Introduction: According to important ecological roles of SOIL ORGANIC MATTER in stabilizing ecosystems, it is essential to consider SOIL ORGANIC carbon condition for managements of worldwide problems such as SOIL quality, carbon cycle and climate change. Also, ORGANIC MATTER is one of the main component of SOIL which have vital impress on its evolution. Therefore, assessing SOIL ORGANIC MATTER fate in various environmental conditions and its relation with environmental factors will be useful for management decisions. Determining SOIL ORGANIC carbon content, stocks and forms by the physico-chemical and micromorphological studies may respond to the question about SOIL ORGANIC MATTER evolution from the different point of views. Based on mentioned reasons, our research work focused on SOIL ORGANIC MATTER content, stocks and forms under various environmental condition of the forest ecosystem to find new aspects of its relation with environmental factors. Material and Methods: This research work was carried out in Arasbaran forest, northwest of Iran, which recognized as a part of the international network of biosphere reserves and has unique species of plants with special ecological properties. Sampling was carried out in a Kaleybar Chai Sofla sub-basin as a part of Arasbaran forest with eastern longitude of 46º 39´ to 46º 52´ and northern latitude of 38º 52´ to 39º 04´ . Based on the Amberje climate classification, the climate of the region is semi-humid and moderate. The SOIL moisture and temperature regimes are Xeric and Mesic, respectively. Hornbeam (Carpinus betulus) and Oak (Quercus petraea and Quercus macranthera) were identified as the main woody species in this area and volcano-sedimentary rocks were the geological structure. Primary site surveying showed 5 forest stand types such as Oak (Quercus macranthera), Hornbeam-Oak (Carpinus betulus-Quercus macranthera), Hornbeam (Carpinus betulus), Hornbeam-Oak (Carpinus betulus-Quercus petraea), Oak (Quercus petraea) along altitudinal transects, that used as environmental parts with different conditions. In each environmental part, a SOIL profile was described and sampling was done for physical, chemical and micromorphological analysis. After preparing SOIL samples in the laboratory, SOIL physico-chemical routine analyses were carried out by standard methods and then the studied SOILs were classified on the basis of 12th edition of SOIL taxonomy. To achieve the main aim of the study, various aspects of SOIL ORGANIC MATTER evolution were assessed. SOIL ORGANIC MATTER content was determined according to the Walkley– Black wet oxidation method and using alteration factor f = 1. 724 recommended by USDA. Variance analysis and means compare of SOIL ORGANIC MATTER content in surface horizons of different environmental parts were performed by using the SPSS software package and Dunkan's multiple range test, respectively. SOIL ORGANIC carbon stocks were calculated for each SOIL horizon and weighted average based on profile depth was used to calculate this index for each SOIL profile. The prepared thin section for micromorphological study was examined under both plane-polarized light (PPL) and cross-polarized light (XPL) using a polarized microscope and explained based on standard terminology to identify various forms of SOIL ORGANIC MATTER all over the study area. Results and Discussion: Results revealed increasing of SOIL evolution with decreasing of elevation. Entisols, Inceptisols, Alfisols and Mollisols with different families were the SOIL observed along altitudinal transects by decreasing elevation. According to the obtained results, environmental effects caused different SOIL ORGANIC MATTER content and evolution with various SOIL ORGANIC carbon stocks in each part. Improvement of environmental condition by decreasing elevation resulted in more evolution of SOIL ORGANIC MATTER, dominant of decomposed forms of ORGANIC MATTER and rise of SOIL ORGANIC carbon stocks from the highest part to the lowest one. SOIL ORGANIC MATTER content in SOIL surface increased by elevation, although the main source of SOIL ORGANIC MATTER have better condition in lower parts due to ecological reasons. This inverse statue can be explained by special environmental conditions causing limited ORGANIC remnants decomposition in the highest parts. In the same trend with SOIL evolution, SOIL ORGANIC carbon stocks increased by decreasing of elevation. This trend refers to the relation of mentioned index ability with various SOIL-forming processes. Micromorphological study showed that ORGANIC intact remnants were the dominant forms in upper parts which changed to well-decomposed forms in the lowest parts. This observation revealed the occurrence of mechanical decomposition processes of ORGANIC remnants in high elevation while biochemical ones happen in the lower parts. Also, this distribution of SOIL ORGANIC MATTER decomposition processes can explain SOIL ORGANIC carbon content and stocks all over the study area. Conclusion: Elevation was identified as an important environmental factor controlling SOIL ORGANIC MATTER in the studied scale. Generally, results confirm the same trend for SOIL ORGANIC MATTER evolution and SOIL ORGANIC carbon stocks with SOIL development, especially in pedogenesis processes in relation to ORGANIC MATTER. Thus, it can be recommended to use SOIL map for management of SOIL ORGANIC MATTER under various environmental conditions in large-scale studies.

This study was conducted during summer and winter of 2018- 2019 in the agricultural research field of Shahid Chamran University. Experimental design was split- plot based on RCBD with three replications. The main plot was the type of agricultural system in three levels including conventional (Conv), ORGANIC (Org) and sustainable (Sust) (integrated between Conv and Org) and sup- plot was the type of pre- cultivated crop in sequence with wheat including cultivation of mung bean (M- W), corn (C- W), sesame (S- W) and fallow (F- W). Yield quantity (yield and its component) and quality (grain protein), an estimate of photosynthesis MATTER transfer index of wheat and SOIL ORGANIC carbon (SOC) after one double-cropping were measured. The result showed that the highest (545.04 g/m2) and the lowest (409.28 g/m2) seed yields were obtained in Conv and Org respectively. In contract, with the changing type of system from Conv to Org, grain protein was increased significantly (from 8.3 to 9.6 %). In addition, the highest (535.47 g/m2) yield of wheat was obtained from M- W double cropping. On the other hands the highest remobilization and current photosynthesis MATTER were obtained in the ORGANIC agricultural system with M- W and conventional with M- W double cropping. The situation of SOC showed that the highest (33.18 mg/g) SOC was obtained in the ORGANIC agricultural system with C- W double cropping. The reason for improving SOC in the ORGANIC and sustainable agricultural system was application of ORGANIC MATTER (compost and vermicompost) and crop residue management. Totally, from the crop ecology point of view, sustainable agricultural method with a sequence of M- W was the most desirable system.

Knowledge on physical and mechanical properties of SOIL is necessary for forest road construction and in turn for optimal forest management. Avoiding a mixture of ORGANIC MATTER with SOIL is considered as being principal in constructing forest roads which is, however, often neglected. Therefore, quantifying the consequences of such mixture can help optimizing the high economic and environmental costs associated with road constructions. The aim of this study was to assess if and how the level of ORGANIC MATTER affects the physical and mechanical properties of SOIL on forest roads. To this aim, SOIL samples were collected by profile excavation. ORGANIC MATTER was collected from residual and litter layer of forest floor. Different mixtures of ORGANIC MATTER with SOIL were tested (0%, 5%, 10% and 15% of weight), followed by Atterberg limits and CBR tests conducted on the samples. Results showed that increasing ORGANIC MATTER content would increase plastic and liquid limits, which in turn increases the CBR values. Results also showed a significant negative effect of ORGANIC MATTER on SOIL engineering properties. Therefore, it necessitates a separation between the ORGANIC MATTER and SOIL during forest road construction.

When aerial parts of the plants, capable of storing and absorbing mineral salts in their leaves, fall, these dissolved materials are transferred to the SOIL surface, changing its physical and chemical properties. Plants have special effects on their habitat and study of these effects can be useful in planning projects. This study aimed to investigate the effect of different tree species on SOIL quality in 0-25 and 25-50 cm depths in Shalman poplar research station, Guilan province. The experimental design was as completely Randomized Block with seven treatments and three replicates. Two different plantations of hardwoods including Populus caspica, Alnus glutinosa, and Quercus castaneifolia) and softwoods (Taxidium disticum, Juniperus excelsa, Pinus taeda), and non-planted site as a control were selected. These sites have same physiography and parent material. Vegetation’s age is 37 years old. Totally 42 SOIL samples were taken from the distance 50-150 cm of three sites. Some SOIL properties including ORGANIC MATTER, total nitrogen, SOIL pH, cation exchange capacity (CEC), C/N ratio, electrical conductivity (EC), mean weight diameter, texture, bulk density and particle density of SOIL sample were measured. the results showed that, SOIL pH, ORGANIC MATTER, total nitrogen, CEC, EC, and C/N ratio (P<0. 01) and percentage of clay and percentage of sand (p<0. 05) were significantly different between the two plantations. The findings of this research indicate that the plantation has major impact on carbon sequestration and thereby controls quality indicators of SOILs. It is concluded that plantation could increase the SOIL quality.

Atrazine is the most important triazine herbicides with moderately persistence in SOIL. The objective of this investigation was to study the degradation of atrazine (50 ppm) in two SOILs different in texture. Experiment was conducted in completely randomized design with factorial arrangement and 3 replications. Experimental factors included, SOIL texture (sandy loam and silty clay) and ORGANIC manure (0, 2 and 5 percent(w/w)). SOIL samples were incubated at 30 oC and dark conditions for 0, 20, 40 and 60 days. At the end of each incubation period, atrazine residue was measured with HPLC. Data was fitted to first order kinetic equation for analysis. Results showed that SOIL texture and ORGANIC manure had significant effects on atrazine degradation rate. Atrazine degradation rate in clay SOIL with no ORGANIC amendment was 1.54 times higher than sandy SOIL and its half life were 138.6 and 90 days in two SOIL respectively. Atrazine degradation coefficient increased by 1.14 , 1.8 times in sandy loam SOIL and by 1.54 , 2.46 times in silty clay SOIL with 2 percent and 5 percent ORGANIC amendment, and the half-life decreased from 138.6, days to 121.57 and 77 days in sandy SOIL and from 90, days to 58.22 and 38 days in clay SOIL. It seems that atrazine degredation in silty clay SOIL is more than sandy loam SOIL and SOIL ORGANIC manure have an important role in atrazine bioremediation.

Suspended sediment resulted from distributed SOIL erosions facilitates SOIL nutrients transportation and influences SOIL depletion. SOIL erosion plays a key role in loss of ORGANIC MATTER and therefore study of the relationship between ORGANIC MATTER and SOIL erosion processes and SOIL nutrient loss is very important. The present case study was conducted in Kojour Educational Forest Watershed with an area of 13263 ha to determine the relationship between eroded suspended sediment and ORGANIC MATTER through daily sediment sampling and measurement of suspended sediment. The water and suspended sediment sampling was made via depth integration.The determination of suspended sediment and ORGANIC MATTER contents was made by decantation and loss on ignition methods, respectively. Then the relationship between variables was assessed by bivariate regression method and descriptive statistics. The results of this study showed that there were high variations of ORGANIC MATTER and suspended sediment with respective coefficient of variation of 150 and 107. Similar trend in variation for both variables in different time periods was also proved by developing regression models with correlation coefficients from 0.48 (P<0.01) to 0.94 (P<0.001) and estimation and verification errors less than 28.05 and 26.60%, respectively.

SOIL ORGANIC MATTER (SOM) is one of the important SOIL parameters which directly and indirectly affects several SOIL physicochemical properties and environmental factors. The aim of this research was to predict SOIL ORGANIC MATTER (SOM) using kriging and cokriging methods using SOIL auxiliary data. SOIL samples were gathered from an area of 63 km2 in Bonab Plain, northwest Iran. An overall 78 samples were collected from depth 0-20 cm. SOM and ten other SOIL physicochemical properties such as electrical conductivity (EC), SOIL texture, calcium and carbonate equivalent (CCE) were measured. Later, correlation between SOM and SOIL properties was determined and those properties with high correlation in 1% probability level with SOM were used to develop cross-semivariograms. Then, SOM prediction was conducted on a grid of 100 m with kriging and cokriging methods using BMElib package developed for MATLAB software. Results showed that among the studied SOIL properties, CCE, silt, sand and wet aggregate stability (WAS) had the highest correlations with SOM and therefore they were chosen as auxiliary data in cokriging of SOM. Spatial prediction of SOM with kriging method resulted in MSE and RMSE of 0. 055 % and 0. 234% respectively. However, SOM prediction with developed cross-semivarigrams using auxiliary data revealed that CCE and silt could improve SOM prediction with MSE and RMSE of 0. 047%, 0. 032% and 0. 216%, 0. 178 % respectively. The better performance of CCE and silt covariates in SOM prediction could be explained by their higher correlation with SOM and decreased nugget effect in developed cross-semivariograms (increased spatial dependency). As a conclusion, due to the nature of SOM which is controlled by some of the SOIL properties,especially SOIL texture, CCE, aeration condition in SOILs, ets., selecting appropriate SOIL parameters with high correlation with SOM and high spatial dependency can improve spatial prediction of SOM. This facilitates taking a step forward in sustainable management of SOM as a key SOIL quality index, especially in areas with salinization and desertification danger.