Research Paper
T. Nazari; M. Baranimotlgh; E. Dordipour; R. Ghorbani nasrabadi; S. Sefidgar Shahkolaee
Abstract
Introduction One of the most important needs in crop planning is the evaluation of different systems of plant nutrition. plant nutrition in a correct way can preserve the environment and increase efficiency of agricultural inputs. Humic acid contains many nutrients that increase the soil fertility and ...
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Introduction One of the most important needs in crop planning is the evaluation of different systems of plant nutrition. plant nutrition in a correct way can preserve the environment and increase efficiency of agricultural inputs. Humic acid contains many nutrients that increase the soil fertility and soil organic matter content and thus affect plant growth and yield. In the present study, the effect of soil and foliar application as well as fertigation application of humic acid on iron and phosphorous availability of canola (Hyola 308) was evaluated. Materials and Methods The soil was air-dried and ground to pass through a 2-mm sieve and then was analyzed to determine soil physical and chemical properties using standard methods. A greenhouse experiment was carried out with 10 treatments in four replications. Treatments include humic acid soil application at three levels (1, 2 and 4 g.kg-1 soil), foliar application at three levels (0.1, 0.2 and 0.4%) and three fertigation levels (1000, 2000 and 4000 mg L-1) and control). Soil application in the form of humic acid powder and in cropping time based on the soil weight of the pots and for spraying and use along with irrigation water, each of the spraying and together with irrigation water levels is divided into three equal parts and in three stages (plant establishment, stem elongation and flowering). At the end of growth period (for 139 days), vegetative growth indices were determined and then plants were harvested and stem and leaves were separated. Phosphorous content in plant extracts was measured by molybdate vanadate method (yellow method) and iron concentration in the samples was determined by atomic absorption (AAS-Unicam-919). Statistical analysis was conducted via SAS software and mean comparisons carried out by LSD test at 5% probability level. Results and Discussion Results show that the application methods and the different levels of humic acid had significant impacts (p < 0.01) on the all parameters but they had no significant effects on the numbers of leaves. The maximum leaf fresh weight was 4.34 gr per plant which obtained water irrigated treatments with 2000 mg/lit. However, there was no significant difference between water irrigation with 4000 and 2000 mg/lit humic acid concentrations. Besides, maximum leaf dry weight was 0.37 gr in the plant that was water irrigated with 4000 mg/lit, however there was no significant difference between water irrigation with 4000 and 2000 mg/lit humic acid concentrations. Also, the maximum stem dry and fresh weight was 5.92 and 1.53 gr which observed in water irrigated with 2000 mg/lit. The application methods and the different levels of humic acid had significant impact (p<0.01) on the content and absorption of Fe and P excluding the Fe content in the root. The maximum Fe content in stem and seed were 321.25 and 85 mg/kg was observed in the treatment of humic acid with water irrigation of 2000 mg/lit. Also, in the treatment of spraying with 0.4 % of humic acid, the maximum of Fe concentration (245.46 mg/kg) was obtained. The humic acid molecules can pass from the cell membranes and cause iron reduction in the Apoplast and increase the availability of Fe. Because of the reduction effect of humic acid on the availability and accumulation of Fe in the plant tissue, increasing in the Fe absorption with humic acid treatment is observed. The increase in the accumulation of Fe by humic material might be due to the releasing phenolic material in the root rhizosphere. The maximum P concentration in the leaf, stem and seed were 0.40, 0.72 and 0.897 respectively that was observed in the treatment of water irrigation with 2000 mg/lit with humic acid. Due to the availability of phosphorus and other nutrients for wheat, humic acid increases the plant yield in the reproductive stage of seeding. Conclusion Results of the study show that humic acid can ameliorate the negative effect of a large amount of phosphorus on iron availability. In fact, humic acid, due to providing nutritional balance for the plant, prevents negative effects caused by the high amounts of specific elements such as phosphorus. Also, the results showed that all three humic acid application methods increased vegetative growth parameters, and iron and phosphate availability for canola plant compared to control. But in general, 2000 mg/L acid humic with irrigation water was more effective than two methods of soil and foliar application.
Research Paper
S. Rostami; B. Hosseinzadeh; O. Bahrami
Abstract
Introduction Clutches are widely used in various vehicle powertrains system. Unlike cars, tractors use a dual clutch system for smooth operation of the external power takes off shaft. The dual clutch system allows the operator, while working with an implement, to change gears without affecting on the ...
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Introduction Clutches are widely used in various vehicle powertrains system. Unlike cars, tractors use a dual clutch system for smooth operation of the external power takes off shaft. The dual clutch system allows the operator, while working with an implement, to change gears without affecting on the operation of implement. When the pedal of clutch is fully pushing, the drive was be interrupted in transmission system and PTO shaft. Because the torque of the tractor’s engine is more than the car’s engine, the extra force is be need to hold the tractor’s clutch. The nature of tasks on a tractor, necessitates a number of actions to be performed by the operator, which puts varying physiological demands on his body. Examples of these tasks are: steering of the tractor, looking backward to observe and control the machine/implement, and force required to operate the clutch, brake, and hydraulic control system. This tasks and workplace, was determines the postures and load distribution on the body structures of the operator. Pedals are one of the most important controllers used in vehicles. Dupuis (1995), reported that a driver pushes the pedal of clutch 230 times per hour on average. Lehmann (1958), pointed out, that the force is exerted on the pedal generally is far greater than the required force. If the force exerted on the pedal is high, the driver cannot detect the moment that the clutch is actually released. Forasmuch as, the clutch is operated by a leg force, and it is mounted on the left side of the tractor driver. Then it’s more important to use a mechanism to amplify the force that applied on the clutch by the driver. use a booster is an appropriate way to amplify the force. Materials and Methods First of all, before installing the booster, the force required for pushing the clutch was calculated. Keeping in mind that no change should occur on the tractor body and pedal position. Then, the booster was installed between the clutch pedal and clutch plug lever. Since the force from clutch to clutch plug lever is tensional, the booster was initially in compression, the direction of the force attached to the clutch was changed using a lever. The direction of resulting force from booster was changed using another lever that to be applied to the clutch plug lever. In order to, providing vacuum for booster, the booster’s vacuum chamber was connected to the engine’s input manifold by a plastic tube. Forty experiments were conducted to calculate the requirement force for pushing the clutch. These experiments were carried out for 5 engine speeds (800,1100, 1400, 1700 and 200 rpm), and 8 inlet diameters of manifold (15, 20, 25, 30, 35, 40, 45 and 50 mm). Experiment was repeated 3 times. Finally, the mean results from three experiments was considered as the true value for each experiment. A load cell (ZEMIC (H3)) was used to calculate the force required for pushing the clutch and data of each experiment was saved in computer distinctively. For measuring the suction in connecting tube that placed between the booster and air manifold, the water column upwelling method was used. Results and Discussion Results of analysis of variance shows that the interaction effect of inlet diameter × engine speed and force, as well as, interaction effect of inlet diameter × engine speed and suction was significant (P <1%). This means that by increasing the engine speed and decreasing the inlet diameter of manifold, more air is sucked in, and therefore, the pressure inside the manifold was be reduce. by decreasing the pressure in the manifold, the difference pressure on both sides of the booster diaphragm was increased, and cause increasing the auxiliary force of booster, thereby, the force required to press the pedal was reduced. Maximum reduction on the force required to push the pedal by using this system is about 170 N, that occur in 15 mm inlet manifold diameter and 2000 rpm engine speed. Conclusion In this paper, a brake booster was installed on the MF285 clutch to reduce the force required to push the clutch pedal. It was observed that this force was about 33.6 kg in the normal state while by using of this system, the required force was reduced to 26 kg.
Research Paper
H. Sorkheh; A. Moezzi; N. Enayatizamir
Abstract
Introduction In Khuzestan province, Iran, huge amounts of organic waste is generated annually, leading to challenges for its safe disposal, with the waste being usually either burned or land filled.Agro-industrial wastes such as sugarcane pith, have been recognized as important renewable sources ...
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Introduction In Khuzestan province, Iran, huge amounts of organic waste is generated annually, leading to challenges for its safe disposal, with the waste being usually either burned or land filled.Agro-industrial wastes such as sugarcane pith, have been recognized as important renewable sources of value-added organic products such as compost.Compost is a mixture of decayed organic material decomposed by microorganisms in a warm, moist, and aerobic environment that release nutrients into readily available forms for plant use. Recycling of organic wastes by the process of composting in agriculture brings in the much needed organic matter to the soils and improves the overall soil fertility and soil productivity Thus, composting is a process for appropriate disposal of waste and is also beneficial from ecological and economic point of view. Lignocellulosic materials are not easily degraded due to the lignin, crystalline and structural complexity of cellulose matrix. Application of chemical and biological treatments may increases waste degradation and decrease composting process time. Bacteria and fungi are the two main microbes that help in decomposition of organic waste and forces of composting. In addition, efficient composting is dependent on the microbial activity. The objective of this research was to investigate the effect of chemical (gypsum) and microbial treatments (consortium of bacteria and fungi) on reduce C/N and shortening process of compost maturity which is used in agricultural fields. Materials and Methods In this research, an incubation experiment was carried out in laboratory condition as a factorial experiment based on a randomized complete design with two factors: 1) gypsum application in three levels including, 1%, 5% and 10% w/w, and 2) microbial inoculation in four levels including control (without microbial inoculation), inoculation of substrate with consortium of bacteria, consortium of fungi and consortium of bacteria + fungi, with three replications. The sugarcane pith for compost production was collected from Dehkhoda sugarcane Agro-industry, Ahvaz, SW Iran. The sugarcane pith was initially boiled for 2h, then air-dried. Sugarcane pith samples were sterilized in an autoclave and 1% w/w urea were added to each samples to reduce their C/N ratio. Then, sterilized gypsum and microbial treatments were added to samples in plastic jars. Samples were incubated for 90 days at constant temperature of 25 ± 2 °C. Samples moisture content was maintained at 80% of field capacity. The samples were weighted every day and the required amounts of distilled water were added. At the end of incubation period, sample properties such as organic matters loss percent (OM loss), ash content, carbon (C), nitrogen (N), hydrogen (H) and sulfur (S) content were measured. Also oxygen (O) content and atomic ratio including carbon to nitrogen (C/N), hydrogen to carbon (H/C), oxygen to carbon (O/C) and hydrogen to oxygen (H/O) ratio were determined. All statistical analyses were performed using SAS software. Means of different treatments were compared using the Duncan’s test at probability level of 5%. Results and Discussion The results of variance analysis showed that the gypsum levels and microbial treatments significantly affected the organic matters loss percent, carbon, nitrogen, hydrogen and sulfur content and O/C, H/O and H/O ratio. In addition interaction effect of gypsum and microbial treatments was significant on nitrogen, hydrogen content and C/N ratio. The results indicated that the gypsum addition and inoculation of bacteria and fungi consortium to sugarcane pith significantly (P < 0.05) decreased the carbon content and C/N, H/C and H/O ratio, while significantly (P < 0.05) increased nitrogen, oxygen and hydrogen content as well as O/C ratio. With increasing gypsum levels (from 1 to 10% w/w) the carbon content and C/N, H/C and H/O ratio significantly (P < 0.05) reduced, while nitrogen, oxygen and organic matter loss percent, hydrogen content and O/C ratio significantly (P < 0.05) increased. Comparison of microbial treatments showed that consortium of bacteria + fungi had higher effect on changes in organic matter loss percent, carbon and nitrogen content and C/N, H/C, H/O and O/C ratio. Maximum organic matter lost and nitrogen content as well as minimum and C/N, H/C and H/O ratio were recorded for co-inoculation of bacterial and fungi consortium combined with application of 10% gypsum treatments. Reduction of C/N, H/O and H/C as well as increasing O/C in the above mentioned treatment, indicating that maturation of sugarcane peat composting was completed three months after composting process. Conclusion From the results of this study, it can be concluded that inoculation of consortium of bacteria and fungi with 10% gypsum led to hasten the sugarcane pith degradation and shortening composting process duration.
Research Paper
E. Shirmohammadi; H.A. Alikhani; A.A. Pourbabaee; H. Etesami
Abstract
Introduction The use of invitro hydroponic culture is one of the useful and practical methods for selection of superior isolates of plant growth promoting rhizobacteria with high colonization potential at root surface. In this regard, the present study was designed to select superior isolates isolated ...
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Introduction The use of invitro hydroponic culture is one of the useful and practical methods for selection of superior isolates of plant growth promoting rhizobacteria with high colonization potential at root surface. In this regard, the present study was designed to select superior isolates isolated from dry-land farming of Qazvin and Zanjan provinces during the previous stages of this investigation. Materials and Methods This experiment was carried out based on a completely randomized design (CRD), including: inoculation of wheat seeds with 16 bacterial isolates and culture of seedlings in Hoagland nutrient solution (EC 8 dS/m and osmotic potential (OP) -0.54 MPa) containing tricalcium phosphate (source of low-soluble phosphorus), as well as non-inoculated seedlings was cultured in Hoagland nutrient solutions containing monopotassium phosphate (control with source of soluble phosphorus) and tricalcium phosphate (control with source of low-soluble phosphorus) at three replications in growth chamber for 45 days. The length of the light (with 196 μmol photons m−2 s-1 light intensity) and dark period in these times was 16 and 8 h, respectively, The day and night temperature were 25±2 and 20±2 °C, respectively. At end of experiment (45 days after transportation of seedlings into invitro hydroponic culture) shoots and roots of plants were harvested separately; then, Population of phosphate solubilizing bacteria (PSB) on root surface, pH and concentration of available phosphorus in nutrient solution, fresh weight, dry weight and length of both section of plants, P-concentration and P-uptake of plant, and relative water content (RWC) of leaf were measured. Ultimately, correlation (Pearson) among measured traits were calculated. Results and Discussion Results showed that inoculated wheat seedlings with B18 isolate perished. It seems that B18 isolate was either a highly pathogenic plant or its metabolites were highly inhibitory to the seedling which in short time killed the wheat seedling. Except B (14, 17, and 32) isolates; the rest of isolates had over 6×106 CFU/g root fresh weight. All bacterial isolates compared to the control with source of insoluble phosphorus, increased available phosphorus and decreased pH of nutrient solution. Dissolution of inorganic phosphates by PSB with chelating processes, secretion of inorganic and organic acids has been proven topic. Thus, reducing pH and increasing soluble phosphorus in nutrient solution at PSB treatments are reasonable. B (1, 2, 3, 4, 5, 6, 14, 17, 32) isolates treatments compared to control with tricalcium phosphate, increased RWC of leaf, and also increased length, fresh weight and dry weight of root and shoot of wheat plants. Previous research has shown that inoculation of plants with PGPR under drought and salinity conditions improved RWC of plant leaves and plant growth indices; Of course, result of some experiment show that some of PGPR do not always improve plant growth under all conditions. There was a significant positive correlation among P-uptake, RWC, root length, shoot height, fresh and dry weight of root and shoot of wheat plant. Also, the pH of nutrient solution had a positive correlation with root length, but it had a negative and significant correlation with P-concentration of nutrient solution and P-concentration of plant. PSB population at root surface had a negative correlation with pH of nutrient solution and root length of plant, but with P-concentration of nutrient solution had positive and significant correlation. Conclusion All of screened and selected PSB isolates in lab (in respect of PGP traits) could not promote plant growth; even some of these isolates (such as B15 and B18) had negative effects on wheat growth indices. Inoculation of wheat with PSB isolates significantly increased the use of insoluble phosphorus. Solubility of tricalcium phosphate by isolates and increased phosphorus availability cannot lonely improve wheat growth indices; it seems that the outcome of the set of PGP effects of these bacteria and the secretion of their metabolites in the presence of plant root are determinative agents for improvement of wheat growth indices. Generally, B (1, 2, 3, 4, 5, 6, and 32) isolates were superior isolates in respect of colonization at root surface, relative water content (RWC) and growth indices of wheat plant; and these isolates are recommended for further experiments in greenhouse and field (in order to production of suitable biofertilizer for dry-land farming of wheat).
Research Paper
N. Yaghmaeian Mahabadi; N. Nobahar Deylami; M. Rahimi Mashkaleh; A. Fatemi Chookami
Abstract
Introduction As one of the pedogenic factors, topography can be an important and effective factor on yield and quality of crop performance through affecting water distribution and soil properties in different landscape positions. This factor affects soil properties by changing the altitude, steepness ...
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Introduction As one of the pedogenic factors, topography can be an important and effective factor on yield and quality of crop performance through affecting water distribution and soil properties in different landscape positions. This factor affects soil properties by changing the altitude, steepness and slope direction of lands. Understanding the soil limiting factors for the production of crop would help policy makers for the sustainable planning and management of the soils. Among many landscape parameters, effect of slope position and aspect on the variability of soil quality attributes and yield were little studied. This study aims to investigate the effect of topography on soil properties, yield and quality of tea in Lahijan, Guilan province. Materials and Methods Four slope positions were selected from one transect in the northern slope and one transect in the southern slope of tea gardens in Lahijan, Guilan province. In each slope position, one profile was drilled. Soil samples (0 to 30 cm depth) and green tea leaves were collected from in three plots (2 m2) around each profile. Physicochemical soil properties, yield and quality of tea were determined according to standard methods. So, this study was carried out in a factorial arrangement based on the completely randomized design with two factors, including slope position (summit, shoulder, backslope and toeslope) and slope aspect (northern and southern) with four replications. The data were analyzed by using SAS and graphs were plotted with the help of Excel program. Qualitative land suitability was also determined using simple limitation and parametric methods for tea production in this hilly region. Results and Discussion The results showed that slope position significantly affected some soil physical and chemical properties including silt content, electrical conductivity, total nitrogen, organic matter, available potassium and phosphorus. The highest content of organic matter, nitrogen and phosphorus in the soil of toeslope position can be attributed to soil erosion and transferred from top of the slope and their accumulation in this situation. The highest values of clay was found in the in the northern-toeslope position. The saturated water content in soil of the northern aspect was significantly higher than the southern aspect. The analysis of data showed that the interaction effect of slope positions and aspects on the yield and qualitative characteristics of tea, including the theaflavin, thearubigin, total color and brightness was statistically significant. Yield was the highest (3112 kg/ha) and the lowest (1762 kg/ha) in the northern-toeslope and southern-shoulder positions, respectively. The highest amount of theaflavin, thearubigin, total color and brightness were related to the northern-toeslope position. The northern aspect of all slope positions had more yield than the southern aspect that have contributed to higher amount of organic matter and saturated water content in northern aspect. Correlation analysis revealed that tea yield, thearubigin and brightness were significantly positively correlated with soil organic matter (P value < 0.05) also tea yield, theaeflavin and total color positively correlated with soil nitrogen (P value < 0.05). Also, theaflavin was significantly and positively correlated with thearubigin (P value < 0.05). This correlation is probably due to the presence of common chemical precursors for the formation of two substances as well as the transformation of theaflavin to thearubigin as one of the path for the thearubigin formation. According to the land suitability evaluation, the climatic factors especially the minimum temperature during the coldest month of the year is the most important limiting factor for tea cultivation in the study area. Another limiting factor was related to the topography (slope), which caused the lowest suitability class (N) in the shoulder and backslope positions. Conclusion Overall, the results showed that higher soil quality in northern-toeslope aspect lead to an increase in yield and quality of tea. The correlation results showed that soil nitrogen and organic matter are two important and effective parameters on the yield and quality of tea. This findings showed that the need to consider physiological characteristics of specific variety and the soil moisture and nutrients status in requirements tables for tea cultivation. Investigations on the soil-landscape relationship revealed that there is a strong link between the soil properties and the slope positions and aspects. More detailed studies would be helpful for the management of the sloping geomorphic surfaces.
Research Paper
L. Rasoli; K. Nabiollahi; R. Taghizadeh Mehrjardi
Abstract
Introduction Rapid population growth in developing countries implies that more food will be required to meet the demands of this population. Wheat as one of the most important grain crops in the world is a great source of food for human which is planted under a wide range of environments and its production ...
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Introduction Rapid population growth in developing countries implies that more food will be required to meet the demands of this population. Wheat as one of the most important grain crops in the world is a great source of food for human which is planted under a wide range of environments and its production influences on local food security. The production of wheat per unit area in Iran is low compared to developed countries in the world. One of the main causes for this low yield is that the suitable land for planting has not been recognized. Therefore, to overcome this problem, land suitability assessment is needed, which can help to increase crop yield. The first step in agricultural land use planning is land-suitability assessment which is often conducted to determine which type of land use is suitable for a particular location Digital mapping approach have been applied to link between soil observations and auxiliary variables to understand spatial and temporal variation in soil class and other soil properties. Little attempt has been made for using Digital mapping approach to digitally map land suitability classes Therefore, this paper applied land suitability assessment framework and digital soil mapping approach to map land suitability for rain-fed wheat in Kurdistan province. Materials and Methods The study area is located in Kurdistan Province, western Iran. It surrounds the city of Ghorveh and covers a region of 6500 ha. The climate is semi-arid whose features can be performed using a cold and rainy winter and a moderate and dry summer. The mean yearly rainfall is 369.8 mm and over 90% of the rain falls between November and March. The mean temperature (10.8℃) is relatively cool. Soil moisture and temperature regimes are Xeric and Mesic, respectively. The physiography units include piedmont, fan, hills, and mountain and slope varies from gentle to very steep. At first land unit component map was prepared by Mahler physiography method, then, 17 representative profiles in each land unit component were dug and described. 105 auger samples also were taken at three depths (0-20, 20-50 and 50-100 cm). Soil texture, acidity, organic carbon, CaCO3, gypsum, ESP, electrical conductivity and gravel were measured in all soil samples. Topography and climate data were also recorded. Numeric ratings of soil, topography and climate parameters based on land requirements of wheat were determined and land suitability index using parametric method were calculated. Then land suitability classes of wheat were determined. A set of auxiliary variables (i.e. land unit component, terrain attributes and remotely sensed data) to predict land suitability classes of rain-fed wheat. In order to generate land suitability class map, artificial neural network were applied to make relation between auxiliary variables and land suitability classes. Results and Discussion The results showed that the area has about 36.61% N2 class, 40.32% N1 class and 22.53% S3 class. The validation results of the model based on the statistical indices including root mean square error, mean error, and determination coefficient (6.56, 4.81, 0. 68, respectively), indicates that the artificial neural network model has suitable accuracy. Auxiliary data including MrVBF index, LS factor, MRRTF index, slope, Land unit component, VDCN and band 2 were the most important for prediction of wheat land suitability index in digital method. The major limitation of the study area to plant rain-fed wheat were rainfall in the flowering stage, sever slope, shallow soil depth, high pH and gravel. Therefore, to increase production and sustainable agricultural system it is suggested land improvement operations such as terracing, decreasing pH, supplementary irrigation and gathering gravel. The highest values of rain-fed land suitability index were observed in the units physiographic of river plain and plateau, while the lowest value were observed in the units physiography of mountain and hill which had high slope, shallow soil and high gravel. These results were confirmed by one-way ANOVA and Duncan tests. Conclusion Based on the results of statistics indices artificial neural network had suitable accuracy for predicting land suitability index of wheat. In general, the study area, because of limitation of sever slope, shallow soil, high pH, and gravel, has low land suitability index for rain-fed wheat. Hence, to improve land suitability of the study area and increasing its production, suitable land improvement operations is required.
Research Paper
F. Torkamani; H. Piri Sahragard; M.R. Pahlavan Rad; M. Nohtani
Abstract
Introduction Spatial variations of soil properties is a natural event, which recognizing these changes is inevitable in order to planning and right management of both agricultural and natural resources. Soil organic carbon (SOC) is the most important factor in soil fertility and quality, climate change ...
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Introduction Spatial variations of soil properties is a natural event, which recognizing these changes is inevitable in order to planning and right management of both agricultural and natural resources. Soil organic carbon (SOC) is the most important factor in soil fertility and quality, climate change and reduction of greenhouse gas emissions. Furthermore, evaluating the rates and spatial distribution of the soil properties, land improvement and restoration can be traced from the carbon sequestration index. According to the above, providing quantitative and qualitative conservation of soil properties such as SOC can be considered an effective way to achieve sustainable development of natural and environmental resources. Digital soil mapping (DSM) can determine the spatial variations of soil organic carbon by exploring the relationship between soil properties and effective environmental variables. Different statistical models such as regression trees and random forest are used in order to communicate between soil characteristics and its spatial distribution. The present study was carried out to investigate the spatial distribution of SOC, as well as, to determine the most important variables affecting their prediction in Ravang watershed in Minab County. Materials and MethodsRavang watershed with an area of 13821.6 hectares is located in Hormozgan province, Minab city. The maximum and minimum elevations are 357 and 33 meters, respectively. Digital Elevation Model of Ravang watershed was used to extract 17 environmental covariates (such as elevation, aspect, slope, valley depth,…) by SAGA software (http://www.gdem.aster.ersdac.or). Moreover, two environmental covariates related to remote sensing including Normalized Difference Salinity Index (NDSI) and Normalized Difference Vegetation Index (NDVI) were determined in the study area. In addition, the maps of land use, sand, silt, clay and pH were used as covariates in modeling. In order to determining the location of sampling points, the conditioned hyper-cube technique was used. After determining of soil sample location, field sampling was carried out at a depth of 0-30 cm. then, 100 soil samples were taken and the amount of SOC was measured. Random forest model was applied to the relationship between SOC and covariates. The model includes two user-defined parameters, including the number of variables used in the construction of each tree, which expresses the power of each independent tree and the number of trees in each forest. Considering the strength of independent trees, the predictive accuracy of the model increases, conversely, the correlation between them will decrease. The accuracy of the soil organic carbon distribution was also evaluated using root mean square error (RMSE), mean error (ME) and correlation coefficient (R2), which were determined. Results and Discussion Based on the present study results, elevation, soil silt and sand maps, channel network base level, slope and NDVI are the most important factors on predicting the of SOC variations. The results indicated that RMSE, ME and R2 were 0.36, 0.26 and 0.38, respectively .Results also showed that affecting erosion and sediment, as well as, human effect, have the most impact on the SOC soil spatial distribution in the Ravang watershed. Moreover, result show SOC deficiency in the soil of Ravang watershed due to high salinity, low percent of vegetation cover and land use changes. In addition, drought intensifying and decrease in precipitation have reduced SOC content, which itself causes changes in the texture and chemical properties of the soil and, as a consequence, makes them more susceptible to erosion. Conclusion The variability of SOC is very high in the study area because of intensive water erosion and land use change. Overall, the results of the present study indicated that the critical condition of soil organic carbon in the Ravang watershed, which requires a comprehensive management of the region's water and soil resources to improve soil conditions and increase the reserves of this important and influential variable in the soil structure. On the other hand, despite of the acceptable performance of the random forest model in estimating of soil properties, due to high variability of some soil properties, model prediction performance may be decreased.
Research Paper
M.J. Malekzadeh; M. Kiani Dehkiani; M. Sajadiyeh
Abstract
Introduction The limitation of fossil fuels and environmental pollution by using them have encouraged researchers toward renewable fuels. The most important renewable fuels are bioethanol, biodiesel and biogas. Biogas is a gas that is produced from biodegradable fermentation, agricultural products ...
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Introduction The limitation of fossil fuels and environmental pollution by using them have encouraged researchers toward renewable fuels. The most important renewable fuels are bioethanol, biodiesel and biogas. Biogas is a gas that is produced from biodegradable fermentation, agricultural products and wastes, animal waste and urban waste by anaerobic digestion. One of the products that has a significant amount of waste is sugar cane. This plant is widely cultivated in Khuzestan Province and annually produces a lot of waste which is currently not useful. One of the most important wastes is bagasse. Bagasse is the solid residues after crushing sugar cane and extracting it. Bagasse is composed of cellulose (45%), humiculus (27%), lignin (21%), extract (5%) and a small amount of inorganic salts (2%). A lot of bagasse is produced in sugar cane production process (about 240 kg with a moisture content of 50% per ton of sugar cane). Every year, a lot of bagasse is wasted. One of the most useful ways is to convert it into biogas and provide the percentage of the required thermal and electrical energy of the plant. Therefore, in this study, the effect of temperature and percentage of cow manure as an additive on biogas production from bagasse sugar cane was investigated. Materials and Methods The used bagasse in this research was provided from Farabi industry and Cultivation, located 48 km from Ahwaz, and a cow manure was provided from a livestock farm in Hamidieh, Ahwaz. In order to increasing the production efficiency of biogas, sugar cane bagasse was milled. Batch reactors of 4 liters was used to produce biogas from sugar cane bagasse. To control and maintain the working temperature, the reactors were placed in a water bath and the temperature of the bath was kept constant by using the thermal element and the thermostat. Cow manure was used to provide source of microorganisms. Cow manure with 5, 10, 15 and 20% weight percentages (B5, B10, B15 and B20) was blended with bagasse (numeric index of B indicates the percentage of cow manure in the blends). Sodium bicarbonate was used to control the pH of the reactors. Stirring was carried out manually in order to homogenize the materials and prevent the formation of hard layer at the top of the reactors. The amount of produced biogas was daily measured by water displacement method. Another measured parameter was the total Solid Index (TS), which represents the percentage of organic and inorganic matter for materials of the reactors. The experiments were carried out by using eight reactors for 30 days and the results were analyzed by completely randomized factorial design. Results and Discussion The results of variance analysis of biogas production in terms of bagasse to cow manure ratio and temperature changes showed that they had a significant effect at 1% level on biogas production. Considering the interaction effects of temperature and bagasse to cow manure ratios have a significant effect on the produced biogas at a 1% level. The results showed that with increasing in the percentage of cow manure in the materials, the amount of biogas production increased at both temperatures, so that by increasing the ratio of cow manure in the blends from 5 to 20% at 35 and 45 ° C, the produced biogas increased by 27.78% and 81.83%, respectively. By increasing the percentage of cow manure in the blends, the number of microorganisms in the digestion increased, and as a result of their activity, the amount of produced biogas increased. It was also observed that with increasing the temperature of digestion from 35 ° C to 45 ° C, the biogas production for B5, B10, B15 and B20 blends increased by 19.82%, 22.5%, 15.85% and 80.8%, respectively. The highest amount of cumulative production of biogas was obtained 0.3 m3.kg.VS-1 for 45 ° C and 20% cow manure to bagasse ratio. Conclusion In this research, the effect of cow manure in blend of sugar cane bagasse and temperature on produced biogas was investigated. The experiments were carried out at two temperatures of 35 and 45 ° C, and four blends with different weight percentages from cow manure to bagasse (5, 10, 15 and 20 percent). The results showed that with increasing the percentage of cow manure in blends, the amount of biogas production increased. Also, with increasing temperatures from 35 ° C to 45 ° C, the production of biogas in all blends increased.
