Soil science
F. Rakhsh; A. Golchin; A. Beheshti Ale Agha
Abstract
Introduction
Soil texture is one of the most influential characteristics that affects the decomposition and retention of soil organic matter, as it directly or indirectly impacts the soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter stability. ...
Read More
Introduction
Soil texture is one of the most influential characteristics that affects the decomposition and retention of soil organic matter, as it directly or indirectly impacts the soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter stability. Organic matter adsorbed on phyllosilicate clays is more resistant to microbial decomposition than organic matter that has not interacted with any mineral. Exchangeable cations through the influence of physical and chemical characteristics of the soil probably cause changes in the absorption and retention of organic matter. In previous studies, the effect of soil texture on organic matter retention has been investigated, but the impact of clay type and exchange cation has not been investigated. This study aimed to examine the effect of different contents of vermiculite and zeolite clays and exchange cations on the mineralization of organic nitrogen.
Materials and Methods
A factorial experiment was conducted in a completely randomized design with three replications to study the effect of the type and content of clay and the type of exchange cations on organic nitrogen dynamics. Experimental treatments include two types of clay (vermiculite and zeolite), four different levels of clay (0, 15, 30, and 45%), and three types of exchangeable cations (Na+, Ca2+, and Al3+). The experiment included 24 treatments and three replications. There were total of 72 experimental units. Artificial soil of 50 grams was prepared separately according to the amount and type of clay and the type of exchange cation. "Next, alfalfa plant residues were added to all samples at a rate of 5% w/w. After inoculating and air-drying the samples, the moisture content was adjusted to 60% of the field capacity (FC) using distilled water. To prevent excess water from affecting the final moisture readings, the samples were first air-dried, and then sufficient distilled water was added to each sample to achieve 60% of FC. The samples were then kept in the dark for 60 days at a temperature of 23 °C. Distilled water was added and sealed to the bottom of the incubation jars to keep the moisture content of the soil samples constant during incubation. The percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were determined in the prepared samples. The data were analyzed using ANOVA, and the means were compared using Duncan's Multiple Range Test (DMRT). Before applying ANOVA, the data's normality and variance homogeneity were checked using Kolmogorov- Smirnov and Levene tests, respectively. The SPSS software (Windows version 25.0, SPSS Inc., Chicago, USA) and SAS software (version 9.4, SAS Institute Inc., Cary, NC) were employed for data analysis.
Results and Discussion
The results of variance analysis of the data showed that the effect of the type and content of clay and the type of exchangeable cation on the percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were significant (p< 0.01). The results revealed that, regardless of the duration of the samples, with the increase in the amount of clay, the percentage of inorganic nitrogen and the activity of enzymes decreased, but the nitrogen of microbial biomass increased. The highest percentage of inorganic nitrogen was obtained 60 days after incubation of the samples and in clays saturated with calcium, and the lowest amount of these attributes was obtained 15 days after incubation of the samples and in clays saturated with aluminum. The results showed that nitrogen mineralization increased with the samples' incubation time. Also, the highest percentage of mineralized nitrogen, microbial biomass nitrogen, and enzyme activity were observed in soils with vermiculite.
Conclusion
The increase in the incubation duration enhanced the percentage of inorganic nitrogen. The percentage of mineralized nitrogen and microbial biomass nitrogen was higher in soils with vermiculite than in soils with zeolite. Moreover, regardless of the incubation duration of samples, with increasing clay content, the percentage of mineralized nitrogen and enzyme activity decreased, but with increasing clay nitrogen content, microbial biomass increased. The highest and lowest amounts of mineralized nitrogen and nitrogen of microbial biomass were measured in soils with calcium and aluminum, respectively. The results showed the effect of the clay type and content and the exchangeable cation type on organic nitrogen dynamics.
Soil science
Z. Sohrabzadeh; Y. Kooch
Abstract
Introduction Shrub covers play a pivotal role in pasture ecosystems, exerting considerable influence on various biochemical processes that occur within the habitat and surface layers of the soil. Despite their significance, there is a scarcity of research exploring the impact of different ...
Read More
Introduction Shrub covers play a pivotal role in pasture ecosystems, exerting considerable influence on various biochemical processes that occur within the habitat and surface layers of the soil. Despite their significance, there is a scarcity of research exploring the impact of different types of shrubs covers on soil properties within pasture ecosystems. Consequently, this present study was undertaken to address this gap in knowledge and investigate the effects of shrub cover on soil characteristics specifically within a semi-arid climate, which is known for its delicate and vulnerable habitats. Materials and MethodsThe implementation of this research involved the consideration of the mountainous region of Kiakola, Nowshahr city. The current investigation focused on assessing the impact of various shrubs, namely Carpinus orientalis Miller, Crataegus microphylla C. Koch, Berberis integerrima Bunge, Prunus spinosa L., and Rhamnus pallasii Fisch. and C. A. Mey, on specific soil properies within the mountainous area of Kiakla, Nowshahr city. To carry out this research, 15 sites were selected for each of the aforementioned shrub species. Soil samples were collected from under the canopy of these species, specifically at a depth of 0-10 cm and a surface area of 30 cm × 30 cm. A total of 75 soil samples were then taken to the laboratory for analysis. The samples were divided into two parts: one part underwent physical and chemical tests after air-drying and passing through a 2 mm sieve, while the other part was stored at 4 degrees Celsius for biological tests. The presence or absence of significant differences in soil properties related to the type of shrub cover under investigation was determined using a one-way analysis of variance test. Principal component analysis (PCA) was utilized to establish the relationship between different soil characteristics within the studied shrub covers. Results and DiscussionAccording to the findings of this investigation, alterations in the shrub species present in the examined pasture habitat resulted in modifications to the majority of soil quality properties. Nevertheless, no statistically significant disparity was observed in the quantity of soil organic matter. However, it is worth noting that the quantity of organic matter in the subsoil of Carpinus species exceeded that of the other examined shrubs. Carpinus and Crataegus shrubs were associated with the lowest values of bulk density, while the shrubs under investigation had no significant impact on soil particle density. Furthermore, the subsoil of the Carpinus shrub cover exhibited the highest values of soil porosity. In the studied area, the most stable soil aggregates were observed beneath the Carpinus and Rhamnus shrubs. The subsoil of Rhamnus and Carpinus shrubs exhibited the highest and lowest quantities of sand, respectively. Similarly, the subsoil of Carpinus and Rhamnus displayed the highest and lowest quantities of clay, respectively. The soil under Rhamnus displayed the highest ratio of CR and MCR indices, whereas the subsoil of Carpinus exhibited the lowest values of these indices. Fulvic and humic acids demonstrated the greatest values beneath the Carpinus, Crataegus, Berberis, Prunus, and Rhamnus shrubs, respectively, following a comparable pattern. Additionally, the subsoil of Carpinus exhibited the greatest quantity of microbial ratio, while the soil under Rhamnus displayed the lowest quantity of this characteristic. The outcomes of the principal component analysis (PCA) revealed that the quantity of organic matter, clay content, fulvic and humic acids, porosity, and stability of soil aggregate in the soil beneath Carpinus played a significant role in enhancing the soil microbial ratio of this shrub in comparison to the other shrubs. Conclusion The findings of this investigation validate the capability of Carpinus foliage to ensure the conservation of soil quality indicators on the hilly grasslands of northern Iran. Therefore, it is proposed that restoration efforts be conducted in the designated region and other areas with similar ecological conditions. Additionally, it is recommended that special attention be given to the implementation of Carpinus and other indigenous shrub species to protect soil integrity.
Soil science
S. Hosseinzadeh; E. Fateh; A. Aynehband; M. Farzaneh; J. Habibi Asl
Abstract
Introduction Tillage is an important component of soil management that affects the production of crops. Maintaining and improving the quality of the soil is a basic requirement to ensure the sustainability of the ecosystem. This experiment was conducted in order to investigate the effect of different ...
Read More
Introduction Tillage is an important component of soil management that affects the production of crops. Maintaining and improving the quality of the soil is a basic requirement to ensure the sustainability of the ecosystem. This experiment was conducted in order to investigate the effect of different tillage methods and the use of plant residues on the yield, protein and nitrogen percentage of triticale plant and physical and chemical indicators of the soil. Materials and MethodsThe experiment was carried out as split plots based on a randomized complete block design with three replications at Shahid Chamran University of Ahvaz during 2023-2024. The main factor including different methods of tillage at three levels (conventional tillage, reduced tillage and no tillage) and the sub factor also including 5 levels of plant residue application (without residues (control), wheat residues, mung bean, sesame and half of wheat residues + half of residues Mung bean) were considered. The amount of residues used for each plot was approximately 30% of the biological yield of the product, which was considered to be 3, 1.5 and 1 ton.ha-1 for wheat, sesame and mung bean, respectively. At the end of the experiment yield and yield components, seed nitrogen and protein of triticale plant and physical characteristics (bulk density, percentage of porosity) and chemical (pH, EC, organic carbon content, nitrogen) soil properties were measured. All statistical calculations were made using SAS 9.3 statistical software and for the LSD test was used to compare the means at a probability level of 5%. Results and DiscussionThe interaction of tillage treatments and the use of plant residues showed that the highest grain yield was equal to 8.6 ton.ha-1 from the treatment of reduced tillage and the use of Mung bean residues, and the lowest value obtained was related to the effect of the treatment conventional tillage and no residues (control) with 3.5 ton.ha-1. The grain yield in the reduced tillage method was 12.5% and 7.6% higher than the conventional tillage and no tillage methods. The reduced tillage method resulted in a 32.2% increase in seed protein and a 32% increase in seed nitrogen compared to conventional tillage. The results also indicated a significant interaction effect between tillage treatments and residue application on grain yield (p < 0.01). Additionally, the interaction between tillage and residue application had a significant effect on soil bulk density (p < 0.01). The lowest bulk density (1.3 g.cm-3) was observed in the conventional tillage treatment combined with wheat and mung bean residues, with this combination falling within the same statistical group. The highest bulk density (1.75 g.cm-3) was obtained from the no-tillage treatment and the use of NO residues (Control). Based on the obtained results, the interaction effect of tillage treatments and the use of residues on soil organic matter, soil organic carbon and nitrogen soil (p<0.05). The interaction between the effects of tillage and the use of residues showed that the highest soil organic matter (1.53%) was from the treatment of reduced and the use of wheat residues. ConclusionThe results showed that tillage methods and the use of plant residues, in addition to affecting the percentage of nitrogen and protein of triticale seeds, also affected the physical and chemical indicators of the soil. The changes related to the physical and chemical indicators of the soil in the method No tillage are more than the two methods of reduced tillage and conventional tillage, and the improvement of these characteristics has been limited even at this time. Overall, from the point of view of soil protection, the results of this experiment clearly show the superiority of conservation tillage methods compared to conventional tillage methods. Sustainable agriculture aims to achieve optimal yields while preserving environmental structure and minimizing the adverse impacts of agricultural activities. One of the key challenges in sustainable agriculture is the lack of organic matter and its associated consequences. Implementing conservation tillage and managing plant residues-critical elements of agricultural production-can help address this issue. By improving soil quality, these practices contribute to increased productivity in farming. Acknowledgement We would like to thank the Research and Technology Vice-Chancellor of Shahid Chamran University of Ahvaz for funding this research, which is part of the research contract SCU.AA1400.309.
Soil science
Sahar Mehrnoosh; Ali Beheshti Ale Agha; Fatemeh Rakhsh; Morteza Pourreza; Ali Akbar Safari Sinegani
Abstract
IntroductionThe maintenance of planted forests in arid and semi-arid lands is important. Soil formation in forest ecosystems is different with different tree species. Tree species have a direct and indirect effect on soil organisms. Forest ecosystems change their species composition and abundance of ...
Read More
IntroductionThe maintenance of planted forests in arid and semi-arid lands is important. Soil formation in forest ecosystems is different with different tree species. Tree species have a direct and indirect effect on soil organisms. Forest ecosystems change their species composition and abundance of microorganisms, and consequently their biogeochemical cycles. The accumulation of vegetation biomass and the improvement of soil fertility can play a significant role in soil restoration.Materials and MethodsIn order to investigate the biological characteristics of the soil from 5 treatments, including agricultural (dry farming and relatively poor lands that are usually cultivated barley and wheat and have low productivity), pasture (pastures with minimal vegetation and high slopes that are affected by overgrazing have been changed to barren lands), forest with Acacia type (under and outside the crown), forest with the Cupressus arizonica type (under and outside the crown) and forest with the Pinus brutia type (under and outside the crown) randomly. Sampling was done in 3 repetitions from the 0 to 5 cm layer. The statistical sampling design of this research was completely random, in which, according to the type of afforested species, two types of coniferous forest stands (including Cupressus arizonica and Pinus brutia) and one broadleaf stand (Acacia species) were selected. Also, the area under the crown trees and outside the crown trees was also investigated. Soil samples were sampled with sterile equipment and crushed through a 4-mm sieve. Fresh and moist soil was kept at 4 °C temperature for soil biological tests. Microbial biomass carbon, soil basal respiration (197 days), substrate-induced respiration, and metabolic quotient were measured. Streptomycin sulfate was used to measure fungal respiration and cycloheximide was used to measure bacterial respiration. The activities of urease, acid, and alkaline phosphatase enzymes were determined. After measuring the biological properties of the soil, the normality of the data was checked by the Anderson–Darling test, and the homogeneity of the variance of the treatments was checked by using Levene's test. Analysis of data variance was done using One-Way ANOVA and average data comparison was done using Duncan's test at 5 and 1% probability levels (SAS 9.4 and SPSS 26).Results and DiscussionThe results of soil biological characteristics analysis showed that the highest values of soil respiration and amount of consumed organic matter, substrate-induced respiration, microbial biomass carbon, enzyme activities, and fungal respiration were measured in conifers. Although the amount of these features was also significant in broadleaf trees, they had significant differences. In this study, the high soil respiration rate in coniferous covers compared to broadleaf can be due to the high organic carbon content of the soil in this cover. According to the results of substrate-induced respiration in different coatings, likely the activity of microorganisms involved in the decomposition of organic matter in the studied habitats had a significant difference; Therefore, different coatings can affect the population of soil microorganisms as the main source of decomposition and emission of carbon dioxide by changing the quantity and quality of organic matter and other factors. Also, the highest values of metabolic quotient and bacterial respiration were observed in agricultural and pasture covers. A higher metabolic quotient in these covers indicates a decrease in the efficiency of the use of leaf litter by the soil microbial community. In general, the metabolic quotient in the bacterial community is higher than the fungal community; Therefore, it seems that the predominance of the bacterial population in agricultural and pasture cover has caused this index to increase, although plowing and cultivation, and disturbance of these covers have caused stress to this bacterial community and as a result increased the metabolic quotient deficit in these covers.ConclusionThe results of this research showed that the type of planted tree species causes significant changes in the biological characteristics of the soil. The current research shows that the forest, whether coniferous or broadleaf, had the highest values of enzyme activities, basal respiration, substrate-induced respiration, microbial biomass carbon, and the lowest values of metabolic quotient compared to agricultural and pasture covers. Afforestation increases biological activity and possibly the number and diversity of microorganisms, and improves soil characteristics in the long term. In agriculture and pasture land, due to the destruction of soil and aggregates by agricultural activities such as plowing or excessive livestock grazing, the amount of organic carbon and the activity of microorganisms decreases, and with the decrease of other soil characteristics, the quality of the soil decreases over time. From this research, it can be concluded that the planting of forest species in the soils of degraded areas in the long term can increase soil organic carbon due to high-quality leaf litter, and as a result, increase permeability and soil moisture. Increasing soil organic carbon increases the activity of microorganisms, and in the long term, it will improve various soil characteristics. Planting forest plants in the natural areas of the country, which were destroyed due to the change of use to agriculture and indiscriminate cultivation and finally abandoned, can improve the characteristics of the soil and, as a result, establish the native vegetation of the region, and increase the permeability of water in the soil, the risk of soil erosion, floods, etc. reduce.
Soil science
S. Rezaei; H. Bayat
Abstract
Introduction
Given the energy crisis in the world, increasing environmental pollution, clean, renewable energy and the reduction of environmental pollution are needed. Soil is the main source of agricultural production. Therefore, maintaining soil health and fertility is very important for sustainable ...
Read More
Introduction
Given the energy crisis in the world, increasing environmental pollution, clean, renewable energy and the reduction of environmental pollution are needed. Soil is the main source of agricultural production. Therefore, maintaining soil health and fertility is very important for sustainable food production. Nanotechnology is a good way to reduce soil issues in agriculture, a promising method to improve soil properties and significant capacity to increase yield. Nanotechnology is one of the newest technologies that is used in all fields of science and research due to its high potential and unique features, including natural resources and soil protection. Nanoparticles have the ability to change some physical, mechanical and chemical properties of soil due to their very high specific surface area and activity. Nanoparticles increase the cation exchange capacity of soil and soil porosity. Among all nanoparticles, zinc oxide (ZnO) is one of the most widely used nanoparticles. Zinc oxide nanoparticles due to their high specific surface area can act as a bonding agent between particles and stabilize the soil structure by flocculating soil particles. Although many studies have used zinc oxide nanoparticles (ZnO) in the field of heavy metal contamination in soil, aqueous solutions and plants, the effect of one nanoparticle on soils with different textures has been less reported. Therefore, objective of this study was to investigate the effect of zinc oxide nanoparticles on some physical and chemical properties of soils with different textures.
Materials and Methods
In this study, three soil samples with different textures, including sandy loam, loam and clay were collected from three locations as Malayer, Abbasabad and Nahavand, in Hamedan province, respectively. Samples were taken from soil surface (0-20 cm depth). The soil samples were transferred to the Soil Physics Laboratory. After air drying, they were passed through a 4 mm sieve and mixed with specific weight percentages of zinc oxide (ZnO) nanoparticles (zero, 0.5, 1 and 3 % W/W) in three replications. After preparing the treated samples, the soils were homogeneously poured into plastic containers measuring 18 × 5.5 × 18 cm with a specific bulk density related to the field. The treated soils in plastic containers, were wetted and dried with municipal water for 120 consecutive incubation period. After 120 days from the start of incubation, the samples were taken from the containers. Some physical and chemical properties including pH, cation exchange capacity, organic matter, calcium carbonate and electrical conductivity were measured.
Results and Discussion
The results showed that the use of nanoparticles increased the cation exchange capacity in two textures of loamy and clay soils. The increment was significant compared to the control in loamy soil at two levels of 1 and 3% and in clay soil in all three levels of 0.5, 1 and 3%. Electrical conductivity increased and decreased (P <0.05) at 3% level for loamy soil and at 3% for sandy loam and clay soils, respectively. In contrast, the application of nanoparticles led to a decrease in pH and organic matter content (P <0.05) in sandy loam and clay soils, respectively. At the level of zero and 0.5%, the order of pH was: sandy loam> clay> loamy soil, with significant differences. But at the level of 1%, the order of pH was: sandy loamy> loamy> clay, with significant differences. At 3% level, the order of pH was: loamy> sandy loam> clay, with significant differences. At all levels of zero, 0.5, 1 and 3% of zinc oxide nanoparticles, the amount of organic matter was significantly in loamy> clay> sandy loam. Application of different levels of zinc oxide nanoparticles in clay soil reduced the percentage of calcium carbonate (P <0.05) (at the 3% by weight level), but had no effect on the amount of this variable in sandy loam and loamy soils. At all levels of zero, 0.5, 1 and 3%, the amount of soil calcium carbonate was significantly in the following order: clay> sandy loam> loam.
Conclusion
According to the results obtained in this study, it can be concluded that the use of nanoparticles can be a good solution to reduce the harmful environmental effects of chemical fertilizers. In addition to the positive effect of zinc oxide nanoparticles on physical and chemical parameters in different textures, the selection of the most optimal level of zinc oxide nanoparticles should be economically applicable. This requires further studies to determine the significant effects of nanoparticles on the physicochemical properties of the soils in different conditions to determine the optimal amount of nanoparticles, in order to save costs.
Iman Nikravesh; Saeid Boroomand Nasab; AbdAli Naseri; Amir Soltani Mohamadi
Abstract
Introduction: Organic matter is considered as the main element for soil fertility by improving the condition of agglomeration, porosity and soil permeability. One of the most useful ways to use plant debris is to turn it into Biochar and Hydrochar. Biochar is a kind of coal produced from plant biomass ...
Read More
Introduction: Organic matter is considered as the main element for soil fertility by improving the condition of agglomeration, porosity and soil permeability. One of the most useful ways to use plant debris is to turn it into Biochar and Hydrochar. Biochar is a kind of coal produced from plant biomass and agricultural waste that is burned in the presence of low oxygen content or its absence. The hydrothermal process involves heating the biomass or other materials in a pressurized in the presence of water at a temperature between 180 and 250 C, and the result of this reaction is coal (Hydrochar) and soluble organic matter. Biochar and Hydrochar have several advantages such as climate change mitigation through carbon sequestration, soil cation exchange capacity (CEC) increasing, soil fertility, plant growth and root development, improved soil structure and stability, increased soil moisture storage capacity and soil pH adjustment. Coarse soils have large pores and they have low ability to absorb the water and nutrient. The aim of this research was to determine the optimum temperature of wheat straw Biochar and Hydrochar production, and to investigate the effect of these materials on bulk density, total porosity and moisture curve of Sandy Loam soil.
Materials and Methods: In order to produce biochar, at first the wheat straw was washed and dried in the oven. Then it was grinded and was made at different temperatures (200 to 600 ̊ C) inside a furnace for four hours. Similar to biochar, for producing hydrochar, after washing and drying the wheat straw it was grinded into particles ranges from 0.5 to 1 mm. Then it was placed in a stainless steel autoclave with deionized water. The autoclave was heated at different temperatures between 140-230 ̊ C for four hours. The optimum temperature for producing of biochar and hydro-char was determined by using stable organic matter yield index (SOMYI), and it was used in this study. The pH and EC of the biochar and hydro-char samples were measured by combining 1 g of a sample with 20 mL DI water. The cationic and anionic exchange capacity were determined by replacing sodium nitrate with hydrochloric and potassium chloride (Chintala et al., 2013). Surface area was obtained using methylene blue method. A CHNSO Elemental Analyzer (Vario ELIII- elementar- made in Germany) was used to determine the content of C, N, H, S and O in the samples. Potassium and sodium content were measured by flame photometer and calcium and magnesium were measured by titration with EDTA. Biohchar and hydrochar treatments were applied at three levels of 2, 5 and 10 mg / kg soil in three replications in 21 lysimeter. The bulk density, total porosity and moisture curve of soil were measured after four-month irrigation period.
Results and Discussion: According to the calculated value of stable organic matter yield index (SOMYI) at various temperatures in this study, the maximum thermal constancy of wheat straw biochar was 16.20 at temperature of 300 ̊ C and for hydro-char was obtained as 6.13 at the temperature of 200 ̊ C. So, the temperatures of 300 and 200 ̊C were determined as the optimum temperature of sustainable carbon biochar and hydro-char production and were used to continue the experiments of this study. The results showed that addition of HW2, HW5, HW10, BW2, BW5 and BW10 to soil compared to control treatment significantly decreased the bulk density of the soil, 8.97, 11.77, 15.17, 7.9, 10 and 13.10 percent respectively. Also, results showed that addition of HW2, HW5, HW10, BW2, BW5 and BW10 to the soil as compared to control treatment increased soil porosity by 8.8, 11.48, 15.77, 6.48, 9 and 22.13 percent, respectively. The reason for reducing the soil bulk density and increasing the total porosity of soil can be due to the mixing of the soil with materials with a lower bulk density and the effect of increasing the organic matter of the soil due to the use of Biochar and Hydrochar. Based on statistical analysis, wheat straw Biochar and Hydrochar had a significant effect (P
azadeh ehsaninezhad; ali abbaspour; hamidreza asghari; hamidreza samadlouie
Abstract
Introduction: Phosphor (P) is the second nutrient element after nitrogen mostly required by plant. P is the main component of nucleic acid, phospholipid, ATP and some coenzymes. The effectiveness of phosphate fertilizer application is only about 15% - 20% and 10 – 25%, based on the different references.Rock ...
Read More
Introduction: Phosphor (P) is the second nutrient element after nitrogen mostly required by plant. P is the main component of nucleic acid, phospholipid, ATP and some coenzymes. The effectiveness of phosphate fertilizer application is only about 15% - 20% and 10 – 25%, based on the different references.Rock phosphate (RP) as a source of P is not expensive, but its availability of P is low. Solubility of RP can be increased by phosphate solubilizing microorganisms. Increasing RP solubility by microorganisms is due to the lowering of pH and/or organic acid excretion. Fungi have been reported to possess greater ability to solubilize insoluble phosphates than bacteria. Among the fungal genera with the phosphate solubilization ability, there are Aspergillus and Penicillium. Aspergillus Niger convert insoluble phosphates into soluble forms through the processes of acidification, production of organic acids, production of acid and alkaline phosphatases, and the release of H+ .These organic acids can either dissolve phosphates as a result of anion exchange or can chelate Ca, Fe or Al ions associated with the phosphates. The aim of this study was to investigate the effect of Aspergillus Niger and green manure on soil P solubility in the incubation conditions.
Materials and Methods: To investigate the effect of Aspergillus Niger and green manure on soil phosphorus availability, an experiment in a completely randomized design with three replications was conducted. The treatments were applied over a period of 70 days and were repeated at 3 incubations. The treatments were included C: control (50 g soil), As: Aspergillus Niger (50 ml/ kg), A: Green manure (1% weight of the soil), S: Sucrose (1 g/kg soil), P: Rock phosphate (150 kg/ha), As + A: Aspergillus niger + Green manure, As + S: Aspergillus Niger + Sucrose, As+P: Aspergillus niger + Rock phosphate, As + S + P: Aspergillus niger + Sucrose+ Rock phosphate , and As + A + P Aspergillus niger+ Green manure +Rock phosphate . Soils were air-dried and crushed to pass through a 2-mm sieve. Treatments were then applied to 50 g of soil and the treated samples were moistened to the field capacity (FC). The moisture of containers was kept near FC soil moisture content throughout the experiment by periodically weighing and replenishing evaporated water. At intervals of 7, 21, 35, 51 and 70 days, the samples were taken and after air drying, pH, EC, available soil phosphorus by Olsen method and soluble phosphorus were measured. The statistical analysis of all data obtained from the experiments was performed using the MSTAT-C software. The mean comparison was performed using Least Significant Difference (LSD) test at 5% level and drawing graphs using Excel software.
Results and Discussion: The results showed that all treatments had a significant effect on the measured parameters at 1% probability level. The effect of treatments and incubation Times on soil pH showed that all treatments were able to reduce soil pH. The greatest decrease was observed in Aspergillus Niger + Green manure (As + A) treatment that could reduce the pH by 0.59 unit. Usually, green manure decreases soil pH through decomposition and release carbon dioxide and organic acids. Aspergillus Niger also reduces pH and thus increases the solubility of soil phosphorus through the production of the metabolites and organic acids and microbial respiration. The effects of the treatments and incubation time on soil electrical conductivity showed that all treatments were able to increase soil electrical conductivity. Most of this increase was related to Aspergillus Niger+ Rock phosphate+ Green manure (As +P+ A) treatment .This increase was probably due to inorganic compounds found in green manure. The effects of the treatments and incubation time on soil available phosphorus and solube phosphorus showed that all treatments were able to increase them. Most of the soluble and available phosphorus amounts were observed in As +P+ A treatment and the amounts of increase resulting from this treatment for soluble and available phosphorus were 0/28 mg/l and 10/79 mg/kg, respectively. However, the green manure treatments and aspergillus alone increased soil soluble phosphorus, but with treatment of Aspergillus Niger (As) in green manure (A) observed that the amount of phosphorus in the soil solution was further enhanced. Organic acids resulting from the decomposition of organic matter by adsorption onto calcium phosphate surfaces and occupy the active sites such as nuclei for the formation of these deposits, prevent the growth of new crystals. These organic acids, in addition to the creation of the complex with calcium cations, reduce the activity.
Conclusions: The results of this study showed that use of phosphate solubilizing microorganisms and organic matter led to the significant decrease in pH and increase in electrical conductivity, dissolved phosphorus and available phosphorus in soil.. However, to obtain more accurate results, it is better to do a pot experiment as well.
tahereh mansouri; Ahmad Golchin; Zahra Rezaei
Abstract
Introduction: Selecting the right source of nutrient in a particular cropping situation requires a consideration of economic, environmental, and social objectives. One of the objectives is to keep all nutrient losses to a minimum. Since the use of nitrogen chemical fertilizers began more than 100 years ...
Read More
Introduction: Selecting the right source of nutrient in a particular cropping situation requires a consideration of economic, environmental, and social objectives. One of the objectives is to keep all nutrient losses to a minimum. Since the use of nitrogen chemical fertilizers began more than 100 years ago, it has been recognized that it can be lost as gaseous ammonia when an ammonical fertilizer is applied to calcareous soil. A process by which nitrogen exit from the soil in form of ammonia and enter to the atmosphere is called volatilization. Agricultural practices (use of chemical and animal fertilizers) are known as major sources of ammonia volatilization into the atmosphere. Nitrogen losses not only economically but also in terms of environment pollution is important. Ammonia volatilization is one way of the nitrogen losses from agricultural and non-agricultural ecosystems. A variety of soil chemical properties interact with environmental conditions at the site of the fertilizer application to determine the extent of NH3 loss. This article study some of the major factors that contribute to NH3 loss from N fertilizer. The aims of this study were to evaluate the impacts of concentrations of soil calcium carbonate (experiment 1), plant residue application (experiment 2), nitrogen fertilizer rate and source on volatilization of ammonia from soil.
Materials and Methods: Two factorial experiment with 36 treatments, three replications and 108 experimental unit for 25 days at a constant temperature of 30 ° C were conducted using a completely randomized design. The experimental treatments were three concentrations of soil calcium carbonate (20, 27 and 35% in experiment 1), three alfalfa plant residue application rates (0, 2.5 and 5% w/w in experiment 2), three rates of nitrogen (0, 200 and 400 kg/ha), four sources of nitrogen (urea, ammonium nitrate, ammonium sulfate and urea- sulfuric acid). Fertilizers were added to soil samples in form of solution and the moisture of soils was brought to field capacity. Samples were placed into special jars and amount of nitrogen volatilization were measured.
Results and Discussion: The results showed that ammonia volatilization from soil increased as the concentration of soil calcium carbonate, rates of nitrogen and alfalfa plant residues application increased. In first experiment the highest amount of nitrogen volatilization rate, as ammonia (33.21 µgr N/gr soil) was measured from 400kgN/ha soil for urea fertilizer and 35 percent calcium carbonate. Also the lowest amount (11.99 µgrN/gr soil) was obtained from 20 percent calcium carbonate without application of any nitrogen fertilizer. In this experiment, with an increase in the amount of soil calcium carbonate by 15%, the amount of volatilized nitrogen in the form of ammonia were six times. By increasing the amount of soil calcium carbonate of from 20 to 27% the amount of nitrogen losses as ammonia slightly increased but with a further increase of calcium carbonate (from 27 to 35%) the amount of nitrogen losses increased a lot and this increase was higher than the initial increase. The presence of calcium carbonate in the soil increase soil pH and ammonia volatilization. In second experiment the highest amount of nitrogen volatilization rate, as ammonia (32.28 µgr N/gr soil) was measured from 400kgN/ha soil for urea- acid sulfuric fertilizer and 5 percent of plant residues. Also the lowest amount (0.33 µgrN/gr soil) was obtained from soil without application of any nitrogen fertilizer and plant residues. The most of nitrogen losses in the form of ammonia in the amount of 15.34 micrograms per gram of soil was obtained from level of 5% of alfalfa residue. With the 2.5 percent increase in the alfalfa residue rate, ammonia volatilization from soil increased in rate of 3.24 micrograms per gram of soil and by increasing it from 2.5 to 5%, nitrogen volatilization increased in the amount of 8.88 micrograms per gram of soil.
Conclusion: The loss of nitrogen as ammonia with application of nitrogen fertilizers and without application of residues was as urea> ammonium sulfate> ammonium nitrate > urea-sulfuric acid and with application of crop residues was as urea-sulfuric acid
R. Jenabi Haghparast; A. Golchin; E. Kahneh
Abstract
Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil ...
Read More
Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil amended with 0 and 5% organic matter. The concentrations of Cd in soils were 0,10,20,40, 60 and 80 mg kg-1 and growth parameters of the earthworms were measured with 15 day intervals over 75 days. Survival, growth and cocoon production of earthworms were determined. The results showed that addition of organic matter to soils reduced the toxic effects of cadmium to earthworms. In soils contaminated with Cd the weights of the earthworms decreased with increasing the concentrations of this metal and cadmium had the highest negative effects on cocoon production. The highest earthworm’s mortality was recorded in soils contaminated with cadmium.
