Soil science
B. Kamali; A. Sotoodehnia; A. Mahdavi mazdeh
Abstract
Introduction Phosphorus is an essential soil nutrient that plays key roles in plant growth and development. Limited availability of P is the main constraint for crop production in many soils. Long-term phosphate fertilizers application in agricultural areas to increase the physiological efficiency ...
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Introduction Phosphorus is an essential soil nutrient that plays key roles in plant growth and development. Limited availability of P is the main constraint for crop production in many soils. Long-term phosphate fertilizers application in agricultural areas to increase the physiological efficiency of crops can lead to a significant P accumulation. The process of P fixation or sorption includes precipitation and adsorption onto mineral and organic surfaces. Various factors such as clay content, organic matter, exchangeable Al, Fe, Ca content and pH soil affect P sorption capacity. In order to achieve the proper management of P fertilization, it is necessary to understand the mechanism of the sorption process and the contributing factors, as well as how to influence these factors. Qazvin plain is one of the most important agricultural plains in Iran, playing a pivotal role in maintaining national food security. Cultivating crops such as wheat, barley, alfalfa and corn in different areas of this plain is widespread. Therefore, high amounts of phosphate fertilizers are applied in this plain every year. In this study, the kinetic and equilibrium adsorption of P in a heavy textured agricultural soil sample in Qazvin plain were investigated under the influence of some different environmental parameters.Materials and MethodIn order to conduct the kinetic adsorption experiment, one gram soil samples were placed in the shaker in contact with 25 ml of 0.01 M CaCl2 solution containing 20 mg P l-1. Time intervals were 0.17, 0.5, 1, 2, 4, 8, 16, 24, 48 and 72 hours. The effects of temperature (12, 25, 38 °C), salinity (0, 8.96, 17.02, 32.09, 46.25 dS m-1), pH (2.5, 3.5, 5.36, 7.5, 9.5, 11.5) and the type of background solution (distilled water and 0.01 M CaCl2 solution) were also investigated on P equilibrium adsorption. In the equilibrium batch experiments, the soil samples were placed in contact with the background solutions containing 0, 15, 20, 30, 50, 80 and 100 mg P l-1 (ratio 1:25) for 24 hours. The concentration of P in the samples was determined by a spectrophotometer after passing through the filter. The amount of P adsorption to each soil sample was then calculated based on the concentrations. The experiments were carried out in the factorial and completely randomized designs with three replications for each treatment. Using CurveExpert 1.4 software, the Langmuir and Freundlich isotherms, as well as the pseudo-first-order, pseudo-second-order, the Elovich and Intra-particle diffusion models were fitted to the obtained laboratory data. Statistical analysis of experimental data was done based on the Tukey test at 5% level using Minitab software. The thermodynamics of P adsorption was also determined by examining parameters of the Gibbs free energy, enthalpy and entropy changes.Results and Discussion According to the results, the highest amount of adsorption occurred in the first 8 hours of soil contact with P solution, and approximate time of achieving the equilibrium conditions was 24 to 48 hours. The process of P adsorption onto soil particles consisted of two fast and slow stages until the equilibrium was reached. The kinetic adsorption properties of the studied soil was best described by the Elovich equation (r2=0.964). The Freundlich model showed better fit than the Langmuir equation to the equilibrium data. The effects of all four parameters of temperature, salinity, pH and background electrolyte solution on the P equilibrium adsorption were significant. By changing the temperature from 25 to 38 °C, qm (Langmuir coefficient) was 2.1 times. It was also 7.5 times under the conditions of using CaCl2 solution instead of distilled water. Increasing pH caused an increase in adsorption rate and the highest amount of adsorption changes occurred in the pH varying between 5.36 and 7.5. However, the highest and lowest P adsorption percentage with the values of 45 and 37% were related to zero and 46.25 dS m-1 salinity, respectively. The results also indicated that the sorption process was endothermic and spontaneous.Conclusion Adjusting and controlling the studied parameters in the soil during the application of phosphate fertilizers can optimize P use efficiency and increase crop yield in the studied area. Based on the results of the present study, it is recommended to add sulfur, ammonium sulfate, ammonium nitrate fertilizers and organic compounds to the studied calcareous soil with high pH and low salinity. Application of this method can reduce soil pH, which leads to a decreased P sorption onto the soil particles and an enhanced P availability for plants. Adjusting the P fertilization time with the crop growth and uptake is also recommended due to the high adsorption of P onto the soil particles in a short period of time.
R. Saeidi; H. Ramezani Etedali; A. Sotoodehnia; .B Nazari; A. Kaviani
Abstract
Introduction: Supplying human and animal nutritional needs requires suitable use of water resources. Due to the decrease of fresh water resources for agriculture, saline water resources cannot be ignored. Increasing water salinity reduces the water absorption by plant, due to decreasing the water potential. ...
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Introduction: Supplying human and animal nutritional needs requires suitable use of water resources. Due to the decrease of fresh water resources for agriculture, saline water resources cannot be ignored. Increasing water salinity reduces the water absorption by plant, due to decreasing the water potential. On the other hand, soil infertility (such as nitrogen deficiency) decreases the evapotranspiration and crop yield. The present study was to increase the water and nitrogen fertilizer use efficiency of maize, under salinity stress condition. This was done by managing the consumption of saline water and nitrogen fertilizer. In this research, irrigation requirement was determined proportional to the plant evapotranspiration to avoid excessive saline water use. Materials and Methods: In this research, two treatments of water salinity and nitrogen deficiency in four levels and three replications were implemented as a factorial experiment in a randomized complete block design. The studied plant was maize (S. C. 704 cultivar) sown in plots with dimensions of 3 × 3 meters and 1.5 meters distance. In this research, fertility stress was in the form of nitrogen fertilizer consumption and at four levels. Treatments of ، ، and consisted of consumption of 100, 75, 50 and 25% of nitrogen fertilizer, respectively. Salinity stress has been applied by irrigation of the plant with saline water. Water salinity treatments were selected based on the yield potential of maize, at four levels of 100, 90, 75 and 50%. According to the above four performance levels, treatments of ، ، and included irrigation water with electric conductivity of 0.5, 1.2, 3.5 and 7.5 (dS/m), respectively. The soil moisture content was measured at the depth of root development during the interval between two irrigations. Daily maize evapotranspiration was measured by the volumetric balance of water at the depth of root development. The stomata resistance of maize leaf was measured by the AP4 porometer device between two irrigations interval. Variance analysis and mean comparison of data were done by SPSS software and Duncan's multiple range test, respectively. Results and Discussion: Water use efficiency In this research, the evapotranspiration and dry matter yield of maize decreased under salinity stress and nitrogen deficiency treatments. This seems to be caused by the water potential decrease (due to salinity stress) and the nitrogen deficit in the soil. Under these conditions, optimum use of water and fertilizer increased water use efficiency. At first without water and fertilizer management, water use efficiency in different treatments ( to ), ranged from 2.74 to 4.4 kg/ (in 2017) and from 2.57 to 4.35 kg/ (in 2018). With suitable management of irrigation, water use efficiency, however, increased in stress treatments and approached to optimum treatment. The range of water use efficiency was from 4.2 to 4.4 kg/ (in 2017) and from 4.15 to 4.32 kg/ (in 2018). The reason for this was the management of irrigation volume based on actual evapotranspiration in stress treatments. On the other hand, increasing soil nitrogen was an appropriate strategy to increase water use efficiency. But in high salinity stress, despite the optimum use of water and fertilizer, it was not possible to achieve optimal water use efficiency. This is explainable by the harmful effect of salinity on the reduction of nutrient uptake (especially nitrogen) by the plant. Nitrogen use efficiency Soil nitrogen deficiency and increasing water salinity reduced nitrogen use efficiency. In different stress treatments, nitrogen use efficiency ranged from 3.34 to 5.11 kg/kg (in 2017) and from 3.06 to 5 kg/kg (in 2018). The results showed the destructive effect of salinity on nitrogen uptake by the plant. Under these conditions, the ions in the soil (especially the sodium and calcium) caused the plant to be unable to absorb nitrogen from the soil. Therefore, the production of plant matter was reduced. The results showed that proper management of nitrogen can increase nitrogen use efficiency under salinity stress. At high salinity levels, the nitrogen fertilizer was not, however, absorbed by the plant and accumulated in the soil. Conclusion: The results showed that water use management could increase the water use efficiency under stress treatments, by controlling evapotranspiration. On the other hand, soil fertility increased nitrogen fertilizer use efficiency under salinity stress. Among all treatments, had optimum water and nitrogen use efficiency. Overall, the volume of water used in the field should be adjusted to the actual requirement of the plant to prevent excessive consumption under salinity stress. In addition, increasing soil nitrogen, rather than more irrigation water, appears to be a suitable strategy to increase crop yield.
B. Kamali; A. Mahdavi; A. Sotoodehnia
Abstract
Introduction: Over application of phosphorous-containing fertilizers is common among the farmers. Excess amounts of phosphorus can potentially cause more phosphorous losses through water flow on the soil surface or leaching into the soil profile. The ability of highly phosphorus-fertilized soils to maintain ...
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Introduction: Over application of phosphorous-containing fertilizers is common among the farmers. Excess amounts of phosphorus can potentially cause more phosphorous losses through water flow on the soil surface or leaching into the soil profile. The ability of highly phosphorus-fertilized soils to maintain excessive amounts of phosphorus and prevent losses largely depends on the phosphorus adsorption capacity of the soil. The purpose of this study was to investigate and compare phosphorous adsorption isotherms in soil samples of four agricultural areas located in Qazvin plain and determine the most appropriate equation to describe the equilibrium adsorption in the studied samples. Identification of the most accurate model of adsorption kinetics using the investigated kinetics equations in one of the soil samples was another objective of this study. The linear regression analysis and correlation between physical and chemical properties of different soils with adsorption coefficients of Langmuir equation was also investigated. Based on mentioned points, the results of this study can help to increase the availability of applied phosphorous for plants, reduce phosphorous losses and proper management of phosphate fertilizers consumption in the study areas.
Materials and Methods: In order to study the soil properties and phosphorous adsorption, soil samples of four villages included Zaaferan (A), Koochar (B), Mehdi Abad (C) and Kamal Abad (D) were taken from 0 to 30 cm depth and stored in plastic bags after air drying. Batch experiments using a standard method recommended by the SERA-IEG17 group were used to determine the amount of phosphorous adsorbed to soil particles. The steps to perform the equilibrium were as follows:
1- Dry soil samples were crushed and passed through a 2 mm sieve.
2- One gram of the soil sample was placed in a 60 ml container.
3- 0.01 M CaCl2 solution was prepared and different concentrations of phosphorous including 0, 5, 10, 15, 20, 30 and 80 mg/l were created by adding certain amounts of KH2PO4 to this solution. 25 ml of these solutions were added to each soli sample to give a 1:25 soil to solution ratio and three drops of chloroform were added to each container to prevent microbial activity.
4- The suspension samples were placed in a shaker machine (250 rpm) at 25°C for 24 hours.
5- Then, the samples were removed from the shaker and allowed to settle for one hour and then passes through a fine filter (Mesh 42).
6- Phosphorous concentration was measured by the molybdate-vanadate method followed by spectrophotometric determination at 470 nm.
7- The amount of phosphorous adsorbed in each soil sample was calculated from the difference of the initial and secondary concentration values.
The adsorption kinetics experiment was similarly performed, with the exception that one soil sample with average adsorption value (sample C) was selected and the phosphorous solution at a concentration of 20 mg/l added to the soil samples. Phosphorous contact times with soil were considered as 0.17, 0.5, 1, 2, 4, 8, 16, 24, 48 and 72 hours. In this study, using CurveExpert 1.4 software and by matching Pseudo-first-order, Pseudo-second-order, Intra-particle diffusion, Kuo and Lotse (1974), Barrow and Shaw (1975) and Panda et al. (1978), equations on the data obtained from kinetics adsorption experiments, and the coefficients were estimated in these equations (adsorption parameters). Furthermore, by calculating the coefficient of determination (R2) of these equations and the standard error of the estimate (s), the most appropriate and accurate model of phosphorous adsorption kinetics for the soil sample was determined. Similarly, from Langmuir, Freundlich, Linear and Van Huay equations, the most appropriate isotherm was determined for estimating phosphorous equilibrium adsorption in the studied areas. Also, correlation and linear regression analysis were performed to determine the relationship between the physical and chemical parameters of the soils and the coefficients of Langmuir isotherm using Minitab software.
Results and Discussion: According to the results, the highest coefficient of determination (R2) and the lowest standard error of the estimate (s) for all four samples were related to Langmuir, Freundlich, Van Huay and Linear equations, respectively. Therefore, in this study, Langmuir isotherm was the most accurate model for estimating equilibrium adsorption of the phosphorus to the soils of the study areas. However, the Freundlich and Van Huay equations also showed a good correlation with the laboratory data. Comparison of the results of various studies in these fields showed that the type of isotherm corresponds to phosphorous adsorption data in each experiment is related to the physical and chemical properties of soil and adsorption sites. The amounts of maximum phosphorous adsorption capacity (qm coefficient in Langmuir equation) for the soil samples A, B, C and D were 0.49, 0.31, 0.42 and 0.4 mg/g, respectively. In kinetic study, Although, Kuo and Lotse, Barrow and Shaw and Panda et al. equations had a coefficient of determination (R2) above 0.95 ; the highest accuracy was related to the Kuo and Lotse equation with R2 of 0.974. The coefficients of this model included k (reaction rate) and m (constant coefficient) were 0.007 l/gr.min and 13.2, respectively. Based on the results of this study and other adsorption studies, soil physical and chemical properties including EC, PH, soil calcium content, clay content and porosity were among the parameters affecting adsorption rate and the type of the most accurate equation of adsorption estimation. Considering the soil properties that were most correlated with adsorption coefficients, it can be concluded that the high percentage of clay and low levels of organic matter and soluble calcium are the main causes of the high phosphorous adsorption in soil. The correlation coefficients (r) of these three soil parameters with the maximum adsorption capacity (qm) were 0.61, -0.97 and -0.92, respectively.
Conclusion: According to the results of this study, Langmuir was the most accurate isotherm model and the soil sample of Zaaferan area has the most adsorption capacity with qm of 0.49 mg/g, which is related to low levels of soil organic matter. Therefore adding organic matter to the soils can be used as a solution to increase cultivated plants access to applied phosphorous and reduce phosphorous adsorption into the soil and thus reduce losses and leaching of excess phosphorous in the profile or soil surface.
reza saeidi; abbas Sotoodehnia; Hadi Ramezani Etedali; Bizhan Nazari; Abbas Kaviani
Abstract
Introduction: Estimating the actual evapotranspiration of the crops, is so important for determining the irrigation needs. Typically, the climatic, vegetative and management parameters are effective on actual evapotranspiration. If the crops are exposed to salinity, fertility and other stresses, reduce ...
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Introduction: Estimating the actual evapotranspiration of the crops, is so important for determining the irrigation needs. Typically, the climatic, vegetative and management parameters are effective on actual evapotranspiration. If the crops are exposed to salinity, fertility and other stresses, reduce actual evapotranspiration and yield. The correct estimation of the actual evapotranspiration of crop will allow agricultural planners to the better agricultural water management. Previous researches show water stress and soil nitrogen deficiency (as management stresses), effect on increasing of stomatal resistance and reducing of crops evapotranspiration. Thus, goal of this study was to investigate the effect of salinity and soil nitrogen deficiency on the amount of Ks coefficient and readily available water of maize.
Materials and Methods: This study was conducted in research farm at University of Imam Khomeini International, Qazvin, Iran during June to November 2017. In this research, the effects of saline water and soil nitrogen deficiency on Maize (SC 704) evapotranspiration, were investigated. The applied treatments included irrigation with saline water (in four levels: 0.5 (S_0), 1.2 (S_1), 3.5 (S_2) and 5.7 (S_3) dS/m) and soil fertility (in four levels: nitrogen fertilizer consumption at 100 (N_0), 75 (N_1), 50 (N_2) and 25% (N_3)). The experimental design used in this research was a completely randomized block design with three replications. In this experiment, maize seeds were cultivated in the plots with Length and width of 3×3 meters. The prometer device (Model: AP4) was also used to measure stomatal resistance of maize leaf. Determining the irrigation schedule, was based on the soil moisture reached to the limit of RAW (Readily Available Water). At the same time, with increasing stomatal resistance, RAW was calculated and irrigation was done. Evapotranspiration of the under stress plants were ET_(c-adj) and evapotranspiration of S_0 N_0 treatment was ET_c. The stress factor (K_s ) is calculated by ET_(c-adj)/ET_c. The values of RAW and K_s were analyzed by SPSS software. K_s coefficient was modeled with amounts of salinity stresses and soil nitrogen deficiency.
Results and Discussion: The results of this study showed that the interaction between two factors of salinity stress and nitrogen deficiency on the K_s and RAW parameters (in level: 1%) are significant. K_s coefficient at the levels of S_1, S_2 and S_3, were 0.95, 088 and 0.77, respectively. In saline water of 0.5 (dS/m), the K_s coefficient of N_1, N_2 and N_3 were 0.98, 0.96 and 0.95, respectively. With increasing the 1(dS/m) salinity of water and 25% reduction in nitrogen consumption, decreased the K_s amount about 4.5% and 1.7%, respectively. The reason of results is that with increasing of water salinity, decreases the osmotic potential of water in the soil and the crop needs to consume more energy to obtain water. Thus, amount of crop transpiration is reduced and soil water content is remained. The linear, exponential, logarithmic, polynomial and power functions were fitted between N_i/N_0 and S_i/S_0 data. The ability of the above functions to estimate the K_s coefficient value was evaluated. The polynomial function has a good function for estimating the K_s coefficient. In the S_0، S_1، S_2 and S_3 treatments, by changing the fertility value from N_0 to N_3, amounts of RAW were 63.7, 58.7, 55.4 and 42% , respectively. Also in N_0، N_1، N_2 and N_3 treatments, with changing the salinity of water from S_0 to S_3, RAW values were 51.7, 46.3, 42.7 and 42%, respectively. Therefore, stresses that reduce crop evapotranspiration are effective on reducing the amount of RAW. In this situation, the actual water requirement of the crop is less than the potential evapotranspiration of the area.
Conclusions: Increasing water salinity and nitrogen deficiency decrease evapotranspiration of maize and increase soil water content. By calculating the stress coefficient (K_s ), it is possible to estimate the actual evapotranspiration of maize, in Qazvin. Thus, the amount of irrigation water is adjusted according to the actual water requirement of maize. Under salt stress conditions with increasing the soil nitrogen, Can be increased the K_s coefficient and evapotranspiration of maize. Therefore, calculating the crop's water requirement based on the existence of strtesse, it will help to saving water.
H. Ramezani Etedali; Maryam Pashazadeh; B. Nazari; abbas sotoodehnia; A. Kaviani
Abstract
Introduction: Regarding population growth rate and drought challenges, one of the effective strategies for sustainable development in agricultural sector is irrigation. In this regard, in recent years, the use of tape irrigation method has been considered in crop plants, but the use of this system will ...
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Introduction: Regarding population growth rate and drought challenges, one of the effective strategies for sustainable development in agricultural sector is irrigation. In this regard, in recent years, the use of tape irrigation method has been considered in crop plants, but the use of this system will be successful if it is to evaluate the system performance in terms of soil sustainability before it is implemented and its problems are solved. Problems in the field of sustainable agriculture are saltinification of soil resources that the tape irrigation over time and due to the continuity of its use in cultivated land, especially in warm and dry areas due to global warming, climate change and decline of the atmospheric precipitation leads to salinity accumulation in the soil.
Materials and Methods: In order to investigate the distribution and changes of salinity of soil profile in the root development zone of wheat, maize, barley and tomatoes grown in Qazvin Plain with initial salinity of 1/5 dS/m and salinity of irrigation water 1 dS/m In hot and dry climate, a type of irrigation was used (strip drip) and during the 20 years of cultivation, the AquaCrop version 5 was used. The results of simulation output were analyzed by Minitab 17 and Excel 2007 softwares.
Results and Discussion: The results showed that in all previous stuides, the amount of salinity accumulated through the tape irrigation in the soil surface is greater, but in this study, due to the time effect on salt accumulation in the soil profile in the root development area, The maximum salt accumulation below the soil surface and at depths (0/5, 1/5, 0/5 and 0/16) meter of the total root development depth of each plant, respectively, for tomato, maize, barley and Wheat has occurred. It can be said that over time, accumulated salt on the surface of the soil evaporated, re-moved with irrigation and redistributed under the soil profile. Simulation results were obtained after statistical analysis with Minitab 17 and Excel 2007 software showed that in tomato and corn products, tape irrigation with irrigation water salinity of 1 dS/m resulted in significant increase in average salinity of The root development zone from 1/5 is 4 and 4/4 dS/m over the course of 20 years (correlation significance at 5% level) and sustainable utilization of soil resources is questioned, While the increase in average salinity of root development zone in wheat and barley products due to tape irrigation over the course of 20 years has risen from 1.5 to 2/03 and 2/02 dS/m, which is not noticeable and at the level of 5% is not significance. This can be attributed to rainfall during the growing season of wheat and barley, which led to salt salting from the root zone. The correctness of this theory was tested by the significance of the correlation between rainfall and salinity in the 5% level and proved to be. Therefore, it is recommended to wheat and barley with the ability to tolerate high soil salinity are placed in the top priority for local irrigation in hot and dry areas with limited atmospheric rainfall and limited water resources.
Conclusions: From the above results, it was observed that, in products such as maize and tomatoes, tape irrigation resulted in a significant increase in the mean salinity of the root development zone over time. However, the increase in average salinity of root development in wheat and barley products due to the tape irrigation is negligible and canceled over time. In other words, the cultivation of crops such as barley and wheat in areas with scarcity of water resources and soil salinity ensures sustainable land management. These results, while using water with salinity of about 1 dS/m, and soil cultivation with an average salinity of 1/5 dS/m, have been taken. Since comprehensive and practical research has not been done on long-term salinity changes and the use of tape irrigation, after the cultivation of important crops such as wheat, barley, corn, tomato, the results of this research can be used in conducting managerial guidelines, The selection and prioritization of the appropriate cropping pattern in the warm and dry areas will be beneficial with few atmospheric precipitations.