Soil science
M. Madahinasab; M. Mousavi nik; S.A. Ghanbari; A.R. Sirousmehr; Sh. Kouhestani
Abstract
Introduction: The use of sewage sludge, which is mixed locally with poultry waste and is available at a relatively low cost, improves the circulation of nutrients and organic matter in the soil, reduces the concentration of CO2 in the atmosphere, and increases the level of soil organic carbon. Fertilization ...
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Introduction: The use of sewage sludge, which is mixed locally with poultry waste and is available at a relatively low cost, improves the circulation of nutrients and organic matter in the soil, reduces the concentration of CO2 in the atmosphere, and increases the level of soil organic carbon. Fertilization with this method is of particular importance in soils of arid and semi-arid regions that face erosion and organic matter reduction. However, there are concerns about the presence of essential and unnecessary heavy metals such as Cd, Cr, Cu, Ni, Pb, and Zn that enter the environment from domestic, light industrial, commercial and municipal wastewater sources and can lead to soil contamination and eventually enters the food chain through absorption, transport, and accumulation in agricultural and non-agricultural products and has threatened human and animal health. Phytoremediation is the cleaning up of polluted terrestrial areas and aquatic sites from heavy metal and organic contaminants by green plants. An appropriate plant for phytoremediation should ideally have a high ability to translocate contaminants into the plant shoot. However, the toxicity of the remains of these plants has become a severe problem for human health. Iran is an arid and semi-arid country and many soils face the problem of using animal manure sources with sewage sludge and the possibility of contamination with heavy metals. Farmers cultivate the barley plant (Hordeum vulgare L.) in these areas widely, and it has a significant role in the food chain of livestock and humans. Therefore, in this study, we evaluated the barley plant in terms of lead and chromium accumulation by increasing drought levels in the field.Materials and Methods: It was a two-year field experiment with three irrigation levels (irrigation per 100 (control), 75 and 50% of field capacity). The amount of chromium and lead in soil and plant samples was measured using atomic spectroscopy with flame mode after extraction by digestion in acid. We used bio-concentration coefficients including root bioaccumulation factor ( ), shoot bioaccumulation factor ( ) and translocation factor ( ) to measure the plants bio-accumulation capacity. A plant with a root bioaccumulation factor bigger than one and a bio-translocation factor of less than one is suitable for plant stabilization of elements. In contrast, a plant with a shoot bioaccumulation factor and bio-translocation factor of more than one and root bioaccumulation factor of less than one is suitable for plant extraction of elements from the soil.Results and Discussion: After barley harvest, the average concentration of lead and chromium in soil decreased by 23% and 17% compared to before harvest. The results of the analysis of variance showed that the effect of experimental years was significant on the concentration of chromium in the soil and the aerial part of barley and shoot bioaccumulation and root bioaccumulation factor of the same elements in the barley (p<0.05). The effect of drought was significant on the shoot and root dry weight, chromium concentration in both shoots and roots, lead concentration in shoots, lead and chromium shoot bioaccumulation factor, chromium root bioaccumulation factor, and lead bio-translocation factor (p<0.01) and chromium bio-translocation factor (p<0.05) but the interaction effect of year and drought was not significant on any of these traits. In all cases, the concentration of elements in the roots was higher than the aerial part, and with increasing drought stress, the concentration of lead in the roots remained constant but increased in the aerial parts while the concentration of chromium decreased. As the amount of drought increased, the shoot bioaccumulation factor increased for the lead but decreased for the chromium. The root bioaccumulation factor of chromium also decreased while the translocation factor increased for both elements, but the increase was more pronounced for the lead. Lead shoot bioaccumulation factor decreased linearly with an increasing dry weight of aerial parts (β = -0.86), but chromium shoot bioaccumulation factor increased (β = 0.62). Root dry weight predicted chromium root bioaccumulation factor (β = 0.85). The total plant dry weight regression model could predict the lead translocation factor (β = -0.89) and chromium transfer factor (β = -0.67).Conclusion: In this experiment, the studied bioconcentration coefficients were all less than one. So, barley is an avoidant plant when encountered with lead and chromium in the soil, and in increasing drought conditions in the field, it does not translocate these toxic metals to the food chain.
Soil science
M. Mahmoudi; Sh. Kazemi
Abstract
Introduction: The consumption of inorganic fertilizers in agricultural ecosystems led to the destruction of soil physical, chemical, and biological characteristics and severely affected the quality of the products. Therefore, the application of compost fertilizers in agricultural lands has been widely ...
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Introduction: The consumption of inorganic fertilizers in agricultural ecosystems led to the destruction of soil physical, chemical, and biological characteristics and severely affected the quality of the products. Therefore, the application of compost fertilizers in agricultural lands has been widely considered, and it has been mentioned as the best environmental measure. Rootstock plays a crucial role in the growth of citrus trees. Among all the nutrients needed by citrus, nitrogen has a vital role, and a large amount of this macronutrient is supplied in the soil every year. The release of nutrients from organic matter, especially nitrogen, is slower than the nitrogen release from chemical fertilizers. Rootstock affects the photosynthetic capacity of the transplanted cultivar, which is related to the annual carbohydrate redistribution and is a determining factor for vegetative growth and reproductive development. The growth, yield and fruit quality of cultivars are, therefore, strongly regulated by rootstock. In the recent study, the effects of compost and nitrogen fertilizers on common rootstocks in Mazandaran province, including citrange, citrumelo, and sour orange, were investigated.Materials and Methods: An experiment was conducted as a completely randomized design at Qaemshahr Horticultural Research Station. The treatments included sulfur granular compost (0, 2.5, 5, and 7.5%), produced by Mazandaran Wood and Paper Industries Company, and pure nitrogen (0, 20, 40, and 80 mg kg-1) in the form of ammonium sulfate. Vegetative growth, including plant height, crown diameter, and the number of leaves, were measured. Also, to study the changes in leaf nutrient concentration, leaf samples were collected, in July and the concentration of nutrients in leaf tissue was measured. A randomized complete block design was conducted at Qaemshahr Horticultural Research Station in 2017. The treatments included sulfur granular compost (0, 2.5, 5, and 7.5%), produced by Mazandaran Wood and Paper Industries Company, and pure nitrogen (0, 20, 40, and 80 mg kg-1) in the form of ammonium sulfate. One-year-old seedlings of the same size from citrange, citrumelo, and sour orange were planted in 7- kg pots containing arable soil and the treatments. The applied soil was analyzed, and its physical and chemical properties were determined. Irrigation of all pots until reaching the field capacity (weight method) was performed uniformly for all treatments. At the end of the growth period, vegetative growth parameters, including plant height, crown diameter, and the number of leaves, were measured. Also, to study the changes in leaf nutrient concentration, fully developed leaves samples were collected, in July and the concentration of nutrients was analyzed. Nitrogen was determined by the Kjeldahl method with a sulfuric acid-hydrogen peroxide mixture. Phosphorus by calorimetric, potassium using a flame photometer, and calcium, magnesium, iron, manganese, zinc, and copper were measured using the flame atomic absorption method.Results and Discussion: Results showed that the highest nitrogen concentrations in citrange and citrumelo seedlings were 2.92 and 2.97% due to 40 and 80 mg kg-1 N and 2.5% compost, respectively. In citrumelo rootstock, plant height increased with enhancing nitrogen application levels at different compost levels. Compost levels did not show a significant increase in citrange height, but the highest height growth was observed at 40 and 80 mg kg-1 nitrogen. In the sour orange rootstock, consumption of high levels of compost and nitrogen significantly reduced plant height. In all three rootstocks, the highest concentrations of potassium were observed in high levels of compost and no nitrogen application. The concentration of iron and zinc in citrumelo leaves increased with increasing compost levels. The trend was different in citrumelo so that consumption of 2.5% compost and 40 mg nitrogen fertilizer showed the highest concentration of leaf iron (151 μg g-1), while the application of 5% compost without nitrogen reduced the concentration of iron to 62.2 μg g-1. Changes in citrange zinc concentration were similar to citrumelo. In sour orange, iron concentration changed limitedly and ranged from 83.8 μg g-1 in 2.5% compost and 20 mg kg-1 nitrogen fertilizer to 61 μg g-1 in control. In this rootstock, the highest concentration of zinc was obtained from no compost application and 40 mg kg-1 nitrogen (28.14 μg g-1), whereas the lowest concentration of iron was observed in control. Citrange seedlings performed better in nutrient uptake than citrumelo and sour orange seedlings. Consumption of 5 and 7.5% levels of compost in sour orange rootstock reduced plant height and crown diameter and caused rosette, led to an increase in the number of leaves. The most effective level of nitrogen in sour oranges was 80 mg kg-1 nitrogen. Application of 80 mg kg-1 nitrogen and 2.5% compost, and 80 mg kg-1 nitrogen and 5% compost led to the highest number of leaves in citrumelo and citrange rootstocks, respectively.Conclusion: According to vegetative growth and concentration of nutrients data, especially from the nitrogen concentration point of view, maximum vegetative growth was obtained in citrumelo rootstock from 2.5% compost and 40 mg kg-1 nitrogen treatment and in citrange and sour orange rootstocks from 2.5% compost and 80 mg kg-1 nitrogen treatment.
Soil science
S.H. Sadeghi; A. Jafarpour; M. Farajolahi; D. Khatibi Roodbarsara; M. Moradi Sefidcheghayi; M. Zabihi Silabi; M. Khosravi; E. Kolani; B. Mohammadi; M.J. Adibi; H. Azarniya
Abstract
Introduction: One of the most important causes of land degradation and reduced fertility is soil erosion, a severe threat to human welfare and food security. With the intensification of erosion and sediment transport in the watershed, water quality is reduced, and sediment production and flood risks ...
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Introduction: One of the most important causes of land degradation and reduced fertility is soil erosion, a severe threat to human welfare and food security. With the intensification of erosion and sediment transport in the watershed, water quality is reduced, and sediment production and flood risks are increased. The consequences of soil impoverishment cause irreparable damage, including the abandonment of farms, increased migration, economic, social, and political problems. In this regard, paying attention to soil and water resources conservation is one of the most necessary measures to control erosion. So that the performance of natural ecosystems increases through conserving the soil and preventing the occurrence and intensification of erosion. Therefore, it is essential to know different stages of erosion and evaluation of the factors governing it in properly managing soil and water resources in a watershed. So far, various biological methods and structures are used to control soil and runoff loss in watersheds. Since biological methods are based on ecosystems' conditions, it is essential to control soil erosion in the early stages. In recent years, extensive methods for the conservation of soil and water resources have been introduced and used in practice. Therefore, one of the most important methods of protecting soil and water resources is the use of biological methods in terms of low use of tillage operations, limited intervention, and manipulation in nature, cost-effectiveness, and also better efficiency than structural measures. However, the biological management of soil erosion has not yet been welcomed by executive experts due to the lack of a proper implementation model.Materials and Methods: The present study was conducted to investigate biological erosion management in the Gavoshan Watershed, Iran, due to distributed and manageable erosion and the available information. The Gavoshan Watershed, with an area of 7736 ha, the mean annual precipitation of 339 mm, the minimum and maximum elevations of 1635, and 2455 meters above sea level, is located in Kermanshah Province. After determining the erosion status, climatic characteristics, and plant growth conditions, the executive procedure of biological management of the region was proposed.Results and Discussion: The results showed that surface erosion is predominant in the area, and therefore the suitability of the conditions for bio-management measures was confirmed. While reporting the prevalence of sheet erosion, the results emphasized the erosion status in the low and moderate classes and the ability to perform biological approaches in the watershed based on the climatic-agricultural map. The results further showed that according to the climatic-agricultural map, the whole study watershed was divided into five categories. In this regard, the second category with an area of 3421 ha had the highest, and the fifth category with 82 ha had the lowest areas. Finally, after determining the area of different land-uses and according to the maps of soil erosion and climatic-agricultural conditions as well as ombrothermic and hetherograph diagrams, suitable rangeland species were selected and suggested for each climatic-agricultural category based on the expected characteristics of elevation, precipitation, temperature, phenology and adequate role in soil conservation. Finally, the executive plan of biological management of soil erosion in the Gavoshan Watershed was presented based on phytosociology and relevant ecological expectations. Since bio-management measures are applicable in rangelands with moderate and poor vegetation conditions, the good rangelands were not prioritized for the planning. Accordingly, moderate and weak rangelands with an area of about 4219 ha, i.e.> 54%, of the watershed were considered for biological activities. It is expected that by taking biological measures, erosion control will be done in the early stages, and by increasing the vegetation level in 54.63% of the watershed, in addition to controlling soil erosion or at least stopping it in the early stages, carbon sequestration conditions, nitrogen fixation, and increase soil fertility. The use of endemic species in this watershed would facilitate ecological balance and at the same time protect the basic resources of water, soil, and vegetation by increasing the level of ground cover.Conclusion: Biological management is a new approach in soil and water resource sustainable management that inhibits soil loss in the early stages of erosion and prevents the destruction of ecosystems. The results of the present study are anticipated to meet the expected needs in the protection of soil and water resources in similar watersheds in the west of the country. The results of the present study can be used in soil and water resources management in the western regions of the country with similar ecological conditions. Although the proposed approach can be used in most parts of the country rangelands, appropriate field studies and continuous monitoring of the proposed function will be necessary to provide comprehensive and integrated conclusions for soil and water resources management.
Soil science
Hamid Reza Matinfar; M. Jalali; Z. Dibaei
Abstract
Introduction: Understanding the spatial distribution of soil organic carbon (SOC) is one of the practical tools in determining sustainable land management strategies. Over the past two decades, the use of data mining approaches in spatial modeling of soil organic carbon using machine learning techniques ...
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Introduction: Understanding the spatial distribution of soil organic carbon (SOC) is one of the practical tools in determining sustainable land management strategies. Over the past two decades, the use of data mining approaches in spatial modeling of soil organic carbon using machine learning techniques to investigate the amount of carbon to soil using remote sensing data has been widely considered. Accordingly, the aim of this study was to investigate the feasibility of estimating soil organic matter using satellite imagery and to assess the ability of spectral and terrestrial data to model the amount of soil organic matter.Materials and Methods: The study area is located in Lorestan province, and Sarab Changai area. This area has hot and dry summers and cold and wet winters and the wet season starts in November and ends in May. A total of 156 samples of surface soil (0-30 cm) were collected using random sampling pattern. Data were categorized into two categories: 80% (117 points) for training and 20% (29 points) for validation. Three machine learning algorithms including Random Forest (RF), Cubist, and Partial least squares regression (PLSR) 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 measurement images, and in order to reduce the volume of data, the principle component analysis method (PCA) was used to select the features that have the greatest impact on quality.Results and Discussion: The results of descriptive statistics showed that soil organic carbon from 0.02 to 2.34% with an average of 0.56 and a coefficient of variation of 69.64% according to the Wilding standard was located in a high variability class (0.35). According to the average amount of soil organic carbon, it can be said that the amount of soil organic carbon in the region is low. At the same time, the high value of organic carbon change coefficient confirms its high spatial variability in the study area. These drastic changes can be attributed to land use change, land management, and other environmental elements in the study area. In other words, the low level of soil organic carbon can be attributed to the collection of plant debris and their non-return to the soil. Another factor in reducing the amount of organic carbon is land use change, which mainly has a negative impact on soil quality and yield. In general, land use, tillage operations, intensity and frequency of cultivation, plowing, fertilizing, type of crop, are effective in reducing and increasing the amount of soil organic carbon. Based on the analysis of effective auxiliary variables in predicting soil organic carbon, based on the principle component analysis for remote sensing data, it led to the selection of 4 auxiliary variables TSAVI, RVI, Band10, and Band11 as the most effective environmental factors. Comparison of different estimation approaches showed that the random forest model with the values of coefficient of determination (R2), root mean square error (RMSE) and mean square error (MSE) of 0.74, 0.17, and 0.02, respectively, was the best performance ratio another study used to estimate the organic carbon content of surface soil in the study area.Conclusion: In this study, considering the importance of soil organic carbon, the efficiency of three different digital mapping models to prepare soil organic carbon map in Khorramabad plain soils was evaluated. The results showed that auxiliary variables such as TSAVI, RVI, Band 10, and Band11 are the most important variables in estimating soil organic carbon in this area. The wide range of soil organic carbon changes can be affected by land use and farmers' managerial behaviors. Also, the results indicated that different models had different accuracy in estimating soil organic carbon and the random forest model was superior to the other models. On the other hand, it can be said that the use of remote sensing and satellite imagery can overcome the limitations of traditional methods and be used as a suitable alternative to study carbon to soil changes with the possibility of displaying results at different time and space scales. Due to the determination of soil organic carbon content and their spatial distribution throughout the region, the present results can be a scientific basis as well as a suitable database and data for the implementation of any field operations, management of agricultural inputs, and any study in sustainable agriculture with soil properties in this area. In general, the results of this study indicated the ability of remote sensing techniques and random forest learning model in simultaneous estimation of soil organic carbon location. Therefore, this method can be used as an alternative to conventional laboratory methods in determining some soil characteristics, including organic carbon.
Soil science
K. Asadzadeh; H. Nadian; A. Siahpoosh; V. Keshavarz-Tohid
Abstract
Background and Objectives: In recent years, the production of healthy foods through environmentally friendly methods has received much attention. Spinach is a vegetable plant rich in minerals and vitamins which is used in green and cooked forms. Thus, healthy production of this plant with the greatest ...
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Background and Objectives: In recent years, the production of healthy foods through environmentally friendly methods has received much attention. Spinach is a vegetable plant rich in minerals and vitamins which is used in green and cooked forms. Thus, healthy production of this plant with the greatest quantitative and qualitative yield is of particular importance. Weeds as unwanted plants in spinach fields can damage this plant significantly. Nevertheless, spinach is severely sensitive to different herbicides. The goal of this study was to investigate the effect of plant growth promoting rhizobacteria (PGPR), filter cake and metribuzin herbicide on growth and mineral nutrition of spinach plant. In this study, the growth and nutritional parameters of spinach interact with PGPR, filter cake and metribuzin herbicide was also aimed.Materials and Methods: The spinach seeds (Spinacia oleracea L. Varamin cultivar) were sown in pots containing 40% field soil and 60% sand (10 seeds in each pots). To investigate the impact of PGPR isolates and filter cake on concentration of macronutrients (K, Ca, Mg, and P), micronutrients (Cu, Zn, and Fe) and leaves dry weight, Pseudomonas protogenes CHA0 (CHA0) as a reference strain, P. alloputida RUM14 (RUM14) which was collected from Iranian field soil and 3% by weight of fresh filter cake (F3%) were used. Spinach seedlings were inoculated for 14 days with 50 mL of bacteria strains suspension with optical density one (OD600=1). 3% by weight of filter cake were mixed to soil of pots before sowing the seeds. Metribuzin herbicide at three levels (0 (H0), 50 (H1) and 100 (H2) grams per hectare) were used. The effects of PGPR, filter cake and metribuzin herbicides and their interactions were also studied (CHA0 + F0 + H1, RUM14 + F0+ H1, CHA0 + F0 + H2, RUM14 + F0 + H2, B0 + F3% + H0, B0 + F3% + H1, B0 + F3% + H2, CHA0 + F3% + H1, RUM14 + F3% + H1, CHA0 + F3% + H2, RUM14 + F3% + H2). The experiment had a randomized complete block design with three replications. The treatments (3 metribuzin herbicide × 2 filter cake × 3 PGPR) were arranged in factorial combination. The statistical analysis was performed using Duncan’s multiple range test at 5% probability level.Results: Statistical analysis revealed that the application of PGPR (CHA0 and RUB14), filter cake, and their interaction increased tissue plant concentration of macronutrients, micronutrient and leaf dry weight of spinach plant. Statistically, the highest concentration of P, K, Ca, and Mg macronutrients (5583.30, 83000.00, 10886.70, 10766.60 mg kg-1 dry matter, respectively), Cu, Zn, and Fe micronutrients (22.73, 73.00, and 221.36 mg kg-1 dry matter, respectively) and dry weight of leaves (8.76 g) was observed in treatment of combination of PGPR and filter cake. The application of Metribuzin herbicide led to decline the concentration of macronutrients, micronutrient, and leaf dry weight of spinach plant. The decline increased with increasing herbicide concentration. The lowest concentration of P, K, Ca, and Mg macronutrients (3233.30, 48867.00, 6403.30, and 6283.30 mg kg-1 leaf dry weight, respectively), Cu, Zn, and Fe micronutrient (4.40, 19.50, and 132.66 mg kg-1, respectively), and leaf dry weight (2.83 g) was observed in B0+F0+H2 treatment (using just herbicide 100 g ha-1). However, the detrimental effect of herbicide on leaf dry weight and mineral nutrition of spinach plant were alleviated using the PGPR (CHA0 and RUB14) and filter cake (F3%) either alone or together (RUM14+F3%, CHA0+F3%). Statistically, the greatest alleviation of the detrimental effect of herbicide was observed in the treatment of RUM14+F3%.Conclusion: The results of this research showed that inoculation of spinach with Pseudomonas PGPR (P. protogenes CHA0, P. alloputida RUM14) with and without filter cake not only improved the growth and mineral nutrition of spinach plant, but also alleviated the detrimental effect of herbicide in the plant. In general, the proper function of PGPR and filter cake in spinach plant growth is due to 1- Supplying more nutrients to the spinach plant due to filter cake rich in nutrients 2- The ability of Pseudomonas bacteria to induce resistance of the plants to stress and supply of some nutrients such as iron due to its ability to produce siderophore 3- Supply of food by filter cake for further growth of PGPR and the possibility of increasing the population of these bacteria. 4- Filter cake rich in organic matter can improve the physical and biological properties of the soil and can provide the better conditions for plant growth and nutrition. The results of this research showed that P. alloputida RUM14 and filter cake can be used as biological and organic fertilizers.
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.
Soil science
A. Zeinadini; M.N. Navidi; A. Asadi Kangarshahi; M. Eskandari; S.A. Seyed jalali; A. Salmanpour; J. Seyedmohammadi; M. Ghasemi; S.A. Ghaffarinejad; Gh. Zareian
Abstract
Introduction: Iran is one of the most important countries in citrus (oranges) production. Citrus fruits are grown in different soils with a wide range of physical, chemical and fertility properties in the country, although some restrictions in the cultivated lands cause yield loss. In this regard, the ...
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Introduction: Iran is one of the most important countries in citrus (oranges) production. Citrus fruits are grown in different soils with a wide range of physical, chemical and fertility properties in the country, although some restrictions in the cultivated lands cause yield loss. In this regard, the present study was conducted to investigate the effect of physical, chemical and soil fertility characteristics on citrus yield in important areas under cultivation, the regression relationships of characteristics with yield, and the rating of soil and land parameters. Materials and Methods: The 138 oranges orchards (118 orchards for rating and 20 orchards for validation) were selected in Fars, Mazanderan, Kerman and Guilan provinces. In each garden, a questionnaire was completed, a soil pedon was studied and soil samples were taken to carry out the appropriate physicochemical analyses. The selected soil and land characteristics were soil salinity (EC), exchangeable sodium percentage (ESP), pH, gypsum content, soil calcium carbonate (TNV), organic carbon (OC), clay, sand, silt, gravel, and soil available phosphorus and potassium contents. From the whole obtained data, 20 data were considered for validation purpose and the remaining data were used for modeling based on stepwise multivariate and simple regression methods. In these equations, the relationship between yield, as dependent variable, with soil and land characteristics, as independent variables, was investigated. Finally, land characteristics rating was obtained by the FAO method and the proposed crop requirements table was evaluated using the validation dataset. Results and Discussion: The results of descriptive statistics analysis showed that the variance values for available potassium, sand, clay, gravel and TNV were high and for pH and OC and gypsum were negligible. Therefore, most soil properties have a wide range of variation which could be related to the fact that oranges are grown in a wide range of soil types. The value of TNV varied between 10 and 33.3%. The presence of carbonate in soil reduces the availability of macro- and micronutrient elements in direct and indirect manners. The average of EC in the studied orchards was 5.4 dS.m-1. Minimum, maximum and average of ESP were 1.7, 28 and 10.7, respectively. The lowest and highest salinity and sodicity were observed in Mazandaran and Kerman soils, respectively. Maximum, minimum and average percentage of gypsum were 12, 0.36 and 3.54%, respectively. The highest amount of gypsum was observed in Bam and Shahdad regions of Kerman province and the lowest gypsum content was observed in Mazandaran and Guilan provinces. The soil pH varied from 6.63 to 8.8 with the average of 7.8. The soil OC values were between 0.05 and 3.53% and its average was 0.89%, showing the fact that the most studied soils were poor in organic matters. The average of soil available phosphorus and potassium in the studied orchards for citrus was less than the critical level. The average, minimum and maximum of available potassium were 224, 100 and 360 mg.kg-1, respectively. The mean, minimum and maximum amounts of available phosphorus were 21.6, 8 and 45.9 mg.kg-1, respectively. According to the multivariate regression model, among soil properties, EC, ESP, TNV, gypsum, gravel, available phosphorus and potassium were selected by the model. The determination coefficient of the model was 0.95, indicating that these properties have the greatest effect on citrus yield. Simple regression equations demonstrated that TNV, gypsum, EC, ESP, sand, clay, gravel, available potassium and phosphorous had the highest correlation (R2 > 0.6); and soil OC and pH had the lowest correlation (R2<0.2) with yield. The equations also revealed that soil EC, ESP, gypsum, TNV and gravel percentage had the greatest effect in yield loss, and soil organic carbon, absorbed phosphorus and potassium had the greatest effect on increasing citrus yield. As stated in equations, reported permissible and critical thresholds for effective soil properties on citrus yield, were 2.4 dS.m-1 for EC, 5 for ESP, 1.5% for gypsum, 20% for TNV, 22 mg.kg-1 for available phosphorus, 280 mg.kg-1 for available potassium, 110 cm for soil depth, and >2 m for groundwater level. Finally, evaluating the proposed crop requirements table with validation dataset fitted between citrus yield and soil index, resulted in the determination coefficient value of 0.79, denoting the acceptable accuracy of proposed table. Conclusion: Overall results showed that the main land limiting characteristics for orange production were soil salinity and sodicity, high amount of soil calcium carbonate and gypsum. Among unsuitable physical and fertility properties of soil, salinity and sodicity are the most effective factors affecting yield reduction. Consequently, proper management practices such as introducing cultivars compatible with these soil conditions, soil remediation and leaching operations to reduce soil salinity and sodicity are necessary. Furthermore, in most areas under orange cultivation such as Fars and Kerman provinces, the soil calcium carbonate content is more than the critical level for plant growth. In addition, the averages of soil available phosphorus and potassium were less than the critical levels, which should be considered for nutrient management of orchards. The proposed table of crop requirements seems to be accurate enough to conduct land suitability studies for orange varieties, especially cultivars grown in the north and south of the country.
Soil science
M. Gheitasi; Sh. Kiani; A. Hosseinpur
Abstract
Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification ...
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Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification inhibitors (NI) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in soil. In different studies, the positive effects of these compounds on the reduction of N losses from soil and increase of N use efficiency and crop yield have been demonstrated. The 3,4-dimethylpyrazole phosphate (DMPP) is a very popular nitrification inhibitor around the world. The efficacy of this molecule depends on climatic conditions and soil properties including of texture, pH, organic matter, moisture, temperature and mineral nitrogen. In this experiment, the effects of NI 3, 4-dimethylpyrazole phosphate on the N use efficiency of two spinach varieties were investigated in different soils.
Materials and Methods: A pot experiment was conducted in a completely randomized design with a factorial arrangement with three replications at Shahrekord University. Experimental factors were different N fertilizer sources, soil types and spinach varieties. Three N fertilizer sources consisted of urea, ammonium sulfate nitrate (ASN) and ASN plus DMPP (0.8 %). A no added N fertilizer treatment was considered as the control. The soil factor contained three different soils with different physical and chemical characteristics. The textures of the soils No. 1, 2 and 3 were loamy sand, loam and silty clay, respectively. Three selected soils were non-saline (EC1:2=0.14-0.31 dS m-1) and alkaline (pH1:2=7.9-8.0). Organic carbon and calcium carbonate equivalent (CCE) ranged from 0.26 to 0.35%, and 28.5 to 36.2%, respectively. Two spinach varieties were smooth-leaf (Giant Santos) and wrinkled-leaf (Viking). The used soils were mixed homogenously with 100 mg P kg−1 soil as triple super phosphate, 5 mg Fe kg−1 soil as Fe-EDDHA, 15 mg Zn kg−1 soil as ZnSO4.7H2O, 5 mg Mn kg−1 soil as MnSO4.H2O and 2.5 mg Cu kg−1 soil as CuSO4.5H2O. Nitrogen was applied at the rate of 150 mg kg-1 soil in two split doses before sowing and after one month. Twelve seeds were sown in 7 kg soil in plastic pots, and then placed in a greenhouse. The pots were thinned to 7 seedlings per pot after plant establishment. One week before harvesting, 10 measurements were done using a chlorophyll content meter to determine chlorophyll content index of leaves. At the end of the experiment, shoot dry weight was determined and plants were mixed and dried to measure N concentration. Finally, shoot N uptake and N use efficiency were calculated in different treatments.
Results and Discussion: In the present study, spinach plants fertilized with ASN+DMPP had a better appearance (dark green color) than those grown without DMPP. The results indicated that application of ASN with DMPP led to significant increase of leaf chlorophyll content index in comparison of ASN and urea fertilizers in all studied soils. Application of DMPP slowed down the process of ammonium oxidation to nitrite. Thus, this increase may be due to the role of ammonium in N nutrition of spinach plants treated with DMPP. This may be explained by the fact that ammonium has a positive effect on the synthesis of polyamines, cytokinins and gibberellins. The presence of these two phytohormones retarded senescence and chlorophyll degradation in plants. However, adding ASN to DMPP resulted in a significant decrease of shoot dry weight as compared with the ASN and urea fertilizers in soils No. 1 (loamy sand) and 2 (loam). In soil No. 3, shoot dry weight was not affected in plants fertilized with ASN+DMPP. Also, agronomic and physiological efficiencies of N significantly decreased by applying ASN+DMPP in comparison with ASN. It seems that application of DMPP strongly delayed the ammonium nitrification to nitrate, and consequently the soil nitrate availability appears not to be synchronized with spinach N needs. Due to short growth cycle of spinach, low availability of nitrate resulted in decreased shoot dry weight of spinach. The highest N use efficiency was observed is soil No. 2 (loam) and Giant Santos had more N use efficiency than Viking.
Conclusion: The results demonstrated that using ASN+DMPP led to yield loss, and we cannot recommend its application as a nitrogen fertilizer for spinach. However, application of ASN+DMPP is an effective strategy for improving qualitative appearance (dark green color) of spinach. Also, all studied indices were not affected in plants fertilized with ASN and urea. Therefore, application of both fertilizers is recommended for spinach production under similar conditions of the present study.
Soil science
R. Naseri; A. Mirzeai; A. Abbasi
Abstract
Introduction: Biofertilizers play a crucial role in soil fertility by dissolving stabilized phosphates and producing the nutrients needed for plant growth in the soil. One of the most important soil microorganisms is mycorrhizal fungi. Mycorrhizal fungi, with their extensive hyphae network and increasing ...
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Introduction: Biofertilizers play a crucial role in soil fertility by dissolving stabilized phosphates and producing the nutrients needed for plant growth in the soil. One of the most important soil microorganisms is mycorrhizal fungi. Mycorrhizal fungi, with their extensive hyphae network and increasing the level and speed of root uptake, increases the plant efficiency in nutrients, especially inactive elements such as phosphorus, and improves plant growth. Mycorrhiza fungi increase nutrient uptake of plants due to stimulation of root formation and subsequent increase in root level through the production of auxin and gibberellin hormones. By extending the root system, mycorrhizal fungi increase the total absorption surface of inoculated plants and thus improves crop plant access to water absorption. Considering the important and critical role of roots in crops, having sufficient information and understanding the morphological characteristics of the root system is important. Therefore, this study was conducted to investigate the role of the root system in the presence of mycorrhizal fungi in new barley cultivars in the Ilam region in rainfed conditions. Materials and Methods: In order to investigate the effect of inoculation with mycorrhiza fungi on the root system of barley cultivars in rainfed conditions, a factorial field experiment was carried out based on a randomized complete block design with three replications in the farm station of Sarablah Agricultural Research Center during 2019-2020 cropping season. Experimental treatments were including barley cultivars (Mahali, Mahour, Khorram, and Fardan) and fertilizer sources treatment including control (without fertilizer), 50% P fertilizer, mycorrhizal fungi (Glomus mosseae, Glomus etunicatum, and Rhizophagus irregularis), mycorrhizal fungi+50% P chemical fertilizer and 100% P chemical fertilizer. Root-related characteristics were measured inside the field at the pollination stage using a metal cylinder with dimensions of 30 cm in length and 2 cm in width, which had been pre-designed by hand. To measure grain yield after removing the marginal effects (50 cm from the beginning and end) were recorded for each plot. Statistical analysis of the data of this research project was done by SAS software, means were compared by Duncan’s multiple range test method, and graphs were prepared by Excel software Results and Discussion: This study showed that the interaction between cultivar× fertilizer sources was significant on the characteristics of rainfed barley roots. So that the maximum root length (76.6%), root volume (75.7%), root area (73.3%), root length density (76.8%), root tissue density (89.9%), root-specific mass (65.7%), and root surface area density (70.6%) was obtained from Fardan cultivar×mycorrhizal fungi+50% P chemical fertilizer compared to control treatment (without fertilizer source). It seems that the presence of mycorrhizal fungi has caused changes in root morphology so that the spread of mycorrhizal mycelium related to the internal tissues of the root has increased root length. Conclusion: The results of this study showed that the use of mycorrhizal fungi increased root system and root morphological changes in new barley cultivars. What is clear and has been mentioned in the reports of other researchers is that the mycorrhizal fungi can gain maximum use of moisture and nutrient uptake by creating a strong rooting system in the host plant from the rhizosphere. Recent research has shown that Fardan cultivar in the presence of mycorrhiza fungi had maximum root length, root volume, root area, root length density, root tissue density, and finally, root surface area density, and when no fertilizer source was used, a large reduction in the rooting system was observed in all cultivars. Therefore, among the cultivars used, Fardan cultivar with co-consumption of mycorrhizal fungi and 50% of P fertilizer can cause the development of root system and ultimately increase grain yield in the region under dryland conditions.
Soil science
M. Zangiabadi; manoochehr gorji; P. Keshavarz
Abstract
Introduction: Soil quality can be considered as a comprehensive index for sustainable land management assessment. Studying the most important soil physical properties and combining them as an index of soil physical quality (SPQI) could be used as an appropriate criteria for evaluating and monitoring ...
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Introduction: Soil quality can be considered as a comprehensive index for sustainable land management assessment. Studying the most important soil physical properties and combining them as an index of soil physical quality (SPQI) could be used as an appropriate criteria for evaluating and monitoring soil physical changes. In this regard, this study was conducted to determine the most important soil physical properties and calculate the SPQI of medium to coarse-textured soils of Khorasan-Razavi province.
Materials and Methods: Torogh Agricultural and Natural Resources Research and Education Station of Khorasan-Razavi province is located in south-east of Mashhad city (59° 37' 33"-59° 39' 10" E, 36° 12' 31"-36° 13' 56" N). Soil texture variability in this research station is one of its outstanding features. The soil textures are classified into loam, silt loam, silty clay loam, clay loam, and sandy loam. More than 90% of agricultural soils in Khorasan-Razavi province are classified in these five texture classes. Using the available data, 30 points with different soil textures and OC contents were selected. The soil samples were collected from 0-30 cm soil depth at each point. Intact soil cores (5 cm diameter by 5.3 cm length) were used for sandbox measurements, and disturbed soil samples were used to determine other properties. Required laboratory analysis and field measurements were conducted using standard methods. In this research, 35 soil physical properties as total data set (TDS) including: soil moisture release curve (SMRC) parameters, particle size distribution and five size classes of sand particles, soil bulk and particle density, dry aggregates mean weight diameter (MWD) and stability index (SI), S-index, soil porosity and air capacity, location and shape parameters of soil pore size distribution (SPSD) curves, relative field capacity (RFC), plant available water measured in matric pressure heads of 100 and 330 hPa for the field capacity (PAW100 and PAW330), least limiting water range measured in matric pressure heads of 100 and 330 hPa for the field capacity (LLWR100 and LLWR330), integral water capacity (IWC) and integral energy (EI) of different soil water ranges were measured and calculated for 30 soil samples. The most important soil physical properties were selected using principal component analysis (PCA) method by JMP (9.02) software. Selected physical properties as minimum data set (MDS) were weighted and scored using PCA results and scoring functions, respectively. In this study, three types of linear scoring functions were used. The soil physical quality index (SPQI) was calculated by two scoring and two weighting methods for each soil sample and the differences between these four SPQIs were tested by sensitivity index.
Results and Discussion: Principal component analysis results showed that among 35 soil physical properties (TDS) which were studied at this research, six properties of mean pore diameter (dmean), PAW100, total porosity (PORT), EI LLWR330, SI and PAW330 accounted for about 90% of the variance between soil samples. Weight of the selected properties (MDS) was calculated by the ratio of variation in the data set explained by the PC that contributed the selected property to the total percentage of variation explained by all PCs with eigenvalue ˃ 1. In this research, the parameters of PAW100, total porosity (PORT), SI and PAW330 were scored using scoring function of more is better, EI LLWR330 was scored using scoring function of less is better and dmean was scored using scoring function of optimum by two scoring methods with score ranges of 0.1-1 and 0-1. Considering unweighted and weighted MDS and two ranges of scores, four SPQIs were calculated for each soil sample. The results showed that SPQIs which were calculated by the MDS derived from PCA method and scoring weighted MDS at the range of 0-1, had the highest sensitivity index and could represent the differences between the studied soil samples better than other SPQIs. By this method, maximum and minimum SPQI values for the studied soils were 0.82 and 0.12, respectively. SPQI is a relative comparison criterion to quantify the soil physical quality which could be applied only for the studied soils with specific characteristics.
Conclusion: The results of this research showed that minimum data set (MDS) explained about 90% of the variance between soil samples. Combining MDS into a numerical value called soil physical quality index (SPQI) could be used as a physical comparison criterion for the studied soils. From the SPQI based on the MDS indicator method, soil quality was evaluated quantitatively. Soil samples with grade I, II, III, and IV accounted for 10%, 36.7%, 30%, and 23.3% of the soil samples, respectively.
