جستجوی مقالات مرتبط با کلیدواژه « کربن آلی » در نشریات گروه « کشاورزی »

Soil aggregate stability is a crucial indicator for evaluating soil structure, quality, and health. This index affects the physical and hydrological functions of the soil, which, in turn, depend on plant primary production and the capacity of organic carbon decomposition. Soil organic carbon plays a positive role in the formation and stability of soil aggregates. Soil organic carbon (SOC) causes a rapid decrease in water penetration into soil aggregates by creating a water-repellent coating around them and increases their stability against instant wetting stress. Land use and management, including cultivation systems and tillage methods, have an important impact on the stability and size distribution of soil aggregates. Mechanized sugarcane cultivation has a long history in Khuzestan province, particularly in Haft Tepe sugarcane cultivation and industry. Haft Tepe Agriculture is the first sugar production unit in Iran. Despite the increase in the use of chemical fertilizers, the yield of sugarcane crops has been decreasing due to the destruction of the physical properties of the soil. The study aimed to investigate the effects of different sugarcane cultivation systems on soil physicochemical-biological properties and soil stability indices in parts of Khuzestan province.

Soils were sampled from the surface of five farms in the Haft Tepe sugarcane cultivation complex located in the northwest of Khuzestan province. The farms included single-row, new planting cultivation (S-P); single-row, third ratoon cultivation (S-R3); double rows, new planting cultivation (D-P); double rows, first ratoon cultivation (D-R1); and uncultivated land (barren) that had been left unused for a long time. Soil organic carbon content, active carbon content, basal respiration, induced respiration, water-stable aggregates, and aggregate organic carbon fractions were measured in the sampled soil. Mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates were also calculated.

The study found that the organic C content was highest in the double-rows+new planting (D-P) method and lowest in uncultivated land (0.95% and 0.12%, respectively). The increase in plant density, biomass, and plant residue addition in D-P cultivation has led to an improvement in SOC content. The higher SOC content in cultivated lands compared to uncultivated land indicates the positive effect of many years of cultivation and irrigation. Among the different cultivations, double-row new planting (D-P) cultivation had significantly higher active carbon. In D-R1 cultivation, returning plant residues to the soil increased the SOC (0.59%) and active carbon content. The burning of sugarcane plant residues during harvesting and land preparation for new sugarcane cultivation in S-P fields appears to have led to a decrease in active carbon. Basal respiration and induced respiration values were significantly higher in single-row, third ratoon (S-R3) and double-row, new planting (D-P) cultivations, respectively. In S-R3 cultivation, the older plants and increased root biomass provided more rhizospheric organic C for microorganisms, resulting in higher microbial activity and respiration.   Microorganisms transform and decompose soil organic matter, which is a source of energy for their metabolic processes. Therefore, there is a close relationship between organic matter and soil microorganisms. Lower basal respiration in newly planted lands may be due to the process of land preparation for cultivation. Additionally, single-row new-planted farms had a clayey texture, which could reduce soil respiration. In general, the recycling of organic matter and microbial activity is lower in fine-textured soils compared to coarse-textured soils. The highest MWD and GMD were found in single-row, third ratoon (S-R3) and single-row, new planting (D-P) cultivations. The uncultivated land had the lowest MWD and GMD, indicating unstable soil structure due to low SOC content. The lower MWD observed in S-P cultivation could be related to tillage and hilling up operations. S-R3 cultivation had more plant residues compared to other cultures. Higher plant ages and increased root biomass and rhizodeposits led to an increase in soil aggregate formation and stability. Soil tillage, which reduces soil organic carbon, can decrease the stability of soil aggregates and structure. The S-P and D-P cultivations had the highest value of coarse aggregates (larger than 2 mm) and fine aggregates (0.53-2 mm). The highest amount of medium aggregates were observed in S-P, D-P, and D-R1 cultivations. Agricultural operations can break large soil aggregates into smaller ones, while low SOC content and burning of sugarcane residues can reduce the formation of large aggregates. The study found statistically significant differences in the OC content of aggregates among the different cultivations. The highest content of aggregates OC was found in coarse aggregates (0.25-2.0 mm) of D-R1, D-P, and S-P cultivations.

This study investigates the impact of mechanized and long-term sugarcane cultivation on the physical and biological properties of soil. Overall, the water stable aggregates and MWD were found to be unsuitable in some of the studied fields due to the low amount of SOC. This is primarily caused by the annual burning of sugarcane residue. Therefore, returning plant residues after harvesting is suggested as a significant solution to improve problems related to compaction, soil instability, and their harmful consequences.

In this research, the effectiveness of five organic matter treatments were investigated to determine the amount of soil organic matter, rhizosphere fungal and bacterial population. Microbial population in rhizosphere and nutrients concentration in the aerial part of corn were carried out in the form of a randomized complete block design in three replications. Before planting maize, soil organic matter was measured before and after adding five organic matter treatments for one year. Then, maize was planted and harvested before it reached seed production, and the concentration of some nutrients in the aerial part of maize was determined. Also, the bacterial and fungal populations were determined in the rhizosphere and non-rhizosphere soils. The results showed that the largest population of rhizospheric bacteria in the treatments of Leonardite (231×104 cfu g-1 soil), fulvic acid (229×104 cfu g-1 soil) and calcium lignosulfonate (218×104 cfu g-1 soil) and the largest population of rhizospheric fungi in the treatment of calcium lignosulfonate (263×103 cfu g-1 soil) was observed to show a significant increase compared to the control treatment. The highest maize leaf nitrogen was observed in the treatment of fulvic acid (35.78 g kg-1) and calcium lignosulfonate (33.9 g kg-1), and the highest leaf phosphorus was observed in the treatment of fulvic acid (4.27 g kg-1) compared to the control treatment. In the treatments of fulvic acid, calcium lignosulfonate, and Leonardite, the highest amount of potassium was measured, and in the treatment of calcium lignosulfonate, the highest amount of calcium and magnesium was measured. Leaf sulfur was the highest in Leonardite treatment, but there was no significant difference with calcium lignosulfonate and fulvic acid treatments. The amounts of leaf micronutrients were the highest in the fulvic acid treatment, but iron and copper in the leaves were also the highest in the calcium lignosulfonate treatment.

The reduction of water resources due to the issue of global climate change and population growth is one of the most critical issues facing the designers and planners of the development of green spaces in cities. Against these challenges, there is an urgent need to improve the efficiency of water consumption and chain use of water resources with suitable options. Due to the significant volume of urban wastewater Effluent, its reuse in green space irrigation is important from the point of view of water resource management from an ecological and economic point of view. The effect of the Parand city wastewater treatment plant on the chemical properties of soil under the cultivation of three types of cover crops (Frankinia (FR), Festuca (FE), Dichondra (DI)) in a bed with sandy loam soil is investigated. This study was conducted as a factorial experiment based on a completely randomized design using mixing of water and Effluent at 4 levels with irrigation treatments of zero (control), 50, 75, and 100% compared to fresh water and 3 replications, and then the soil chemistry characteristics such as pH, EC, OC, Na, Cl, Ca, and Mg were evaluated. The results obtained from the soil chemical analysis parameters showed that the pH value decreased in all the treatments with effluent compared to the control, and this decrease was not significant in any treatment. The values of EC and Cl have increased in all plants, and these values were significant in the FR100 treatments with an increase of about 195 and 561% compared to the control, and in the FE100 treatment with an increase of about 54 and 162%, respectively, at the 5% probability level. The amount of OC in the FR100 treatment was significant with an increase of about 41% compared to the control treatment, but in other plants, this ratio was not significant in any treatment. The maximum amount of Mg in the FR50 treatment was 30.27, which has a significant effect compared to other treatments. The amount of Na and Ca in the FR100 treatment was significant with an increase of about 343% and 130%, respectively, compared to the control treatment, while in FE and DI plants, this ratio was not significant in any treatment.

Large amounts of agricultural waste such as straw, leaves and pulps, with high nutritional value are produced every year. Grape pomace (GP) is rich in macro- and micro-nutrients and can be used as a soil amendment. However, due to its slow decomposition rate and the spread of diseases and pests, it should not be applied directly to the soil. Therefore, GP is composted in combination with other wastes. There is not enough information about the composting of GP and the effect of the produced composts on soil fertility in Iran. Hence, the aims of this study were twofold: to explore the impact of various GP composts on both soil fertility and spinach yield, relative to two levels of urea fertilizer, through a pot experiment conducted over two consecutive cultivation seasons; to categorize soil treatments based on fertilization regimes and timing (season), thus elucidating any patterns or trends in the observed effects. 

To investigate the effects of GP composts on soil fertility and spinach (Persius hybrid) yield, was conducted as a randomized complete block design with eight compost treatments, two levels of urea fertilizer (46%), and a control treatment (C0), in three replications and two continuous cropping seasons (spring and fall). Compost treatments included: high grape pomace (HG) (60-63%) with chickpea straw and alfalfa (HG-Ch-A), high GP with chickpea straw and sugar beet pulp (HG-Ch-B), high GP with alfalfa and sugar beet pulp (HG-A-B), high GP combined with chickpea straw, alfalfa, and sugar beet pulp (HG-All); four other compost treatments included low level of grape pomace (LG) (37-42%) combined with other residues/wastes similar to the first four treatments (LG-Ch-A, LG-Ch-B, LG-A-B, and LG-All). Urea treatments included: 150 kg per hectare (C150) (two-step top dressing) and 500 kg per hectare (C500) (three-step top dressing). A sandy loam soil was used for this experiment. The composts were separately mixed into the soil at a rate of 2% (by weight(. The first crop was grown for 50 days in May 2018 and the second crop was grown for 45 days in September 2018. In both seasons, the fresh and oven-dried weigh of spinach shoot and root were determined. Also, total concentration of K, Na, Ca, Mg, P, Fe, Zn, Cu, and NO3- were measured in spinach to determine the amount of soil elements taken up by the crop. In both seasons, soil pH and EC, and contents of soil organic carbon (OC), active carbon (AC), total nitrogen (TN), NO3-, NH4+, and exchangeable K, Ca, Mg, and Na, as well as available forms of P, Fe, Cu, and Zn were determined. One-way ANOVAs were applied separately to spring and fall data, and mean comparisons were made using Duncan's test at 0.05% level. To determine the similarities and dissimilarities of the different treatments based on their effect on soil characteristics, cluster analysis was performed on all soil characteristics that showed significant differences between treatments. 

In both cultivation periods, TN levels exhibited no significant variance across treatments. Notably, the highest potassium (K) levels were consistently observed in the HG-All and LG-All treatments, while the lowest K levels were consistently recorded in the C0, C150, and C500 treatments. In the initial cultivation period, no notable differences were observed between the C0, C150, and C500 treatments, except for potassium (K) and ammonium (NH4+), with significantly higher levels detected in the C0 treatment. Conversely, during the second cultivation period, significant disparities were observed among the C0, C150, and C500 treatments solely in terms of nitrate (NO3-) content, with notably higher nitrate levels detected in the C150 and C500 treatments. Through cluster analysis, all treatments from both cultivation periods were categorized into five distinct groups. Specifically, the C0, C150, and C500 treatments for each season were consistently grouped together, respectively, into groups one and two. All compost treatments of each season, except the HG-All treatment in the spring cultivation, were grouped into one class. In the second cultivation, the HG-Ch-A showed significantly higher EC than all treatments, except the HG-Ch-B. The LG-A-B treatment showed the highest amount of OC and C/N (in both cultivations), and NH4+ and Cu (in the second cultivation). The HG-Ch-A and HG-Ch-B treatments increased TN, P, K, Mg, OC, and AC in the second cultivation compared to the first. The amounts of all macronutrients and micronutrients, except Fe and Ca, increased in the compost treatments compared to the control and chemical treatments. In addition, an increase in EC was observed in the compost treatments compared to the control and chemical treatments, and an increase in pH compared to the C500 treatment. In the first cultivation, the LG-Ch-A and C500 treatments had significantly higher yields than the control. In the second cultivation, the LG-All, HG-All, HG-Ch-A, and LG-A-B treatments were the best compost treatments, while the LG-Ch-B and HG-Ch-B treatments were the weakest treatments in terms of soil fertility and plant yield. In both seasons, the absorption of elements by spinach depended on multiple factors, including the element type, its available content in the soil, its initial content in the composts (or fertilizer), soil pH, and yield. 

The application of GP composts over two consecutive growing seasons increased the levels of nitrogen, phosphorus, potassium, magnesium, zinc, copper, active carbon and organic carbon in the soils. These results are very important as magnesium, copper and zinc are rarely applied by farmers. In contrast, depletion of all elements, except organic carbon, occurred in the control and chemical fertilizer treatments due to plant uptake of elements. The combination of chickpea straw with sugar beet pulp is not recommended for the production of GP compost, especially at low GP levels, due to its minimal effect on soil fertility and plant yield. Despite the positive effect of the GP composts in increasing soil fertility, the continuous application of large amounts of these composts is not recommended in the arid regions due to the increase in soil EC and pH. The difference between the compost treatments after two applications of GP composts was less than after one application; these results were confirmed by cluster analysis, in the sense that all compost treatments in the second season were placed in one cluster.

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.

The quality of irrigation water has an important effect on the growth and concentrations of nutrients. The application of boron-rich irrigation water is a global issue and the most important boron pollution source in the environment. Poor water quality unavoidably leads to decreased growth of plants. One of the problems of irrigation in tropical regions is the high concentration of boron element in water and its concentration in irrigation water increases every year. In dry areas where agriculture takes place, boron is often found in high concentrations along with saline soils and salty waters. Boron stress occurs widely and limits plant growth and crop productivity worldwide. Boron is in the form of boric acid in the soil solution and it is washed from the soil in heavy rains, but it is not washed enough when it rains, and by accumulating in the soil, it poisons the plant and prevents its growth. Therefore, in arid and semi-arid areas, irrigation with groundwater that has a high boron content reduces crop growth. Therefore, this experiment aimed to evaluate the effect of activated carbon on nutrient concentrations by tomatoes, cucumbers, and eggplants under the boron stress of irrigation water.

To evaluate the effects of activated carbon on the concentrations and translocation of boron in the plant a factorial experiment with a completely randomized design and three replications was performed in the greenhouse conditions. Treatments included three plants (tomato, cucumber, and eggplant), three levels of boron concentration in irrigation water (0.03, 2.5, and 5 mg l-1) from a boric acid source, and four levels of activated carbon (0, 1, 2, and 3% soil). To prepare seedlings, first, a sufficient number of healthy seeds were selected and for better germination, they were placed in wet napkins for one day and night. Then the seeds were planted in seedling trays with coco peat substrate. In this stage, watering was done once every two days until finally, after 30 days and when the seedlings reached the four-leaf stage and the true leaves appeared, the plants were ready to be transferred to the pots. For cultivation, each of the plastic pots was filled with 3 kg of sampled soil, which was mixed with a proportion of activated carbon according to the type of treatment. Then, in the middle of each pot, several seedlings of the same size were planted. Then the pots were placed in the greenhouse according to the plan. The experiment was conducted with 36 experimental treatments in three replications and a total of 108 experimental units. The soil used was prepared with geographical coordinates (longitude 57˚ 37ʹ and latitude 28˚ 42ʹ) and depth of 0-30 cm and was classified according to the American classification system Sand, mixed, hyperthermic typical Torriorthents. During the growing period, the plants were irrigated daily according to the farm capacity (FC). The day temperature of 25 – 30 °C, the night temperature of 15 – 20 °C, and the relative humidity was 50 – 70%.

The results indicate that the main effects of boron and activated carbon levels had a significant effect (p < 0.01) on the concentration of iron, zinc, manganese, and copper in the aerial parts of the plant. With the amount of boron increased in the treatments, the amount of copper and iron in the aerial parts increased while the amount of manganese and zinc decreased. Regarding the effect of activated carbon, the results showed that by increasing the amount of activated carbon in the treatments, the amount of copper, manganese, and zinc decreased. In contrast, the amount of iron has increased. The highest concentration of iron in the aerial parts (219.6 mg kg-1) belonged to the level of 3% of activated carbon. Also, with the increase in activated carbon in the treatments, concentrations and accumulation of boron in the aerial parts decreased. The highest concentration of boron in the aerial parts (31.77 mg kg-1) was obtained in the cucumber and the level of 0% activated carbon, and the lowest concentration (5.75 mg kg-1) was obtained in eggplant and the level of 3% activated carbon.

It is concluded that the use of activated carbon under boron stress conditions can reduce the concentrations and toxicity of boron in plants.

Biochar is a carbon-rich charcoal material resistant to decomposition, which is produced by heating biomasses in an oxygen-free environment or with limited oxygen. It is used with the aim of increasing organic carbon and improving the physical, chemical and biological characteristics of the soil. Thus its use in the low-fertile soils of hot and dry regions of Iran, which are often deficient in organic carbon, is important. Addition to its high stability in the soil, biochar can sequester atmospheric carbon dioxide in the soil for several hundred to several thousand years. In addition, it can improve soil fertility for a long time by affecting its physical, chemical, and biological properties. The stability of biochar is affected by several factors, such as the characteristics of biochar and soil, the interaction of biochar with soil components and environmental factors, which are examined in this article. Therefore, it is important to use biochar in the soils of arid and semi-arid regions of Iran, which are often deficient in organic carbon.

In this review article, while investigating the evidences of the high stability of biochar in the soils, the   most effective factors the fate of biochar in the soil, including the mechanisms of biochar removal from the soil, biochar stabilization in the soil, and interactions of biochar with soil components, and the gaps and required research areas are presented.

Biochar is higher resistant to degradation than the original carbon compounds in biomass. However, by interacting with soil components, biochar undergoes changes over time and is removed from the soil. The intensity of these changes and biochar residence time in the soil depends a lot on the type of biochar; So, biochars produced from grassy biomass and biochars produced at low temperatures are less stable. In addition, biochar interacts with all soil components, including organic matter, mineral particles, nutrients, living organisms, and soil water and atmosphere, and the result of these interactions determines the stability of biochar in soil. External factors such as the presence of plant and induced root changes, wind and water erosions, leaching, and fire also affect the fate of biochar in the soil. Among these, considering the interactions between microorganisms and biochar in soil, it seems that soil microorganisms play the most important role in the decomposition and destruction of biochar in soil. However, mechanisms such as the entrapment of biochar particles inside aggregates, binding of biochar with organic and inorganic components of soil, and inactivation of soil enzymes by biochar can increase the stability and durability of biochar in soil.

Considering the very high stability of biochar in soil and the necessity of increasing soil organic carbon as the main factor of soil fertility factor, the use of biochar in Iranian soils it can directly and indirectly improve the fertility of these soils while increasing soil organic carbon. However, after biochar is added to the soil, it interacts with the soil components and its characteristics change and evolve over time (aging). However, due to the novelty of biochar technology and the wide range of its application fields, our information on its interactions with various soil components, its long-term changes and developments in the soil and environment, and its long-term effects on the soil and the environment are not yet clearly defined and much research is needed in this field.

More than 80% of Iran's area is arid and semi-arid. Arid and semi-arid soils have various problems and limitations. One of the most important factors limiting soil fertility and crop production in these areas is the lack of soil organic matter (SOM). In more than 60% of Iran's agricultural lands, the amount of SOM is less than 1%; While its optimal level in soils should be 2-3%. SOM, as one of the most important indicators of soil health, plays a vital role in soil fertility and crop production; So, by increasing the amount of SOM, the physical, chemical, and biological characteristics of the soil and crop yield can be improved. However, the stability and residual effects of the fertilizers and organic wastes in the soil are low. Nowadays, converting organic wastes and residues into biochar and adding them to the soil is one of the new methods of increasing soil organic carbon, which enhance soil fertility and crop yield and has high residual effects due to its high stability. However, due to the specific characteristics of the soils of arid and semi-arid regions, using biochar in these regions is associated with challenges and has received less attention. In this review article, while reviewing the positive effects of biochar on soil quality indicators and crop production, the challenges of using biochar in the soils of arid and semi-arid areas, especially in drylands, and the solutions to overcome these challenges have been reviewed.

Forest destruction causes soil destruction as the basis of terrestrial ecosystem life. Therefore, monitoring the soil and evaluating the process of changes over time can prevent the destruction of the soil and consequently the ecosystems with scientific data. In this study, the chemical and biological properties of soil were investigated in two Brant's oak (Quercus brantii Lindl.) sites, Chari and Mavarz, as a part of Zagros Forests in Chaharmahal and Bakhtiari province, Iran. Soil samples were collected from a depth of 0-10 cm and chemical and biological characteristics were measured in two years 2019 and 2021. The results in Chari site showed that the values of organic carbon, organic matter, substrate induced respiration, and nitrification potential increased significantly in the second year compared to the first year. This finding can be attributed to the more species diversity, higher canopy percentage, and relative protection of the Chari site. While in Mavarz site, only electrical conductivity and dry weight of soil showed significant changes in the second year compared to the first year which could be caused by livestock grazing and decrease in rainfall. The trend of changes in the Chari site has been positive which made improvement of some soil characteristics. Generally, management based on protecting the Zagros habitats as well as its positive effect on the biological and chemical characteristics of the soil can have a significant role in the health of oak trees which are encountering the oak decline.

The purpose of this research was to investigate the impact of pH, EC, and organic carbon (OC) on the amount of total nitrogen in the soil of the Zarin Shahr Region using statistical analyses (borderline analysis and step-by-step regression). In the Zarinshahr region, a comprehensive study was conducted for a duration of one year across all four seasons. The study employed GPS technology to select a total of 60 points in agricultural, tree plantations, and bare soil areas while ensuring an average distance of 546 meters between each point. The plots areas were 50x50x20 cm in length, width, and height. The various soil samples collected from these plots were analyzed. Then, the maximum reaction of a biogeochemical process to a certain environmental factor was determined using borderline analysis. According to the findings, the soil's EC exhibited higher readings during the hotter seasons of the year, in comparison to other seasons. Specifically, during the summer, the maximum value of this parameter was approximately 1587 dS/m, while in the winter, the values were nearly 1140 dS/m. Also, pH levels of the soil was generally alkaline. The seasonal variations in soil OC and organic matter percentage were evident, with notably lower values (ranging from 0.04-2.52) in the autumn and winter, followed by a marked increase during the summer and spring (0.12-2.39). Boundary line analysis was used to investigate the relationships between variables and the values of indicators that caused the maximum increase in soil nitrogen. It was ascertained that OC percentage and soil nitrogen percentage exhibited a significant linear correlation in all land uses. Hence, increase in OC percentage resulted in an increase in the total nitrogen content in the soil. The step-by-step regression analysis in a systematic manner revealed that, within the variables under investigation, the percentage of total nitrogen in the soil can be determined based on the impact of two key parameters, namely, EC and the percentage of OC. The results suggest that use of boundary line analysis and step-by-step regression represent a viable approach for determining the effects of the significant factors on the levels of nitrogen content in the soil.

Nowadays, agricultural products are moving towards organic farming in response to consumers' desire for healthier products. One of the ways to produce and increase yield in these conditions is using biological and organic inputs such as biochar and mycorrhiza. Therefore, this experiment was conducted at Safadasht Golazin Agro-industrial in Safadasht, Tehran, in order to investigate spinach yield. The experiment was carried out as split plots in the form of a randomized complete block design in 3 replications. The experimental treatments included four levels of control, two, four, and six tons per hectare of biochar as the main factor and two inoculation levels with mycorrhiza and control as secondary factors. The results showed that the effect of the investigated treatments on the measured traits was significant. The highest plant height (15.24 cm), total chlorophyll (2.44 mg/g fresh weight), root fresh weight (19.56 g), and shoot (30.95 g) at the application level of mycorrhiza and six tons of biochar per hectare was observed. The effectiveness of mycorrhiza increased with the increase of biochar level. In general, the results showed that the synergism effect of biochar and mycorrhiza increased the yield of spinach traits; this synergy can be one of the strategies to reduce the consumption of chemical fertilizers.

Zagros forests play an essential role in providing groundwater resources, air conditioning, soil protection and preventing erosion, and providing wildlife habitat. Today, the ecosystem of these forests has become completely fragile due to improper exploitation and destruction. This study was conducted in areas of Zagros forest in Kermanshah province that were included in the implementation of the protection plan, including Sorkhak and Tappeh Goleh in Islamabad and Qeshlaq in Ravansar. The main purpose of this study was to evaluate the implementation of the forest conservation plan on soil properties.

For this purpose, composite soil samples were collected by random-systematic method from the mentioned area and their respective control area, and their physical, chemical, and biological properties were measured. Soil characteristics in Tappeh Goleh, Sorkhak and control sites were analyzed by one-way analysis of variance and Qeshlaq soil characteristics were analyzed by T-test. The soil samples collected from the forest were air-dried in the laboratory environment and sieved (2 mm). Then their physical and chemical properties (pH, EC, bulk density, and soil organic carbon content) were measured. Soil samples were collected with sterile equipment and sieved through a 4 mm sieve. Fresh and moist soil was kept at a temperature of 4 °C for soil biological tests (basal soil respiration, metabolic quotient, and microbial biomass carbon).

The results showed that no statistically significant changes in soil EC and pH were observed in all study areas. The amount of organic carbon in Sorkhak was significantly higher. Among the measured biological properties of soil, no significant change was observed in organic carbon mineralization in all study areas. However, microbial biomass carbon and soil metabolic quotient in Sorkhak were significantly higher than those in control and Tappeh Goleh areas.

The results of this study showed that the forest protection plan if properly implemented in the field (Sorkhak area) will be able to revive some soil quality indicators. The provisions of forest protection management and the process of soil regeneration in these forest lands should be investigated. Among the studied indicators, soil organic carbon and microbial biomass carbon were among the indicators that responded well to the correct and complete implementation of the forest protection plan, and we have witnessed the improvement of these parameters in managed lands. This suggests that biological soil quality indicators are more sensitive to responding to land management and respond more quickly to these changes.

In recent years, one of the most suitable options for saving water resources is the recycling of urban and industrial wastewater for irrigation which is common practice in different parts of the world, but if the use of wastewater Sewage can not be managed properly for irrigation, which may cause environmental problems. the purpose of this study was to investigate the effects of long-term irrigation with municipal treated wastewater (TWW) compared to well water (WEW) as a control treatment on soil chemical in three layer with three replications in a two-year split plot trial design was performed. in three It has been repeated. due to the availability of this source and the possibility of leaching, the risk of saltinification of this land has been somewhat overcome. the risk of sodiumization of this land has led to the fact that, due to the high clay content of this land, its future consequences include traps and reduced permeability. Irrigation with TWW resulted in a significant increase of 0.3 units of pH in irrigated soils with wastewater compared to WEW. The TN content varied between %11.30 and %25, which indicates the variable percentages of this parameter at the region of the study area. Also, the results of soil organic carbon (OC) changes as a result of irrigation with TWW showed that this irrigation effect was significant and increased by 55% for irrigation compared to treatments irrigation with WEW due to Organic contents in the wastewater.

The aim of this study was to investigate the effect of crop type on soil carbon accumulation in soybean (Glycin max L.) and wheat (Triticum aestivum L.) rotation, in 150 fields of soybean and 89 wheat fields in Gorgan county, in the cropping years of 2016-2017 and 2017-2018, respectively. In order to determine the amount of organic carbon and its changes, soil samples from two depths of 0-15 cm (first depth) and 15-30 cm (second depth) were prepared and then soil carbon was measured by Walkley-Black method. Spatial distributions of soil organic carbon and carbon accumulation potential at different depths and also, in the pre-sowing and post-harvest stages were performance using different types of interpolation methods in ArcGIS enviroment. The results of interpolation methods showed that Kriging was the best model for interpolation of organic carbon distribution and carbon accumulation in agricultural fields of Gorgan. Average amounts of soil organic carbon in the first depth of soybean fields were as 14.84 mg ha-1and 13.41 mg ha-1for the second depth in the pre-sowing stage. Also, it was estimated as 16.85 mg ha-1 in the first depth and 15.52 mg ha-1 for second depth, in the post-harvest stage. The amounts of soil organic carbon in the wheat fields were determined about 16.78 and 15.25 mg ha-1for first and second depths in the pre-sowing stage, respectively. Those were 13.68 and 12.30 mg ha-1for of first and second depths in the post-harvest stage sampling, respectively. The results showed that the eastern, northern, northeastern, southern, southeastern and central parts of the county had the highest carbon accumulation due to access to modern irrigation systems, more water resources, better crop management, suitable return of crop residue to the soil, develop of minimum tillage, minimizing the burning of residue and using manure. Results showed that the western and southwestern parts of the county had the lowest carbon accumulation.

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.

Investigation of soil attributes is one of the ways to evaluate and manage forest ecosystems. Altitude is considered as one of the effective factors on the soil quality, especially soil organic carbon (OC). However, variation of the soil OC stocks at different altitudes of Arasbaran forests is still unknown. Therefore, this study was conducted to examine the spatial distribution of OC values, and some other chemical properties in different soil depths affected by altitude in Arasbaran forests.

In this study, a factorial experiment was conducted in a randomized complete block design in three replications. Overall, 60 soil samples were collected on a north slope of the region at four different altitude ranges, including 0–600, 600–1200, 1200–1800, and 1800–2400 m, and from five soil depths of 0–20, 20–40, 40–60, 60–80, and 80–100 cm. Then, the amounts of OC, cation exchange capacity (CEC), dilute-acid-soluble and hot-water-soluble carbohydrates, calcium carbonate, available phosphorus and potassium as well as soil acidity (pH) were determined in the soil samples.

The results showed the significant effect of soil depth, altitude and their interaction on most of the studeid soil properties. In fact, with increasing elevation and soil depth, the amount of OC, CEC, and dilute-acid-soluble carbohydrates increased and decreased, respectively, and a very strong correlation was found between them. Additionally, on average more than 50% of the OC was allocated to the top 20 cm of the soils at all four elevations that reduced averagely about 79% with increasing soil depth to the depth of 80–100 cm. Moreover, the highest increase rate of OC contents with altitude of about 9% was observed between the elevation ranges of 600–1200 and 1200–1800 m. Furthermore, with increasing altitude and soil depth, other soil properties such as pH, calcium carbonate, and available potaium showed a decraese of about 2%, 16%, and 16%, and an increase of around 4%, 16%, and 18%, respectively. In addition, with increasing soil depth, the amount of soil available phosphorus increased; meanwhile, the effect of altitude on this parameter was not significant.

Based on the findings of this study, soil OC stocks and overall the quality of Arasbaran forest soils are significantly affected by the factors of altitude and soil depth so that surface soils of higher elevations in the study area are of higher quality in terms of OC content, CEC, and dilute-acid-soluble carbohydrates, which should be given more attention. In fact, considering the significant role of these soils in carbon sequestration, these areas should be preserved intact and undisturbed through proper management as well as various protection practices.

Recognition of effective Parameters in sediment Production has an important role in understanding the phenomenon of erosion and its consequences and is one of the important principles of optimal management of a watershed. In the study of the relationship between watershed environmental and hydro geomorphological parameters with erosion and sediment, the quantity and amount of sediment has been considered so far, while in this research, has been studied the relationship between important climatic parameters including average annual rainfall, average annual temperature, altitude, slope, aspect and geological factor (formation) with sediment organic carbon as an important parameter and qualitative indicator in some of the Ardabil province watersheds. 98 samples of sediment after collecting from the study area, were analyzed in the laboratory by Walkley - Black method to extract the amount of organic carbon, then performed statistical analyze on samples using stepwise regression and partial least squares regression (PLSR) models. Findings showed that among the hydrogeomorphological parameters, slope and formation with regression coefficients of - 0.293 and -0.078, respectively, were identified as factors affecting the sediment organic carbon, so that both parameters have an inverse correlation with the sediment organic carbon and aspect parameter is more effective than the formation and output of both regression models is almost the same. Therefore, sediment organic carbon, in addition to the quantity and amount of sediments, can be considered as an important indicator for studying the degradation processes, watershed erosion and loss of soil organic carbon.

Fire has different effects on soil quality and its physical, chemical and biological properties. In order to investigate these effects, in this study, various physical, chemical and biological properties of soil in a part of Arasbaran forest located in Kalibar city that were affected by fire were studied. Soil samples were taken from burned areas (32 samples) and adjacent areas that were not affected by fire as blank samples (32 samples) by systematic random method from a depth of 0 to 15 cm and different soil properties were measured. The results showed that the values of pH, organic carbon, total nitrogen, moisture content, basal respiration and soil microbial biomass in the blank samples were significantly higher than the values in burned samples; while the highest amounts of absorbable P and K and bulk density were observed in burned samples. There was no significant difference in the percentage of sand, silt, clay, porosity, PD and substrate Induced Respiration in the blank and burned samples. Based on PCA analysis, absorbable P and Microbial Biomass Carbon were significantly affected before and after fire, respectively. The results of this study showed that the chemical and biological properties of Arasbaran forest soils (except P and K) were more affected by fire than physical properties.

Nowadays, vast areas of forests have been changed to farmlands, and the change in land use is one of the important factors reducing soil quality. The purpose of this research is to investigate the effect of land use change from forest and pasture to agriculture on some soil characteristics in Sarab Badia area (Kermanshah province). Sampling was done in 2018 from points with the same slope in the form of a nesting site. For this purpose, four areas near each other that have the same landscape and include 3 uses of forest, pasture, and agriculture and also two depths of 0-20 and 20-40 cm were considered. Composite samples were prepared from each depth. After transferring the samples to the laboratory, the important characteristics of the soil were measured based on standard methods. The results showed that among the physical characteristics of the soil, MWD was affected more than the other physical characteristics due to the change in land use, so that by changing the land use from forest to agriculture in the subsoil layer (20-40 cm), MWD decreased by 51.04%. Among the soil chemical properties, organic carbon and total nitrogen with 52.95% decrease in top layer of the soil (0-20 cm), had the most variability due to the change of land use from forest to pasture. The metabolic coefficient was sensitive to the change in land use from forest to agriculture, as its value decreased by 92.92% in the sub layer (20-40 cm). Characteristics such as; MWD, organic carbon, total nitrogen, and metabolic coefficient are highly sensitive to changes of management conditions at the field level, so these characteristics can be used to monitor soil quality.