Gypsiferous Soils Research Articles

Effect of humic application on qualitative traits of bread wheat cultivars (Triticum aestivum L.)

A field experiment was carried out at the research station of the Department of Field Crops in the College of Agriculture at the University of Tikrit during the winter agricultural season 2020-2021 AD in gypsum soil. The aim of study was the effect of three stages of ground addition of humic with an amount of 32 kg.ha, which is the stage of four leaves and flowering in addition to (control treatment) in the chemical traits of soft wheat varieties, which are Al-Rasheed, Tammuz 2 and Ibaa 99). The results were as follows. Significant differences were observed between the studied varieties. The cultivar Tammuz 2 excelled in the traits of protein percentages (13.23) %, gluten (26.66) %, and dry gluten (9.60%), while the rational cultivar recorded the highest average of the two labels, the gluten coefficient (60.14) and the sedimentation coefficient (26.22). The date of addition in the branching stage excelled in the traits of humidity, protein and wet gluten, and the addition stage in the flowering stage excelled in the trait of the gluten coefficient. Sedimentation coefficient, while the overlapping treatment of cultivar Tammuz 2 with the date of addition in the branching stage was superior in the proportions of protein and wet gluten, and the treatment of overlap Tammuz 2 with the date of addition in the flowering stage was superior in the percentage of dry gluten.

Behavior of Reinforced Gypseous Soil Embankment Model under Cyclic Loading

The construction of embankment for roadway interchange system at urban area is restricted due to the large geometry requirements, since the value of land required for such construction is high, and the area available is limited as compared to rural area. One of the optimum solutions to such problem is the earth reinforcement technique which requires a limited area for embankment construction. Gypseous soil from Al-Anbar governorate area was obtained and subjected to various physical and chemical analysis to determine it is properties. A laboratory model box of 50x50x25 cm was used as a representative embankment; soil has been compacted in five layers at maximum dry density (modified compaction) and an aluminum reinforcement strips were introduced between layers. The model was subjected to cyclic loading and the vertical and lateral deformations were detected at different stages of loading cycles using LVDT. The reinforced soil embankment under soaking condition exhibited vertical settlement at the top surface was (12.55 mm) while the lateral displacements at (1st, 3rd layer) were (2.18, 1.32) mm respectively at (47 load cycles).For reinforced gypseous soil, embankment without soaking cured for 24 hours, the Number of load cycles was found to be (165) loading cycles with vertical displacement (9.12 mm), that means an improvement of 59%. Accordingly, the lateral displacement in 1st and 3rd layers were (3.28, 2.59) mm respectively which observes improvement by (28% and 5%) respectively. The rates of improvement are taken with respect to the reinforced pure dry soil sample.

Compressibility characteristics of collapsible gypseous soil: A review

Gypseous soil is located in dry and semi-arid areas in unsaturated conditions and this type of soil becomes a serious issue for engineering and geotechnical when it becomes wet. the properties and structure of this soil change, when exposed to soaking and leaching, because gypsum is dissolved in water causing a rupture in the bonds that hold soil particles together and a reduction in the suction power that holds them together. Large settlements and potential collapse will happen which cause problems for the constructions built on it. This paper gives an overview of some of the properties of gypseous soils and previous research on the behavior of this soil. It was found that the collapse potential of gypseous soil increases with increasing the gypsum content and void ratio, and collapse potential decreases when the initial water content and dry density increase.

Short-term Effects of Indaziflam on Non-native Brome Grass (Bromus spp.), Biological Soil Crusts, and the Endangered Dwarf Bear Poppy (Arctomecon humilis)

Controlling invasive annual grasses is one of the top conservation priorities in the American West. Brome (Bromus spp.) has more recently invaded areas of White Dome Nature Preserve, a conservancy for endemic and endangered or threatened plants in Washington County, Utah, United States, where the use of herbicides could be effective in managing invasion. Ideal habitat for these plants is on gypsiferous soils that are largely associated with biological soil crusts. Intact biological soil crusts are important in a biological communities' ability to resist invasion by annual grasses and are critical for nutrient cycling. However, there is a lack of research on how herbicides affect biological soil crusts and specific rare plant species that are of high conservation priority. We found that indaziflam (Rejuvra, Bayer CropScience, Monheim am Rhein, Germany), applied as a preemergent, was effective at reducing brome density the first growing season after application. Indaziflam also did not initially injure the biological soil crusts. Indaziflam is reported to have multiyear effects of reducing annual grasses, which makes indaziflam a promising herbicide for conservation purposes in areas where the invasive species seed bank needs to be depleted with as little disturbance to biocrusts as possible.

Storage of persistent organic matter in temperate gypsum soils –Relevance of the parent material and vegetation cover

By storing large amounts of terrestrial carbon (C), soils prevent it from being released into the atmosphere as carbon dioxide, the main greenhouse gas. We examined soils derived from gypsum and limestone, assuming the former had a special ability to accumulate and stabilise soil organic matter (SOM) under temperate climatic conditions when compared to limestone-derived soil. We compared the benefit of gypsum or limestone as a parent material and the effect of vegetation cover on the quantity and quality of SOM. Properties of the soil humus horizons were determined, including texture, available potassium (K) and phosphorus (P), pH, amount of gypsum and calcite, enzyme activity, and vegetation cover (biomass, K, P, sodium, calcium (Ca), and amount of lignin in the plant upper parts, coarse roots and fine roots). The structure and composition of humic acids (HAs), as indicators of SOM quality, were also studied. Stocks of organic carbon accumulated in 0–20 cm depth were much higher in gypsum soils (9.72 and 10.09 kg/m2) than in limestone soils (5.02 and 6.36 kg/m2). We found that the SOM in the gypsum soils was more mature, and contained more aromatic HAs, than in the limestone soils. Also, the gypsum soils had higher enzyme activity and a greater mass of vegetation cover, the fine roots providing higher amounts of lignin than the limestone soils. The factors that shaped the soil properties were identified and the interaction between the parent material and the vegetation cover and its effect on SOM storage was determined, indicating the importance of fine-root composition (lignin, Ca, K) and enzyme activity on C accumulation. Gypsum as a parent material favoured SOM accumulation through its physical stabilization, by providing active Ca cations to protect the SOM together with silt and clay, and its biochemical stabilization, through high enzyme activity and the quantity and quality of the biomass. Our results show that gypsum soils are important as a response to global warming through their ability to preserve SOM over the long term.

Biocrust carbon exchange varies with crust type and time on Chihuahuan Desert gypsum soils.

In dryland systems, biological soil crusts (biocrusts) can occupy large areas of plant interspaces, where they fix carbon following rain. Although distinct biocrust types contain different dominant photoautotrophs, few studies to date have documented carbon exchange over time from various biocrust types. This is especially true for gypsum soils. Our objective was to assess the carbon exchange of biocrust types established at the world's largest gypsum dune field at White Sands National Park. We sampled five different biocrust types from a sand sheet location in three different years and seasons (summer 2020, fall 2021, and winter 2022) for carbon exchange measurements in controlled lab conditions. Biocrusts were rehydrated to full saturation and light incubated for 30 min, 2, 6, 12, 24, and 36 h. Samples were then subject to a 12-point light regime with a LI-6400XT photosynthesis system to determine carbon exchange. Biocrust carbon exchange values differed by biocrust type, by incubation time since wetting, and by date of field sampling. Lichens and mosses had higher gross and net carbon fixation rates than dark and light cyanobacterial crusts. High respiration rates were found after 0.5 h and 2 h incubation times as communities recovered from desiccation, leveling off after 6 h incubation. Net carbon fixation of all types increased with longer incubation time, primarily as a result of decreasing respiration, which suggests rapid recovery of biocrust photosynthesis across types. However, net carbon fixation rates varied from year to year, likely as a product of time since the last rain event and environmental conditions preceding collection, with moss crusts being most sensitive to environmental stress at our study sites. Given the complexity of patterns discovered in our study, it is especially important to consider a multitude of factors when comparing biocrust carbon exchange rates across studies. Understanding the dynamics of biocrust carbon fixation in distinct crust types will enable greater precision of carbon cycling models and improved forecasting of impacts of global climate change on dryland carbon cycling and ecosystem functioning.

Evaluation the behavior of Ring Footing on Gypseous Soil Subjected to Eccentric and Inclined Loads

An extensive program of laboratory testing was conducted on ring footing rested on gypseous soil brought from the north of Iraq (Salah El-Deen governorate) with a gypsum content of 59%. There are limited researches available, and even fewer have been done experimentally to understand how to ring footings behave; almost all the previous works only concern the behavior of ring footing under vertical loads, Moreover, relatively few studies have examined the impact of eccentric load and inclined load on such footing. In this study, a series of tests, including dry and wet tests, were carried out using a steel container (600×600×600) mm, metal ring footing (100 mm outer diameter and 40 mm inner diameter) was placed in the middle of the container top surface that filled with the gypseous soil. Subject to (vertical and inclined) (concentric and eccentric) loads was carried out for dry and soaking soil to discover the differences in bearing capacity as well as ring behaviors. According to the results when the load eccentricity increases on the ring footing from the rate (e = 0B, e = 0.04B e = 0.08B, e = 0.16B) and the inclination load increases as (0°, 5°, 10°, 15°) respectively the ring footing ultimate loads will be reduced.

Effects of Domestic Sewage Sludge on Gypseous Soil's Geotechnical Properties

Effects of Domestic Sewage Sludge on Gypseous Soil's Geotechnical Properties

EFFECT OF SPENT MUSHROOM SUBSTRATE AND SULFUR ON GROWTH AND YIELD TRAITS OF BROCCOLI IN GYPSIFEROUS SOIL

The tendency to use natural organic wastes is one of the environmentally safe applications in crop production. Therefore, the presented study aimed to determine the effect of adding mushroom and sulfur residues to gypsiferous soil and their efficiency in improving the production of broccoli ‘Balimo F1’ (Brassica oleracea var. ‘Italica’). The study set out in a randomized complete block design with three replications. The 10 combined treatments of the spent mushroom substrate (SMS) and sulfur residues consisted of 0% and 15% (SMS), and 0, 1000, 2000, 3000, and 4000 S kg ha-1. The interaction of the spent mushroom substrate with sulfur showed significant differences for most growth and yield-related traits of broccoli, including leaf length, leaves per plant, roots per plant, head diameter, head weight, total yield, and harvest index, as compared with the control treatments. Among all the treatments in broccoli, the highest total yield (148,702 kg ha-1) resulted in the treatment SMS – 15% + Sulfur – 3000 kg ha-1, followed by the total yields of 111,608 and 105,663 kg ha-1 produced by the treatments SMS – 15% + Sulfur – 4000 kg ha-1 and SMS – 15% + Sulfur – 2000 kg ha-1, respectively. However, the minimum total yield in broccoli (28,295 kg ha-1) came from the treatment SMS – 0% + Sulfur – 3000 kg ha-1, followed by a total yield of 33,793 kg ha-1 obtained in the treatment SMS – 0% + Sulfur – 4000 kg ha-1. Overall, and compared with the control, a significant influence occurred due to the interaction of spent mushroom substrate and sulfur with levels of 15% and 3000 kg ha-1, respectively.

The anatomical and micromorphological properties of endemic species to gypsic soils of Semnan, Iran

The gypsum habitats of Iran are significant reserves of biodiversity containing endemic and rare species. Despite the limited understanding of its characteristics and habitat, it has become essential to study the endemic species of the Semnan gypsic soil. Fresh samples of studied species including Acantholimon cymosum, Astragalus fridae, Astragalus semnanensis, Euphorbia gypsicola, Gypsophila mucronofolia, Moltkia gypsaceae and Nepeta eremokosmus were collected in the wild during the growth season. Leaf surface and leaf cross-sections were considered. The longest hair length was related to A. fridae, A. semnanensis and M. gypsaceae species. The shorter hairs belong to the species A. cymosum, G. mucronofolia and E. gypsicola. Crystals called cystolites were seen in the epidermal cell wall of A. semnanensis leaves. The anatomical characteristics of these species' leaves indicate the presence of dry structures. Using micromorphological studies, we analyzed the hairs of the studied species in terms of their shapes, sizes, and densities. We found some species have hairs with special appendages, which is due to the special conditions in which they have grown. Xeromorphic stomata were found on both leaf surfaces of all endemic gypsophyte plants of Semnan. Several studies have shown that gypsophytes have a specialized mechanism for regulating the absorption of sulfur and calcium from soils containing calcium sulfate or gypsum by their roots. The current study provides novel insights into the response of plant species to extreme conditions and potential adaptation strategies at micromorphological levels.

Evaluation of the Collapse Potential Magnitude of Untreated and Treated Collapsible Gypseous Soil — A New Procedure

Many researches have been conducted to study the collapse potential of collapsible soils using collapse tests; single-oedometer tests, and double-oedometer tests. The radical rearranging of particles in response to a significant volume loss from wetting under loading is the definition of collapse. The main goal of this study is to create a method for recognition of gypseous soil that is susceptible to collapse. The suggested procedure depends on using a sample larger than that used in conventional collapse tests and the saturation of sample is done by flowing water from the bottom to the top of the sample. The new idea for the modified collapse test was made because of the limitations of conventional tests including the small size of sample that may not give a suitable collapse. In addition, the saturation process of the sample may not saturate all the particles. Also, the behavior of collapsible gypseous soil was investigated on soil improved with different Magnesium Oxide percentages (0, 5, 10, and 15%) and carbonated Magnesium Oxide with variable carbonation times (0, 1, 3, and 24 hours). The soil was prepared at two relative densities of 35 and 75 percent relative density. The collapse potential was investigated using a modified Rowe cell with soil moisture content sensors. The results illustrated that the size of the sample affects the collapsibility, the collapse potential increased from 15.8% to 22.3% and the collapse severity is changed from (severe trouble) to (very severe trouble) for the natural untreated gypseous soil using the conversional tests and modified test, respectively. The collapse potential increased by about 40% for the soil treated with different percentages of “Magnesium Oxide”. For the modified test, the collapse potential decreased by about 93% when using 10 percent of Magnesium Oxide then the sample was carbonated for 3 hours as compared with untreated soil.

The Behavior of Gypseous Soil under Vertical Vibration Loading

The dynamic response of foundation rest on collapsible soil in dry and soaked states is studied through wide experimental programmed. Gypseous soil from Tikrit governorate area was obtained and subjected to various physical and chemical analysis to determine its properties. Steel rectangular footing (400x200x20) mm is manufactured. The machine is fitted to the footing, then the model machine foundation is placed centrally over the prepared soil layer in steel container (1200x 1000x1000)mm with proper care to maintain the center of gravity of whole system lie in the same vertical line with container.Then, the footing is subjected to vertical harmonic loading using a rotating mass type mechanical oscillator to simulate different dynamic loads. The effect of soaking and eccentric mass was investigated. The results showed that the amplitude of displacement in dry state is greater than its value at soaked state, while the resonant frequency in the soaked state is greater than in dry state. Also, the results showed that for specific frequency ,an increasing in eccentric mass leads to increase in amplitude of displacement. Moreover, an increasing in resonant frequency can be absoreved when eccentric mass is increased.

Patterns of Richness and Endemism in the Gypsicolous Flora of Mexico

Gypsum soils occur around the world, mainly in arid regions. These harsh environments promote unusual flora with high degrees of endemism. Mexico has extensive gypsum outcrops, but their flora has been poorly studied. However, the highest species richness and endemism are expected to be concentrated in Mexico’s northern dry regions. To promote the study of this flora and its conservation, we estimate how well sampled it is, quantify species richness, identify centers of endemism, and detect which gypsum outcrops lie within federal protected natural areas (PNA). We conducted exhaustive literature and herbaria reviews to generate a database of botanical records on gypsum soils. The total species and gypsophyte richness were calculated using cell grids. Centers of endemism were identified using the corrected weighted endemism index (CWE). We mapped the gypsum outcrops within PNA polygons. The most collected sites are Cuatro Ciénegas (Coahuila) and Santo Domingo Tonalá (Oaxaca), which also had the highest total species richness. Nevertheless, gypsophyte richness was higher in Cuatro Ciénegas and Nuevo León. The CWE identified seven gypsophyte centers of endemism. Mexico hosts the most diverse gypsophile flora in the world, despite having been only partially studied and collected. The regions with the highest species richness and endemism are unprotected.

Effect of Gypsum, Compost, and Foliar Application of Some Nanoparticles in Improving Some Chemical and Physical Properties of Soil and the Yield and Water Productivity of Faba Beans in Salt-Affected Soils

Two field experiments were conducted at Kafr El Sheikh Gov., Egypt, during two winter growing seasons (2020/2021 and 2021/2022). The objective of this study was to improve some chemical and physical properties of soil and the yield and water productivity of faba beans (Viciafaba L.), Cv. Sakha-4 by application of gypsum, compost, and some nanoparticles in salt-affected soils. The experimental treatments were arranged in a split-plot design with three replications. The main plots had the following soil amendments: T1: control treatment, T2: 10 tons compost/hectare, T3: soil gypsum requirement (GR) of 8.59 ton ha−1, and T4: GR + 10 tons compost/hectare. The subplots were treated with foliar application as follows: no treatment, manganese nanoparticles (Mn-NPs), selenium nanoparticles (Se-NPs), and Mn-NPs + Se-NPs. According to the findings, the application of compost + GR significantly decreased soil salinity (EC), exchangeable sodium percentage (ESP), and soil bulk density (BD). However soil porosity, soil penetration resistance (SPRa), and basic soil infiltration (IR) were significantly increased. On the other hand, the results revealed significant positive effects onthe 100-grain weight as well as proline, chlorophyll, superoxide dismutase, and catalase contents due to the interaction between gypsum + compost and Mn-NPs + Se-NPs, which enhanced the productivity of both the seed and straw yields of faba beans compared to the alternative treatments. In addition, the seed yield and irrigation water productivity (PIW, kg m3) of faba beans were significantly increased with addition of gypsum and compost and foliar application of nanoparticles. The highest values of these parameters were achieved due to the interaction between gypsum + compost and Mn-NPs + Se-NPs. It can be concluded that application of GR of 8.59 ton ha−1 and 10 ton ha−1 compost as well as foliar application of Mn-NPs and Se-NPs may be a key strategy for improving some chemical and physical properties of soil and the yield and water productivity of faba beans in salt-affected soil under these experimental conditions.

Effect of Seedling Age and NPK Fertilization on Growth and Yield of Kohlrabi (Brassica oleracea var gongylodes) Planted in Gypsiferous Soil

Kohlrabi (Brassica oleracea var. gongylodes) ‘White Vienna cv.’ was grown in the Experimental Station of the Department of Horticulture and Landscape in the College of Agriculture at Tikrit University in Salah al-Din, Iraq, during the winter of 2021–2022. The purpose of this research was to examine the impact of seedling age and NPK combinations on kohlrabi plant growth and yield. Most values for vegetative growth traits and yield were found to be highest for seedlings aged 45 days. Plant growth and yield were enhanced by applying a 120:90:50 kg, ha-1 NPK combination fertilizer rather than a single kind of NPK. For optimal growth and highest output, the 45-day-old seedlings plus the 120-90-50-kg-ha-1 NPK fertilizer combination treatment was chosen over other interaction treatments.

The Thermal Conductivity and Matric Potential (Moisture Tension) Relationships for Soils of Different Gypsum Content

The soil samples have been taken from a soil profile at the Research Station of College of Agriculture in the University of Tikrit at a longitude of 430 38- 23= in the east and at a latitude of 340 48- 40= in the north. The samples were taken from the surface horizon with a gypsum content of 62 g.kg-1 (G1) and also from the subsurface horizon of 443g.kg-1 (G7) gypsum content. Different gypsum content samples were prepared as G2, G3, G4, G5, and G6 that have Gypsum contents of 106, 153, 202, 245, and 337 g.kg-1 respectively. These samples were prepared by mixing the surface soil samples with the soil of gypsic horizon. The prepared soil samples were wetted by water spraying to two thirds the field capacity levels (0.25 kg.kg-1). Then they incubated for two months in order to make soils homogeneity in addition to moisture distribution in soil. The plastic rings of 10.4 cm diameter and 10 cm heights were drilled from the middle to fix the sensor of heat flux of thermometer plug. The size and height of the soil to be placed in the plastic ring was calculated based on the area A and height h of ring and then the mass of the soil (m) was calculated based on the value of the bulk density. The samples were oven dried at 70° degree until the weight of samples were fixed to obtain the completely dry soils. The amount of water to be added per sample was calculated based on the moisture characteristics curve and by the tensions specified in this study (0.1, 5, 15, 33 and 100) kPa. The moisture was converted to a depth of water and then soil samples were wetted in a light spraying manner with continuous flipping and the thermometer sensors were fixed up and down the heat flux sensor and then six readings per replication were recorded. The time from one reading to another was 60 seconds and their rate was extracted. Based on the results of the experiment, it can be concluded that by the fixation of moisture tension, the thermal conductivity values of the soil decreased with the increased soil content of gypsum, as the G3 treatment with gypsum content 15% gave the highest significant value while the least significant average value of thermal conductivity values at the G7 treatment with gypsum content was 43%. The increase in gypsum from 25% at G5 to 30% and 44% in G6 and G7 successive treatments did not significantly affect the values of the soil’s thermal conductivity averages. The overlap point of the relationship between soil gypsum content and thermal conductivity was found at G3 and G4 that have gypsum content of 15% and 25% respectively. The average of gypsum decreases the thermal conductivity values of the soil with increased moisture tension values, as the tension gave 0.1 kPa a significant increase in the values of the average thermal conductivity from the rest of the tensions and for all treatments while the least significant average of thermal conductivity values at tension was 100 kPa.

Collapsibility of Gypseous Soil Treated with Pectin-Biopolymer through Leaching

Gypsum reinforcement in dry soil provides activity resistance. It quickly becomes a source of danger in the conditions of partial and complete soaking of gypsum soil as a result of the dissolution of gypsum, which poses a great danger to the structures built on this soil. The danger increases when water flows through it and works to leach the soil, which leads to the loss of its mass by leaching gypsum. The soil is chemically and mechanically improved to enhance its geotechnical properties, but despite its great advantages in strengthening, it has significant negative effects on the ecosystem, so the use of environmentally friendly materials is essential. Pectin was selected as an improved biopolymer and added at three different contents (0.5, 1, and 2)% to create a soil mixture and at four different gypsum contents (10, 20, 40, and 62%) to evaluate the chemical and mechanical properties of the improved mixture. Develop an engineering model to leach the soil and pectin mixture. The results showed a significant decrease in CH and CP. values due to biogel encapsulation of soil particles and pore filling properties. The percentage decrease in the values of (CH) reaches (0.67, 73, 75, and 68%) for soils 1, 2, 3, and 4, respectively. After soil (1, 2, 3, and 4), CP values decreased in percent (0.63, 0.63, 0.65, and 0.7%). TDS decreased at a biopolymer content of 2% from 1050, 1200, 2200, and 2500 mg/ml to 320, 540, 468, and 570 mg/ml of soils 1, 2, 3, and 4, respectively.

Experimental Study on the Behavior of Square-Skirted Foundation Rested on Gypseous soil Under Inclined Load

This work investigates experimentally the effect of using a skirt with a square foundation of 100 mm width resting on dry gypseous soil (i.e., loose soil with 33% relative density), and subjected to an inclined load. Previous works did not study the use square skirted foundation rested on gypseous soil and subjected to inclined load. The investigated soil was brought from Tikrit city with 59% gypsum content. Standard physical and chemical tests on selected soil were carried out. Model laboratory tests were carried out to determine the effect of using a skirt with a square foundation on the load-settlement behavior of gypseous soil and subjected to inclined load with various Skirt depth (Ds) to foundation width (B) ratio Ds/B (0,0.5,1, and1.5). The results show that using a skirt with a square foundation improves load-carrying capacity and reduces settlement of foundation rested on loose gypseous soil and the amount of improvement increase with increasing skirt depth to foundation width Ds/B. Bearing capacity improved by about (193) %, and Settlement ratio (Sᵣ) reduced from (1) % for square foundation without a skirt to (0.14) at Ds/B, equal to 1.5 at θ =0° with the y-axis (Where θ is the inclination angle of the applied load); and bearing capacity improved by about (162) % for the square skirted foundation with Ds/B, equal to 1.5 and θ =15° with the y-axis.

Electrical resistivity tomography of a gypsiferous subsurface soil: Geotechnical detection of a geoenvironmental phenomenon

The near-surface soils are generally exposed to environmental changes and can be influenced by water, humidity, temperature, and other factors related to erosion or physical changes. It has been reported that serious distress occurred in the ground surface and below ground for many areas subjected to seasonal weather changes. The gypsum rich material is often linked to the cavity formation, uplift, and cracking of road surfaces due to the high solubility of gypsum in water and acidic media. Electrical resistivity techniques along with the advanced method of identifications (Scanning electron microscope; SEM and X-ray diffraction: XRD) were utilized to detect cavities and gypsum rich subsurface soils. A site where many cavities were formed as a result of dissolving gypsum and anhydrite was considered for this study. Syscal R1 electrical resistivity equipment (IRIS instrument) was used for several cross-sections established within the site. Several electrical resistivity tomography lines were constructed and studied. The SEM (scanning electron microscope) was used to examine and compare forms and fabrics of gypsum and minerals containing sulfates. The chemical analysis (EDAX) using an electron beam was conducted to establish elements present within tested samples. Quantitative chemical tests for some parameters including sulfate ions were carried out. A prediction model based on statistical correlations between sulfate ion content and the electrical resistivity is presented. Electrical resistivity is found to be inversely proportionalto the sulfate content for concentrations of 0 to 5%.

Preparation of Biofertilizer from Azospirillum brasilense Bacteria and test its Impact on Growth and Yield of Wheat Triticum aestivum L. in Gypsiferous Soil

After confirm the bacterial strain that it is belong to Azospirillum brasilens and test the efficiency on nitrogen fixation , Indolic Acetic Acid (IAA) Hormone production , this strain was grown in slants and transferred to liquid broth in the rotary shaker to prepare mother (starter) culture which contain 5 x 109 CFU.ml-1 and then mixed starter culture with two types of carriers ( powder of date palm nucleus and powder of olive nucleus).
 After that, field experiment was conducted in gypsifores soil ( Typiccalcigypsids) to study the efficiency of this biofertilizer on promoting the wheat growth and yield at three levels of nitrogen (0 , 50% , 100%) of fertilizer recommendation .
 Results showed that the biofertilizer which was added alone either with date palm nucleus powder or with olive nucleus caused significant increases in plant high , dry weight of vegetative part , roots dry weight after 60 days from germination and the dry weight of straw and grain yield compare with control treatment with percentage increases of 22.68 , 92.84 , 171.01 , 75.5% for biofertilizer which held on date palm nucleus powder and 21.2 , 59.46 , 134.7 , 40.01 and 37.11% respectively . Also the results refered to not significant differences between two carriers. The result also appear that the beneficial effect of biofertilization continuous with increase of nitrogen levels , the treatment ( biofertilize with date palm nucleus powder + 100% nitrogen fertilizers) gave highest values in straw and grain yield where is ( 5.41 and 4.30 ) ton. ha-1 in compare with the same treatment which take half of fertilizers recommendation which gave (5.33 and 3.86) ton.ha-1. Also the result showed significant effect of bio-fertilization on the number of Azospirillum bacteria , ( 32 x 104 and 30 x 104 )CFU . gm-1soil for bio-fertilizer which was carried on date palm nucleus powder and olive nucleus powder, respectively in compare with control which gave 13.33 x 104 CFU. gm-1soil.