Gypsiferous Soils Research Articles

Evaluation of Inoculation with Bradyrhizobium manausense and Bradyrhizobium venae on the Elemental content of Cowpea Plant in Gypsum Soil

A field experiment was conducted during the spring season on 3/25/2022 in the fields of the University of Tikrit / College of Agriculture located in the research station of the Department of Soil Sciences and Water Resources, with the aim of studying the effect of inoculation with Rhizobia bacteria and nitrogen fertilization on the growth and yield of cowpea in gypsum soil, conducted in a randomized complete block design. R. C. B. D With three replications, the experiment included two main factors: inoculation with rhizobium bacteria, and the second factor was nitrogen fertilization. The inoculation factor was three levels (A0 = no inoculation, A1 = inoculation with the first strain, Bradyrhizobium manausense, and A2 = inoculation with the second strain, Bradyrhizobium vignae), and the second factor was nitrogen fertilization. At three levels N0 and N1 = 40 kg / ha and N2 = 80 kg / ha, the process of isolation and development of Rhizobium bacteria was conducted on the optional medium (YEMA), and the two isolates were identified and recorded in the National Center for Biotechnology Information (NCBI) by number Global OP740389 Bradyrhizobium vignae, as for the results of the field experiment, the inoculation treatment with root nodes bacteria Bradyrhizobium vignae was superior to the control treatment and even to the second strain Bradyrhizobium manausense in all studied traits of cowpea plant, and the percentage increase of the inoculation treatment with Bradyrhizobium vignae with 40 kg of nitrogen fertilizer was higher than The control treatment in the number of root nodes and their wet weight (1474.87, 267.101)%, respectively, and the concentration of nitrogen, phosphorus and potassium in the vegetative part (61.300, 1.600, 7.102)%, respectively.

Suction Variation of Natural and Treated Unsaturated Gypseous Soils During Wetting

Abstract The current work is directed to study the variation of suction with time and soil water characteristics curve (SWCC) for natural and treated gypseous soil treated with two types of additive (lime and silica fume) compacted at different initial degrees of saturation S0 = 20 and 50 %. Soil subjected to wetting in an upward direction. Three types of gypsum soils were experimented with different gypsum content 15, 35, and 60 % taken from various sites in Salah Al-dean government, Iraq. The main results show that the air-entry value, residual values, and the time required for the entire saturation stage increases with increasing gypsum content and treatment with lime and silica fume and they for soil treated with silica fume are greater than for soil treated with lime. The rate of flow for soil treated with silica fume is less than that of soil treated with lime. The treated soil is more effective in increasing the time required for the entire saturation stage and decreasing the rate of flow when compacted at an effective degree of saturation S0 = 50 %.

Estimation of Saturated Hydraulic Conductivity using Pedotransfer Function (PTFS) in Gypsiferous Soil

This study was conducted to evaluate the performance of pedotransfer functions (PTFS) in estimating the saturated hydraulic conductivity in gypsum soil. The saturated hydraulic conductivity was measured for 26 unexcited samples using the permeability of the falling head, and then some chemical and physical properties of the study soil were measured. Rosetta and a number of models were used to predict the saturated hydraulic conductivity. Three statistical criteria, namely NSE, RMSE, and R2, were used to evaluate the performance of the models. The results showed that the second model of Rosetta, which depends on sand, silt, clay, and bulk density as input, is the best, as the values of NSE and RMSE were -13.28 and 0.31, respectively, while the other models, Puckett, Smettem, Bristow, and Saxton, were the best in predicting the saturated hydraulic conductivity of Among the models, the RMSE values were 0.52, 0.54, and 0.47, respectively, and the NSE values were 0.92, 0.91, and 0.93, respectively.

The Effect of Adding Poly-γ-Glutamic Acid (γ-PGA) on the Moisture Content of Gypsiferous Soil Under Partial Drip Irrigation System

The alternate partial root-zone irrigation APRI is a modern irrigation method to save irrigation water. A field experiment was conducted to study the effect of the conventional irrigation(CI) system and the APRI system, using different levels of poly-γ-glutamic acid (γ-PGA) (0, 15, 30, 60, and 120) kg ha-1 in Gypsiferous Soil, on soil moisture content and water use efficiency. The APRI method achieved the best water extraction efficiency of 3.25 kg.m-3. The depths of water added in the traditional irrigation method were (435.58, 420.52, 416.71, 410.98, and 398.67) mm, and in the alternating irrigation method, they were (390.42, 370.50, 361.27, 340.40, and 322.40) mm for the additional levels of (γ-). PGA), respectively. The APRI method achieved an abundance of irrigation water compared with the CI of (11.57, 13.50, 15.35, 20.74, and 23.66)% for the different addition levels of (γ-PGA), respectively. The decrease in moisture content with the increase in the applied water voltage. There is a direct relationship between the amount of water available to the plant and the level of addition of (γ-PGA).

The Effect of Tillage Systems, Type of Organic Fertilizer and the Level of Binary Addition of Nitrogen and Phosphorus on the Growth and Yield of Clover in Gypsum Soil

A field experiment was conducted at the research station of the College of Agriculture - University of Tikrit for the agricultural season (2021-2022), and the experiment factors were three, namely: the first factor is tillage systems, as two systems of tillage were applied (no-tillage and Reduced tillage) and the second factor was the type of organic fertilizer and it included (Sheep waste and waste Mushroom), while the third factor was the level of binary addition of nitrogen and phosphorus, and it included three levels of fertilization (0%, 100%, and 125%), according to the fertilizer recommendation. The experiment was carried out according to the split-split plot system with a randomized complete block design (R.C.B.D) and with three replications. The treatments were distributed as follows: tillage systems (NT, RT) in the main plot, and the application of the type of organic fertilizer (O1, O2) In the sub plot, the levels of binary addition of nitrogen and phosphorus (M0, M1, M2) were placed in the sub-sub plots, and the results of the experiment showed that the system of Reduced tillage was significantly superior to the system of no-tillage in all the studied traits, and sheep waste was significantly superior to mushroom waste in All the characteristics of the study, as well as the level of binary addition M2 was significantly superior to the other levels in all the characteristics of the study. The results showed that the treatment (T1O1M2) was significantly superior in all traits of vegetative growth and yield traits of clover plant.

The Effect of Addition Humic and Fulvic Acid on the Adsorption of Copper in Gypsum Soils

In order to study the interaction between humic acids and gypsum levels and their effect on the adsorption of copper in soil, three soil levels with gypsum content were chosen and prepared in the laboratory. They were treated with three levels of humic acids: (H0) with no addition (0%), (H1) with an addition of (1%), and (H2) with an addition of (2%). Copper ions were measured for the adsorption experiment. The data were treated using Langmuir and Freundlich equations to describe the adsorption nature. The results were as follows: both soils had high values for both Freundlich (82%) and Langmuir (92%) equations. Thus, the second equation outperformed the first equation by a difference of 10%. The adsorption values using the Langmuir equation ranged from (2500-588), while for the Freundlich equation, the sorption capacity values ranged from (186.98-47.53). Only the Langmuir equation recorded values for binding energy, which ranged from (53.76-1.059), and the highest binding energy values were associated with humic acid additions compared to untreated soil.

An Experimental Study Evaluating the Negative Skin Friction on Single and Group of Close-ended Circular Pipe Piles Embedded in Gypseous Soil

An Experimental Study Evaluating the Negative Skin Friction on Single and Group of Close-ended Circular Pipe Piles Embedded in Gypseous Soil

Assessment of shear strength characteristics of the unsaturated gypseous soil at various saturation degrees

Assessment of shear strength characteristics of the unsaturated gypseous soil at various saturation degrees

Collapsibility and leaching behavior of an artificial sandy gypseous soil

Collapsibility and leaching behavior of an artificial sandy gypseous soil

Isolation and Diagnosis of the Root Nodule Bacteria Associated with Mung Bean Plant in Gypsiferous Soil and Testing the Promotional Criterion of Isolates

The root nodule bacteria are utilized in the production of natural biological fertilizers to achieve clean agriculture by reducing chemical fertilizers. In this study, 35 samples of the root nodules associated with mung bean plants were collected from various agricultural areas of Iraq, Salah Al-Din Governorate on 4\\7\\2022, ten samples isolated by growing them on yeast extract mannitol agar (YEMA) and the phenotypically pure isolates were diagnosed based on the culture, microscopic and biochemical characteristics., The phenotypic diagnosis results showed that The color of the colonies was between white, creamy and yellow, Spherical, convex and smooth, gram-negative, was able to move and pink and light pink on Congo red stain medium and 9 isolates it was fast growing as it gave yellow color on YEMA-BTB bromothymol blue medium except for one isolate it was slow growing as it gave blue color and all isolates unable to grow on Hofer alkaline medium except for one isolate, The efficient isolate was selected in the production of indole acetic acid, chelating compounds and phosphate solubilization,. The results showed that isolates (M3, M4, M5, M6, M7) have a high ability for iron chelation. It was found that the (M6) isolate gave the highest phosphate solubilization and indole production, which showed a phosphorus solubilization of 39.504 mg P.L-1 and an indole production rate of 21.5 μg.ml-1. This was followed by the isolate (M3), which showed a phosphorus solubilization of 23.723 mg P.L-1 and an indole production rate of 17.2 μ.g.ml-1. Molecular diagnosis was performed for five competent isolates in the production of Indole acetic acid, production of chelating compounds, and phosphate solubilization. The isolates were molecularly diagnosed by PCR, the 16SrRNA gene was amplified, then the sequence of nitrogenous bases was analyzed and when matching with the global strains included in the NCBI Genetic Bank website, The results of molecular diagnosis showed that two isolates belong to Rhizobium bacteria. the results showed that (M3) isolate is %99.50 similar to the Rhizobium leguminosarum isolate OTU21_I. and the results showed that (M6) isolate is 99.48% similar to the Bradyrhizobium japonicum strain A3 and 99.96% to the Bradyrhizobium japonicum, strain:NK5 and therefore the isolates is genetically close to Rhizobium leguminosarum strain AE15 and Bradyrhizobium japonicum strain AE14 bacteria and has been recorded in the Global genome bank under accession number OP975690 and version number OP975690.1 for Rhizobium leguminosarum and accession number OP975688 and version number OP975688.1 for Bradyrhizobium japonicum and this record is the first for this bacteria which associated with mung bean in gypsiferous soils in Iraq.

Effect of Different Ferrous Concentrations on the Growth Characteristics of Genotypes of Sorghum bicolor L.

A field experiment was carried out during the fall season of the agricultural season 2022 AD at a research station of the Department of Field Crops, College of Agriculture - University of Tikrit in Salah al-Din Governorate, located at longitude 43.679 degrees east and latitude 34.616 degrees north of the equator in gypsum soil in order to know the effect of foliar feeding with two levels of Iron In addition to the comparison treatment, which is (0, 75, and 150) mg L on fivegenotypes of white corn, namely (J, Giza, Inqaz, Rabeh, and Li). Ferrous sulfate was used as a source of iron. Using the randomized complete block design (RCBD) with three replications, and each replicate contains (15) experimental units, each experimental unit contains four lines, the distance between one line and another is 60 cm, and between one line and another is 20 cm, to study growth characteristics. The Li variety was superior in leaf area and the percentage of iron in the leaves, reaching (4086.61 cm2 and 60.92 mg Fe/kg). As for the following characteristics, the number of days from sowing to 50% flowering and plant height, the J variety was superior to (99.11 days and 177.48 cm). and the characteristics, number of leaves per plant, estimation of chlorophyll A and estimation of chlorophyll B were lost The variety was superior to Giza, which reached (23.40 μg.cm2, 19.83 μg.cm2, and 16.43 leaves). As for the fertilizer additions, it was superior to (Fe2) and gave the highest averages in the characteristics of plant height, number of leaves per plant, leaf area, chlorophyll A, chlorophyll B, and iron content inthe leaves, as it reached 157.94 cm, 15.80 leaves, 3783.76 cm 2, and 23.34 μg. cm2 and 21.03 μg.cm2 and 64.38mg Fe / kg, respectively, and the addition of Fe (1)) in the characteristic of the number of days from sowing to 50% flowering exceeded 95.46%. The combination (Li + fertilizer additives (Fe2) was characterized by giving the highest averages in the characteristics of leaf area and the percentage of iron in the leaves. As for the characteristics, the number of days from cultivation until 50% flowering and plant height, it was outperformed by variety J + fertilizer additives (Fe2) and the characteristics of the number of leaves per plant Estimation of chlorophyll A and estimation of chlorophyll B were lostIt is superior to Giza + fertilizer additives (Fe2).

The Effect of Planting Dates and Spraying with Boron and Sulfur on Raising the Yield Efficiency of Maize (Zea mays L.)

A field experiment was carried out during the spring period of the agricultural season 2022 AD at a research station of the Department of Field Crops, College of Agriculture - University of Tikrit in Salah al-Din Governorate, located at longitude 43.679 degrees east and latitude 34.616 degrees north of the equator in gypsum soil, in order to know the effect of different planting dates. With three datesThe first date (15/3), the second date (5/4), and the third date (25/4). And add boron and sulfur before flowering by spraying on the plant (boron 50 mg L in the form of boric acid, sulfur 25 mg L in the form of liquid sulfate, boron + sulfur). Its effect on the number of ears, the number of ear beans, the number of its rows, the weight of 300 seeds, the biological yield, the total grain yield, the protein percentage and the ash percentage of the yellow corn cultivar (Sara), using the randomized complete block design (RCBD) with three replications, as each experimental unit included four lines and the length of the line was 3 m and the distance between lineAnd the last 0.75 cm, and between one plant and another 20 cm, and to study the characteristics of growth, yield, its components, and quality characteristics. The first date was superior in all the studied traits except for the following traits: the number of earwigs and the percentage of ash, and there were no significant differences. We conclude from the fertilizer additions the superiority of the addition (sulfur and boron), and it gave the highest averages in the characteristics of the number of ears, the number of ear seeds, the number of rows, the weight of 300 seeds, the biological yield, and the total grain yield, as it reached 1.68 ears, 441.33 ears, 15.00 ear rows, 69.94 g, and 7.94 ton e and 12.69 ton e respectively, outperformingThe addition of boron as a percentage of protein is 11.93% and the percentage of ash is 1.27%. The combination (planting dates + fertilizer additions (first date × sulfur and boron) gave the highest averages in the characteristics of ear number, number of ear pods, number of rows, weight of 300 seeds, total grain yield, and biological yield. for ashes.

Optimal Management of Nitrogen Fertilization in some Yield Traits of Corn Plant in Gypsum Soil

A field experiment was conducted in the fields of the College of Agriculture - University of Tikrit during the autumn season for the year (2022) to find out the effect of nitrogen fertilizer fractionation on the growth of corn in gypsum soil.Where the experiment included three factors, the first factor, five dates for nitrogen fertilizer fractionation, symbolized by the letter T (T1, the first appointment / half of the quantity at planting and the other half after (30) days of planting, and T2, the second appointment / one-third of the quantity at planting and two-thirds after (30) days of cultivation and T3 third date / one-third of the quantity at planting and one-third after (30) days of cultivation and a third after the passage of (60) days of cultivation and T4 the fourth date / one-fifth of the quantity when planting, fifty-five after the passage of (30) days of cultivation and fifty after the passage of (60) days of cultivation and T5 the fifth date / two-fifths at planting and fifty after a month of cultivation and one-fifth of the quantity After the passage of (60) of cultivation. The second factor is two levels of nitrogen fertilizer, denoted by the symbol N, namely (N1) (320) kg N ha-1 and (2N) (360) kg N ha-1. The third factor is Adding method, denoted by the symbol M, the BroadcastingM1 method) and the Bands(M2) method. All the results showed that the retail treatment of the fourth appointment, T4, excelled in all traits, and the second level, N2 (360) kg N ha-1, gave the highest significant difference in all traits, and the addition of the second method, M2 (Bands method), also gave excelled in all studied traits.The results showed that the treatment T4N2M2 gave the highest values in the studied traits (the number of rows per ear, the number of grains per ear, the weight of 500 grains, and the total grain yield), as it reached (18.01) row cob-1, (739) grain cob-1, (163.01) gm, and (14.08)) ton ha-1, respectively.

Genetic Heterogeneity of Genotypes of Sorghum under Different Ferrous Concentrations

A study was conducted of five genotypes of white corn (J, Giza, Inqaz, Rabeh, Li) in gypsum soil. The effect of foliar feeding with three levels of iron (0, 75 and 150) mg L was used (ferrous sulphate) on the growth of white corn at the plant. Research for the Department of Field Crops, College of Agriculture - University of Tikrit, for the fall season 2022 AD, with a sandy texture. As for the design type, random complete blocks (RCBD) with three replications, and each replicate contains (15) experimental units, each experimental unit contains four lines, the distance between one line and another is 60 cm, and between one line and another is 20 cm, to study growth characteristics. The Li variety excelled in the number of grains per head, head weight, weight of 1000 grains, grain yield per plant, total grain yield, harvest index, and the percentage of iron in the seeds, which amounted to (2316.0 seeds, 112.55 grams, 29.45 grams, 64.08 grams, 6.01 tons, 44.21%, and 67.75 mg Fe / kg), while the biological yield was superior to the J variety, which reached (12.93 tons). The percentage of protein was higher than the Giza variety, reaching (6.73%). As for fertilizer additions, (Fe2) was superior and gave the highest averages in traits, number of grains per head, head weight, weight of1000 grains, grain yield per plant, total grain yield, biological yield, harvest index, percentage of iron in seeds, andpercentage of protein, as it reached 2361.0 grains, 107.80 g, and 27. 43g, 64.67g, 5.33t, 12.20 tons, 44.26%, 72.75 mg Fe/kg, and 6.59%, respectively. The combination (Li + fertilizer additives (Fe2) was characterized by giving the highest averages in the characteristics of number of grains per head, weight of 1000 grains, grain yield per plant, grain yield, harvest index, and percentage of iron in seeds. The biological yield was outperformed by class J + additives Fertilizer (Fe1) and the characteristic of the percentage of protein was superior to the variety Giza + fertilizer additives (Fe2). The genetic variance contributed more than the environmental variance to all fertilizer additions (Fe2) and their quantitative characteristics, which was reflected in the degree of heritability in the broad sense, in addition to that the coefficient of genetic, environmental and phenotypic variation and the expected genetic improvement as a percentage was average for most of the traits under study.

Comparison of Hydraulic Conductivity Estimation using Falling Head and Mini Disk Infiltrometer in Gypsiferous Soil

Hydraulic conductivity (K) was calculated using falling head (FH) and Mini Disk Infiltrometer (MDI) for 15 Gypsiferous soil. In this study the hydraulic conductivity was predicted by basic infiltration rate (BIR) and using two methods, Wooding-Gardner (W-G) and van Genuchten-Zhang (V-Z). Hydraulic conductivity was measured using a falling head permeability test, and the results were compared to the expected values. A statistical analysis (t-test) was performed to show the significant differences between the two methods and the falling head. The results showed high agreement between (K) values estimated by (FH) and (BIR) for different gypsum content, the results showed that Both methods did not succeed in estimating the hydraulic conductivity for different gypsum content. Values derived from (W-G) method are exaggerated and the values derived from the (V-Z) method are very low compared to the values derived from (FH).

Response of Yield Traits and its Components to Sesame Genotypes for Different Plant Distributions

A field experiment was carried out at the research station of the Department of Field Crops at the College of Agriculture at the University of Tikrit in Salah al-Din Govemorate under gypsum soil conditions during the summer agricultural season (2022 AD), to evaluate the performance of six sesame genotypes, namely (Al-Mahalli, Wada’, Had, Sumer, Rafidain and Baytim) and three distributions. Plants, which are (60 x 10, 40 x 15, and 30 x 20) cm2, and Interaction between two factors of the study in traits, yield, its components, and the percentage of oil. The cultivar Wadaa gave the highest arithmetic mean for traits of the number of capsules per plant (86,111) capsules per plant, number of seeds per capsule (67,811) seeds per capsule, and the total seed yield (3,402) tons. hectares and percentage of oil (46.500)%. The cultivar was superior in seeds thousand weight average of (3.496) g. Third plant distribution recorded highest arithmetic averages for traits of number of capsules per plant (86.655) capsules. Plant-1 and number of seeds per capsule (67.561). seed. Capsule-1, seeds thousand weight (3.426) gm and the total seed yield is (2.678) tons. hectares and the first plant distribution gave highest arithmetic average for trait of percentage of oil amounted to (46.600)%, and the intreaction treatment (Wadaa variety and third plant distribution) achieved highest arithmetic averages for the number of capsules in plant (81.111) capsules. Plant-1, seeds thousand weight was (3.381) gm and the total seed yield was (3.761) tons. hectares and the combinatorial treatment (variety Wadaa and first plant distribution) recorded highest arithmetic mean for trait of oil percentage amounted to (50.00)%.

Estimation of Genetic Parameters and Path Analysis of Sesame Genotypes under Three Plant Distributions

A field experiment was carried out at research station of Department of Field Crops at the College of Agriculture at the University of Tikrit under gypsum soil conditions during the summer agricultural season (2022 AD). plants, which are (60 x 10, 40 x 15, and 30 x 20) cm2. genetic parameters were estimated in the three environments for studied traits under study. path was analyzed to determine most traits in single plant yield. The most important results were as follows: genetic variation was higher than the environmental in the three studied environments and for all traits, and values of the coefficient of genetic and phenotypic variation were average for most of the traits studied in the three environments and broad sense heritability was high in most of the studied traits and in three environments, and expected genetic advance was high as mean for traits of single plant yield in (the second and third environment) and it is possible to adopt the two traits of number of capsules per plant and seeds 1000weight with direct selective evidence to improve single plant yield because the direct effect of these two inpath analysis was positive and high.

Analysis of building failure associated with water seepage into gypsiferous soils in an arid area located in the northwestern town of Ouled Djellal (Algeria)

The present article aims to investigate the root causes of building failures that are associated with water seepage into gypsiferous soils in the arid region of the northwestern town of Ouled Djellal in Algeria. For this, a comprehensive diagnostic assessment, including in-situ measurements and laboratory analysis, was implemented to understand the failure mechanisms in the buildings. The study revealed that water infiltration affects the stability of the gypsiferious soil beneath the buildings foundations and triggers differential settlement, thus contributing to building failures. This research offers valuable insights through a case study and provides practical recommendations for construction practices aimed at reducing the risks of building failures due to water seepage in gypsiferous soils. Moreover, it emphasizes the importance of understanding soil behavior, implementing effective water management strategies, and using appropriate foundation designs in arid regions.

Evaluation Effect of Inoculum Prepared from Local Bacterial Isolates of Rhizobium and Nitrogen Fertilization on some Growth Traits of Mung Bean Plant in Gypsiferous Soil

The root nodule bacteria are utilized in the production of natural biological fertilizers to achieve clean agriculture by reducing chemical fertilizers. Therefore, the bacterial inoculum was prepared from local isolates of Rhizobium leguminosarum and Bradyrhizobium japonicum, which were morphologically and molecularly characterized. Subsequently, the efficacy of the prepared inoculum was tested in the formation of root nodules and some growth traits of mung bean plants in gypsiferous soil at three levels of nitrogen fertilization (0, 40, 80) kg N ha-1 The results showed a significant increase in all plant growth traits during the flowering stage for the treatments inoculated with Rhizobium leguminosarum and Bradyrhizobium japonicum bacteria in comparison to the treatment without inoculation. The inoculated treatments outperformed the non-inoculated treatment significantly. Additionally, the treatment inoculated with Bradyrhizobium japonicum showed a significant superiority over the treatment inoculated with Rhizobium leguminosarum in all studied growth traits, the recorded values for the count of root nodules were (0.00, 8.33, 35.11) nodule. plant-1, The wet mass of nodules was (0.00, 0.091, 1.802) g. plant-1, and dry mass of nodules was (0.00, 0.010, 0.337) g. plant-1. The plant height was (52.11, 56.22, 58.05) cm. plant-1. The dry mass of the vegetative part, was (14.03, 20.10, 23.05) g. plant-1, and, the dry mass of the root part was (1.37, 2.57, 2.67) g. plant-1. The nitrogen content was (1.547, 2.765, 3.028) % phosphorus (0.121, 0.236, 0.377) %, and potassium (1.168, 2.342, 3.562) % in the vegetative part. The absorbed nitrogen in the vegetative part was (217.41, 541.10,718.02) mg. plant-1. These values were recorded for the non-inoculated treatment, Rhizobium leguminosarum inoculated treatment, and Bradyrhizobium japonicum inoculated treatment, respectively. The results showed a significant superiority for the 40 kg N ha-1 fertilized treatment in comparison to both the unfertilized treatment and the 80 kg N/ha-1 fertilized treatment in all studied traits. The interaction effect was significant, as the treatment that was inoculated with Bradyrhizobium japonicum and 40 kg N ha-1 fertilized treatment exhibited significant superiority over the other treatments in all studied traits.

Enhancement of Gypseous Soil Engineering Properties Through High-Density Polyethylene Polymer Addition: A Comprehensive Experimental Assessment

An experimental investigation was conducted to scrutinize the influence of high-density polyethylene (HDPE) polymer on the engineering properties of gypseous soil. Soil samples, possessing 38% gypsum content, were extracted from the Tikrit region, Iraq, and were subsequently subjected to varying HDPE polymer concentrations of 1%, 3%, and 6%. An observed augmentation in the maximum dry density was noted when a minuscule quantity of 1% HDPE polymer was incorporated. However, a subsequent increase in polymer concentration resulted in a discernible decrease in dry density. Examination via the double oedometer test elucidated a significant reduction in collapse potential by 64%, 77.7%, and 83.2% upon addition of 1%, 3%, and 6% HDPE polymer, respectively. Direct shear test outcomes revealed a complex influence of HDPE polymer on soil cohesion. In the dry state, a 1% and 6% HDPE polymer addition led to a cohesion increase by 50% and 16.67%, respectively, whereas a 33.3% decrease was observed at a 3% polymer concentration. Conversely, in the soaked state, cohesion was found to decrease by 50% at 1% and 6% HDPE polymer concentrations, and entirely diminished with a 3% polymer addition. Interestingly, the internal friction angle (ϕ) exhibited an increase in both dry and soaked states with escalating HDPE polymer percentages. A contradictory behavior was noted in the California Bearing Ratio (CBR), which decreased in the dry state but increased in the soaked state with a rise in HDPE polymer ratios. In conclusion, the present study substantiates that the addition of HDPE polymer induces modifications in the engineering behavior of gypseous soil. Further research is encouraged to optimize the HDPE polymer concentration for ground enhancement applications.