Soil science
S. Sanjari; M.H. Farpoor; M. Mahmoodabadi; S. Barkhori
Abstract
Introduction: Playa, as an important geomorphic position in arid areas, covers about 1% of the continents and has attracted attention of soil scientists and geomorphologists. Soil genetic processes related to landforms and geomorphic processes are of great importance. Micromorphology is among necessary ...
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Introduction: Playa, as an important geomorphic position in arid areas, covers about 1% of the continents and has attracted attention of soil scientists and geomorphologists. Soil genetic processes related to landforms and geomorphic processes are of great importance. Micromorphology is among necessary techniques in soil studies which has been used by several researchers. Micromorphological features together with other soil characteristics provide invaluable data for reconstructing soil genetic processes. Moreover, classification and identifying characteristics of soils are pre-requisites for the optimum use and management of soil resources. Soil Taxonomy and World Reference Base (WRB) is among the most extensively used classification systems worldwide. Since no data about soils of the Jazmoorian Playa is available, the present research was performed with the following objectives: 1) studying physical, chemical, and micromorphological properties of soils in the Jazmoorian Playa related to different geomorphic surfaces, and 2) classifying soils of the region by Soil Taxonomy (2014) and WRB (2015) systems. Materials and Methods: The Jazmoorian playa is located in Kerman and Sistan Baloochestan provinces. The Jazmoorian Playa is a continental depression of late Pliocene. The playa is about 360 m above sea level with about 65 km length and 45 km width located between 58 ˚ to 60 ˚ longitudes and 27 ˚ to 28 ˚ latitudes. The area extends to the igneous Bazman Mountains to the northeast, the igneous Jebalbarez Mountains (granodiorite, andesite, granite) to the north and northwest, the Beshagard Ophiolite Mountains of Cretaceous and Paleocene to the south, and the colored Mélanges to the Oman Sea. Soil moisture and temperature regimes of the area were aridic (and aquic in limited areas) and hyper thermic, respectively. Wet zone, fan delta, clay flat, puffy ground clay flat, sodic clay flat, and salt crust were among the geomorphic surfaces investigated in the playa. In order to study the maximum soil variations in the area, eight representative pedons were described and sampled. Collected soil samples were air dried, grounded, and passed through a 2 mm sieve, and routine physical and chemical soil properties were then analyzed. Undisturbed soil samples were used for micromorphological observations. The soils were classified according to Soil Taxonomy (33) and WRB (11) systems. Results and Discussion: Results showed that EC contents of the saturated extracts ranged from 0.5 (fan delta) to 222.2 (salt crust) dS/m. The soils of the playa in Kerman Province affected by the Halilrood River had less salinity compared to the soils on playa surfaces in Sistan Baloochestan Province under influence of the Bampoor River. In addition, salt crust was only formed in parts of the playa located in Sistan Baloochestan Province. Clay coating and lenticular gypsum crystals were among the micromorphological features observed in the Jazmoorian Playa’s soils. The clay coating was formed due to high Na content. However, lenticular gypsum was formed due to small volume pore spaces as well as high salinity of the area. High soluble salts (Table 3) caused a salt coating around pore spaces to be formed due to evaporation of saline water table. WRB system could better classify soils into Solonchak and Solonetz RSGs compared to Soil Taxonomy system which classifies all soils as the Salids sub order. Natric Aquisalids, Typic Natrisalids, Natric Haplosalids, and Puffic Haplosalids sub groups and Natrisalids great group are recommended to be added to Soil Taxonomy system for more harmonization between the two classification systems. Furthermore, the definition of salic horizon in WRB system (EC of at least 15 dS/m and the EC multiplied by thickness of at least 450) is recommended to be included in Soil Taxonomy, because of limitations induced by salts and for a better correlation of the two systems. Conclusion: Results of physicochemical properties clearly showed that electrical conductivity of soil saturated extracts was in the range of 0.5 to 222.2 dS/m. The part of the playa located in Sistan Baloochestan Province is more saline than the part in Kerman Province. More salinity of playa in Sistan Baloochestan Province was attributed to the Bampoor River which passes through evaporative formations located in east and southeast of the area. Micromorphological observations showed clay coatings and lenticular gypsum crystals as pedogenic features. The soils of the area were classified as Aridisols and Entisols (according to Soil Taxonomy system) and Solonetz, Solonchaks, Fluvisols, and Regosols Reference Soil Groups based on WRB classification system. Moreover, WRB system was capable of separating saline from saline-sodic soils, however, Soil Taxonomy classifies both soils as Salids suborder. Therefore, WRB system is better suited for classification of the soils of our study area as compared with Soil Taxonomy.
S. Sanjari; M.H. Farpoor; M. Mahmoodabadi; S. Barkhori
Abstract
Introduction Increasing demand for an international classification system as a unique communication tool in soil science has caused development of different systems. Like many other countries, Soil Taxonomy and WRB are the most popular soil classification systems in Iran. Genetic and morphologic ...
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Introduction Increasing demand for an international classification system as a unique communication tool in soil science has caused development of different systems. Like many other countries, Soil Taxonomy and WRB are the most popular soil classification systems in Iran. Genetic and morphologic soil properties are used for soil classification in both systems. However, correlation of the two systems and efforts to harmonize them have been a major concern among soil scientists. Comparing Soil Taxonomy and WRB in gypsiferous and calcareous soils of central Iran, Sarmast et al. (13) reported that WRB using various qualifiers is more effective than Soil Taxonomy. Since no study on soils of Iranshahr and Dalghan Regions located in Sistan and Baloochestan Province has performed and/or no reported data is available, the present research was performed to: 1) study morphological, physical, and chemical soil properties in the area, 2) classify soils based on Soil Taxonomy (2014) and WRB (2015) systems, 3) compare the two systems for soil description in Iranshahr and Dalghan regions as a part of Sistan and Baloochestan Province, central Iran. Material and Methods: The study area starts from Iranshahr (590 m asl) in the center of the province and extends to Dalghan (390 m asl) in west. Alluvial fan, pediment, playa, and hill were among different landforms identified using field studies, topography maps (1:50000), and Google Earth image observations. To cover the maximum soil variations in the area, 10 representative pedons were selected, described, and sampled. Results and Discussions: Calcic, gypsic, anhydritic, argillic, natric, and salic horizons identified after field work and laboratory analysis. Results of the study showed that addition of Yermic Torrifluvent, Yermic Torriorthent, Calcic Gypsiargid, Gypsic Natrsalid, Natric Gypsisalid, Anhydritic Gypsisalid, Anhydritic Calcisalid subgroups to Soil Taxonomy system from one hand, and addition of anhydrite and aquic (for Solonchak reference soil group) qualifiers to WRB system from the other hand, causes a higher correlation and more harmonization between the two classification systems. Meanwhile, the minimum percentage of calcium carbonate equivalent necessary for calcic horizon identification in coarse textured soils including gravel in Soil Taxonomy is also suggested to be added to WRB system. Besides, requirements of salic horizon in WRB system is recommended to be added to Soil Taxonomy. At the same time, soil names in WRB system provide more information and data about soil properties and characteristics in young soils (such as yermic qualifier showing desert pavement) compared to Soil Taxonomy. Soil Taxonomy is not able to properly classify saline soils of arid regions down to subgroup level which is a weak point for this system. That is why newly added Gypsic Natrsalids is suggested for soils with natric, gypsic, and salic horizons in the upper 100 cm of the soil. On the other hand, the requirements of salic horizon in WRB system (the minimum EC content of 15 dS/m and the EC multiplied by the horizon thickness of more and/or equal to 450) are also suggested for Soil Taxonomy. Conclusion: Results of the study for both saline and sodic soils show more capability of WRB system compared to Soil Taxonomy to classify soils. From soil management point of view, natric horizon causes more negative effects compared to salic horizon because Na disperses the soil particles and destroys soil structure and sodic soils need more practices to be improved compared to saline soils. Results for gypsiferous soils also show more capability of WRB system compared to Soil Taxonomy because gypsum content which is important for gypsiferous soils management is properly concerned in WRB system. However, lack of anhydritic horizon in WRB seems to be a weak point for this classification system. That is why it is suggested to be added to WRB (13). Since Soil Taxonomy does not use independent abbreviations for anhydritic horizon compared to gypsic horizon, the Ba and Baa abbreviations are also suggested for Soil Taxonomy to be added.
Z. Dianat Maharluei; M. Fekri; M. Mahmoodabadi; A. Saljooqi; M. Hejazi
Abstract
Introduction: Today, soil pollution is an important environmental issue that should be taken into account. Industrial activities cause pollution and accumulation of heavy metals in the soil. Soil pollution significantly reduces the quality of the environment and threatens human health. Heavy metals are ...
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Introduction: Today, soil pollution is an important environmental issue that should be taken into account. Industrial activities cause pollution and accumulation of heavy metals in the soil. Soil pollution significantly reduces the quality of the environment and threatens human health. Heavy metals are one of the most important pollutants in the environment, which has received a lot of attention in recent decades. Heavy metal pollution is a serious problem in developing countries and urban areas. Among heavy metals, lead is found in large amounts in the Earth's crust, which has several effects on human health and the environment. Lead is an essential element for the plant and one of the most important pollutants, which is toxic even at very low concentrations. Its presence in the culture medium has a negative effect on germination rate, water status in the plant, dry root weight and aerial part of the plant, photosynthesis, absorption of nutrients and enzymatic activity. Much research has been done to use alternative and modern methods to clean the environment of heavy elements. One way to stabilize heavy metals in the soil is to use biochar. Due to its cation exchange capacity and high specific surface area, biochar is able to reduce the pollution caused by organic pollutants and heavy metals, stabilize heavy metals and improve the condition of plants and soil in terms of pollution. The aim of this study was to investigate the effect of modified biochars rice husk and almond soft husk on lead desorption kinetics in contaminated calcareous soil. Materials and Methods: To conduct this research, a sufficient amount of soil from a depth of zero to 30 cm was collected from the farm of Shahid Bahonar Agricultural College in Kerman. Physical and chemical properties of the studied soil were measured after air drying and passing through a 2 mm sieve. To prepare the biochars (rice husk and almond soft husk), the residues, after collection, were air-dried and ground and then packaged in aluminum foil to limit the oxygenation process. They were then placed in an oven at 500 0C for four hours to produce a charcoal called biochar. Also, to prepare the modified biochar (NaOH and HNO3), one gram of biochar was added to 100 ml of distilled water and then 10 ml of concentrated acid (or 10 g of alkali) was added to it. Stirring at 60 0C for 24 hours. Finally, it was filtered using a centrifuge and washed several times with distilled water to neutralize the pH. The produced powder was dried at 70 0C for 24 hours. The lead desorption kinetics experiment was studied at several times (5, 15, 30, 60, 120, 240, 480, 960, 1440 and 2880 minutes) in two levels of biochar (0 and 4 wt %) and three levels of lead (0, 300 and 600 mg kg-1), which were incubated for 5 months under field moisture in a greenhouse. Results and Discussion: The kinetics results showed that the desorption of lead has the same pattern in all the time studied. Early rapid desorption occurred in the early desorption times (initial 30 minutes) followed by low-velocity desorption (8 hours) and finally, equilibrium was observed in the treated and control samples. The significant difference between the amount of lead released from the treated soils and control indicated a positive effect of both used engineered biochars on reducing lead desorption. The highest amount of lead desorption was observed in soil without biochar, while the lowest desorption rate occurred in treatments of rice husk and almond soft husk modified by sodium hydroxide. The application of modified biochar rice husk highly reduced lead desorption, compared to modified biochar almond soft husk. Conclusion: According to the results, the modified biochar with sodium hydroxide caused a significant reduction in lead desorption compared to other treatments, and this reduction was more in biochar rice husk than the almond soft husk one. It can be stated that rice husk biochar has been more successful than almond soft husk biochar due to its more porous structure and cation exchange capacity. Among the equations used for lead desorption estimation, the two-constant rate equation was selected as the best model for data fit due to high explanatory coefficient (R2) and low standard error (SE). According to the above, the use of biochar can be recommended as a modifier in lead contaminated soils.
H. Hosseini; M. Fekri; Mohammad Hady Farpoor; M. Mahmoodabadi
Abstract
Introduction: The availability of the applied phosphorus (P) is controlled by sorption-desorption reactions in soil. Since the sorption-desorption reactions are affected by physical and chemical properties of the soil, the presence of organic matter (OM) and carbonates can also effect on the ...
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Introduction: The availability of the applied phosphorus (P) is controlled by sorption-desorption reactions in soil. Since the sorption-desorption reactions are affected by physical and chemical properties of the soil, the presence of organic matter (OM) and carbonates can also effect on the P sorption capacity in soil. The purpose of this study was to investigate the effects of OM and carbonates on phosphorus sorption isotherms in some calcareous soils of Kerman province.
Materials and Methods: Six surface soil composite samples (0-30) were collected from Kerman Province located in southeast of Iran. The soils with a wide range of OM and calcium carbonate were selected for sampling. Samples were air dried and passed through a sieve of 2 mm. Physicochemical properties of the soil samples were determined according to the Soil Survey Laboratory Manual. Thereafter, the soil samples were divided into three parts. One portion was used for treatment with sodium hypochlorite to remove organic matter. The second part was treated with sodium acetate buffer (pH = 5) to remove carbonates. The third was used as a control without any treatment. Batch experiments were carried out to determinthe P-sorption isotherms in soil. The sorption behavior of P was studied by Langmuir and Freundlich isotherm models. All experiments were conducted in three replications.
Results and Discussion: The results showed that organic matter and equivalent calcium carbonate, removed from the studied soils with an average efficiency of 86.7% and 84.9%, respectively. Although the isotherms data showed that both Langmuir and Freundlich equations fits to data,Langmuir equation with higher mean of correlation coefficient (R2=0.982) and lower standard error (0.022) showed the best fit to P-sorption data for all soil samples (with and without treatment). Removal of organic matter by sodium hypochlorite increased the phosphorus adsorption capacity in the studied soils. After removal of soil organic matter, an increase in phosphorus adsorption capacity in the studied soils. With respect to control, removing the organic matter increased the adsorption capacity parameters (qmax and kf) about 37 to 104 mg.kg-1 and 11 to 23 L.kg-1, respectively. These results indicate that Fe- and Al-oxides and other available adsorption sites on the mineral surfaces are coated by organic matter and are activated after removal of OM. Removal of carbonates from the soil significantly reduced the P-sorption capacity. qmax and kf were decreased by 17% and 32%, respectively, compared to untreated soils. It is, therefore suggested that available P adsorbing surfaces decreases by removing carbonates from the soil.Constants related with bonding energy increased by 17.03% and decreased by 28.78% by removal of OM and calcium carbonate, respectively. The P maximum buffering capacity is an important indicator for assessing phosphorus stabilization capacity in soil. The greater P buffering capacity, the fewer ability of phosphorus replacement to soil solution. After removal of carbonates, this parameter decreased by an average of 42.5%. The results suggested that carbonates is an important factor in availability of phosphorus in soil. The required phosphorus standard increased by 14.43% by removing OM in the studied soils. However, the removal of carbonates reduced the need of soil for phosphorus by 40.5%.
Conclusion: In this study was investigated the effect of removing organic matter and carbonates on phosphorus sorption isotherms in some calcareous soils of Kerman province. The results of this study showed that P sorption capacity is affected by the amount of carbonates and organic matter. Removal of organic matter from the soil increased the sorption capacity of phosphorus due to Fe- and Al-oxides. Other available adsorption sites on the mineral surface which are coated by the organic matter are active. Carbonates is known as an active site for maintaining phosphorus in the soil and its removal from soils reduces the phosphorus adsorption capacity. Applying/Preserving organic matters to/in soil can increases the efficiency of phosphate fertilizer application and improves plant nutrition. The removal of carbonates from the studied soils reduced their need for phosphorus. Therefore, as well as the addition of organic matter to soil, the removal or reduction of carbonates from agricultural soils is important for improving phosphorus utilization efficiency and plant nutrition management.
Samira Zamani; Majid Mahmoodabadi; Najme Yazdanpanah; Mohammad Hady Farpoor
Abstract
Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion ...
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Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion dominates large parts of the country due to the climate and land mismanagement. In this regard, Kerman as the largest province in Iran has been under influence of erosive winds with high damaging potential. Wind erosion is a function of two agents including erosivity and erodibility. As wind velocity increases, the rate of wind erosion increases as well, while an increase in threshold friction velocity results in sand drift potential reduction. On the other hand, soil properties can control wind erosion rate through affecting both soil erodibility and threshold velocity. In addition, wind erosion is directly influenced by the direction and velocity of wind. Therefore, for better understanding of this phenomenon, analysis of wind erosivity based on meteorological data is of importance. The aim of this study was to analysis wind erosivity in Kerman province and the wind erosion potential in different parts of the province.
Materials and Methods: This study was conducted to investigate the potential of wind erosion in different parts of Kerman province based on seasonal wind data obtained for the period from 2006 to 2010. For this purpose, eight synoptic stations were selected and wind rose and sand rose were plotted for each station using WR Plot View.8 and Sand Rose Graph 3. For each season and for the whole period, erosive wind speed classes, prevailing wind direction, and the sand rose components including drift potential, sediment load and uni-directional index were obtained for each station.
Results and Discussion: This study results indicated that the intermediate wind speed class i.e. 7.7 to 9.8 m s-1 with the west and southwest directions had the highest frequency at most stations. The most erosive winds occurred during winter and summer, while the lowest ones were found in autumn. In winter, the highest wind speed class i.e. >13 m s-1 was the most frequent class. However, precipitations mostly occurring during winter can moderate the sand transport potential, since the higher precipitation causes a higher soil moisture level and enhanced threshold velocity. In addition, Jiroft station had the most frequent calm winds, whereas Lalehzar station exhibited the least frequency of these winds as this site is located in a mountainous region. Among the stations, the highest potential of sand transport (1637 vector unit) and the greatest sediment discharge (102.62 kg m-1 s-1) were observed at Rafsanjan station. However, the lowest sediment discharge was found at Jiroft station with 22.40 kg m-1 s-1. In all stations, the values of DPt were more than 400 indicating high wind erosion potentials in most areas of the province. The assessment of the uni-directional index illustrated that the investigated wind properties varied for different seasons and regions. Analysis of this index showed that Zarand and Jiroft had multi-directional winds, while other stations with a uni-directional index ranging from 0.3 to 0.8 experienced bi-directional winds with moderate variations. Furthermore, the analysis of resultant drift direction implied that the sand transport direction in Kerman, Jiroft, Sirjan, Rafsanjan and Shahrbabak sites was from west to east, at Lalehzar station was from southwest to northeast, at Bam station was from north to south, and at Zarand station was from northwest to southeast. The highest values of total drift potential in Bam, Jiroft and Zarand were obtained in summer season, while the maximum total drift potential was recorded in wintertime for Kerman, Rafsanjan, Shahrbabak, Sirjan and Lalehzar locations. The findings of this study revealed the significance of wind erosivity analysis in order to make a better understanding of wind erosion processes and achieve a more suitable strategy to combat this environmental threat.
Conclusions: It was concluded that due to climate conditions, Kerman province as the largest province of Iran has experienced high potentials of wind erosion and sand transport. In addition, the prevailing direction and most frequent velocity classes of winds differ among different parts of the province demonstrating the possibility of the formation of different features of wind erosion. Finally, the high values of DPt (> 400) were obtained for most stations, showed a high wind erosion potential in the province.
M. Mahmoodabadi; O.L. Rashidi; M. Fekri
Abstract
This study focused on the effect of organic manures as well as potassium fertilizer on some soil properties and onion yield at the field condition. The experiments were carried out as factorial in a randomized complete block design with three replications. The treatments were poultry manure (10 t ha-1), ...
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This study focused on the effect of organic manures as well as potassium fertilizer on some soil properties and onion yield at the field condition. The experiments were carried out as factorial in a randomized complete block design with three replications. The treatments were poultry manure (10 t ha-1), alfalfa residue (10 t ha-1) and control each together with two levels of potassium fertilizer as K2O (0 and 250 kg ha-1). The results showed that application of poultry manure and alfalfa residue resulted in yield increasing about 57.7 and 40.9 % in comparison to the control, respectively. On average, the onion yield for the potassium treatment was 7.8 % higher than for the untreated one. The application of poultry manure and alfalfa residue increased final infiltration rate 73.2 and 56.1 %, respectively. Inversely, potassium fertilizer caused a significant reduction in the final infiltration rate. Moreover, application of organic manures particularly poultry manure, significant increases in saturated moisture, porosity, EC, organic carbon and available phosphorous and decrease in bulk density and pH was observed, while potassium only increased soil EC, significantly. Application of poultry manure and alfalfa residue increased soil organic carbon 129.8 and 80.2 % and available phosphorous 104.8 and 51.9 %, respectively. Among different soil properties, organic carbon showed the highest influence on yield increase.
