The presence of Damghan Erg in West of Damghan Playa indicates high wind activity in this desert region. Due to technological advances and population growth in recent decades, large parts of past land uses have changed. These changes can exacerbate wind erosion and affect lands sedimentation. In this study, first, the land use maps of years 1974 and 2003 were prepared. The comparison of these maps shows that a significant area of rangelands have been converted to agricultural lands. Also, part of the agricultural lands has been converted to residential and industrial lands and a small area of ​​agricultural lands has been dilapidated. The soil or surface sediment were sampled in three treatment as old agricultural lands (that they have preserved their use), new agricultural lands (that they were formerly rangelands) and ranelands (with five replications). Soil particles grading have been studied by sieves of 2000,1180,600,250,150,75 and less than 75 micron based on the weight and frequency percent of each particle size class and indicators of particle (diameter mean, skewness, sorting and elongation) were specified using software GRADISTATE. At last, land sedimentation assessment was identified based on the abundance of particles with a diameter less than 2000 micron (susceptible to erosion). The results have been prepared as 7 maps that they express region sedimentation in each particle size class. Particles dispersion map with diameter larger than 2000 micron indicates stable particle dispersion against wind erosion and other maps show unstable particles dispersion. Comparing the land use map with particles dispersion maps show that the most unstable particles dispersion is in rangelands, the least dispersion of them is in agricultural land and rangelands have more sedimentation than the other treatments.

This study was conducted to investigate the effects of slope gradient and land use changes on soil organic pools in particle-size fractions under natural forest in hilly regions in western Iran. Three common land uses in the selected site including natural forest (NF), disturbed forest (DF) and cultivated land (CL) and three slope gradients (0-10%, S1, 10-30%, S2, and 30-50%, S3) were selected as a basis for soil sampling. A total of 108 soil samples were taken from the 0-10 cm surface layer in the whole studied region. Some physical and chemical properties as well as particulate organic matter (POM), particulate total nitrogen (PTN) and organic carbon (OC) and total nitrogen (TN) associated with different primary particle size fractions were measured. The results showed that the POM in the forest land use was considerably higher than the deforested and cultivated lands in all slope gradients. POM was mainly concentrated in the sand-size fraction. The values of PTN were significantly higher in the forest land use and in the down lower slopes than in the deforested and cultivated counterparts and steep slopes except for the CL land use. The C:N ratios in POM fraction were around 17-18 in the forest land and around 23 in the cultivated land. In forest land, the silt-associated OC had highest values among the primary particles. The enrichment factor of SOC, EC, was the highest for POM. For the primary particles, EC of both silt and clay primary fractions for selected land uses and slope gradients tend to be in the following orders: CL>DF>NF and S3>S2>S1. Slope gradient significantly affected the OC and TN contents associated with the silt and clay particles, whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes. Overall, the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountain regions with high rainfall in western Iran.

Soil organic carbon has been the most important soil quality measurement factors and has intense relation with soil physical, chemical and biological characteristics. Organic matter and its components are important factors of soil aggregates constitution and stability and play significant role in its structure.So, this research has been done for achieving this purpose. This area is arounding saman _ one of the charmahalobakhtiari counties in distance 20_30 km northeast. In this study, from 127 point in 3 land uses of fruit garden, degraded range, and dry farming, soil sampling of surface depth 0_30 cm was done. The soil samples were analyzed chemically and physically. Also ,soil organic carbon supply , mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon were measured. For considering lands username type effect on soil characteristics and organic carbon physical distribution in case study area, variance analysis by SAS software and comparing averages by dancon method were done. Comparing soil characteristics in 3 land uses of garden, degraded range and dry farming showed that land uses changed on pH, lime and soil bulk density have not been affect significantly but have affected on total soil organic carbon, soil nitrogen, EC, soil organic carbon supply, mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon. In garden land use, most total organic carbon rates, total nitrogen rate, soil organic carbon supply, mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon has been observed. Increasing MWD in garden land use is related to high rate of organic material in this soil.

Soil organic carbon has been the most important soil quality measurement factors and has intense relation with soil physical, chemical and biological characteristics. Organic matter and its components are important factors of soil aggregates constitution and stability and play significant role in its structure. So, this research has been done for achieving this purpose. This area is arounding saman _ one of the charmahalobakhtiari counties in distance 20_30 km northeast. In this study, from 127 point in 3 land uses of fruit garden, degraded range, and dry farming, soil sampling of surface depth 0_30 cm was done. The soil samples were analyzed chemically and physically. Also ,soil organic carbon supply, mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon were measured. For considering lands username type effect on soil characteristics and organic carbon physical distribution in case study area, variance analysis by SAS software and comparing averages by dancon method were done. Comparing soil characteristics in 3 land uses of garden, degraded range and dry farming showed that land uses changed on pH, lime and soil bulk density have not been affect significantly but have affected on total soil organic carbon, soil nitrogen, EC, soil organic carbon supply, mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon. In garden land use, most total organic carbon rates, total nitrogen rate, soil organic carbon supply, mean weight diameter, particle organic carbon in macro and micro soil aggregates and total particle organic carbon has been observed. Increasing MWD in garden land use is related to high rate of organic material in this soil.

Movements of sand and small particles (dust) because of wind occur in many different environments, but the phenomenon is much more powerful in arid areas and cover larger areas. The phenomenon is one of the most important issues arid areas face. In order to preserve buildings, agricultural lands, pipe lines and transport networks from sandstorms and from being buried in dust and sand, it seems necessary to create and develop monitoring tools and confront this natural phenomenon. Urban areas in arid lands can block movements of sand and dust suspended in wind. In arid lands and deserts population is centralized around ground water resources. Cultivated lands are limited which results in more pressure on the earth due to centralization and population being attracted to settlements. Thus, desert ecosystem near urban areas faces more damages, plant life faces destruction and soil structure will be damaged. Movements of sand and small soil particles increase and wind-related problems and issues display in a larger scale. In this regard, factors creating problem of sand and small soil particles depend on desertification factors which have gained attentions in recent years (A. J. Pilor and Honey, 1976; United Nation, 1977).
To decrease disagreeable results of sand and small soil particles movements, we need to gain enough information regarding the natural characteristics of such movements and identify factors accelerating this process, while trying to decrease the quality and quantity of these natural events. Therefore, the present article aims to identify natural characteristics, intensity, dispersion and movement of sand and small soil particles in arid areas and problems caused by wind processes. Then, the study seeks to create a new model to identify and observe sand and small soil particles movements. Furthermore, it tries to find a way to evaluate sand and small soil particles movements and dangers cause by wind erosion, and also a way to measure these movements precisely and bring them under control.

Watersheds are the sources of drinking water for cities and villages, and their pollution with heavy elements threatens the health of the inhabitants who use their water and agricultural products. Considering the importance of Baghan watershed in Bushehr province, the purpose of this study was to evaluate the contamination of soil particle size fractions (<63 and <2000 µm) by some heavy metals (Cd, Mn, Ni, Pb, Zn, Cu, and Fe) in three major land uses (range lands, croplands and orchards). Location of 120 surficial composite soil samples (0-20 cm) were determined using the Latin Hypercube technique on the topographical map. After pretreatment of soil samples, heavy metals were extracted by the Sposito method and measured using an atomic absorption spectrometry and geochemical pollution indicators including contamination factor (CF), geo-accumulation index (Igeo) and the pollution load index (PLI) were calculated. A significant increase in the concentration of Cu, Cd, and Fe has been observed by decreasing the particle size in different land uses. The contamination factor (CF) for particle sizes <2000 and <63 were ordered as Cd>Mn>Pb>Ni>Cu>Zn>Fe and Cd>Mn>Cu>Ni>Pb>Zn>Fe, respectively. The CF index indicates that the orchard soils for Cd were considerably polluted and for other metals moderatly polluted. Positive and significant amount of geo-accumulation index (Igeo) for Cd and Mn was observed for both soil particle classes in all land uses. Overall, the results of this study confirmed concentration of some heavy metals in smaller particles size. Comparing contaminants concentration of Cd and Mn in croplands and orchards soils with the range lands soils indicated anthropogenic effects on soil pollution. The results revealed risk of heavy metals in the watershed and necessity of reconsidering management policies.

For a uniform distribution of water، decrease in water waste and decrease in erosion of soil، it is important that a land be prepared with proper slopes along its length as well as width. The aim of leveling is to create appropriate slopes for irrigation and drainage on the lands that were not already properly levelled and of the same time creating the level surface with a minimum transport of soil. Throughout the present study، characteristics of a level plane of an agricultural land are modeled by programming algorithm with the results being compared with Minimum Least Square method. Statistical and descriptive results show that Genetic Algorithm and Particle Swarm Optimization algorithm benefit from more accuracies than Minimum Least Square. Also، practice of such restrictions as maximum depth of excavation is easy to be applied in this method. In addition، using Genetic Algorithm method decreased the volume of excavation by 20% and 17. 5%. Another method، called Particle Swarm Optimization، was also applied with the results indicating that the volume of the soil cut and fill for Particle Swarm Optimization method was recorded as less than that in Genetic Algorithm method.

Organic carbon pools and carbon lability directly affect soil biological، physical and chemical characteristics. Besides، capacity of self-organization of soil is related to the organic carbon pools. Sand size fraction (> 50 µm) organic matter is more labile than silt+clay size fraction organic matter. Assessment of this organic carbon variation can be a suitable index to determine soil quality. The aim of present study was to evaluate the impact of land use change on particle size fractions of organic carbon and carbon pool index. In September 2010، soil samples were collected from the three major land use types including wetlands around the lake، wetlands converted to wheat، and alfalfa cultivations. Soil samples were collected from the 0-30، 30-60 and 60-90-cm depths in each of land use. According to the results of particle size fractionation of organic carbon in 0-30-cm layer، the highest and lowest amounts of sand size fraction organic carbon were obtained in wetland (67. 01 g. C. kg-1soil) and wheat land use (24. 57 g. C. kg-1soil)، respectively. Land use change from wetland to alfalfa and wheat caused a decrease of silt+clay size fraction organic carbon in 0-30-cm by 48. 39 and 45. 14 t. C. h-1، respectively. In the 30-60-cm layer of cultivated land، soil organic carbon storage in silt+clay size particle was more than sand size fraction organic carbon. Results showed that carbon pool index in alfalfa، and wheat land was decreased by 50 and 60% compared to wetland، respectively. And carbon management index in alfalfa and wheat was declined by 44. 90% and 66. 70%، respectively.

For assessing of soil quality, the sensitive indicators can be used in land use managements. Monitoring all soil characteristics is costly and laborious therefore, limited soil characteristics for this mean are recommended. The purposes of this study were comparing several soil attributes of different land use types and determination of minimum effective soil characteristics on soil quality in Chughakhor Basin, Chaharmahal va Bakhtiari Province, Iran. To fulfill the objectives slope, land use and soil maps and Latin Hypercube strategy were used and locations of 125 composite and surficial soil samples were determined. After pretreatment of soil samples, 29 soil physical and chemical characteristics were measured using appropriate methods. The mean comparison of different land uses showed that mean weighted aggregate diameter, available water content, air content, Dexter index, organic carbon, particle organic carbon in macro aggregate, the proportion of particle organic carbon in macro to in micro aggregates, P, Fe and Cu contents values of land use types were in the order Orchards>cultivated areas>Good rangelands>Dry land areas>Weak rangelands. For determination of effective indicators in soil quality assessing, the principle component analysis and stepwise discriminant analysis are used. The soil characters like water stable aggregates, soil texture elements, proportion of particle organic carbon in macro to in micro aggregates and soil Cu and Zn concentrations as minimum data set for soil quality assessment.

Although many studies have been done on the effects of agricultural land abandonment, there is very little information about the impact of climate conditions on the restoration of abandoned agricultural lands. Human has changed most of rangelands to agricultural lands causing a decrease in carbon sequestration, depending on land management and tillage operations. One of the methods for rebuilding the land cover is the land abandonment, which results in enhanced organic carbon and decreased CO2 emission. Understanding the storage and dynamics of soil organic matter, especially in relation to changing land use, is fundamental to evaluate the role of soil as a carbon source or sink. After land use change from rangeland to cropland, agricultural practices decrease the C stored in soils and cause a net release of C into the atmosphere, which has strongly influenced the atmospheric CO2 levels and global C balance over the last centuries. For this purpose, this study aimed to assess the effect of interaction between agricultural land abandonment and climatic conditions on organic material reserves of primary soil particles.

The study area was located in semi-steppe rangelands of Sheida and Khargosh in about 60 km northwest of Shahrekord city, Chaharmahal-va-Bakhtiari province, central Iran. In this study, four treatments including rangeland, agricultural and cultivated land abandoned in the time series of 10-15 and 15-40 Year were selected. The sample plots were placed in the distance of transects, and the soil samples were collected from 0-30 cm depths with different rainfall conditions from two above-mentioned regions in three replications. For each region, the soil samples were transferred to the laboratory and then analyzed. The selected locations had same soil shape, topography, parent material, and slope. The soil samples of three plots were then combined and 24 samples were prepared. The distribution of carbon and nitrogen concentrations was determined at different soil particle components.

The results showed that the rangeland change to cultivated land did not have a significant effect on the amount of organic carbon, total nitrogen, and total carbon to total nitrogen ratio. However, the values of these indicators decreased significantly in the Sheida region. Under all land management, the amount of carbon and nitrogen of soil particles increased with decreasing the particle size from sand to clay. Hence, the abandoned agricultural land and rangelands did not significantly affect the amount of carbon and nitrogen concentration in sand, silt and clay particles. The amount of carbon, however, increased with the abandonment time and non-agronomic activity of carbon in sand and silt particles, although the carbon content of clay particle was not influenced. Agricultural practices may negatively or positively impact natural ecosystem depending on climatic condition and soil quality in unchanged lands. However, despite suitable climatic conditions (in terms of precipitation) and land cover in the rangelands over Sheida, the cultivation adversely influenced the soil quality and organic matter of the unchanged land. Although, the precipitation and soil quality were relatively lower in Khargosh region, the agricultural activities seem not to negatively affect the land quality. Moreover, rangelands change to cultivated lands did not have a significant effect on the amount of soil nitrogen in this region. The greatest nitrogen amount was measured in clay fractions of cultivated and abandoned lands for 40 years, and the minimum nitrogen content was detected in sand particles of lands abandoned for 15 years. The highest and lowest amount of nitrogen over all three fractions was, respectively, found for unchanged and abandoned lands in Sheida region. Therefore, the cultivated land depending on climate condition and management may considerably increase or decrease the organic carbon content in sand, silt and clay particles.

The results indicated that the agricultural land abandonment may differently affect the rangelands restoration measures such as the vegetation reclamation and soil carbon sequestration depending on climatic condition