scholarly journals An Environmentally Friendly Soil Amendment for Enhancing Soil Water Availability in Drought-Prone Soils

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 133
Author(s):  
Ting Yang ◽  
Xuguang Xing ◽  
Yan Gao ◽  
Xiaoyi Ma

Applying soil amendments plays a critical role in relieving water stress in arid and semiarid areas. The natural clay mineral attapulgite (ATP) can be utilized to adjust the balance of water and soil environment. In this study, we investigated four different particle size distribution typical soils in the Loess Plateau: (1) lou soil (LS), (2) dark loessial soil (DS), (3) cultivated loess soil (CS), (4) sandy soil (SS). Five ATP application rates (0, 1%, 2%, 3%, and 4%) were selected to test the effect of ATP on the soil water retention curve, soil saturated hydraulic conductivity, and soil structure. The results showed that applied ATP significantly increased the soil clay content, and the relative change of SS with 3% ATP applied increased by 53.7%. The field water holding capacity of LS, DS, CS, and SS with 3% ATP applied increased by 8.9%, 9.6%, 18.2%, and 45.0%, respectively. Although applied ATP reduced the saturated hydraulic conductivity, the values of CS and SS were opposite when the amount of ATP applied was >3%. The relative change in the amount of 0.25–1 mm soil water-stable aggregates of SS was 155.9% when 3% ATP was applied. Applied ATP can enhance soil water retention and soil stability, which may improve limited water use efficiency and relieve soil desiccation in arid and semiarid areas or similar hydrogeological areas.

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
Csilla Farkas ◽  
Csaba Gyuricza ◽  
Márta Birkás

AbstractIn the present work the effect of five tillage methods on the hydraulic properties and water regime of a brown forest soil was studied. In each treatment, measurements of bulk density and soil water retention characteristics were carried out 3 times (March, June and August) within the vegetation period. Near-saturated hydraulic conductivity and soil water content measurements were performed five and eight times, respectively. Statistically valuable differences were obtained between the soil properties, measured in different tillage treatments. The effect of the tillage treatments on the water retention curves was significant in the low suction range (pF < 2.0) only. Differences between the soil water retention curves, measured at the end of the vegetation period reflected the indirect effect of different tillage systems on soil hydraulic properties. The seasonal variability of both the soil hydraulic functions was proofed. Saturated hydraulic conductivity values, evaluated in the ploughing treatment at the beginning and end of the vegetation period differed up to 4-times. The near-saturated hydraulic conductivity values measured in March were nearly two times higher in all the treatments, except no till, than those, measured in August. The applied tillage systems did not influence the potential amount of water available for the plant; still, valuable differences between the soil water contents were measured. According to the soil hydraulic properties and measured soil water regime, ploughing and deep loosening created the most favourable soil conditions for the plants. The biological activity, however, was the highest in the no till treatment. Further studies on the application of the soil conserving tillage systems under Hungarian conditions are recommended.


Author(s):  
Shaoyang Dong ◽  
Yuan Guo ◽  
Xiong (Bill) Yu

Hydraulic conductivity and soil-water retention are two critical soil properties describing the fluid flow in unsaturated soils. Existing experimental procedures tend to be time consuming and labor intensive. This paper describes a heuristic approach that combines a limited number of experimental measurements with a computational model with random finite element to significantly accelerate the process. A microstructure-based model is established to describe unsaturated soils with distribution of phases based on their respective volumetric contents. The model is converted into a finite element model, in which the intrinsic hydraulic properties of each phase (soil particle, water, and air) are applied based on the microscopic structures. The bulk hydraulic properties are then determined based on discharge rate using Darcy’s law. The intrinsic permeability of each phase of soil is first calibrated from soil measured under dry and saturated conditions, which is then used to predict the hydraulic conductivities at different extents of saturation. The results match the experimental data closely. Mualem’s equation is applied to fit the pore size parameter based on the hydraulic conductivity. From these, the soil-water characteristic curve is predicted from van Genuchten’s equation. The simulation results are compared with the experimental results from documented studies, and excellent agreements were observed. Overall, this study provides a new modeling-based approach to predict the hydraulic conductivity function and soil-water characteristic curve of unsaturated soils based on measurement at complete dry or completely saturated conditions. An efficient way to measure these critical unsaturated soil properties will be of benefit in introducing unsaturated soil mechanics into engineering practice.


2020 ◽  
Vol 195 ◽  
pp. 01004
Author(s):  
Ali Kolahdooz ◽  
Hamed Sadeghi ◽  
Mohammad Mehdi Ahmadi

Dispersive soils, as one of the main categories of problematic soils, can be found in some parts of the earth, such as the eastern-south of Iran, nearby the Gulf of Oman. One of the most important factors enhancing the dispersive potential is the existence of dissolved salts in the soil water. The main objective of this study is to explore the influence of water salinity on the instability of a railway embankment due to rainfall infiltration. In order to achieve this goal, the embankment resting on a dispersive stratum is numerically modeled and subjected to transient infiltration flow. The effect of dispersion is simplified through variations in the soil-water retention curve with salinity. The measured water retention curves revealed that by omitting the natural salinity in the soil-water, the retention capability of the soil decreases; therefore, the unsaturated hydraulic conductivity of the soil stratum will significantly decline. According to the extensive decrease in the hydraulic conductivity of the desalinated materials, the rainfall cannot infiltrate in the embankment and the rainfall mostly runs off. However, in the saline embankment, the infiltration decreases the soil suction; and consequently, the factor of safety of the railway embankment decreases.


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