Background and purpose: With the increase in world population and the need to provide food, farmers are now using a variety of chemical fertilizers, organic pesticides have turned. Indiscriminate use of these inputs without considering its side effects, both environmental problems and brings in terms of human health. Among these, organic fertilizers contain soluble compounds such as nitrate. These compounds through precipitation or irrigation of the soil solution, groundwater and surface water resources are. The purpose of this study was to determine the amount of nitrate transport in clay and simulation software using HYDRUS0D.Methods: In order to perform it, 5 different height of soil column 20, 40, 60, 80 and 100 cm selected. In thicknesses of 20, 40, 60 and 80 cm respectively output levels after a period of 6, 12, 18 and 22 hours to input the concentration of nitrate (50 mg/lit) is. In thicknesses of 20, 40, 60 and 92 cm, respectively, after the time of 5.6, 5.12, 21, and 25-hour concentration of 50 mg/lit is output. In thickness 20, 40, 60 and 80cm, outlet concentration after 6, 12, 18 and 22 minutes inlet concentration (50mg/lit).Results: The result showed that Hydrus software ability of simulates nitrate movement in soil and result of Hydrus software and laboratory data near.Conclusions: With increasing soil thickness difference HYDRUS0D results and experimental data more and more time to transfer nitrate were spent with increasing thickness.

Soil strength and elasticity modules are important parameters in the engineering characteristics of soils. Bearing capacity is increased by soil strength. Elasticity module determines the potential of soil deformation. In this experiment, stabilization of problematic clay soils using sands were investigated. The samples were prepared with variable soil moisture and compaction, and were tested in single-axis compression apparatus in the soil mechanics laboratory of Shahid Chamran University (SCU) in Khuzistan province. The samples were tested with soil moistures as follows: optimum humidity, 2% and 4% less than optimum, and 2% and 4% more than optimum moisture. The compaction of applied, R.C, were equal to 85, 95 and 100 percents. Using the obtained data, the soil strength and elasticity modules were calculated. Our findings show that for all in clay and sandy-clay samples tested increasing moisture lead to decrease of soil strength. However, reduction of soil strength in the sandyclay sample is more than problematic clay soils samples. Results of these experiments regarding the moisture change from 4% less than optimum to 4% more than optimum, decreased soil strength of problematic clay soil, approximate 84%, while, for sandy-clay soil it was about 93 percents. Moreover, decreasing of elasticity module in sandy clay samples with 100% compaction and 13% moisture is approximately 51 percents.

This research explores the stabilization of clay soil through the application of geopolymer binder derived from silicomanganese slag (SiMnS) and activated by sodium hydroxide (NaOH). This research aims to evaluate the effects of key parameters, including the percentage of slag, the activator-to-stabilizer ratio, and curing conditions (time and temperature), on the mechanical properties of the stabilized soil. Unconfined compressive strength (UCS) tests were conducted to assess improvements in soil strength, while scanning electron microscopy (SEM) was employed to analyze the microstructural changes and stabilization mechanisms. The results demonstrated that clay soil stabilized with SiMnS-based geopolymers exhibited significant strength enhancement. Specifically, the sample stabilized with 20% SiMnS and an activator-to-slag ratio of 1.6, cured at room temperature for 90 days, achieved a UCS of 27.03  kg⁄(cm^2 ). The uniaxial strength was found to be positively correlated with the SiMnS content, activator ratio, curing time, and temperature. Additionally, the strain at failure remained below 1.5% for all samples, indicating a marked improvement in soil stiffness. SEM analysis revealed that geopolymerization led to the formation of a dense matrix, enhancing soil particle bonding and overall durability. These results emphasize the potential of SiMnS-based geopolymers as a sustainable and effective soil stabilizer for geotechnical applications.

Drying of soils and shrinkage cracks is a crucial issue in geotechnical and geo-environmental engineering. Better understanding of the soil cracking process is essential in analyzing desiccation effects on buildings integrity. In this study, cracking behavior of the clay due to desiccation investigated experimentally at different temperatures on thin clay layer. Experimental tests carried out on the clay slurry saturated with water content about 60%, (1.5 times of its liquid limit). In this study, the clay supplied from clay mine in Abadeh, a city in Fars province in Iran.Experimental results showed that the critical water content, which corresponds to the initiation of desiccation crack increases when the temperature rises. In addition, the number of produced cracks decreases by increasing the temperature. This phenomenon can be attributed to the reduction of water surface tension force or voids central tendency in soil mass. Also, the width of crack opening decreases by increasing the temperature.

Expansive soils have the tendency to more swelling, shrinking and compressibility by variation in soil-water interaction affecting the alteration in the bearing capacity of soil. There are several methods used to stabilize the soils and promote sustainable development in the construction industry. In this, soil stabilization is prime and efficient techniques to improve the strength by altering the physical characteristics of the soil. In addition, admixtures improved the chemical characteristics of soil and also attained stability by improving the bonding between the soil structures. Soil stabilization has been experimented by many researchers and successfully used in several field applications especially using cement, lime, ashes, chemicals etc. An alternative to these options mentioned is using natural cementitious material such as calcined clay as an admixture. This work focuses on the effect, the development of the strength properties of treated soils with varying percentages of calcined clay as 2%, 4%, 6%, 8% and 10% under varying curing times. The enhanced strength behaviours of the expansive soil were determined by performing the unconfined compression test and also the microstructural studies like SEM and XRD for the selected samples. The results indicate that the maximum strength was attained on 8% admixture treated soil. Thus calcined clay acts as a natural cost-effective and eco-friendly stabilizer in place of replacement of cement to stabilize expansive soil which develops the strength characteristics of the expansive soil and also reduces environmental pollution.

The engineering properties of stabilized soils are varied for many factors such as soil heterogeneity, soil composition, soil structures, geological conditions, and the difference of interaction between the soil and stabilizers. These variations required the consideration of stabilization at a specific site option. These natural materials, therefore, critically influence the success of a construction project. The reason for this study was to quantify the improvements achieved in the engineering properties of expansive soils due to lime stabilization. This study considered quantitative experimental to determine lime-stabilized expansive clay soil's engineering properties using a laboratory program. Laboratory tests were to determine Atterberg Limits, compaction test, free swell test, California Bearing Ratio (CBR), and pH values of the mixtures. The collected soil samples were stabilized using 2, 4, 5, 6, and 8% of hydrated lime by weight. The optimum lime for the stabilization of expansive soils was 5% using hydrated lime. As percentages of hydrated lime increased, there were improvements in stabilized subgrade soil properties. The more significant upgrade in engineering properties was observed on California Bearing Ratio (CBR), and lower improvements were on maximum dry density. The result indicated that the stabilizer is very effective in improving strength parameters than index parameters. The hydrated lime stabilized soils under the optimum ratio fulfill the standard requirements as subgrade soils.

Background and Objective: In studies realted to hydrology, water conservation and management, accurate information of the water capacity in different soils for measuring water infiltration, drainage and erosion control is essential in order to launch irrigation projects in watersheds. The purpose of this study is to evaluate the effect of clay layers in the transfer of water through loamy sand. Method: Soil columns with a height of 150 cm and a diameter of 15 cm, were filled with clay layers to depths of 13 and 20 cm. Then the same volume of water with different salt concentrations was added to all columns. Also water sampling was carried out on a daily basis. Findings: Results showed that the layer clay could reduce the volume of water passing through the columns and by increasing the thickness of the clay layer, the ratio of passed water decreased. The results showed that by increasing the depth of the clay layer in the control treatment to a depth of 20, the amount of water at a concentration of 13 mEq and 20 mEq decreased by 16 and 35 percent. Discussion and Conclusion: Different performances were due to the thickness of clay layer. Because of the small clay texture and high compressibility, the movement of water in the soil can be delayed. This feature can be used to prevent the movement of leachate and pollution into the soil and contaminate groundwater. It seems that by changing the depth of the clay layer, the conductivity can be controlled in sensitive areas.

manure sources to available forms to promote food security in context of rising climate change is vital. Effect of manure (types, nutrients, high rates and application time) on soil N transformation requires further investigation.This study evaluated effects of three animal manures on soil N mineralization of sandy clay loam. Methods A 22-week field study in a Randomized Complete Block Design (three replicates) was conducted using dried Cattle, Goat and Poultry Manures (CGPM), applied at 5, 10, 20, 40, 60, 80, 120 and 150 t ha-1 once at onset of the study. Also, N15P15K15 (0.4 t ha-1) was incorporated in three splits of 2, 8 and 14 weeks after incorporation (WAI) of manures as reference. Soil NH4+–N and NO3-–N were determined bi-weekly.Results The results showed N release peaked at 10 WAI with highest NH4+–N (830, 400, 253 mg kg-1) and NO3-–N (316, 398, 250 mg kg-1) at 150, 60 and 60 t ha-1 for CGPM, respectively. Initial rapid N release phase occurred at 0–4 WAI, NH4+–N and NO3-–N increased averagely by 182, 183, 139% and 131, 175, 144% for CGPM, respectively. Declines occurred at 8, 14 and 22 WAI but reduction observed at 22 WAI tripled 8 and 14 WAI.Conclusions Application of NPK and all the manures provided highest soil NH4+–N and NO3-–N at 12 WAI. High rates of CGPM were not injurious to these soil properties; hence this has implication for N to maximize plants uptake as well as decrease losses to environment.