جستجوی مقالات مرتبط با کلیدواژه « soil » در نشریات گروه « آب و خاک »

Arsenic, one of the most critical environmental toxins, accumulates in plant and animal organs through root absorption in plants and subsequent ingestion by humans via the food chain or direct consumption of contaminated water. Reports have highlighted the contamination of regional drinking water sources in Bijar city, Kurdistan province, with arsenic and its adverse effects on local residents. Therefore, this research aimed to investigate the distribution of arsenic in the water and soil sources of the region and evaluate the capacity of native pasture plants to absorb and accumulate this element.

Arsenic concentrations were measured in surface and subsurface waters of a 360 km2 region using the atomic absorption-graphite furnace method. The distribution of arsenic in the contaminated area was mapped using the ArcGIS program. Three sampling areas with varying pollution intensities (A > B > C) were selected. Soil samples and aerial parts of 13 plant species were collected and analyzed for arsenic concentrations, enabling a comparison of different plant species' ability to absorb arsenic.

The intensity of arsenic contamination in surface water, soil, and plants studied in this research exceeded typical concentrations of arsenic in water, soil, and plant sources. Total arsenic concentrations in water samples ranged from 4.5 to 280 μg l-1 and correlated with electrical conductivity, total dissolved solids, and total hardness (p < 0.001). Arsenic concentration in the soil of area A (Ali-Abad village) exceeded 2059 μg g-1 of dry soil, with contamination decreasing with distance from area A. A high correlation was observed between the intensity of water and soil pollution (R2=0.84). Arsenic concentrations in the aerial parts of 13 plant species with three replications varied depending on the plant species and the intensity of soil contamination (0 to 47.8 μg g-1). The intensity of soil contamination was on average 27.66 times higher than the amount of arsenic accumulated in the plant, indicating the high resistance of native pasture plants in the region to arsenic toxicity.

Field monitoring revealed that 45% of water resources in the sampling areas exceeded the national drinking water standard for arsenic (50 μg l-1), reaching 78% according to the World Health Organization standard (10 μg l-1). Concentrations of parent materials containing arsenic compounds were higher in areas A and B than in area C, with decreasing concentrations further from area A. The sampling region significantly influenced the average arsenic concentration in water and soil samples (P < 0.05). Arsenic uptake by the plant samples exceeded typical concentrations (0.1 to 3 μg g-1), with the highest mean arsenic concentrations found in the leaves of Astragalus bisulcatus, Chenopodium album, and Mentha longifolia, accumulating more than 47.8, 35.5, and 22.5 μg g-1, respectively. The study demonstrates heavy contamination of water, soil, and plant resources in the region, with most surface water resources utilized for agricultural irrigation, animal consumption, and occasionally drinking water for village residents. The entry of arsenic into the human body, directly or through the food cycle, poses a severe health risk to the region's residents, necessitating immediate intervention measures.

Investigating the effect of agricultural management methods on the amount of nitrate and urea in the soil has special importance. The purpose of this study is to model and investigate the interrelation of hydraulic, reactivity, and solute absorption variables of different soil depths collected in the year of (2020-2021) from the pilot rice farm located in the Sari Agricultural Sciences and Natural Resources University, Mazandaran province, with an area of 0.6 hectares. In this study, the residual moisture of the soil (θr), nitrification rate (kn), and urea hydrolysis rate (kh) variables were modeled based on four, four, and two defined scenarios, respectively, using Wavelet-Artificial Neural Network (WANN), Wavelet- Artificial Neural-Fuzzy Inference System (WANFIS), and Wavelet-Gene Expression Programming (WGEP) models. The results showed that the performance improvement percentage of WGEP models compared to WANFIS and WANFIS model compared to WANN considering the RMSE evaluation index were obtained (16.96, 41.87), (85.72, 1.00), and (20.37, 3.27) for three variables of θr, kn, and kh, respectively. the volumetric residual moisture in the soil, and the urea hydrolysis rate variable is also highly dependent on the residual moisture in the soil. Also, the results showed that the hydraulic variables, reactivity and absorption of soil solutes can be affected by the climatic conditions of the region. Therefore, providing intelligent applicable models to estimate nitrate and urea variables in soil can help managers and farmers in proper management of water and soil resources and optimal use of nitrogen fertilizer with less time and cost.

Soil hydrocarbons can affect the physical, chemical and biological characteristics. Soil samples were prepared from the oil-rich area of Kermanshah province, which have been under oil pollution for a long time. 120 soil samples were collected from a depth of 0-15 cm with three pollution levels of low (L), moderate (M) and high (H) and the physicochemical characteristics were measured. Then bacteria were counted in NA and CFMM media and a positive and significant correlation was observed between bacterial population and oil concentration. The mean of oil measured by Soxhlet method was 4.03%, 9.95% and 22.50% for L, M and H levels, respectively. With the increase of oil in soil samples, ACP and ALP increased. In all samples, ACP was lower than ALP. The highest ACP and ALP were obtained 45.78 and 84.90 (gPNP.g-1.h-1µ) respectively in soil with high pollution level. Regression analysis showed that the oil percentage, sand percentage and EC with an regression coefficient of 0.71 were effective variables on the ACP, and the oil and sand percentage were also effective variables on the activity of ALP with an regression coefficient of 0.43. PCA analysis was also performed and the results showed that the first two components explained 68% of the variance between the samples. Based on the results, it was observed that natural and long-term oil pollution, with the passage of time led to the adaptation of microbial communities resistant to pollution and the number of these microorganisms and the activity of phosphatase enzyme increased.

 Soil classification is the systematic categorization of soils based on distinguishing soil characteristics, aiding in the comprehension of soil properties through soil surveys, and establishing suitable strategies for effective soil utilization and management. One of the main reasons for creating soil classification systems is to identify the differences in important soil characteristics for management purposes. Globally, Soil Taxonomy (ST) and the World Reference Base for soil resources (WRB) are widely used for soil classification. However, these two classification systems have varying criteria which can pose difficulties when exchanging classification results. After years of intensive worldwide testing and data collection, new versions of the ST and WRB systems have been released. In its current state, ST has a strong hierarchy with six categorical levels: order, suborder, great group, subgroup, family, and series (Soil Survey Staff, 2022), while the WRB has a flat hierarchy with only two categorical levels: reference soil groups and soil units (IUSS Working Group WRB, 2022). Several scientists have endeavored to evaluate the merits and demerits of these soil classification systems and offer recommendations for their enhancement. The arid and semi-arid regions located in the western and southwestern parts of Kohgiluyeh and Boyerahmad Province, distinguished by their considerable diversity in parent materials, topography, climate, and land use, present an excellent opportunity for scrutinizing and contrasting the effectiveness of soil classification systems. Remarkably, no prior research has delved into this subject in this specific geographical area. Consequently, this research aims to compare the effectiveness of the ST and WRB systems in characterizing soil attributes. Furthermore, it seeks to analyze the alterations that these two systems have undergone during an eight-year period, spanning from 2014 to 2022.

This study was conducted in the western and southwestern regions of Kohgiluyeh and Boyerahmad Province, specifically in the divisions of Gachsaran, Basht, Choram and Kohgiluyeh. A total of 26 soil profiles were excavated, described, and sampled based on aerial photos, satellite images, topographical and geological maps, as well as field observations. These profiles were selected following the soil description guide provided by the Department of Soil Conservation of the US Department of Agriculture. Subsequently, after reviewing the preliminary results and aligning with the research objectives, 12 representative soil profiles were chosen for further analysis. Soil samples were collected from all genetic horizons and transferred to the laboratory. After air-drying, the samples were passed through a two-millimeter sieve and the routine physical and chemical analyses were conducted, including soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon, cation exchange capacity (CEC), and gypsum analyses. For mineralogical studies, soil clay minerals were separated and identified using standard methods. Additionally, soil thin sections were prepared from intact soil samples of selected soil horizons and examined under a polarizing microscope. Finally, the soil profiles were classified based on the criteria outlined in Soil Taxonomy (2022) and WRB (2022).

Soil Taxonomy and WRB, as the two most popular classification systems, aim to encompass as manysoil characteristics as possible. According to the ST classification, the soils were classified into four orders: Entisols, Inceptisols, Alfisols, and Mollisols. In the WRB system, they were grouped into seven reference soil groups: Regosols, Flovisols, Luvisols, Cambisols, Kastanosems, Gypsysols and Glysols. The results revealed that WRB was significantly more effective in describing the characteristics of the studied soils. One of the key advantages of this two-level system is its flexibility, allowing for the inclusion of additional principal and supplementary qualifiers to cover all essential soil characteristics. Moreover, in many cases, WRB exhibits better prioritization compared to ST. For example, the presence of gypsic, combic, calcic horizons, as well as fluvic and gley properties, can allocate the soil to the reference groups of Gypsisols, Cambisols, Calsisols, Fluvisols, and Gleysols, respectively. However, a limitation of the WRB system is the absence of mineralogical information in soil classification. Enhancing this classification system's quality and making it more appealing to planners could be achieved by incorporating suitable mineralogical attributes for the reference groups or criteria that express soil fertility conditions with relatively straightforward measurements. In addition, it is proposed to add three subgroups to ST: Gypsic Haplustalfs, Fluventic Gypsiustepts and Cambic Haplustolls. Similarly, following the WRB model, it is recommended to introduce a qualifier in ST to indicate the presence of lithological discontinuity. Regarding the WRB system, suggestions include adding qualifiers such as "Cutanic" to gypsisols with clay films, "hypercalcic" to reference groups of Kastanozems and Luvisols with a calcic horizon comprising more than 50% of calcium carbonate, and "aridic" for better expression of soil characteristics with Aridic-Ustic moisture regimes.

The results of this research demonstrated that WRB is more effective in describing the conditions and characteristics of the studied soils. The WRB system, through its diverse set of qualifiers, is capable of representing field conditions more efficiently. However, it is suggested that the surveyors have the freedom to select an appropriate qualifier from the list provided by WRB without limitation, which can enhance its success in practical applications. Furthermore, it is recommended that both classification systems be used to categorize soils, not only to evaluate their efficiency for the soils in other regions but also to gain a comprehensive understanding of their suitability for different contexts.

Runoff is one of the most important hydrological processes in ecosystems, which is very important in the management of water and soil resources. Although the use of soil microorganisms as soil inoculants in the bioengineering management of runoff has been confirmed, the use of soil microorganisms to control runoff in soils contaminated with petroleum has not been considered. Therefore, in order to evaluate inoculation of soil Bacteria, Cyanobacteria and fungi in reducing runoff in soil contaminated with petroleum, the present study was carried at plots of 0.5×0.5 m with slope of some 25% and level of 20000 mg kg-1 of gasoil and control contamination in three replicates. The plots will be then subjected to rainfall intensity of some 35 mm h−1 and duration of 30 min installed at the Rainfall Simulation Laboratory of Tarbiat Modares University at Faculty of Natural Resources. The results showed that the inoculation treatments, although there was no significant difference compared to the control treatment (P>0.05) except for the start of runoff (P<0.05), improved the components of runoff. The comparison of the mean of the study variables showed that the bacteria, cyanobacteria, fungi, bacteria+fungi, bacteria+cyanobacteria, cyanobacteria+fungi, and bacteria+cyanobacteria+fungi caused +47.10, -0.08, -10.72, -24.86, +14.85, +49.88 and +27.88 percent changes in runoff start time, +4.58, -54.04, +65.19, +72.20, -41.36, -84. 53 and +40.15 percent changes in runoff volume, and +4.75, +54.06 and -65.15, +72.28, -41.39 and -84.55 and +40.20 percent changes in runoff coefficient, respectively. The results of the research indicated the relative synergistic performance of the combination treatment of cyanobacteria + fungi in reducing the effect of gasoil on runoff properties. Finally, the results of the present study showed that the inoculation of native soil bacteria, cyanobacteria, and fungi can be an efficient and sustainable biological technology to improve runoff characteristics in areas contaminated with petroleum.

This research was carried out to investigate the physical and chemical properties of the soils obtained from dredging of the drainage drains in Abbas Irrigation channels in Ilam province. The area encompasses 16 thousand hectares. In this study sampling was carried out from two major branches. The drainage No. 1 with 21 km length, is flooded to the Rafahyeh river and drainage No. 2 with 5 km length is flooded to the Chikhab River. Sampling was done from drainage soil, dredged soil and the arable land around drainage. A comparison was performed between the three regions of drainage floor area, drainage agricultural land and dredged soil. Soil physico-chemical properties such as particle and bulk density, potassium, magnesium, sodium, calcium and phosphorus, carbonate and bicarbonate, sodium absorption ratio, exchangeable sodium percentage, organic matter, organic carbon, cation exchange capacity, sulfate, base saturation percentage and nitrogen. The results showed that the amount of potassium in dredged soil is more than recommended for soil. Phosphorus concentration was also higher than recommended for soil. Sodium, magnesium and calcium was lower than soil recommended levels. Due to the presence of calcareousmaterial,the amount of limein soils washigh and the amount of gypsum was high as well, due to the warm and dry climate and low rainfall. Soil pH of the region was mostly higher than 7 so they are categorized as alkaline and semi-alkaline soil. The studied soil is classified as saline soil due to high electrical conductivity.Soil texture was sandy clay loam.

In this study, keratinase-producing bacteria were used to produce natural fertilizer from chicken feathers. Twenty-nine soil samples were collected from 0-30 cm depth of agricultural fields and mixed with chicken feathers. After three weeks, 31 isolates were isolated from the soils mixed with feathers, which were able to grow on the special culture medium of Feather Meal Agar (FMA). The isolates were transferred to a liquid medium containing feathers and their ability to degrade the feathers was investigated. A completely randomized design was used to examine the effect of the solution created by the degradation of chicken feathers on lettuce growth. The experimental treatments included the foliar application of three solutions obtained from the degradation of chicken feathers (gh1, b1, c11), and control (distilled water). The results showed eight isolates were able to completely decompose the feathers in seven days by producing keratinase enzyme. The highest activity of the keratinase enzyme (with the ability to fully degrade the feather: 8.56 U / ml) was related to that of Bacillus methylotrophic strain gh1. Also, the maximum concentration of free amino acid (1065 μg / ml) was observed in the growth medium of Bacillus siamensis strain c11. The three solutions obtained from feather degradation had a significant effect (p < 0.01) on lettuce fresh weight, lettuce dry weight, and fresh root weight. The results showed that the lettuce fresh weight increased by 28.8%, 26.1%, and 14.1%, using Bacillus methylotrophicus (gh1), Bacillus velezensis (b1), and Bacillus siamensis (c11) respectively, compared to the control. In addition, the lettuce dry weight increased by 25.7%, 19.9%, and 15.2%, with the aid of gh1, b1, and c11 treatments, respectively, compared to the control. The results showed that using keratinase-producing bacteria, feather degradation could be increased, and the obtained product can be used as a growth stimulant for lettuce.

Estimation of soil moisture is essential for optimal management of water and soil resources. Landsat images with appropriate spatial and temporal resolution are good tools for these studies. The purpose of this study is to estimate and zoning the soil surface moisture in agricultural lands of Shushtar County in Khuzestan province using remote sensing indicators. To do this, first 25 soil samples of agricultural lands were taken from a depth of 0-15 cm and their moisture was measured. Then, normalized vegetation difference index (NDVI), soil reflection adjustment index (SAVI), surface temperature (LST), normalized moisture difference index (NDMI), normalized agricultural differential index (NDTI) and soil moisture index Infrared short band (SMSWIR) were applied to the Landsat 8 Image. In the next step, the values ​​of these indices were transferred to SPSS software for statistical regression and the soil moisture estimation functions were obtained by multivariate linear regression. The results showed; Due to the high coefficient of determination (0.73) and the low root mean square error (1.31) in the simultaneous method (Enter Method), this model was considered suitable for estimating and zoning the surface moisture of agricultural lands in the region. According to the research results, soil surface moisture was directly related to NDVI, SAVI, NDMI, NDTI and SMSWIR indices and inversely related to LST index. Also, LST index has a better estimate of soil moisture, which indicates a significant effect of this factor on the amount of soil surface moisture.

Understanding the behavior of plants in relation to ecological factors provides basic information in order to improve and properly use rangeland. Also, determining distribution area of species and studying the characteristics of their habitat helps to choose the right place for their establishment. Rheum species is one of the rangeland species which, in addition to having important medicinal properties, is valuable for soil protection in dry and semi-arid rangeland. Considering the decrease in the density of this species in natural habitats during recent decades, knowing the characteristics of the habitat can be an effective help in the improvement and development of Rheum. Therefore, in this research, the effect of environmental factors on the vegetative characteristics of rhubarb species in three different habitats is investigated.

In this research, the habitat characteristics in three habitats of Chubak, Targh and Karkaz in the Kouhsorkh region located in Kashmar city and the relationship of ecological factors with characteristics of Rheum ribes L. including excluded base weight, stem weight without pods, length of stems of a plant, and number of stems in each base have been investigated. The ecological factors included soil factors such as EC, pH, N, P, K, organic matter, clay, silt, sand and physiographic factors include slope, aspect and altitude. in each the studied habitat, 10 samples of Rheum ribes were collected. In the first stage, the weight of each harvested stem was measured and then the weight of stems without pods was determined. Also, the number of stems in each sample was counted and the length of each stem was measured separately. Finally, the matrix of environmental conditions and vegetative characteristics of Rheum ribes was analyzed using redundancy analysis (RDA).Method

The findings of the research showed that the characteristics of the soil in Chubak, Targh and Karkaz sites are different and in the same site it is different in different soil depths. Among the physiographic factors, the altitude has the greatest role on the characteristics of the Rheum ribes. The altitude has a positive and strong relationship at a significant level of 5 percent with the length and number of Rheum ribes stems. So that with the increase in altitude, the length of their stem also increases. Among the soil characteristics, the percentage of sand, silt, P, K and lime percentage are the most important factors affecting the characteristics of Rheum ribes. The percentage of sand has a srtrong correlation with the weight of the Rheum stem, and with the increase of the percentage of sand, the weight of the stem increases. EC parameters and silt percentage have a negative relationship with Rheum ribes characteristics. So that with the increase of these parameters in the soil, the number and length of stems as well as their weight decreases.

The results of this study showed that Rheum ribes in Chubak site has the highest amount of growth characteristics, therefore Chubak region has provided more suitable conditions for growth of this species than the other regions. In this site, the samples of Rheum ribes have the highest number of stems and the highest average weight of the stems at 1316 gr. Therefore, this site can be introduced as the best growing area for Rheum ribes. Also, in terms of environmental parameters affecting the growth characteristics of Rheum ribes, among the topographic factors, altitude, among soil properties, the percentage of sand, silt, phosphorus, potassium and lime are the most important factors affecting the characteristics of Rheum ribes.

Water scarcity, the reduction of very high costs for the development of new water resources and the protection of the environment necessitate the use of unconventional water in agriculture. These waters include two main groups of effluents and saline waters, the direct use of which causes environmental problems and soil pollution. One of the ways in which water and soil can be improved and the total amount of water used for irrigation can be reduced is the use of magnetic water technology, which increases crop yield per unit volume of water used. In this study, the effect of using treated magnetic effluent on maize water productivity was investigated. For this purpose, a factorial experiment was conducted in a randomized complete block design with three replications in 2020 at Babolsar city. Treatments include irrigation with well water (W1), irrigation with mixing 25% of effluent and 75% of well water (W2), irrigation with the mixing of 50% of effluent and 50% of well water (W3), irrigation with mixing of 75% of effluent and 25% of water well (W4), irrigation with 100% effluent (W5) under magnetic field (I1) and without magnetic field (I2) was. The results showed that the effect of irrigation type and water and wastewater mixing on biological, physical, wet and dry forage productivity was significant. On average, irrigation with magnetic effluent significantly increased biological (10.33%), physical (9.35%), wet forage (10.07%) and dry forage (11.49%) productivity compared to non-magnetic effluent. Also, all the mentioned parameters increased with increasing the percentage of effluent used in irrigation. Using magnetic technology, effluent can be used to increase the productivity of maize.

Loose stone check dams are among the least expensive structures in watersheds and are usually used to protect soil resources and reduce sediment transfer in small waterways. The effectiveness of these dams has received less attention from researchers in particle deposition in the forest area. The purpose of this study was investigating the effect of loose stone check dams and the role of the factors affecting on the amount of sedimentation in the forest area. Also, grading of sediments were studied at consecutive dams and different distances from each dam and compared with the soil particle size distribution of upstream soil. In this research the eleven loose stone check dams follow each other were investigated in the Marg watershed located in the southwest of Kermanshah. These dams have been constructed in the second order waterways during the year 2016. The results showed the upper dams of the waterway had the highest amount (9245 kg h-1) and the lower dams had the lowest amount of sediment (3575 kg h-1). The sediment amount of the back dams was directly affected by the slope and area of the dam drainage area. The amount of sand was 1.5 higher than the upstream soil, while the amount of silt and clay in the sediment samples was lower of the upstream soil, 75.5% and 23.8%, respectively. The amount of sand particles increases but the silt and clay particles had a declining trend with distance from the dam during the sedimentation surface. This study showed that loose Stone dams play an important role in sedimentation of coarse particles and they are one of the important structures in the watershed to prevent sediment transfer due to the low cost of their construction. Although, the construction of low drainage dams is necessary to prevent the transfer of fine particles.

Corn is considered as one of the most important and strategic cereals in the world that needed a lot of nitrogen fertilizer and often this need is supplied by chemical fertilizers. In addition to the severe need to fossil fuels for chemical fertilizers production, they are also important environmental pollutants (23). Therefore, organic fertilizers such as green manures of legume species can be a good alternative to chemical fertilizers. Also, conservation tillage operations that are accompanied by proper management of crop residues, it is an appropriate solution to prevent the elimination of residues in sustainable agriculture, and plays an important role in improving the physicochemical and biological properties of soil, and can lead to increasing crop yield (22). Therefore, developing and promoting the use of green manure and conservation tillage operations is essential. Therefore, the present study investigates the effect of organic fertilizer application on corn yield under different tillage levels.

This experiment was carried out as split plot in randomized complete block design with three replications at 2018-19 in a farm located in Ghale-No village, Zahak city. Vetch (Vicia villosa) was used as a green manure in this study. The experimental treatments were included two levels of green manure, consumption and no consumption as main factors; and three levels of tillage, no tillage, minimum tillage and conventional tillage as sub plots. In this experiment agronomic traits of plant height, dry and fresh forage yield and seed yield; ecological traits of weeds biomass, photosynthetically active radiation, soil moisture percentage and soil temperature; and some soil physicochemical properties such as soil porosity, bulk density, particle density, organic carbon and nitrogen percentage were evaluated. Data analysis was performed with SAS software.

The experimental results showed that the highest amount of dry and fresh forage yield and seed yield, photosynthetically active radiation, soil porosity percentage, soil organic carbon and nitrogen percentage was obtained from green manure consumption and conventional tillage treatment and there was no statistically significant difference between the consumption of green manure under conventional and minimum tillage conditions. The lowest amounts of the above traits were obtained in the treatment without green manure and no tillage. In addition, the treatment green manure consumption and no tillage system resulted in obtaining the highest soil moisture percentage and the lowest soil temperature. For weed biomass, it was also found that the use of conventional tillage significantly reduces weed biomass, but green manure consumption hadn’t any significant effect on weed biomass.

In this experiment, it was shown that the green manure consumption by increasing the amount of soil organic matter and improving soil structure increased the amount of access to nutrients, especially nitrogen for the plant, which led to enhancing plant yield and growth. Also, increasing the soil porosity and reducing the soil bulk density under the influence of minimum tillage led to soil structure improvement, and it increases the root permeability in soil which this allows the plant to absorb more water and nutrients. Therefore, according to the results of this experiment, it can be suggested that the combination of green manure consumption with minimum tillage can create a good yield in corn cultivation in the study region.

Soil erosion is one of the most serious environmental issues in the world, causing soil degradation, reduction of land productivity, increasing flood, water pollution and pollutions transportation; it is also a serious threat to sustainable development in the world. Therefore, the soil conservation and the prevention of soil erosion and use of conditioners as the nanoclay can be considered as a solution to improve   land productivity and protect environment. The present study was, therefore, conducted to address the effect of the application of montmorillonite nanoclay with three rates of 0.03, 0.06 and 0.09 t ha-1 on changing runoff and soil loss variables under laboratory conditions. The results showed that the nanoclay with the rate of 0.03 t ha-1 could decrease the runoff coefficient, soil loss and sediment concentration with the rate of 40.65, 88.38 and 82.19 percent, respectively. The average of soil loss in control treatment and conservation treatments of nanoclay with various rates was measured to be 3.76, 0.44, 1.33 and 3.16 g, respectively. Also, the results showed that the most sediment concentration was the control treatment with the rate of 5.84 g l-1 and the conservation treatments with nanoclay in the applied rates was 1.04, 3.47 and 2.96 g l-1, respectively. Also, the results showed that the nanoclay effect was significant on changing the soil loss and sediment concentration at the level of 99 percent. Finally, due to the effect, the use of this conditioner in natural conditions and investigation of the effects on environment and aggregates stability are recommended.

Today, biological methods are considered as one of the effective approaches to control soil erosion at early stages. Biologic management is a scientific and applied approach to manage and control runoff and soil loss. However, there is no practical and specific algorithm for preparing and implementing biological programs for managing or controlling soil erosion in the watershed scale. Therefore, the present study was conducted as a pioneer study to develop a practical framework for the biologic management of soil erosion. In this regard, the erosion status in the watershed was initially considered to identify areas prone to bio-management. Then Ombrothermic and Hythergraph diagrams were prepared and combined with topographic, temperature, precipitation, and evapotranspiration data layers for zoning and obtaining an agroclimatic map. Finally, providing a list of endemic and dominant species of the study area obtained from phytosociological studies and soil characteristics, biologic management of soil erosion for each agroclimatic category was suggested as a final step for the proposed framework. The applicability of the proposed algorithm was evaluated for the Oshnavieh Galazchai Watershed in West Azerbaijan Province, Iran. The results showed that 24 and 76% of the watershed are classified in low and moderate situations in soil erosion, respectively. Based on the agroclimatic map, the suitable species for biological management of soil erosion were identified, and their associated characteristics were extracted. Finally, among the rangeland species in the studied area, Achillea millefolium, Agropyron desertorum, Agropyron tauri, Galium verum, Melica persica kunth, and Stachys inflata benth were suggested for biologic management of soil erosion in almost 64% of Galazchai Watershed. Therefore, the results of the present study could be extended at the country level for the appropriate biologic management of soil erosion.

The study of moisture patterns under a single dropper is necessary for the design, management, and implementation of drip irrigation systems. The proper design of these systems should be a desirable combination of dropper discharge, soil characteristics, application time and type of used water that affect the water dynamics in the soil under surface dropper. However, less attention has been paid to the effect of water type, especially magnetic water, on the dynamics of water in the soil. Magnetic fields, while changing the physical and chemical properties of water, lead to changes in the characteristics of water movement in the porous medium. The purpose of this study was laboratory investigation of combined and separate effect of magnetism and organic matter on the distribution of moisture in layered soils.

The experiments were carried out in a 50*50*50 cm box of transparent plexiglass to observe the movement of the moisture front in the soil. Also, the experimental model of the present study includes water resource, plastic pipe, magnets set for applying magnetic field to water and dropper with a constant discharge rate of 4 liters per hour. In this study, four permanent pairs of magnets were applied with two specific magnets (three pairs of magnets with 0.2 T, and a pair of magnet of 0.3 T magnitude). The Porous media treatments of this study includes two samples of sandy loam soil (74% sand, 11% clay and 15% silt) and clayey soil (15.5% sand, 52.5% clay and 32% silt) and hydroponics porous media (peat moss organic matter). Soil and hydroponic treatments were prepared in the form of homogeneous mixture of soil (80%) with organic matter (20%). Also, the total thickness of the soil layer was considered 35 cm (the thickness of the coarse textured layer (SL) 25 cm and the fine textured layer (C) 10 cm) that 15 cm was kept empty from the top of box. For this purpose, the effect of plain and magnetic water in the form of eight treatments, on the moisture movement in coarse-textured, fine-textured, coarse textured mixed with peat moss, fine-textured mixed with peat moss were evaluated. Also this tests in the irrigation and drainage and Soil Laboratories were designed and implemented. Finally, the chemical properties of drainage water extracted from soil samples and samples of soil mixed with peat moss were measured by pH meter (pH meter) and electrical conductivity meter (EC meter).

The results of this study showed that due to the application of magnetism on irrigation water, electrical conductivity of drainage water was decreased in all treatments with the highest decrease to 0.875 mmho/cm in the fine-textured soil, except the fine-textured soil mixed with peat moss. Also, drainage water pH was increased in all four soil treatments, with the highest increase in the fine-textured soil to 7.6. Furthermore, Investigation about moisture dynamics showed that the significant effect of magnetic water application on certain treatments and the patterns of moisture distribution with their progressive radii were tangible. Also, for infiltration depth factor, the most general variability of magnetic water treatment was observed in T1 (increment), T7 (decrease), T3 (decrease) and T5 (increment) treatments. On the other hand, the highest influence of forward width was obtained in T7 (increment), T1 (decrease), T5 (increment) and T3 (increment) treatments. In addition, the analysis of forward curves-soil moisture distribution showed that due to the application of magnetic water for example in the horizontal direction, the maximum horizontal progression radius increased by 19.81% to 38.9 cm. Also, T7 (the fine textured soil on the coarse textured soil with magnetic water) can be described as a treatment that has the most beneficial result of magnetic water in the present study. As a result, even without using organic matter treatment and application of its fertilizers, it is possible to use the existing condition of agricultural soils with desired results, which have the same status as the present treatment and even the same treatments. In general, the results of this study were indicated that the magnetism on the chemical properties of soil water and especially the dynamic characteristics of water in the soil, including the pattern of moisture distribution and forward velocity was effective.

Assessment of land use capabilities based on regional conditions is essential to reduce human impacts on natural resources and to identify suitable land uses. However, the selection of appropriate method for evaluating the potential of the land at the watershed scale has received less attention. Therefore, the present study aimed to apply and validate three methods of FAO, USDA and the Forests, Range and Watershed Management Organization (FRWMO) in assessing the land capability of the Oshnavieh Galazchai Watershed in West Azerbaijan, Iran. Towards this, different criteria were assessed for designation of land capability for the Galazchai Watershed based on the available standards. Corresponding available data were consequently obtained using 122 soil samples taken throughout the watershed as well as topographic and meteorological information. According to the results of the study, the highest and the lowest absolute changes were regarded to the FRWMO and FAO methods with an area of 6682 and 5656 ha, respectively. On the other hand, the maximum disagreement was found between the current land use with the FRWMO method with Kappa of 0.64, which is due to allocation of land with steep slope to agriculture and orchard. Hence, it is recommended to allocate land to different uses according to the land potential of the region and also considering the economic and social conditions of watershed stakeholders after applying land use changes to maximize the satisfaction of all stakeholders and lead to sustainability of the study watershed.

In order to determine salinity tolerance threshold and yield decrease per unit increase of soil salinity in selected pomegranate genotypes, a factorial experiment was carried out based on completely randomized design (CRD), with two factors: genotypes in 12 types (Shisheh Kap Ferdus, Malas Yazdi, Malas Saveh, Rabab Neyriz, Golnar Saveh, Golnar Sarvestan, Golnar Shahdad, Narak Lasjerd Semnan, Vahshi Babolsar, Post Siyah Ardakan, Chah Afzal and Voshik Torsh Saravan) and soil salinity at five levels (1.5, 3.8, 6.2, 9.3 and 12.6 dSm-1). According to the results, the lowest salinity tolerance threshold was observed in Voshik Torsh Saravan (3.02 dS/m), Malas Saveh (3.25 dS/m) and Golnar Saveh (3.40 dS/m) genotypes, and the highest salinity tolerance threshold was observed in Golnar Shahdad (4.90 dS/m), Chah Afzal (4.70 dS/m), Post Siyah Ardakan (4.38 dS/m), and Malas Yazdi (4.17 dS/m) genotypes. The highest yield reduction slope was observed in Golnar Saveh (7.89%), Golnar Sarvestan (7.39%), Voshik Torsh Saravan (6.69%), and Malas Saveh (6.33%) genotypes, respectively. In contrast, the lowest yield reduction slope was observed in Chah Afzal (2.83%), Post Siyah Ardakan (2.88%) and Narak Lasjerd Semnan (2.89%) genotypes, respectively. Overall, the results showed the levels of salinity that reduced the yield by 50% in Chah Afzal, Post Siyah Ardakan and Narak Lasjerd Semnan genotypes were about twice greater than salinity that reduced the yield by 50% in Golnar Saveh, Golnar Sarvestan, Voshik Torsh Saravan and Malas Saveh genotypes. EC50 in Chah Afzal, Post Siyah Ardakan, and Narak Lasjerd Semnan genotypes were observed at 22.37, 21.74 and 21.10 dS/m. At salinity level of 8.4 dS/m, yield reductions in Chah Afzal, Post Siyah Ardakan and Narak Lasjerd Semnan genotypes were only 10.47%, 11.58%, and 13.30%, respectively, which were lower than the 50% value previously reported. Therefore, these three genotypes were selected for further studies and planting as rootstocks in Chah Afzal Station of National Salinity Research Center.

Water and tillage-induced soil erosion on steep slopes farmlands are primary causes of land degradation process that gradually change land morphology. Measurement of soil erosion and sedimentation in most watersheds are nearly impossible. So soil erosion modelling and simulation to understand the processes of soil erosion, to predict runoff and soil erosion and also to determine the best management practices of soil conservation is highly important.

Area of study (Sample sub- catchment) is a sub-watershed of the Kachik watershed in Golestan province, which is one of the sub-basins of the Gorganroud basin. This area is around 197 ha which completely covered with fertile and erosive loess deposits and is a part of Iranian Loess Plateau (ILP). In this study, WaTEM / SEDEM version 2004 used to estimate water and tillage erosion. After soil sampling in 20 different location respected to the model based sampling method on minimax approach, 137Cs activity determined, and all three distinct erosion phases prepared. Finally, erosion map using 137Cs by considering conversion models including Mass Balance II for farmland and Diffusion and Migration for other land uses produced. Then the erosion and sediment point map produced separately for model evaluation.

Using 137Cs radionuclide, 90 % of the soil measurement locations devoted to erosion. Mean annual soil erosion using radionuclide conversion models was 21.1 ton ha-1. This rate of soil erosion regards to 97% SDR (Sediment Delivery Ratio) illustrates high potential for sediment production in the area of interest. Mean of water and tillage erosion by WaTEM/SEDEM were 8.28 and 4.87 ton ha-1 year-1 respectively in erosion locations and this rate for sediment was 18.14 and 7.89 ton ha-1 year-1 for sediment zones as well. Soil erosion and sedimentation rate using WaTEM/SEDEM model was estimated to be 1.46 and 0.85 ton ha-1 year-1 in turn. SDR for WaTEM/SEDEM in this study was around 58 %.

Given that the entire study area covered with sensitive and fertile loess deposits, and a significant percentage of area devoted to farmland, so water and tillage induced soil erosion is of great importance. The results of this research indicate a low estimation (under-estimation) of the WaTEM / SEDEM model compared to the actual values (measured 137Cs). As a result, WaTEM / SEDEM erosion model is not effective in the loess deposits of the northeast of Golestan province. On one hand spatial pattern of water and tillage induced soil erosion can be used in soil and water conservation practices. On the other hand, pertaining to large vast area devoted to farmland in Gorganrood Basin, tillage erosion should be taken by decision maker. Although for higher certainty, it is necessary to calibrate the model and repeat its implementation in other watersheds.