جستجوی مقالات مرتبط با کلیدواژه « Organic carbon » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Determining the organic carbon content of rangeland vegetation is essential for monitoring rangeland condition and facilitating reclamation efforts. Satellite data provides a valuable tool for conducting extensive vegetation studies. This research aimed to estimate the organic carbon content of vegetation using field assessments and remote sensing indices in the rangelands of Lashgardar protected area, Malayer. Leveraging Landsat time series images, this study utilized Landsat 8 data from the Operational Land Imager (OLI) sensor.

Field sampling was conducted in the rangelands of Lashgardar protected area on May 28, 2016. The dominant growth form in these rangelands is herbaceous-shrub, with Asteraceae family species being the most abundant. Forty points were randomly selected as the centers of sampling plots for plant biomass. To account for GPS accuracy error, a factor of twice the pixel size was applied, resulting in the selection of 40 plots measuring 30×30 m2 for field sampling. Subplots measuring 1×1 m2 were utilized to collect composite aboveground biomass samples from the central point and the four corners of each main plot. Samples were processed in the Rangeland Science Laboratory at Malayer University following coding for laboratory procedures. The organic carbon content of vegetation was determined using the loss on ignition (LOI) method after air-drying. Vegetation indices were extracted from Landsat 8 satellite images captured by OLI sensors, including digital bands 1 to 7 with a spatial resolution of 30 meters. Various vegetation indices such as Greenness, RVI, NDVI, IPVI, DVI, WDVI, ARVI, SAVI, TSAVI, BI, OSAVI, GEMI, EVI, LAI, and GARI were derived from Landsat images.

Comparative analysis of estimated organic carbon data with measured organic carbon content revealed that only the Green Atmospherically Resistant Vegetation Index (GARI) could effectively estimate the organic carbon content of vegetation. The best model was achieved using the GARI index for organic carbon estimation, represented as OC = 5.4 + 1.38 GARI, with an explanatory coefficient (R2) of 0.13 and Root Mean Square Error (RMSE) of 0.7. These findings suggest that remote sensing indices can serve as complementary methods in vegetation studies.

The GARI index demonstrated promising results for estimating organic carbon content in vegetation within the study area and is recommended as a suitable indicator for similar areas. However, the efficacy of each index may vary depending on specific area characteristics and vegetation types. It is advisable to conduct time-series studies with larger sample sizes tailored to the unique conditions of the study area to identify the most appropriate indices.

About 80 percent of the world's agricultural lands, supplying nearly 60 percent of all human food, is under rain-fed cultivation. Considering the uneven distribution of global rainfall, arid and semi-arid areas call for measures to prevent soil and water salinization. Being one of the most important resources for agricultural production, especially in the face of the current restrictions on the development of irrigated lands, drylands are especially stressed by soil salinity as an important limitation on dry farming, which causes decreased production especially when combined with other limitations such as lack of moisture. In order to gain an enlightened knowledge of the salinity status of rain-fed lands in Iran, a research project of national-scale including 849 study sites was performed and soil samples were collected from different depths across the study sites to determine their Electrical Conductivity (EC) as well as soil physical and chemical characteristics. The results showed that the highest and lowest salinity levels of the surface soil (depths of 0-30 cm) in rain-fed lands under cultivation were 97.5 and 0.19 dS/m, respectively, with an average value of 2.28 dS/m while more than 50% of the soils collected exhibited salinity levels greater than 0.6 dS/m. The results of principal component analysis showed that the variability of soil salinity in rain-fed lands were affected by climatic parameters (such as temperature and precipitation as well as indices resulting from their interactions including standardized precipitation indices and effective drought). Moreover, soil characteristics such as organic carbon, clay, and soluble salt (especially sodium) contents were found to have due effects on salinity level.

During photosynthesis, plants secrete atmospheric mineral carbon into their biomass, which is eventually stored in the soil through plant debris. It was used and finally the organic carbon balance was calculated. The area has three land uses, including agriculture (wheat, canola, beans and alfalfa), pasture and palm grove. From each land use, 5 plant samples in quadrats with dimensions of 1m ×1m were taken. Samples were milled and the percentage of carbon in the total plant biomass and each part of the plants (stem, leaf, and root) was calculated. The amount of gases emitted from the soil surface was also measured by a closed chamber. The results showed that the percentage of carbon in the total plant biomass of the studied land uses is significant at 99% confidence level, so that the average percentage of carbon in rapeseed, wheat and beans is the highest and in rangeland and palm crops is the lowest. Also, the percentage of carbon in different parts of plants (stem, leaf, and root) in each cultivation was performed according to a factorial experiment based on a completely randomized block design with 2 replications in SAS software. The results showed that the highest percentage of carbon was present in the stems, roots and leaves of the plants of each use, and the organic carbon balance was the highest in the agricultural use and the lowest in the pasture land use.

The aim of this study was to investigate the effect of conversion of rangeland into agricultural and horticultural land uses on important soil properties including aggregate stability in Salavatabad watershed in Eastern Sanandaj. For this purpose, simultaneously with the predominant growth of plants, four land uses including 1) rangeland 2) orchard 3) chickpea field 4) wheat field were selected as the study area and 42 soil samples were random-systematically collected. Then soil physico-chemical properties including aggregate stability, total nitrogen, total carbon and particulate organic carbon of each sample were measured in the laboratory. One-way ANOVA of the data showed that due to the conversion of rangeland into three uses of orchard, chickpea and wheat fields, aggregate stability, particulate organic carbon at the level of 5%, total organic carbon and total nitrogen in all three uses at the level 1% decreased significantly. As the aggregate stability in orchard, chickpeas and wheat 35.51, 25.94 and 19.56% respectively, particulate organic carbon in orchard, chickpeas and wheat 62.5%, 79.16 and 75%, respectively, total organic carbon in orchard, chickpea and wheat use decreased by 23.63%, 50% and 49.09%, respectively, and total nitrogen decreased by 31.25% in orchard, 62.5% in chickpea use and 75% in wheat use. According to the results of this study, the conversion of rangelands to any of the agricultural and horticultural uses is unacceptable, but in case of forced conversion, the use of the orchard is recommended because the orchard has less negative effects on soil quality factors than wheat and chickpeas. It is also emphasized in converting rangeland use to cropland, as much as possible to maintain the balance between the input and output of the plant residual into the soil bed, it should be prevented the exit or fire of remaining straw, or grazing livestock after harvest.

Iran, is located in the arid and semi-arid regions of the world, so due to geological and topographic conditions, has various and extensive limitations in soil resources and lands. These restrictions, along with unprincipled and intensive exploitation over the past few decades, have posed many challenges to these resources and thus endangered food security and public health. In this article, while briefly stating the importance and functions of soil, the current situation, and the most important challenges and limitations of soil resources in the country are explained. According to available information and data, soil water and wind erosion is the most important cause of soil degradation in Iran, which has many economic, social and environmental consequences. The lowest soil erosion estimated in the country is much higher than its tolerable (average amount of soil formation). The most important cause of soil degradation in agricultural lands, especially irrigated farms, is soil salinity. At least 50% of the country's irrigated lands are facing an increasing problem of salinity. Land use change can be considered as the most important and urgent challenge of the soil resources, especially fertile lands, which also has negative economic, social, cultural and security consequences. Lack of organic carbon and loss of soil fertility, especially agricultural lands, are important limitations of soil quality that severely threaten food security and health. The degradation of soil resources has not only affected its productive function, but has also drastically reduced the capacity of lands and territories to cope with climate change, drought and floods. Occurrence of floods with a frequency greater than the return period of rainfall events, as well as hydrological and agricultural droughts, more severe than climatic droughts, are signs of this degradation.

Micro-organisms of biological soil crusts have a major role in carbon (C) cycling and atmospheric CO2 removal. Currently, the ability of erodible soils to store atmospheric C is reduced. Thus, we assessed how inoculating soil cyanobacteria onto degraded soil affects C sequestration from the atmosphere. The existing cyanobacteria (Nostoc sp., Oscillatoria sp. and Lyngbya sp.) for the C sequestration were proliferated. They were inoculated on the 40 m2 plots located in degraded land. After 83 (middle of the period) and 172 (end of the period) days, we measured the effect of this inoculation on soil organic C, calculated potential C sequestration, and potential CO2 removal from the atmosphere. The results showed that in the control treatment, the sequestrated carbon in the middle and at the end of the experiment was 0.25 and 0.27 g.m-2.day-1, respectively. Inoculation of cyanobacteria led to a significant increase of 312% and 226% of C sequestration in the middle and end of the experiment, respectively. After 172 days, the rate of C sequestration and removal of CO2 by inoculation of cyanobacteria was estimated to be 3.59 and 13.17 ton.ha-1.year-1, respectively, which was 1.10 and 4.03 ton.ha-1.year-1 in control. The results showed that inoculation of cyanobacteria by hydro-seeding technique before the wet season (early autumn) and at least 1.5 g.m-2 of biomass has the desired effect, and is also approved economically. Eventually, field-scale inoculation of cyanobacteria could be considered as a bio-based tool for sustainable development goals through carbon sequestration and rehabilitation of lands.

Soil properties and land use affect the soil carbon content and reduce the adverse effects of climate change. This study aims to assess the effect of some physical properties of soil and land use on the amount of soil organic carbon content (SOC) and model development to estimate the amount of SOC. This investigation was carried out in 2020 in the areas of flood spreading in of Fasa (Kowsar station). Land uses included acacia (Acacia salicina Lindl.), eucalyptus (Eucalyptus camaldulensis Dehnh.), atriplex (Atriplex lentiformis (Torr.) Wats.) plantation, and natural rangeland, all of which are irrigated by flood spreading. By sampling in three replications of the soil of different land uses from the depth of 0-30 cm (15 composite samples), percentage of sand, silt, clay, silt+clay, percentage of soil saturation moisture (SP), bulk density (BD), particle density (PD), porosity percentage (PS), void ratio (VR) and SOC were determined. Obtained data were statistically analyzed in a complete randomized design and the means were compared with the Duncan test at P<0.05. The analysis of variance showed that the effect of land use (PT) on the percentage of sand, silt, silt + clay, SP, BD, PS, VR, and SOC has been significant at P<0.01, and the clay, at P<0.05. Comparison of the means of SOC in different land uses showed that the Eucalyptus forest, with 1.68%, has the highest value and the control with 0.14% organic carbon has the lowest value. There was no statistically significant difference between the SOC in Acacia forest, Atriplex, and rangeland. Stepwise regression analysis was used to present the model. Soil physical properties and land use were considered as independent variables and SOC was considered as a dependent variable. The results showed that the variable of silt explains 77.00% of the changes in organic carbon. Based on the principal component analysis (PCA) method, according to the specific values, considering the first two axes, about 91.70% of the changes can be explained. Considering the first axis, 69.71% and considering the second axis, 21.99% of the changes are justifiable. The PT, with 91.40%, sand with 84.30%, BD, 82.70%, showed a negative correlation with SOC. While the SP had 90.30%, percentage of clay+silt had 84.80%, PS, 80.70%, VR, 79.10%, silt, 78.50%, clay, 78.50%, had a positive correlation with SOC.

Increased concentration of atmospheric carbon dioxide due to human activities has resulted in accelerated global warming process. Forestation is the most effective way to absorb atmospheric carbon dioxide and store it in terrestrial ecosystems in order to reduce and mitigate global warming. This study aimed to investigate the comparison of soil carbon sequestration in various stands in ​​Kuhdasht Aquifer and to present the best regression model for carbon sequestration based on all soil characteristics. In each stand (20-year old) of Ficus carica, Punica granatum, Pistacia vera, Amygdalus lycioides and Cupressus arizonica species as well as control rangeland, a number of 10 sample plots (5×5 m) were randomly selected and soil samples were taken in each plot at 0-10, 10-30 and 30-50 cm depths. All soil samples were transferred to the laboratory in order to measure soil characteristics including soil texture, organic carbon, bulk density, electrical conductivity, lime percentage and soil acidity. The results showed that the highest value of carbon sequestration in soil of Pistacia vera stand (54.94 tha-1) significantly (P <%1) higher compared to other stands, followed by Ficus carica (50.23 tha-1), Amygdalus lycioides (31.53 tha-1), Punica granatum (27.09 tha-1), Cupressus arizonica (24.17 tha-1) and control rangeland (9.01 tha-1) stands. Results also showed significant differences (P <%1) between the studied stands in terms of soil texture, acidity, organic carbon, electrical conductivity and soil bulk density. Also, the result of stepwise regression indicated that soil texture and acidity were the most important components affecting soil carbon sequestration, respectively.

Soil organic carbon is one of the most important indicators of soil quality. The purpose of this study is to study the spectral and non-spectral behaviors of soil in order to estimate the organic carbon of topsoil using factor analysis and multiple regression methods in the semi-steppe rangelands of Asuran, Semnan province. Soil sampling was performed using stratified random sampling method. After creating a map of homogeneous units in the area, in each homogeneous unit according to its area, several sampling points were selected completely randomly. A total of 145 sampling points were collected. At each sampling point, a composite soil sample (a mixture of 9 observations) was taken. Soil organic carbon was measured using Valkyli-Block titration method. Data of 114 samples were used to calibrate the model and data of 31 samples were used to validate it. The results showed that the correlation of spectral variables obtained from Landsat OLI sensor with surface soil organic carbon is higher than non-spectral variables obtained from 1: 25000 topographic maps. Also, the results of factor analysis by principal component analysis with eigenvalues greater than one showed that the total cumulative variance explained by 14 variables was equal to 90.2%, which was explained by three factors. The regression equation generated by the three extracted factors had suitable potential for predicting surface soil organic carbon (R2 = 0.59). The root mean square error (RMSE) of the proposed model was calculated to be 0.3.

Rising atmospheric carbon dioxide is one of the main causes of climate change and its devastating environmental consequences, such as global warming. Soils are the third largest carbon storehouse, and the amount of carbon storage is strongly influenced by the land use management. The aim of this study was to investigate the changes in carbon storage in different land uses included Punica granatum orchard, Medicago sativa farm, rangeland, Hordeum vulgare farm and fallow, under impact of soil properties such as sand, clay, silt, nitrogen, phosphorus, potassium, organic carbon, pH and EC, in Ala area of Semnan. In the selected land uses 30 soil samples were taken in both 0 - 5 and 5 - 30 cm soil depths in three. In order to investigate the effect of land use type in two soil depths studied on soil carbon content, analysis of variance and Duncan's test was used to compare the means. Pearson correlation was used to investigate the relationship between soil properties as independent variables and soil organic carbon as a dependent variable. Also, multiple regression analysis was performed to determine relationship type between the variables. According to the results, the type of land use in both soil depths has a significant effect on soil carbon storage. The highest average soil carbon storage in 0 - 5 and 5 - 30 cm soil depths in alfalfa and pomegranate orchard land uses are 16.14 and 68.11 t/ha, respectively. The lowest amount of carbon storage in 0 - 5 and 5 to 30 cm soil depths related to rangeland use are 6.23 and 16.58 hectare/ha, respectively. Pearson correlation coefficient between organic carbon and soil factors of nitrogen and phosphorus were statistically significant with r of 0.8 and 0.59, respectively. Since the correlation between organic carbon and phosphorus is low, it was omitted in the regression analysis. Finally, the percentage of soil organic carbon was obtained based on the percentage of soil nitrogen. In general, land use change from pasture to arable land and pomegranate orchard can have a significant effect on increasing soil carbon storage in the study area. Soil properties other than nitrogen have no significant effect on soil organic carbon.

Rangelands which could save more than one third of the earth biosphere carbon, are one of the most important source of carbon sequestration. These lands have the greatest potential for carbon sequestration. Carbon sequestration of dominant rangelands plants namely Artemisia sieberi, onobrychys cornuta, Stachis inflate, Stipa hohenakeriana are the scoop of this study. Soils of the study area, Tilabad rangelands in Golestan province, were taken from the established plots to determine organic carbon content and bulk density. Species with the highest carbon sequestration were identified using the Tukey multiple comparison method in R software. Results of 32 plots samples showed that the highest amount of biomass carbon is sequestration has happened in Artimisia siberi (1.35 kg/ha) and the lowest by Stipa honenackerian (1.15 kg/ha). The amount of soil carbon rate for Onobrychys cornuta species was 31.67 ton per hectare that indicates its outstanding role in soil carbon sequestration. Recognition of capacity of native species for each region helps to understand the importance of natural ecosystem. Safety of natural resources is a major  rehabilitation operation to U-turn of degraded and eroded lands from perspective of carbon sequestration.

Now a day, carbon sequestration is an important issue due to its serious role on global warming. The aim of this research was to evaluate mechanical measure of check dams on vegetation cover and soil carbon storage in watersheds of Kermanshah Province, Iran. These check dams were constructed in the drainage systems to reduce surface runoff velocity and optimize channel slope. Small sedimentary dams are made by gabions and dry structures. The soil and vegetation characteristics of the areas under mechanical operation and its control (severe grazing and grazing management) by field survey in selected sites of Gilan Ghab, Kangavar and Sarfirozabad. The plant biomass including canopy cover and plant root as well as plant litter were samplled along transect path using the quadrat plot. 36 soil sampls were collected from 0-20 cm of soil depths and were air dried and sieved through two milimeter mesh and analyzed in the soil laboratory. Soil organic carbon was measured by the Walkley and Black method and statistical analysis was carried out using SPSS software (version 19). Results showed that both mechanical (check dams) contributed to store 49.28 tonha-1 of carbon which was significantly lower than biological measures. It was concluded that vegetation cover has the most effects on carbon sequestration of the rangelands compared to mechanical methods.

Forest and land use change has many negative consequences including increased flooding, erosion, sedimentation and dust storms. The aim of the research was thus to investigate the effects of land use change in Zagros forests on erodibility and sedimentation via soil quality reduction in some forests of Kermanshah Province, Iran. In order to achieve this aim, in the first step, afforest area and its adjacent rain-fed farm (which is developed during recent 10 years a result of forest land change), were selected and 35 soil samples were collected from the surface layer (0-20 cm). Then, the physico-chemical analyses were done on the soil samples. In the next step, soil erodibility factor was calculated and sediment yield was assessed using portable rainfall simulator. The results showed that six key properties of soil including soil aggregate stability, bulk density, organic carbon, total nitrogen, total absorbable potassium and cation exchange capacity were significantly (p<0.05) influenced by land use type. Additionally, in all tested samples, the total clay and silt content was about 80%, which  resulted in the formation of soil with heavy texture. Subsequently soil erodibility factor (K) and sediment yield intensity in rain-fed farm was found significantly (P<0.05) higher than those of forest. According to the results and  the role of  Zagros forest ecosystem on water harvesting, aquifer recharge, flood and dust control, the current trend of changing forest landuse to arable lands accompanying improper tillage practice, crops residue burning and heavy machinery traffic in nearby rain-fed farms, cause accelerating global warming, increasing runoff coefficient and evaporation as well as water scarcity in future.

The importantroleof soil fertility in food production warrants long-term monitoring to track changes in soil properties. Long-term soil tests are field trials conducted onpermanent plots that are regularly sampled to quantify soil changes over time scales of decades. This article intends to introducelong-term soil fertility testsusing permanent plots aimed atcollecting information on the effects of long-term soil fertility management practices on soil properties. Efforts are also made to develop a general methodologyfor future research. Mosttests on permanent plots in the past mainly focused on soil carbon concentrations over long-term periods to find that continuous applicationof organic matter toarable land led not only to improved soil physical and chemical properties but also toits enhanced biological activity.This is while organic modifiers, especially when improperly applied,may reportedly contributeto environmental pollution. So far few long-term soil tests have been conducted in Iran,most of which havemainly determinedthe residual effects of fertilizers containing single nutrient elements such asphosphorus, zinc, orpotassium. This lack of consistent tests and the scant information thus far obtained necessitate planningfor drastic and targetedtestson Iranian soils.Evaluation of long-term experiments revealed that it will be necessary to employsuch variedland management practicesof livestock manuring, proper crop rotation, and avoidance of severe tillage to enhancecarbon sequestration in soils. Finally, it was observed that the use of chemical fertilizers combined with organic and biological agentsis favorable to increased agricultural production and enhanced sustainable soil fertility.

The aim of this study was to investigate the effects of environmental factors on distribution of Prangos uloptera in rangelands of Ardabil province. The habitats of Prangos were identified and the habitats, in which the study species was present, were selected. Sampling was also carried out in the vicinity of each habitat where the study species was not present. Three transects of 100-m length were established, on which canopy cover percentage and density of species were measured within 10 plots of 4m2. Soil samples were taken from the beginning, middle and end of each transect. In sampling places, altitude, slope, aspect, and soil characteristics were measured. Independent t test and cluster analysis were applied to comparison and classification of presence and non-presence areas and determination function was applied to determine the importance of factors affecting the presence of this species. The results of t test showed that there were significant differences between all variables except for temperature and precipitation. According to the results of cluster analysis, the studied species had more distribution in places with high altitude and steep slopes, high organic matter, and high nitrogen and sand. The results clearly showed that climatic parameters including precipitation and temperature as awell as altitude and sand percentage in the first grade and then aspect and soil characteristics including nitrogen and phosphorus in the second grade were the most important factors affecting the distribution of study species. According to the results, better decisions could be taken to use this species for range management, improvement and reclamation.

Improve soil quality for sustainable agricultural development to ensure food security for a growing population are the subject undeniable. Soil organic carbon is a decisive factor in the soil (chemical, physical and biological properties and improving the quality and quantity of yield. Studies show that soil organic carbon in the northern Khuzestan declined due to inappropriate management practices, so that based on the latest results available ,the soil carbon content in 100% of soils is less than one percent; while the national average is 60 percent. Farmer's awareness of the role of soil organic carbon in their lands enables them to make the right decisions to adopt appropriate management practices to increase soil fertility, which require the use of soil and product management such as integrated soil fertility and plant nutrition management in a comprehensive and continuous approach. It is noted that organic carbon can be called by applying a coefficient (1.724) organic matter.

This study aimed to determine the effect of land use changes from rangeland to horti-agricultural lands on the most important qualitative characteristics of soil such as total soil carbon and particulate organic matter, in Salavatabad region, Sanandaj. In the present study, one rangeland, two cultivated pea lands, two cultivated wheat lands and two gardens were selected in growth season in the end of spring, 2014. Forty two soil samples were taken randomly and systematically from the study region. Then, soil micro- and macro aggregates were separated using 0.25 mm and 2 mm sieves. Total soil carbon and particulate organic matter of soil samples were measured in the laboratory. The results showed that land use changes from rangeland to horti-agriculture significantly decreased total carbon and particulate organic matter in micro-aggregates. While total carbon and particulate organic matter in macro-aggregates was not changed by land use changes from rangeland to horticultural land. We suggested that if rangeland will be converted into agricultural land, horticultural land is the best for land use changes.

The quantity and quality of Zagros Forests (west Iran) are declining through improper management and land-use practices negatively affecting life in the regional scale. The objective of this research was explored the change in soil quality through conversion of forest to rain-fed practices which was conducted in the Gazaf-e-olya village in the Merek watershed, Kermanshah, Iran. Thirty five soil samples were collected from surface soil layers and subjected to soil physicochemical analysis. The data also were analyzed both classical and semivariance using SAS software. The results showed that there was no significant difference for soil particles distributions (sand, silt and clay) in the forest and rain-fed areas. The respective level of bulk density (BD) in the forest and rain-fed was 1.26 and 1.32 gr-1cm-3, indicating significant difference (p