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.

Although soil ORGANIC MATTER (SOM) constitutes a small portion of soil bulk weight, it has a tremendous effect on physico-chemical and biological properties of soils. It is also one of the most important indicators of soil quality and its production. Soil ORGANIC MATTER determination is required for soil fertility management and soil pollution purposes. Wet oxidation procedure of Walkley-Black is a routine, relatively accurate and popular method for the determination of soil ORGANIC MATTER, but it involves the use of chromate and high cost of analysis. Therefore, LOSS-on-ignition (LOI) procedure as a simple and cheap method of SOM estimation which also avoids chromic acid waste has got more attention. The aims of this study were (i) to establish the relationships between LOI method and SOM as determined by Walkley-Black method for four major plains of Chaharmahal-va-Bakhtiari province and (ii) to determine the optimal temperature of the LOI. To do this, 205 soil surface samples were randomly collected from 0-25 cm depth of Shahrekord, Farsan, Kohrang and Lordegan plains to determine soil ORGANIC MATTER by Walkley-Black method and LOI procedure at 300, 360, 400, 500 and 550oC for two hours. To determine the optimum temperature for ignition, 40 soil samples were selected to compare the SOM and CCE before and after ignition for each temperature. Results showed a positive, linear significant relationship existed between LOI and wet oxidation in each plain. Coefficient of determination (R2) of the equations was higher for individual plain than the overall equation. Coefficient of determination and line slope decreased and error (RMSE) increased with increasing ignition temperature. At higher contents of calcium carbonate, the rate of line slope decrease with increasing ignition temperature was more noticeable. This may be due to the destruction of carbonates at higher temperature. A temperature of around 360oC was identified as optimum as it burned most ORGANIC carbon, destroyed less inORGANIC carbon, caused less clay structural water LOSS and used less electrical energy.

Soil erosion posses play a key role in ORGANIC MATTER LOSS from watershed. Therefore, study of the ORGANIC MATTER on suspended sediment is very important for watershed management and soil and water conservation planning. The present study was conducted in Kojour Watershed to determine LOSS of the suspended sediment associated ORGANIC MATTER. The suspended sediment and ORGANIC MATTER sampling was made via depth integration. The results of this study showed that 57 ton ORGANIC MATTER LOSS from 8 rainfall events and 48gr om in 1 kg sediment LOSS in each rainfall this period.

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.

Soil erosion washes out the nutrients from watershed, caused soil depletion and water pollution. Information on nutrient LOSS variations is therefore very important. The aim of present study was to study of phosphorus (P) and ORGANIC MATTER (OM) LOSS and relationship between sediment graph and OM and P LOSS in Kojour watershed in hyrcanian ecosystem. For this purpose, Discharges, suspended sediment (SS), P and OM LOSS resulting from storm events were sampled at one fixed point of river using the manual sampler. Results showed that 48 gr OM and 11.5 mlgr P in 1000 gr sediment were bonded. Also results depict P and Om LOSS dramatically affected by suspended sediment.

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.