Najmeh Asgari hafshejani; shamsollah ayoubi
Abstract
Study of relationship between soil diversity index and soil-landscape evolution in Juneqan plain, Chaharmahal-Va-Bakhtiyari ProvinceABSTRACT ARTICLE HISTORYIntroduction Addressing the concept of soil diversity over landscape as a set of different land units with different spatial distribution, shape, ...
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Study of relationship between soil diversity index and soil-landscape evolution in Juneqan plain, Chaharmahal-Va-Bakhtiyari ProvinceABSTRACT ARTICLE HISTORYIntroduction Addressing the concept of soil diversity over landscape as a set of different land units with different spatial distribution, shape, and arrangement that are affected by natural phenomena and human activities is essential for optimal use, proper management and conservation of this valuable resource. Soil diversity is a criterion for quantifying soil variability that deals with changes in soil properties or classes and understanding of the structure of these changes in the area. Soils evolve continuously under the interactive effects of propulsion and backward pathways, factors, processes, and endogenous and exogenous conditions. In other words, the development of soils is a function of divergent pedogenic pathways (increasing soil evolution followed by increasing soil diversity) and converging (increasing soil evolution and subsequently increasing soil uniformity). In the present study, we investigate the relationships between soil-landscape evolution in a hierarchical sequence of different soil classification and geomorphic levels using diversity indices in some parts of Juneqan plain, Chaharmahal va Bakhtiari province, as an example of semi-arid regions.Materials and Methods The study region with an area of nearby 16000 hectares is located in the Juneqan plain, Charmahal va Bakhtiari Province, Iran, between the coordinates 50° 33ʹ and 50°44ʹE longitude, and 32° 5' and 32°16ʹN latitude. Based on the US Soil Taxonomy (Soil Survey Staff, 2014), the study area has a Mesic soil temperature regime and the soil moisture regime is mainly Xeric and partially Aquic over the study area. A total of 102 soil profiles were dug, described and classified up to the great group level according to US Soil Taxonomy system and soil samples were collected from various genetic horizons. Mountain, hill, piedmont and low lands were the main detected landscapes in the studied area. In order to study the soil evolution the spatial structure of landscape changes, pedodiversity indices were calculated at different taxonomy hierarchical levels (from order to great group in Soil Taxonomy classification) and geomorphic hierarchical levels (landscape, landform, lithology and geomorphic surface) using appropriate indices such as the Shannon diversity index, richness index, Margalef Index, Menhinick Index and O’Neill index.Results and Discussion The soils in the studied area were classified in three main soil orders including Entisols, Inceptisols and Mollisols. The results demonstrated that soil evolution in the studied area was mainly influenced by topography, parent material and locally the underground water level. In the higher lands (like mountain and hills), the lowest evolution was observed whereas, more evolved soils were observed in lower lands with more stable conditions. The results also indicated that all of the pedodiversity indices showed nearby a similar trend and increased under the decrease of the taxonomy and geomorphic hierarchy levels. So that, the minimum diversity was related to order and landscape levels and the maximum diversity was observed in soil great group and geomorphic surfaces levels. Besides, there was a positive linear relationship between species richness index and area of landform units. In other words, as the area of landform units increases, the diversity and consequently the richness index increases. The results also show a positive and nonlinear relationship between number of observations and Shannon entropy index and species richness index.Conclusion The obtained result showed that soil evolution and its properties is affected by some soil formation factors including parent material and topography. In conclusion, it seems, diversity indices are powerful tools in the demonstration of quantitatively soil diversity and provide useful information for soil mapping and optimum soil management purposes. In this study, different soil differentiation indices were calculated and reported for the level of classification hierarchy as well as geomorphic hierarchy. The results showed that by decreasing the level of hierarchy, the dispersion indices increased. This upward trend indicates that the soil evolution is divergent in this region and that as the soil evolves, its dispersal increases. The results also showed that by increasing the area of earthquake surfaces, both species richness index and Shannon entropy index increased. Also, a positive and non-linear relationship was observed between both Shannon entropy indices and species richness indices. Increasing soil richness and dispersion index in geomorphic hierarchy and soil classification as well as increasing richness and Shannon indexes with increasing extent of earthquake surfaces indicate that the soils studied are a nonlinear dynamic system.Keywords: Diversity index, Geomorphology map, Landscape, Landform, Topography.All right reserved. ReceivedReceived in revised formAcceptedKey words:Diversity indexGeomorphology map < br /> LandscapeLandformTopography* Corresponding authorayoubi@cc.iut.ac.ir
N. Asgari; S. Ayoubi; A. Dematte; H. Khademi
Abstract
Introduction Carbonates are an essential and prominent constituent of soil chemical properties particularly in arid and semiarid regions, in regards with soil productivity and conservation. The conventional techniques for assessing soil properties rely on direct laboratory measurements which are expensive, ...
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Introduction Carbonates are an essential and prominent constituent of soil chemical properties particularly in arid and semiarid regions, in regards with soil productivity and conservation. The conventional techniques for assessing soil properties rely on direct laboratory measurements which are expensive, time consuming and labor intensive. Hence, it is required to develop fast and cost-efficient techniques for evaluation of mentioned parameters. The Koppen climatic classification generally categorizes Iran among the arid and semi-arid climates. About 90 % of its lands are arid or semiarid. According to Soil Survey Staff (2014), calcareous soils contain 5% or more volumes of inorganic carbon (or carbonate calcium equivalent), which are the prevailing formation in arid and semi-arid areas. These soils are typical of areas where minerals cannot be leached away from the soil profile due to low precipitation. Based on the reports of FAO.UNDP (1972), approximately 12% of soils all over the world and 65% in Iran are calcareous. Therefore, carbonate is a key component that physically and chemically influences soil properties, as well as its fertility and productivity. One of the fast, easy-to-use, cost-effective and non-destructive methods of soil analysis is the visible to near-infrared (Vis-NIR) and mid-infrared (mid-IR) spectroscopy, that can partly be employed for the optimization of traditional techniques. Therefore, the reflectance spectroscopy is considered as one of relatively inexpensive and fast techniques to evaluate these features. The purpose of the present study was to evaluate the capability of the reflectance spectroscopy technique in Vis-NIR (250-2500 nm) and mid-IR (400-400 cm1-) ranges to estimate soil carbonates content as one of the key components affecting the physical and chemical properties of soils (especially in arid and semi-arid regions). Materials and Methods The study area is located in Juneqan District, Chaharmohal and Bakhtiari Province, southwest of Iran. 272 soil samples were collected from a depth of 0-10 cm, air dried and passed through a 2 mm sieve. The carbonates value of each sample was determined by standard laboratory method. The spectral reflectance of soil samples was extracted in the Vis-NIR (250-2500 nm) and mid-IR (400-400 cm1-) ranges using a spectroradiometer FieldSpec 3 (ASD-Analytical Spectral Devices, Boulder Colorado, USA) and Nicolet 6700 Fourier Transform Infrared (FT-IR) (Thermo Fisher Scientific Inc., Waltham, MA), respectively. In the next step, seven preprocessing methods included absorbance transformation (log [1/reflectance]) (Abs), multiplicative scatter correction (MSC), standard normal variate transformation (SNV), Savitzsky-Golay derivation (SGD), Continuum removal transformation (CR), Normalization in range <-1,>1 (Nor) and Detrend (Det), were performed over original spectra for correcting light scattering in reflectance measurements and data improvement before using data in calibration models. Afterward, The dataset (272 samples) for each spectra range was randomly divided in calibration (70%) and validation (30%) datasets. Four different calibration models were fitted over Vis-NIR and mid-IR spectra to develop carbonates prediction models including: Partial Least Squares Regression (PLSR), Support Vector Machine (SVM), Random Forest (RF) and Gaussian Process Regression (GPR). The evaluation of soil predicting models was done according to the value of R2, RMSE and RPD. According to some researches, RPD values more than 2 shows that the models provide precise predictions, values of RPD between 1.4 and 2 are considered to be reasonably representative, and values less than 1.4 indicate poor predictive value. Results and Discussion The carbonates content in studied samples ranged from 1 to 76% with an average value of 24.7%. Overall, carbonates content promoted increase of spectral reflectance intensity on several region of spectrum in both spectral ranges. The specific absorption wavelength in Vis-NIR spectra used to indicate the presence of soil carbonates was 2338 nm and in the mid-IR range were 714, 850, 870, 1796, and 2510 cm1. The results showed that the best performance of the used models in the Vis-NIR spectral range was related to the SVM model (R2=0.81, RMSE=5.36) and in the mid-IR range allocated to PLSR model (R2=0.86, RMSE=4.5). Both of these models showed great accuracy in carbonates estimating (RPD>2). Besides, the results showed that the mid-IR spectral range in the prediction of carbonates provided better performance than the Vis-NIR range. This can explained by the fact that the fundamental molecular vibrations of soil components occur in the mid-IR range, while only their overtones and combinations are detected in the Vis-NIR range. Conclusion It seems that the reflectance spectroscopy technique can be considered as a precise substitute for the conventional methods of measuring carbonates, which are sometimes costly, time consuming and destructive. However, due to the spatial and temporal variability of soil properties as well as the huge variety of models and spectral preprocessing methods, it is necessary to examine the capability of this technique in other areas with other preprocessing methods and regression models.
Soil Genesis and Classification
samaneh Tajik; shamsollah ayoubi; mohmmad mehdi darvisihi; hossein khademi
Abstract
Introduction Soil snails constitute an important part of the forest ecosystem and play an essential role in litter decomposition and soil calcium concentration. Snails are known as bioindicators because of narrow distribution, short lifetime, and high sensitivity (22, 24). The abundance and distribution ...
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Introduction Soil snails constitute an important part of the forest ecosystem and play an essential role in litter decomposition and soil calcium concentration. Snails are known as bioindicators because of narrow distribution, short lifetime, and high sensitivity (22, 24). The abundance and distribution of soil snails are dependent on different environmental conditions, such as precipitation, pH, soil calcium, and plant cover. Also, soil properties are mainly related to topographic parameters. Because ecosystem components have complex relationships, we need powerful models to find effective factors and spatial variations of the soil fauna (23). Linear Regression and random forest are popular and applicable models in soil science. Up to the present, no study has investigated the effect of soil parameters on snail abundance using linear regression and random forest. This study was performed to investigate the effect of soil properties and topographic parameters on the abundance of soil snails and their distribution in a part of forest area located in Bahramnia forest, an experimental site in Golestan Province, in the north of Iran. Materials and Methods This study was conducted in Shast Kalate (Bahramnia) forest, an experimental forest of Gorgan University of Agricultural Sciences and Natural Resources, located at the eastern Caspian region, north of Iran (36° 43′ 27″ N latitudes, 54°24′ 57″ E longitudes). 153 soil samples were collected from 0-10 cm; then soil snails were gathered and classified into the Gastropoda taxonomic class group. Soil properties, such as Soil particle size distribution (clay, silt, and sand), soil pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), soil organic carbon (OC), total nitrogen (TN), and Soil microbial respiration (Resp), were measured via laboratory analysis. Also, digital elevation model and satellite images were used to determine the topographic parameters, such as Elevation, slope, slope aspect (Aspect), land surface temperature (land temp) wetness index (WI) and normalized difference vegetation index (NDVI). We used linear regression and nonlinear random forest models for investigating linear and nonlinear relationships between soil properties, topographic parameters, and the abundance of soil snails. Likewise, sensitive analysis was done to find the importance of the input parameters. Results and Discussion The PCA analysis showed that first and second components explain 38 and 21 percent of the variation. In the first component, EC, OC, TN, pH, and silt were the most variable, and in the second component CCE, Clay, OC, sand, and EC were the most important parameters. In both components, topographic parameters had no effect. The PCA graph showed that CCE, sand, and pH had the most correlation with snail abundance and EC, Resp, OC, and TN affected their abundance. The validation results of regression and random forest models showed that random forests have more accuracy (0.49) and low error (1.82). In addition, the sensitive analysis showed that CCE, pH, EC, OC, aspects, elevation, and land temp are the most important parameters on snail abundance. Different studies reported that pH and CCE are effective parameters on snail abundance (20, 17). Also, Ondina., et al. (27) reported that EC has an important effect on soil snail abundance. We hypothesize that topographic parameters affect soil snail nonlinearly and by affecting soil properties. Aspect is one of the topographic parameters that, via an effect on land temperature, land cover, and pH (8), has an important role in soil snails. In this way, elevation, by affecting pH, wetness, land temperature, OC, and TN, affects soil snail abundance (13). Land temperature is the other topographic parameter that is affected by aspect and elevation and had a significant effect on snail abundance by affecting OC and wetness (17). Conclusion Based on the results, nonlinear random forest model had more accuracy than linear regression in predicting snail abundance. Results showed that calcium carbonate equivalent, pH, EC, and organic carbon were the most effective soil priorities on snail abundance. There was no linear relation between soil properties and soil snails, but in the nonlinear model, we found their role. Aspect, elevation, and land temperature were the most effective parameters on snail abundance that probably affected soil properties, such as calcium carbonate and soil moisture.
Soil Physics, Erosion and Conservation
shamsollah ayoubi; zanyar feizi; Mohammad reza Mosaddeghi; Ali asghaar besaltpour
Abstract
Investigating the application of biochar, bentonite clay and polyvinyl acetate polymer on some mechanical properties of sand deposits Introduction Wind erosion seriously threatens bare soils and is recognized as a global environmental problem; however, little is known about this process in comparison ...
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Investigating the application of biochar, bentonite clay and polyvinyl acetate polymer on some mechanical properties of sand deposits Introduction Wind erosion seriously threatens bare soils and is recognized as a global environmental problem; however, little is known about this process in comparison to rainfall or tillage erosion. Due to the heavy costs of controlling wind erosion and the difficulty of detecting which control measure is the most effective, the correct selection of technical methods is indispensable for a suitable land management. Since the last decades, the methods of sand stabilization studied are diverse, but basically based on wind speed reduction by including chemical, mechanical and biological methods. One of the most important methods of stabilizing sandy soils is the use of mulches. In recent years, due to the disproportionate development of residential in peri-urban areas, humans use polymeric and oil mulches to stabilize sandy soils. Therefore, in this research, the effects of bentonite clay, polyvinyl acetate and palm biochar on reducing soil erosion by wind in peri-urban areas were investigated. Methods and Materials Three selected treatments were compared with a control plot without any treatment: palm biochar, polyvinyl acetate and bentonite clay. In order to prepare the palm biochar, palm remnants including the trunk, foliage and palm leaves were poured into the mill and turned into small pieces. The fragments were passed through a 2 mm sieve. The remnants transmitted from the sieve were poured into the trays of the discharger unit and placed inside a discharger at 350°C for 4 hours, and the biochemicals were prepared to the extent necessary for this research. Polyvinyl acetate treatment was provided by Isfahan Resin Co. and the bentonite clay by the Derin Kashan enterprise (both of them from Isfahan, Iran). To apply the treatments, each of them was mixed with a certain proportion of water per m2: i) 20 g l-1of palm biochar treatments; ii) 7 g l-1 of polyvinyl acetate treatment; and, iii) 20 g l-1 of bentonite clay.In order to apply the treatments, 36 galvanized trays with a same size (5×35×105 cm) were prepared and filled up from the air to the top edge with sand. After 1, 2, 4, 10 and 20 weeks some mechanical and physical properties were measured in laboratory. Results and Discussion A significant difference was observed among different treatments in terms of the impact on aggregates formations and stabilities at different moments. The application of bentonite clay treatment significantly increased the stability of formed aggregates compared to control treatment. The rest of treatments showed lower aggregability. The mean weigh diameter (MDW) for the control plot was 0.28 mm. The lowest MWD was obtained by the palm biochar treatment, which increased by 20.1, 14.9, 9, 2.5 and 1.6% after the first, second, fourth, tenth and twentieth weeks of application, respectively. Polyvinyl acetate treatment increased MDW by 65.1, 61.6, 58.8, 41.9 and 31.5% after the first, second, fourth, tenth and twentieth weeks, respectively. The highest MWD was obtained by bentonite clay treatment, which generated an increase by 77.8, 71, 65.1, 59.9 and 49.7% in the first, second, fourth, tenth and twentieth weeks, respectively). The images from thin sections of bentonite clay and polyvinyl acetate treatments showed that soil particles were joined to form larger aggregates in all of cases. No significant differences was observed for hydraulic conductivity at different times were observed. There was a significant difference among different treatments at different monitoring periods. The application of bentonite clay significantly reduced the fractal dimension. On the contrary, the lowest effect was registered for the palm biochar treatment. The effect of bentonite clay treatment on soils was higher than other selected treatments showing a reduction by 10.6, 9.7, 8.7 6.7 and 6.3% in the first, second, fourth, tenth and twentieth weeks, respectively. The impact of different treatments on shear resistance showed that the application of the selected treatments significantly increased the shear strength in all the cases. Among the selected treatments, the effect of bentonite clay treatment on shear resistance was higher than other treatments. The lowest and the highest shear resistance were registered for the palm biochar and bentointe clay, respectively. Palm biochar increased shear resistance by 9.3, 9.3, 8, 5.3 and 3.3% compared to the control plot in the first, second, fourth, tenth and twentieth weeks after its application. On the other, bentonite clay registered the highest improvement in shear resistance by 44.7, 44.7, 42.7, 37.3 and 31.3% in the first, second, fourth, tenth and twentieth weeks, respectively. Keywords: Mulches, Bentonite, Clay, Biochar, Palm, Mechanical properties
Soil Physics, Erosion and Conservation
Nasim Bazshushtarizadeh; shamsollah ayoubi
Abstract
Introduction 137Cs is an artificial radionuclide with a half-life of 30.2 years and strong gamma radiation that, due to nuclear explosions in the 1950s, and 1960s entered the earth's surface by the rain. The radionuclide has been widely used for the evaluation rates and patterns of soil erosion and deposition. ...
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Introduction 137Cs is an artificial radionuclide with a half-life of 30.2 years and strong gamma radiation that, due to nuclear explosions in the 1950s, and 1960s entered the earth's surface by the rain. The radionuclide has been widely used for the evaluation rates and patterns of soil erosion and deposition. 137Cs was rapidly adsorbed to fine particles of soil surface horizon and its distribution is basically accompanied by the physical processes of soil, such as erosion and tillage. 137Cs is distributed exponentially as a function of depth to a maximum depth ranging from 5 to 15 cm in the undisturbed soil. The basis of calculating of erosion by 137Cs method is based on comparison between the amount of 137Cs in studied soil and the reference site (local, flat, un-eroded, undisturbed and stable site) and 137Cs loss or gain, relative to the reference inventory, indicates soil erosion and deposition, respectively. So, the reliable and accurate reference estimate of 137Cs is essential. No attempt has been made to explore the variability of 137Cs inventory in the reference sites in Iran. Therefore, This study was conducted to evaluate variability of 137Cs inventory and its relationship with some soil properties at the reference site located in Fereydan district in western of Isfahan province. Materials and Methods 96 soil samples were collected from 0-15 cm and 15-30 cm depths. Moreover, for evaluation of vertical distribution of 137Cs, two profiles were excavated and 8 soil samples were collected from 0-5, 5-15, 15-25 and 25-35 cm depths. Gamma-ray spectrometry device was used for 137Cs analysis. Magnetic susceptibility values were measured using Bartington susceptimeter at low (0.46 kHz) and high (4.6 kHz) frequencies and magnetic susceptibility dependent was calculated by low and high frequency values. Soil properties including total nitrogen, organic material, cation exchange capacity, calcium carbonate equivalent, EC, pH, texture, gravel and bulk density were determined. Descriptive statistics including mean, minimum, maximum, standard deviation (SD), coefficients of variation (CV), skewness, and kurtosis were calculated by SPSS software, v.16. The distribution of variables was evaluated using the Kolmogorov-Smirnov test. Pearson correlation coefficient and regression analysis were used to examine the relationships between 137Cs and soil properties. Results and Discussion The coefficient of variation of 137Cs inventory were 15.05 and 14.05% in 0-15 cm and 15-30 cm depth respectively. The result indicated that 137Cs has uniformly distributed in studied reference site. The results of the study showed that OM, OM/Clay, CEC/Clay, EC, Sand, BD, χlf and χhf were correlated with 137Cs. The results of multiple regression analysis indicated that bulk density, clay content and magnetic susceptibility at low frequency explained 43% of total variability of 137Cs in the studied reference site. Conclusions In the present study, variability of 137cs was investigated in a reference site in Ferydan district in Isfahan Province. The study showed that 137Cs had low variability. Among the soil physical and chemical properties, Soil pH, silt, gravel, nitrogen and calcium carbonate equivalent did not show significant correlation with 137Cs. The highest positive significant correlation was obtained for BD and 137Cs. Also, magnetic susceptibility at low and high frequencies showed significant correlations with 137Cs. In the multiple regression analysis, BD, clay content, and magnetic susceptibility were included in the model for explaining the 137Cs variability. It is suggested that similar study be done in the other reference sites in the western Iran.
Land Evaluation and Suitability
V. Shahrokh; S. Ayoubi
Volume 37, Issue 1 , September 2014, , Pages 77-92
Abstract
This study was conducted to evaluate land suitability in Zarinshahr and Mobarakeh areas located in Isfahan Province using Analytical Hierarchy Process (AHP) technique. The hierarchy structure for evaluation was established to select the proper land use for 32 land units. Two alternative land utilization ...
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This study was conducted to evaluate land suitability in Zarinshahr and Mobarakeh areas located in Isfahan Province using Analytical Hierarchy Process (AHP) technique. The hierarchy structure for evaluation was established to select the proper land use for 32 land units. Two alternative land utilization types (the cultivation of wheat and rice) were selected at the lowest level. The intermediate levels of the hierarchy were comprised of seven criteria for evaluating the alternative land uses including soil, climate, gross income, water resources, market, physical environmental impacts and chemical environmental impacts. The weight for each element was calculated using 30 questionnaires which were completed by experts and software EXPERT CHOICE 2000. Then the overall weight for each land use was obtained by multiplying standardized attributes and local weights. The results showed that maximum and minimum calculated land indices for wheat cultivation were 77.4 (unit 2-3) and 18.86 (unit 4-9) and for rice 26.85 (unit 4-10) and 7.43 (unit 4-11), respectively. The climate suitability was the most important factor for selecting the proper land use, followed by soil suitability. The least importance was contributed to market accessibility. The inconsistency ratio related for all the matrices was 9 percent. The results of this study showed that the cultivation of wheat has higher performance for production in all land units.
