to −5 C for only a few hours.

scholarly journals Problems of water supply of the population and application of the method of electrolysis-structural activation for partial solution

2018 ◽  
Vol 193 ◽  
pp. 02019
Author(s):  
Ludmila Prikhodko ◽  
Galina Bryukhanova ◽  
Ekaterina Beljakova
Keyword(s):  
Water Supply ◽  
Reverse Osmosis ◽  
Arid Regions ◽  
Sea Water ◽  
Partial Solution ◽  
Global Scale ◽  
Membrane Technology ◽  
Saline Groundwater ◽  
Desalinated Water

We analyzed the problems of water supply for the population of global scale and regional importance. A method for the electrolysis-structural activation of water oriented on the use of initial fresh rainwater or desalinated membrane technology of sea water in a mix with biologically purified household sewage waters. This method can be used on sea vessels, in arid regions of the planet, and in areas with saline groundwater. Activation of water is achieved by mixing biologically purified wastewater obtained by technology that ensures the quality of purified water at the level of requirements for release in a fishery pond and desalinated water (rainwater) or obtained by reverse osmosis in a ratio of their volumes not more than 10:1

Enhancing Groundwater Recharge with Sand Ditches

2019 ◽  
Vol 35 (4) ◽  
pp. 543-549
Author(s):  
Majed M Abu-Zreig ◽  
Haruyuki Fujimaki ◽  
Mohamed Abdel Baset
Keyword(s):  
Groundwater Recharge ◽  
Arid Regions ◽  
Sandy Loam ◽  
Drainage Water ◽  
Relative Effect ◽  
Experimental Results ◽  
Low Density ◽  
Deep Percolation ◽  
Soil Matrix ◽  
Water Percolation

Abstract. Localized and artificial groundwater recharge is an important water management strategy in arid regions. However, artificial recharge is limited by the hydraulic characteristics of surface soil which control downward water percolation to the aquifers. In heavy soils with low infiltration and hydraulic conductivity rate, water percolation can be enhanced by constructing deep ditches filled with highly permeable materials, such as sand. Laboratory experiments were conducted to examine the effect of constructing a deep sand ditch across the slope of a soil box (50 × 20 × 25 cm3) on runoff and deep percolation to the drainage outlet of the soil box. A sandy loam soil packed in two bulk densities (1200 and 1500 kg/m3) was used for the experiments. The experiments were carried out using simulated steady runoff of about 300 mL/min for a duration of 60 min. Experimental results showed that sand ditches greatly enhanced water deep percolation in soils but their relative effect was more profound in compacted high-density soil compared to soil having low-density. The drainage water collected from compacted soil boxes in the presence of sand ditches increased by 10 times compared to control soil without sand ditches. In the case of low-density soil, the presence of sand ditches eliminated the runoff but the increase in drainage water was about 18% compared to control. The experimental results clearly revealed that creating high infiltration zones within the soil matrix, such as sand ditches, significantly increased water deep percolation and herewith groundwater recharge in drylands, especially in heavy soils. Keywords: Arid regions, Groundwater recharge, Percolation, Rapid infiltration.

EVAPORATION FROM TWO POROUS MEDIA DURING DIURNAL RADIATION CYCLES

1978 ◽  
Vol 58 (4) ◽  
pp. 465-474
Author(s):  
N. K. NAGPAL ◽  
L. BOERSMA
Keyword(s):  
Porous Media ◽  
Pore Size ◽  
Water Loss ◽  
Maximum Rate ◽  
Experimental Period ◽  
Evaporative Demand ◽  
Flow Equations ◽  
Average Value ◽  
Saturated Media ◽  
Rate Of Evaporation

The process of evaporation from porous media subjected to diurnal radiation cycles was studied. Information about pore size effects on evaporation was also obtained. Two porous media consisting of glass beads with diameters ranging from 53 to 74 μm and from 149 to 210 μm were used. Rates of water loss from the initially saturated media varied during the diurnal cycle. The initial rise in rate of surface irradiation increased the rate of water loss from both media. For the coarser material the rate of evaporation continued to increase for several hours after the maximum rate of irradiation was reached while for the finer material the rate of evaporation reached a maximum value even before the maximum rate of irradiation was attained. As a result, the ratio of the evaporation rates, Ecoarse/Efine, varied during the day from approximately 1.0 during periods of low evaporative demand to 2.60 during periods of high evaporative demand with an average value of 1.47 for the full day. The total amount of water lost per day from each medium remained constant during a 7-day experimental period, even though the surface layers dried out during periods of high irradiation. The pore size dependency of the rate of water loss was shown to be determined by the hydraulic conductivities of the porous media. The rates of water loss predicted by unsaturated water flow equations agreed well with the experimental data.

scholarly journals Influence of salinization on seeds germination of the fodder semi-shrub of the eastern saltwort (Salsola orientalis S.G. Gmel.)

2020 ◽  
Vol 222 ◽  
pp. 02022
Author(s):  
Elmira Shamsutdinova
Keyword(s):  
Salt Stress ◽  
Nutritional Value ◽  
Arid Regions ◽  
Sandy Loam ◽  
Dry Mass ◽  
Distilled Water ◽  
Sulphate Chloride ◽  
Adverse Environmental Conditions ◽  
Seeds Germination ◽  
Regions Of Russia

Eastern saltwort (Salsola orientalis S. G. Gmel.) belongs to the goosefoot family (Chenopodiaceae Vent.), the genus Salsola L., a semi-shrub with 25-70 cm high with fleshy leaves. It is distributed on saline sandy loam and stony soils from plains to low mountains. It is widely used to restore productivity of degraded natural pastures in arid regions of Russia and Central Asia countries. It is characterized by good palatability, nutritional value, exceptional resistance to salt stress, drought and other adverse environmental conditions. The objective of the study is to find out the effect of different salt concentrations on the germination of eastern saltwort seeds. The influence of various types of salinization on the germination of eastern saltwort seeds in concentrations was tested (0.2; 0.4; 0.6; 0.8; 1.0; 1.2; 1.4; 1.6; 1.8 and 2.0% to the absolutely dry mass of sand): chloride, sulphate, sulphate-chloride, chloride-sulphate, control – sand moistened with distilled water. With chloride salinization at concentrations of 0.2-0.4%, the germination energy and germination of eastern saltwort seeds decreased slightly, and at concentrations of 1.2-1.4%, germination stopped. Sulfate salinization was the least toxic. With all types of salinization, with an increase in the salt concentration, the sowing – germination period is delayed and the process of germination of eastern saltwort seeds is expanded. Although eastern saltwort is a true halophyte, its seeds germinate better on a nonsaline substrate.

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