Showing 15 results for Organic Carbon
A. Dehghani, A. Fotovat, Gh. Haghnia, P. Keshavarz,
Volume 11, Issue 41 (10-2007)
Abstract
J. Fallahzade , M. A. Hajabbasi,
Volume 15, Issue 55 (4-2011)
Abstract
The salt–affected lands in arid regions of central Iran are characterized by low rainfall, low fertility, high evaporation and salinity. The cultivation of salt–affected lands may have a major influence on soil quality. The aim of this study was to determine the response of soil quality indicators to reclamation and cultivation of salt–affected lands occurring in Abarkooh plain, central Iran. Soil quality indicators were evaluated in three land use systems including salt-affected land, wheat, and alfalfa fields. Composite soil samples were collected at 0–10, 10–20, 20–30, and 30–40 cm layers and analyzed for soil organic carbon, total nitrogen, carbohydrate, particulate organic carbon in macro-aggregates (POCmac) and micro-aggregates (POCmic), organic carbon mineralization and wet aggregate stability. The cultivation of salt–affected land caused a significant decrease in electrical conductivity at all layers and increased the amount of soil organic carbon, total nitrogen, carbohydrate, POCmac, POCmic, and organic carbon mineralization. At all layers, the POCmac/POCmic ratio in the alfalfa fields was higher than that in the wheat fields. The cultivation of salt-affected land caused a significant increase in soil aggregate stability (MWD) at all layers. In most cases, the amounts of soil organic matter and MWD were greater in alfalfa than in the wheat fields, reflecting a better soil quality and thus higher potential for increasing soil organic carbon sequestration in the alfalfa fields
Z. Fahim, M. A. Delavar, A. Golchin,
Volume 17, Issue 63 (6-2013)
Abstract
Organic carbon is the most important component of terrestrial ecosystems and any change in its abundance can have a major impact on the processes that take place in ecosystem. The aim of this study was to estimate carbon sequestration in three different elevations (200 to 1200 m from sea level) and according to vegetation type in the Khairoodkenar forest. The highest carbon sequestration was observed in the surface layer of a soil with Fig-Carpinus betulus vegetative cover and it was estimated to be 167.4 ton/ha. But when carbon sequestration was measured in soil solum, it was found that soils with Fagus orientalis-Carpinus betulus vegetation cover had the highest amount of organic carbon (514.4 ton/ ha). The results showed that clay fraction had the highest carbon content but the highest enrichment factor (1.59) was measured for sand fraction in soils with Fagus orientalis- Carpinus betulus vegetative cover. The highest organic carbon content (7.89%) and aggregate stability (MWD= 7.79mm) and lowest bulk density (1.21 g/cm3) were measured in soils with Figs- Carpinus betulus vegetative cover.
F. Maghami Moghim, A. Karimi, Gh. Haghnia, A. Dourandish,
Volume 17, Issue 65 (12-2013)
Abstract
The quantity and variability of soil organic carbon (SOC) is one of the most important indices to determine the effect of land use changes on the soil quality. Regarding long-term changes from rangeland to dry farming in the Roin area of North Khorasan, the objectives of this study were to investigate the effect of long-term land use changes on the SOC in different slope faces and use SOC as an index to make a proper decision about the future of land use in this area. 140 soil samples were taken from 0-15 cm soil depth of back slope position of north-, south-, west- and east-facing slopes of rangeland, dry farming, alfalfa dry farming and garden in 7 points. 14 soil samples were taken from irrigated farming, too. The results showed that garden and irrigation farming with averages of 2.03 and 0.78% have the maximum and minimum SOC content. The average of SOC content in rangeland was 1.40% that decreased by land use change to 1.04 and 1.27% in dry farming and alfalfa dry farming, respectively. SOC content in southern slope aspects showed a significant difference compared to other slope aspects. The most SOC content occurred in east aspects. It seems that after long-term land use changes, the SOC content have equilibrated to environmental and land use conditions. The average SOC content in different slope aspects except south one changed from 1.4% in rangeland to 1.11% in dry farming and 1.32% in alfalfa dry farming, which are a suitable value for semiarid regions. In conclusion, to protect land from degradation and considering this fact that dry farming is the main income of the people in the study area, it is recommended to stop dry farming on south aspects and continue on east, north and west aspects with conservation practices.
H. Mahmoudzadeh, M. Sheklabadi, A. A. Mahboubi,
Volume 18, Issue 68 (9-2014)
Abstract
Organic carbon pools and carbon lability directly affect soil biological, physical and chemical characteristics. Besides, capacity of self-organization of soil is related to the organic carbon pools. Sand size fraction (> 50 µm) organic matter is more labile than silt+clay size fraction organic matter. Assessment of this organic carbon variation can be a suitable index to determine soil quality. The aim of present study was to evaluate the impact of land use change on particle size fractions of organic carbon and carbon pool index. In September 2010, soil samples were collected from the three major land use types including wetlands around the lake, wetlands converted to wheat, and alfalfa cultivations. Soil samples were collected from the 0-30, 30-60 and 60-90-cm depths in each of land use. According to the results of particle size fractionation of organic carbon in 0-30-cm layer, the highest and lowest amounts of sand size fraction organic carbon were obtained in wetland (67.01 g.C.kg-1soil) and wheat land use (24.57 g.C.kg-1soil), respectively. Land use change from wetland to alfalfa and wheat caused a decrease of silt+clay size fraction organic carbon in 0-30-cm by 48.39 and 45.14 t.C.h-1, respectively. In the 30-60-cm layer of cultivated land, soil organic carbon storage in silt+clay size particle was more than sand size fraction organic carbon. Results showed that carbon pool index in alfalfa, and wheat land was decreased by 50 and 60% compared to wetland, respectively. And carbon management index in alfalfa and wheat was declined by 44.90% and 66.70%, respectively.
A. Esmaili Dastjerdipour, M. H. Farpoor, M. Sarcheshmehpour,
Volume 18, Issue 69 (12-2014)
Abstract
Organic substances produced by cyanobacteria and some polymeric compounds play a role in soil aggregation and increase soil structure stability in sandy soils. Effects of biological soil crusts and some polymeric compounds on some properties of a sandy soil were investigated in this research. Inoculation of three cyanobacterial treatments (Nostoc sp., Phormidium sp. and their combination) and four time intervals on crust formation, organic carbon and calcium carbonate contents, resistance to penetration and MWDD in soils below the crusts were studied in the first experiment. Combination of two cyanobacterial species in 60 days treatment with 2.2 % organic carbon, 0.2 Mpa resistance to penetration, and 96.7 % large aggregates was introduced as the superior treatment. Effect of superior cyanobacteria and time treatments on aggregate size distribution was studied in the second part of this experiment. Sixty-day treatment with 96.7 % of large aggregates was the most effective treatment. Structural stability of a sandy soil influenced by four concentration levels (0, 1, 2 and 4%) of anionic polyelectrolyte polymer at the depths of 1, 2 and 3 cm was investigated in the second experiment. Four percent concentration treatment of polymer with 0.6 Mpa resistance to penetration and 90.9 % large aggregates was the most effective one. A significant difference in resistance to penetration among three depth intervals was also observed
N. Parsamanesh, M. Zarrinkafsh, S. S. Shahoei, Weria Wisany,
Volume 18, Issue 70 (3-2015)
Abstract
Reduction of quality and soil productivity due to organic carbon losses is one of the most important consequences of land use changes, that creates irreparable effects on the soil. To evaluate the land use effect on the amount of soil organic carbon in Vertisols, Sartip Abad series with extent of 1850 hectare in south of Bilehvar area in Kermanshah province was studied by using the completely randomized block design in factorial experiment with 10 repeats in farmland and grassland, some soil physical and chemical properties in two Lands compared with each other. The results showed that the soil organic carbon in surface horizons of grassland has been more than farmland and accordingly increase the amount of sequestrated carbon in grassland. No significant differences were found in the amount of soil organic carbon in lower horizons of two lands. Due to land use change from grassland to farmland, noticeably increase in Bulk density, Nitrogen, Acidity, soil Electrical Conductivity and decrease the organic carbon percent and the soil organic material. Pedutorbation, clay amount (higher of 50%), numerous small subsoil, and stable structure are the important factors in saving the organic carbon of vertisols that can reduce the effects of land use changes on organic carbon amount. Generally, it can be conclude that: the land use changes not only can create the severe damage on soil physical and chemical properties but with the carbon losses and more release of greenhouse gases exacerbate the pollution of environment which endangers the life in a earth planet.
W. Zarei, M. Sheklabadi,
Volume 18, Issue 70 (3-2015)
Abstract
The aim of the study was to investigate the effects of land use on soil quality parameters using multivariate statistical analysis. Soil samples (0-25 and 25-50 cm depths) were taken from three land uses in forest area of Marivan including forest, rangeland, and cultivated land. Soil characteristics of pH, EC, sand, silt, clay and CaCO3 content, water-stable aggregates and their organic carbon content were measured. Principal component, cluster and discriminant analyses were used to evaluate the soil quality. Principal component analysis classified soil properties into five factors. The most important factors were soil aggregates organic carbon content and aggregate stability indices. Schematic distribution of factors and also cluster analysis showed the same pattern. Soil aggregates organic carbon content, water-stable aggregates and aggregate stability indices were the most sensitive factors to land use changes. These soil properties and factors had the same pattern in forest and rangeland, but significantly reduced in the cultivated land use. Land use change from forest to cultivated land resulted in significant decrease of aggregates organic carbon content, water-stable aggregates and also an increase of pH. The results showed the usefulness of multivariate statistical methods for integration of the soil properties and determination of different soil quality indices.
M. Mollaei, H. Bashari, M. Basiri, M. R. Mosaddeghi,
Volume 18, Issue 70 (3-2015)
Abstract
Soil aggregate stability is considered as a key indicator of soil quality and health assessments in rangelands. Many factors and properties such as soil texture, organic carbon, calcium carbonate, sodium adsorption ratio, and electrical conductivity might affect soil aggregate stability. The effects of these factors on aggregate stability of 71 soil samples collected from 4 rangeland sites (2 in semi-arid and 2 in arid lands) in Isfahan province were investigated. Aggregate stability was measured using the wet-sieving method. To optimize the trial conditions for the investigated soils, three shaking times (5, 10 and 15 minutes) were used to impose different hydromechanical stresses on the aggregates of ten soils selected out of the studied soils. The structural stability was assessed using mean weight diameter (MWD) and geometric mean diameter (GMD) of the water-stable aggregates. Significant differences of MWD were observed between the shaking times. The 10-min shaking was selected as best for structural stability assessment in the studied regions because it resulted in better differentiation of soils on the basis of structural stability. Among the intrinsic properties, soil organic carbon content had the most important role in aggregate stability in all zones. However, electrical conductivity (in addition to organic carbon content) had an important role in aggregate stability in the arid rangelands. Log-normal distribution and GMD could represent better the aggregate size distribution when compared with normal distribution and MWD in the studied regions. Overall, wet-sieving method with shaking time of 10 min is suggested to assess the soil structural stability in rangelands of Isfahan province. Therefore, soil aggregate stability and the factors affecting this vital indicator can be used efficiently for assessing and monitoring management effectiveness and rangeland functionality trend.
M. Nadi, A. Golchin, E. Sedaghati, S. Shafie, S. J. Hosseini Fard, G. Füleky,
Volume 21, Issue 1 (6-2017)
Abstract
Soil organic matter is the largest source of organic carbon in the soil surface which played an enormous role in restoring balance, environmental sustainability, soil elements and climatic conditions. Organic materials influence physical, chemical and biological properties of soil and thus soil fertility directly and indirectly. The amount, type and composition of organic matter are different in different soil and climatic conditions. Different soil components can hold different combination of soil organic matter. In this study soil samples were collected from virgin, Populus and Alnus forests from Guilan Province, Iran. The amount of organic matter in the original samples and sand, silt and clay fractions were measured and the quality of organic carbon (13C) and hydrogen (1H) were determined in fractions by Nuclear Magnetic Resonance. Based on the results the amount of organic carbon in the original samples of Alnus forest was highest. among fractions, clay had the highest amount of organic carbon. The result of Nuclear Magnetic Resonance showed presence of different aliphatic and aromatic carbons and hydrogen in different samples. Virgin forest had the highest proportion of alkyl to oxygenated alkyl carbon ratio and Alnus forest showed the highest ratio of aliphatic to aromatic carbon,. Both mentioned ratios was higher in clay fraction than other two fractions.
Z. Bigdeli, A. Golchin, T. Mansouri,
Volume 21, Issue 4 (2-2018)
Abstract
To assess the effects of different levels of soil lead on mineralization of organic carbon and nitrogen, a factorial pot experiment was conducted using litter bag method. The factors examined were different levels of soil lead (0, 25, 50, 100, and 200 mg kg-1soil) and incubation periods (1, 2, 3 and 4 months) in three replications. At the end of incubation periods, the litter bags were pulled out of the pots and the weights of plant residues remained in bags were measured. The plant residues were also analyzed for organic carbon and nitrogen. Organic carbon and nitrogen losses were calculated by subtracting the remaining amounts of organic carbon and nitrogen in one incubation time interval from those of former one later incubation time interval. The results showed that the losses of organic carbon from wheat residues and carbon decomposition rate constant decreased as the levels of soil lead increased over than 25 and 50 mg/kg of soil respectively. The losses of organic nitrogen was more affected by lead pollution and decreased as the levels of soil lead increased, but nitrogen decomposition rate constant decreased as the levels of soil lead increased over than 25 mg/kg. The losses of organic carbon and nitrogen in 200 mg Pb/ kg of soil were 3.2 and 11.7 % lower than control treatment. The results of this research indicate that contamination of soil by lead increases residence time of organic carbon and nitrogen in soils and slows down the cycling of these elements.
S. Shakeri,
Volume 22, Issue 1 (6-2018)
Abstract
Potassium fixation is one of the most important factors influencing the availability of this ion for plants. This research was carried out to evaluate the relationship between potassium (K) fixation with some physical and chemical characteristics of soils and clay minerals and to investigate the effect of the dry and wet cycle on potassium fixation in Kakan Plain, in Kohgilouye & Boyerahmad Province. To measure the amount of Potassium fixation, four levels of K were added to the samples and the samples were shaken for 24 h and then dried in the oven at 50°C for 24 h. The drying and wetting cycle was repeated three times. Another set of soil samples was similarly incubated for a period similar to the previous treatment, but drying was performed at room temperature in an equilibrium state. The results showed that potassium fixation was increased with the potassium concentration increment, whereas K fixation percentage was reduced. Also, potassium fixation showed a positive significant relationship with cation exchange capacity (CEC) as well as clay content, in both normal and dry and wet treatments, and a negative significant relationship with organic carbon. Moreover, potassium fixation was enhanced with the increase of smectite content in both normal and dry and wet treatments. Besides, due to more organic carbon and less smectite, surface horizons fixed K less than the subsurface horizons.
E. Esfandiary Ekhlas, M. Nael, J. Hamzei, A. A. Safari Sinegani, M. Sheklabadi,
Volume 22, Issue 2 (9-2018)
Abstract
Evaluation of the ecological sustainability of different cropping systems is crucial to achieve sustainable agriculture. This evaluation is accessible via soil quality assessment. Therefore, to study the mid-term effects of different conservation tillage systems (no tillage and minimum tillage) and cover cropping on the biological indicators of soil quality, a factorial experiment in a completely randomized block design was conducted in Dastjerd region (Hamedan). Three levels of tillage (NT: no tillage, MT: minimum tillage and CT: conventional tillage) and two levels of cover cropping (C1: Lathyrus sativus and C2: no cover crop) were applied for four consecutive years. Soil sampling was performed in the fourth year of experiment in two steps (1- before cover crop plantation, and 2- after harvesting main crop) with three replications. Most indices (total organic carbon, active carbon, basal respiration, phosphatase activity) were significantly affected by cover crop, tillage systems and sampling time, as the highest values were obtained in NT-C1 in time 2 and the lowest ones in CT-C2 in time 1. For instance, after four years application of treatments, the mean active carbon content was increased from 927 mg/kg in the conventional tillage + no cover crop to 1350 mg/kg in the conservation tillage systems + cover crop. Therefore, conservation tillage practices combined with Lathyrus sativus cover crop were shown to be the most appropriate management for soil quality maintenance and improvement.
A. Abdollahi, M. Norouzi Masir, M. Taghavi, A. Moezzi,
Volume 24, Issue 2 (7-2020)
Abstract
Nowadays, one of the ways to confront with the micronutrients deficiency is application of Nano materials to increase the availability of elements such as zinc for plants. Therefore, this study was conducted to investigate the effect of functionalized iron oxide nanoparticles and zinc sulfate chemical fertilizer on the zinc chemical forms in soil solution phase and its correlation with zinc concentrations and uptake in wheat. This study was carried out in a completely randomized design with three replications. Treatment consisted of functionalized iron oxide nanoparticles of Hydroxyl (OH), Carboxyl (COOH) and Amine (NH2), each at three levels (100, 200 and 300 mg.kg-1), ZnSO4 (40 kg.ha-1) and Control (without using iron oxide nanoparticles). At the end of the cultivation period, soil chemical properties such as pH, soil available zinc and dissolved organic carbon and concentrations and the uptake of zinc in plant were measured. The results showed that pH, available zinc and dissolved organic carbon content of soil solution were significantly affected by the treatments. The results obtained from the Visual MINTEQ Geochemical model showed that the highest amount of the free form of zinc (Zn2+) was obtained at the level of 300 mg.kg-1 of carboxyl iron oxide nanoparticles. Also, the experimental treatments significantly influenced the concentration of Zn-DOM species. The positive and significant correlation between Zn+2 and Zn- DOC species with the concentration and total Zn uptake of wheat indicated that these pools of Zn could be liable species in soil. The results of this study, therefore, showed that the application of functionalized iron oxide nanoparticles could help to improve soil conditions in order to increase the zinc availability for plants.
Miss S. Bandak, A.r. Movhedei Naeani, Ch.b. Komaki, M. Kakooei, J. Verrlest,
Volume 27, Issue 3 (12-2023)
Abstract
Soil organic carbon (SOC) is one of the most important components of soil physical and chemical properties that have an important role in sustainable production in agriculture and preventing soil degradation and erosion. Data mining approaches and spatial modeling besides machine learning techniques to investigate the amount of soil organic carbon using remote sensing data have been widely considered. The objective of the present study was the evaluation of SOC using the remote sensing technique compared with field methods in some areas of the Gonbad Kavous and Neli forests of Azadshar. The soil samples were collected from the soil surface (0-10 cm depth) to estimate the SOC. Data were categorized into two categories: 70% for training and 30% for validation. Three machine learning algorithms including Random forest (RF), support vector machine, extra tree decision, and XGBoost were used to prepare the organic soil carbon map. In the present study, auxiliary variables for predicting SOC included bands related to Lands 8 OLI and sentinel 2 measurement images, topography, and climate. The results showed that the extraction of the components related to the bands along with the calculation of indicators such as normalized vegetation difference, wetness index, and the MrVBF index as auxiliary variables play an important role in more correct estimation of the amount of soil organic matter. Comparison of different estimation regressions showed that the Sentinel 2 random forest model and in Landsat8 with the values of coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MEA) of 0.64, 0.05, and 0.17, respectively, was the best performance ratio compared to other approaches used in the study to estimate the organic carbon content of surface soil in the study area. In general, the results of this study indicated the ability of remote sensing techniques and learning models in the spatial estimation of soil organic carbon. So, this method can be used as an alternative to laboratory methods in determining soil organic carbon.
