Water movement and salt leaching in drained and irrigated marsh soils of southwest Spain

doi:10.1016/0378-3774(95)01128-6

Agricultural Water Management

Volume 27, Issue 1, April 1995, Pages 25-44

https://doi.org/10.1016/0378-3774(95)01128-6 Get rights and content

Abstract

The Guadalquivir river marshes in southwest Spain, are situated in a former estuary that has now been drained. They cover some 140 000 ha. Soils formed in this zone are alluvial, very clayey, salinesodic, and of vertic character with a shallow, very-saline water table. An area within these marshes, reclaimed in 1979, is the object of this detailed study which looks at some physical and chemical properties of soil, and also the influences of sprinkler and furrow irrigation on drainage and salt leaching. These studies were conducted between 1988 and 1990. A 1 ha experimental plot was used for this purpose. The plot is situated within an area of the marshes being used for standard agricultural practices, equipped with a drainage system of ceramic pipes buried 1 m deep and spaced 10 m apart, ending at an open ditch collector which is perpendicular to them. The following measurements have been carried out: soil bulk density changes with water content, hydraulic conductivity and sorptivity, soil water content and water tension profiles changes, water table level, drainage outflow and salt content of soil, soil solution and drainage water. Cotton was used as the crop. The results obtained show that after ca. 10 years in reclamation the electrical conductivity and exchangeable sodium percentage decreased in the 0–90 cm layer of this soil, particularly in the top 50 cm, that reduces the adverse effects of salinity on crop development. During both sprinkling and furrow irrigation a rapid response of the drain pipes was observed because of the soil fissures and crack network that resulted from the shrinking and swelling processes. Maximum drainage outflow was reached when the irrigation stopped. Water movement in this soil is characterized by an initial rapid phase, due to the soil fissures and cracks, followed by a second slow one controlled by the soil matrix. The efficiency of irrigation in salt leaching was higher in the case of furrow irrigation (16 g of salt leached per litre of applied water) than in the case of sprinkling irrigation (10 g l⁻¹), owing to the use of more water in the latter. The salinity of soil and soil solution decreases after irrigation starts, the time taken to reach a minimum value for the different soil layers and the irrigation method used were different. In 1989 due to water restrictions at some time of the crop period, the irrigation schedule was different to that normally used, and the crop was affected by water stress and capillary rise of saline water.

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Effects of water application intensity of micro-sprinkler irrigation and soil salinity on environment of coastal saline soils
2020, Water Science and Engineering
Citation Excerpt :
This was because the initial soil salinity in the S3 treatment was very high (resulting in the soil being classified as very strongly saline). The variation of soil salinity in the soil profile was similar to that found by Oster et al. (1972) and Moreno et al. (1995), who observed that soil salinity decreased with increasing soil depth as was the pattern in the present study. Although the soil profiles were saturated in some treatments, the soil salt content was still low.
To achieve the greatest leaching efficiency, water movement must occur under unsaturated flow conditions. Accordingly, the water application intensity of irrigation must be chosen carefully. The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents. To achieve this objective, a laboratory experiment was conducted with three soil salinity treatments (2.26, 10.13, and 22.29 dS/m) and three water application intensity treatments (3.05, 5.19, and 7.23 mm/h). The results showed that the effect of soil salinity on soil water content, electrical conductivity, and pH was significant, and the effect of the water application intensity was insignificant. High soil water content was present in the 40–60 cm profile in all soil salinity treatments, and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment. Significant salt leaching occurred in all treatments, and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment. In the medium and high soil salinity treatments, pH exhibited a decreasing trend, with no trend change in the low soil salinity treatment, and the pH value was higher in the medium water application intensity treatment than in the other two treatments. These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts (E_C) in the upper 20 cm of the soil profile, and it would be better to maintain a lower value of the water application intensity.
A coupled model for simulating water flow and solute transport in furrow irrigation
2019, Agricultural Water Management
For optimal water and fertilizer management under furrow irrigation, it is important to understand the water and solute dynamics on the land surface and in the subsurface. An efficient mathematical tool is required to describe these dynamic processes. We propose a coupled model in which surface water flow and solute transport are described using the zero-inertia equation and the average cross-sectional convection-dispersion equation, respectively, while the two-dimensional Richards equation and the convection-dispersion equation are used to simulate water flow and solute transport in soils, respectively. Solutions are computed numerically using finite differences for surface water flow and finite volumes for solute transports in furrow. Subsurface water flow and solute transport equations are solved using the CHAIN_2D code. An iterative method is used to couple computations of surface and subsurface processes. Both surface and subsurface water flow and solute transport modules are coded in program subroutines and functions in the Intel FORTRAN environment. The coupled model was validated by comparing its simulation results with measured data. Results showed that simulated water front advances in the furrow and water contents in the soil agreed with the observations reasonably well. Good simulations can be achieved with a relatively fine temporal resolution. Numerical oscillations can be eliminated by adopting appropriate time steps. As compared with the traditional furrow irrigation model, the proposed model can better quantify soil water and solute dynamics by considering interactions between surface and subsurface water flow and solute transport processes. The proposed model can be used as a decision tool to design and manage furrow irrigation.
Influence of drip irrigation level on salt leaching and vegetation growth during reclamation of coastal saline soil having an imbedded gravel–sand layer
2017, Ecological Engineering
Water resources are very scarce in coastal saline areas; as such, water-saving irrigation regimes are needed. Drip irrigation combined with an imbedded gravel–sand layer has been proved to be a good method for constructing ecological landscapes in coastal saline soils. A 3-yr experiment (2009–2011) was conducted to evaluate the effects of different drip irrigation amounts controlled by soil matric potentials (SMP) (−5, −10, −15, −20, and −25 kPa) on soil salinity and landscape species growth in coastal saline soils with an imbedded gravel–sand layer in Northeast China. The mean electrical conductivity of the saturated paste extract (EC_e) of the soil profile significantly decreased to less than 4 dS m⁻¹ for SMP treatments higher than −20 kPa after two months, then remained at the low level. No significant differences in the extent of desalinization occurred among the drip irrigation treatments based on −5, −10, −15, and −20 kPa SMP. The −20 kPa treatment could reduce irrigation water usage by 150–610 mm in the first three years of reclamation compared with higher SMPs (−5, −10, and −15 kPa). Variations of pH of the saturated paste extract (pH_e) in the soil profile were relatively moderate. After the 3-yr experiment, the landscape species that are moderately sensitive or sensitive to salt grew well, with an average survival rate of 72%. To balance salt leaching and water saving, a SMP of −20 kPa could be used to guide landscape construction in the first three years of reclamation.
Salt leaching in fine-grained, macroporous soil: Negative effects of excessive matrix saturation
2017, Agricultural Water Management
Citation Excerpt :
In contrast, the influence of macropores on removal of in situ contaminants, such as salt, within the vadose zone and shallow groundwater has received far less attention. Salt leaching effectiveness in fine-grained, macroporous soils has traditionally been studied from the perspective of the method of irrigation application (e.g., ponding, progressive ponding, sprinkler, drip, and furrow irrigation) (Moreno et al., 1995; Prendergast, 1995; Youngs and Leeds-Harrison, 2000; Crescimanno et al., 2007), as well as water application intensity (Tanton et al., 1995). Although field studies (Qadir et al., 2000) and numerical modeling (Xin et al., 2016) suggest that macropores may decrease the efficiency of salt leaching, our understanding of the influence of macropores and matrix-macropore exchange is limited.
Irrigation and tile drainage are commonly used to reclaim salt-affected soils, but salt leaching can be hindered in low permeability soils when infiltrating water preferentially flows along vertically connected macropores and bypasses the saline soil matrix. To identify the important controls on salt leaching effectiveness in fine-grained, macroporous soil, a two-year irrigation and drainage field experiment was undertaken to return a salt-affected soil to agricultural production. Salt leaching effectiveness in a 20 × 20-m irrigated test plot was evaluated using time-lapse electrical resistivity tomography, soil sampling, drainage monitoring and subsurface water sampling. Results were compared to an adjacent unirrigated control plot. During the first year of the irrigation experiment, effective leaching resulted in a 23–40% decrease in salt mass over a depth of 0–2.4 m. In the second year, similar amounts of applied water (irrigation + precipitation) resulted in negligible salt leaching due to a rise in the regional water table and wetter soil conditions that limited macropore-matrix interaction. Chloride mass recovery in tile drainage water, which was greater in Year 2 due to upward seepage, was not a reliable indicator of leaching from the root zone. Proper monitoring and control of irrigation and drainage to avoid overly wet soil matrix conditions can increase salt leaching efficiency, giving shorter reclamation timelines and reduced volume of applied water.
Dynamics of meltwater quality and quantity during saline ice melting and its effects on the infiltration and desalinization of coastal saline soils
2014, Agricultural Water Management
Citation Excerpt :
The infiltrations of water with different qualities and volumes may lead to differences in the leaching of different cations (Na+ Ca2+ and Mg2+) in soil column (Kolahchi and Jalali, 2007; Jalali and Ranjbar, 2009). Moreno et al. (1995, 2001) reported that soil SAR variation pattern was similar to that of Na+. The reduction in soil SAR values in the upper soil layers may be caused by Na+ leaching from low salinity meltwater or even fresh water at later time as well as increased Na+ accumulation in the deeper soil layers.
Laboratory experiments were conducted to investigate the changes in the quality and quantity of meltwater during saline ice melting and the redistribution of water, salt, and sodium adsorption ratio (SAR) in coastal saline soils following the infiltration of saline ice meltwater. Three salinity levels (5, 10 and 15 g L⁻¹) and three SAR (mmol L⁻¹)^0.5 levels (5, 10 and 30) of saline ice were tested, with salt-free ice as the control treatment. The results showed that during saline ice melting, the initial meltwater contained extremely high concentration of salts with high SAR, and about 60% of low salinity (<4 g L⁻¹) and low SAR (<9) water were produced from melting saline ice. The infiltration rate of saline ice meltwater to saline soils was greater than that of salt-free ice meltwater, and was increased with the increase of ice salinity and decrease of ice SAR. After infiltration, soil water content of the upper soil layers under saline ice treatments was lower than that of the salt-free ice treatment, and was increased with the increase of ice SAR. This trend was reversed in the deeper soil layers. Both salt contents and SAR values in the upper soil layers were reduced in all salt treatments, and were lower than those of salt-free ice treatment. The highest desalting rate and lowest SAR were observed in the SAR 5 saline ice treatment, but there was no significant difference among saline ices within the same SAR treatments. These results indicate that saline ice can be desalinized efficiently with melting, and saline soils can be improved through infiltration with melting saline ice water.
Implications for food safety of the uptake by tomato of 25 trace-elements from a phosphogypsum amended soil from SW Spain
2014, Journal of Hazardous Materials
Citation Excerpt :
The radionuclide and heavy metals content of this PG is well characterized [9,19]. Since the last sixties, this PG was crucial in the reclamation of the saline-sodic marshlands from SW Spain [4,20–22] where it was applied as Ca-amendment at a usual rate of 25 Mg ha−1 (wet weight, after being sun-dried, and with typical remaining water content of 20%). This amendment was essential to achieve a reduction of Na saturation and improvements of physical properties in soil [6,7,23].
Phosphogypsum (PG) has been usually applied as Ca-amendment to reclaim sodic soils such as those in the marshland area of Lebrija (SW Spain). This work aimed at the effects of PG amendments on the uptake of trace-elements by tomato and its implications for food safety. A completely randomized experiment was performed using a representative soil from Lebrija in a greenhouse involving six replicates and four PG treatments equivalent to 0, 20, 60, and 200 Mg ha⁻¹. Soil-to-plant transfer factors (TFs) were determined for Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Pb, Th and U. The highest TF in shoots was observed for Cd (4.0; 1.5 in fruits), its concentration being increased with increasing PG doses due to its content in this metal (2.1 mg Cd kg⁻¹ PG). Phosphogypsum applying decreased the concentrations of Mn, Co and Cu in shoots; and of B, Cu, Sb, Cs, Ba, Tl and Th in fruits, however enhanced the accumulation of Se in fruits. Although Cd concentrations in tomato were below the maximum allowed levels in control pots (0 Mg PG ha⁻¹), PG amendments above 60 Mg ha⁻¹ exceeded such limits.

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Water movement and salt leaching in drained and irrigated marsh soils of southwest Spain

Abstract

Geoderma

Soil Tech.

Catena

Soil Technol.

Movimiento de agua y sales en suelos recuperados a la Marisma del Guadalquivir

The Grendon Underwood field drainage experiment

Salt movement in Guadalquivir marshy soils under field and laboratory conditions

Egypt. J. Soil Sci.

The alkali soils of the lower valley of the Guadalquivir: physico-chemical properties and nature of their clay fraction