JWSS - Journal of Water and Soil Science

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For the study of field wind erosion and the design and evaluation of wind erosion control techniques, detailed observations of soil particle transport and vertical destribution of eroded soil particles are needed. The objectives of this study were: 1) To describe one device for soil transport particle measurement, i. e. the BSNE sediment catcher and 2) To assess vertical distribution of wind–eroded sediment with height in eastern Isfahan. The BSNE sediment catcher is a wind erosion sampler that traps eroded material at seven heights of 0.24, 0.60, 1.08, 2.00, 3.00, and 4.00 m above the soil surface. Each trap consists of a steel container with an inlet and outlet, mounted on a wind vane that rotates about a central pole. Before using the sampler in the field, it was tested and calibrated in the wind tunnel. The results showed that the average trapping efficiency with speeds ranging from 5.2 to 7.2 m sec^-1 for 4 different wind–eroded sediments was 0.44 to 0.68. However the trapping efficiency depended on wind speed, particle size distribution, particle density and type of sediment. The sampler had the lowest efficiency for particles < 44 μm. A BSNE sediment catcher was installed in Babaii Air Base. After a sampling period, the sediment in each trap was collected and weighed. The trapped materials were a mixture of saltation and suspension particles. Vertical distribution of wind–eroded sediment showed that the amount of soil collected decreased with increased height and the percentage of fine particles (<63μm) increased with height. The amount of trapped materials for each cm2 frontal intake with increased height were 12.00, 3.42, 1.44, 1.56, 0.75, 0.21, and 0.39 g cm-2, respectively, for the one sampling period.

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Clay minerals deserve special attention as they play a crucial role in many soils. The clay mineralogy of five gypsiferous soils from different landforms in eastern Isfahan was investigated using X-ray diffraction (XRD). In addition, soil aggregates and wind-deposited sediments were examined by scanning electron microscope (SEM) and analyzed by energy dispersive X-ray analyzer (EDX). The results indicate the presence of palygorskite, mica, kaolinite, chlorite, and quartz with a trace amount of vermiculite and randomly interstratified layers in all soils. Smectite occurs in soils of both the piedmont plain and old river terrace, but not in the alluvial fan soils. Mica, chlorite, quartz, and kaolinite were probably inherited from the parent material. Palygorskite seems to increase with depth in the alluvial fan, whereas, in the old terrace soils, this clay mineral decreases with depth. Palygorskite present in alluvial fan soil appears to have been formed authigenically when the basin was covered with shallow hyper-saline lagoons toward the end of the Tertiary. Palygorskite in the old terrace seems to be mostly detrital and an eolian origin of palygorskite is likely because a large amount of palygorskite is present in upper soil horizons. A higher proportion of smectite in deep soils of the old terrace, as compared with palygorskite, suggests the possibility of authigenic formation of smectite from palygorskite. .

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Stabilizng sand dunes has been one of the main challenges in the arid regions. So far, different kinds of mulches have been used extensively for sand dune stabilization. This study was carried out to determine the optimum composition, concentration and thickness of clay mulch for sand dune stabilization. For this purpose two soil samples from clay flats of a playa with different amount of salinity from Ardestan area were used to make clay mulches. A sand dune sample was selected as bed for applying the mulch. To select the right ingredient and treatments, clay samples were mixed with sand and different amount of water, and sprayed on sand dune bed. In addition, wheat straw was added to some mixture to test its effect on stability of the mulch. Treatments with lowest crack and highest penetration of mulch in sand bed were selected for the experiment in this study. Mulch treatments contained (1): 250g sand dune + 250g clay + 25g straw (2) 250g clay + 25g straw (3) 250g sand + 250g clay (4) 250g clay (5) 125g sand + 125g clay and (6) 125g clay. All treatments were mixed with 500ml water. The experimental design was a CRD with a 6(mulch) * 2(thickness)* 2 EC factorial method with 3 replications. The results showed that clay mulch were resistant to wind erosion, but erosion took place when they had been bombarded with sandblast. The mulches with straw showed the highest resistance to erosion as compared to other treatments. With increasing the number of mulch layers, resistant to erosion also increased. The added stability of mulch was due to the increase in mulch thickness and also increases in clay and silt content. The overall result of this study shows that the mulch with two layers and higher mixture of clay and sands was the best treatment for the stabilization of sand dunes.

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In order to classify and determine the plant communities in Karkas mountainsides, central Iran, quantitative data of 46 environmental characteristics including climate (12 characteristics), soil (26 characteristics), geology and physiology (8 characteristics), were analyzed based on partial Euclidean distance indicator using minimum variation method. The results showed the clustered separation of studied sites at 68% similarity level with three different growth places. Of these 46 factors, 24 factors (8 climate characteristics and 16 soil characteristics) were effective in this classification at 95% certainty level. Only 24 of these 46 factors were effective in this classification at 95% certainty level. These 24 effective factors were divided into 8 climate and 16 soil characteristics. In another classification, combinational percentage index of 17 plant species were investigated as an effective factor in separating growth place and determining the plant communities. Result of cluster classification indicated that the studied sites cold be classified to 3 habitats.

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The purpose of this study was to compare the physical and chemical characteristics of soils covered with vegetation and soils without vegetation in Dagh-e- Sorkh Ardestan area.To achieve the goal, first the vegetation was classified using physiognomic method, and for each vegetation type, the distinctive area was specified for soil and vegetation sampling. Vegetation sampling was done by stratified random sampling. Alongside pursuing the case, twenty two soil physical and chemical factors were investigated also for each growth type and area without vegetation. In the next step, to investigate the similarities and dissimilarities of the soils of desert areas by means of PC-ORD software, the cluster analysis was performe. After simplifying the one-way ANOVA, the most important soil factors which were effective in causing differences in the area’s soils were identified. Results show that the soils of area covered with vegetation differed much from the soils without vegetation physically in such a way that, the soil texture became heavier and gravel percentage became less in the areas without vegetation. Regarding the chemical characteristics, the frequencies of sodium, magnesium, calcium and chlorines and electrical conductivity were highly different. Because of topographic condition of land without vegetation, runoff is directed to this place and deposits salts there. Also, high groundwater level and capillary flowing salts are the important reasons for the salinity of this place. These are the limiting factors for the vegetation establishment in the desert areas of Ardestan.