abdolmajid liaghat; masoud Pourgholam amiji; pourya mashhouri nejad
Abstract
Introduction: With due attention to the limitation of water resources in Iran and specific geographical conditions of the country, using modern methods of irrigation with low water usage is inevitable. By applying suitable management in water system, soil and plant, while increasing product, we can establish ...
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Introduction: With due attention to the limitation of water resources in Iran and specific geographical conditions of the country, using modern methods of irrigation with low water usage is inevitable. By applying suitable management in water system, soil and plant, while increasing product, we can establish a sustainable agriculture. Today, subsurface irrigation systems are used in various methods around the world, especially in the countries encountering water shortage. One of the newest methods is applying sponge plastic pipes such as tuporex which is installed in the area of plant root. Then, water with the pressure of 0/6-2 atmosphere flows inside it and by exuding, it dampens the area.
Materials and Method: For this purpose, in this study number of 12 concrete lysimeters with the dimension of 2×2×1/25 m was used to investigate the effect of vegetation (mulch) on the efficiency of water consumption and product function for corn, salt accumulation as well as the amount of nitrate wash on soil profile under two permeable subsurface irrigation and surface irrigation. For irrigation, a body of water with salinity of 4 ds/m was used. The plan includes two main treatments (permeable subsurface and surface irrigation) and two sub-treatments (mulch and without mulch) withfactorial experiment in a randomized complete block design with three replications at the College of Agriculture Research Campus, Tehran Universityof technology Located in Karaj, Iran in 2010. Surface irrigation was performed based on the moisturein the soil and permeable subsurface irrigation was performed per dayas much water as was consumed.. Lysimeters soil is prepared from farm soil and through examination, its appearance special weight was registered to be 1.4 gr per cm3 equals to 1400 kg per m3. The amount of nitrogen fertilizer (Urea) was applied on the lysimeters according to the region convention, was 300 kg per hectare (120 gram per each lysimeter(. A half of this amount was used at the time of cultivation and another half was used for the plant 60 days after cultivation; because the amount of water given in this type of system is higher.On the other hand due to the lack of vegetation, the significant amount of evaporated water and water productivity have decreased.
Results and Discussion: Results disclosed that the subsurface irrigation system has important effect in decreasing consumed water (58% with mulch and 40% without mulch) and increasing crop yield (46% in seed corn yield, 50% in forge yield and 12% in weight of one thousands seed corn) in comparison with the surface irrigation system. As well as the subsurface irrigation has prevented lower soil layer from contamination and being salty by decrease salt and nitrate leaching. Besidespresence of mulch in lysimeterhas shown important role in decreasing water consumption and seed corn yield. The important thing is that the highest yield in two type of performance, was recorded in subsurface irrigation treatment with mulch (TM) and this subject is so important when we remind that (TM) treatment had the least amount of water uses. Itmeans that with the least amount of water consumed the highest amount of product was obtained among the treatments.On the other hand, surface and non-mulching (SO) irrigation is expected to have the lowest yield per unit water consumption.
Conclusions: Also in both subsurface irrigation with preamble tube and surface irrigation system, existence of mulch caused to decrease salt concentration to 40% and 30% in soil surface respectively which makes it suitable for the areas facing water shortage. It can be concluded that, existence of mulches in the both subsurface irrigation with permeable tube and surface irrigation system causing water saving 13 and 23 percent, respectively and the rate of saving water in surface irrigation system with presence of mulch has also increased. Thus, it is recommended that some of the plant residuals, like mulch remain on the ground after harvest. The subsurface irrigation with permeable tube system has been prevented from washing nitrate to the depths of the soil. As a result, the environmental pollution caused by nitrate losses in this system is minimal and this system saves fertilizer. Also the concentration of salt solution in the soil profile in subsurface irrigation system was significantly lower than the salt concentration in surface irrigation. As a result in areas that use the saline water for irrigation, the subsurface irrigation with preamble tube confirm better function than surface irrigation system and use mulch can increase yield and reduce leaching.
Hamzehali Alizadeh; Abdolmajid Liaghat; Taymour Sohrabi molayouef
Abstract
Introduction: Agricultural activity in Varamin plain has been faced with many challenges in recent years, due to vicinity to Tehran the capital of Iran (competition for Latian dam reservoir), and competition with Tehran south network in allocation of Mamlou dam reservoir and treated wastewater of south ...
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Introduction: Agricultural activity in Varamin plain has been faced with many challenges in recent years, due to vicinity to Tehran the capital of Iran (competition for Latian dam reservoir), and competition with Tehran south network in allocation of Mamlou dam reservoir and treated wastewater of south wastewater treatment plant. Mamlou and Latian dam reservoirs, due to increase of population and industry sectors, allocated to urban utilization of Tehran. Based on national policy, the treated wastewater should be replaced with Latian dam reservoir water to supply water demand of agricultural sector. High volume transmission of wastewater to Varamin plain, will be have economical, environmental, and social effects. Several factors effect on wastewater management and success of utilization plans and any change in these factors may have various feedbacks on the other elements of wastewater use system. Hence, development of a model with capability of simulation of all factors, aspects and interactions that affect wastewater utilization is very necessary. The main objective of present study was development of water integrated model to study long-term effects of irrigation with Tehran treated wastewater, using system dynamics modeling (SD) approach.
Materials and Methods: Varamin Plain is one of the most important agricultural production centers of the country due to nearness to the large consumer market of Tehran and having fertile soil and knowledge of agriculture. The total agricultural irrigated land in Varamin Plain is 53486 hectares containing 17274 hectares of barley, 16926 hectares of wheat, 3866 hectares of tomato, 3521 hectares of vegetables, 3556 hectares of alfalfa, 2518 hectares of silage maize, 1771 hectares of melon, 1642 hectares of cotton, 1121 hectares of cucumber and 1291 hectares of other crops. In 2006 the irrigation requirement of the crop pattern was about 690 MCM and the actual agriculture water consumption was about 620 MCM (supplying 90 percent of the demand), 368 MCM of which was supplied through groundwater and 252 MCM was supplied by surface water. In recent years supplying water from Latyan Dam to the agriculture in Varamin Plain due to water supply of Tehran and the recent droughts has been reduced to lower than half (the average 68.8 MCM). On the other hand, shortage of surface water resources has caused an additional pressure to the groundwater resources of the Plain. Excessive groundwater withdrawal and use of brackish reused waters in the southern parts of the plain has caused the quality loss in groundwater resources, so that groundwater salinity has increased about 0.5 dS/m from the year 2000 to 2011. Obviously, by continuing the present situation, in less than two decades the groundwater resources in Varamin will be either quite destroyed or unable to be used due to inappropriate quality. Another source of surface water is allocated to the Varamin Plain is treated wastewater produced from Tehran Wastewater Treatment Plant. Utilizing the phases 1 to 4 of this treatment plant, about 80 MCM (2.5 up to 4 m3/s) of wastewater is annually transferred to Varamin Plain. According to the projections, it is assumed that wastewater will be used in near future as the most important water resource to Varamin Plain. In this study, SD was applied as the system analysis method for the Varamin wastewater management. The spatial boundary of the SD model for Varamin model was the whole Varamin area, which is 1584 km2. The historical review period was from 2001 to 2011, the simulated period was from 2011 to 2036, and the simulation time interval was one year. The most important scenarios evaluated consisted of four wastewater allocation scenarios [(i) keeping the excising condition, (ii) complete allocation of Latian dam reservoir water to Tehran domestic use, allocation of 200 MCM treated wastewater during growing season to agricultural sector and 40 MCM to artificial aquifer recharge during non-growing season starting year 2016, (iii) similar to scenario number two w/o artificial aquifer recharge and (iv) similar to scenario number two plus allocating 50 MCM starting year 2021]. Mass flow or convection method by considering surface adsorption of solute was used to survey movement and adsorption of elements in soil. Adsorption isotherms delineated and determined by field and experimental measurement.
Results and Discussion: The result indicated that if raw wastewater be used till 2031, Cadmium and Copeer concentration will be outstanding and will have harmful effects on farmer’s health. Utilization of treated wastewater will be safe and will have not harmful effects on farmer’s health by heavy metals, to about 150 future years. Also, simulating result showed that Nitrate concentration in groundwater will exceed from allowable limitation for potable water in all scenarios to 2031. Application of scenarios (iv) and (iii) lead to the lowest and the highest Nitrate concentration, respectively.
Conclusion: In this model a systems system dynamics approach was applied to understand how various factors related to operation of wastewater and water sustainability interrelate. The developed model is capable to simulation of all factors, aspects and interactions that affect wastewater utilization. Result of this study demonstrated that SD is a useful decision support tool for sustainable wastewater management. By considering severe water shortage problems in the study area, and safe utilization of treated wastewater, treated wastewater transmission of Tehran plant to Varamin Plain can help to solve water shortage problems. Increase of treated wastewater allocation lead to decrease of raw sewage and hereby decreasing hygienic harmful effects.
M. Ghorbanian Kerdabadi; Hamideh Noory; A.M. Liaghat
Abstract
Introduction: Crop coefficient varies in different environmental conditions, such as deficit irrigation, salinity and intercropping. The effect of soil fertility and texture of crop coefficient and evapotranspiration of maize was investigated in this study. Low soil fertility and food shortages as a ...
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Introduction: Crop coefficient varies in different environmental conditions, such as deficit irrigation, salinity and intercropping. The effect of soil fertility and texture of crop coefficient and evapotranspiration of maize was investigated in this study. Low soil fertility and food shortages as a stressful environment for plants that makes it different evapotranspiration rates of evapotranspiration calculation is based on the FAO publication 56. Razzaghi et al. (2012) investigate the effect of soil type and soil-drying during the seed-filling phase on N-uptake, yield and water use, a Danish-bred cultivar (CV. Titicaca) was grown in field lysimeters with sand, sandy loam and sandy clay loam soil. Zhang et al (2014) were investigated the Effect of adding different amounts of nitrogen during three years (from 2010 to 2012) on water use efficiency and crop evapotranspiration two varieties of winter wheat. The results of their study showed. The results indicated the following: (1) in this dry land farming system, increased N fertilization could raise wheat yield, and the drought-tolerant Changhan No. 58 showed a yield advantage in drought environments with high N fertilizer rates; (2) N application affected water consumption in different soil layers, and promoted wheat absorbing deeper soil water and so increased utilization of soil water; and (3) comprehensive consideration of yield and WUE of wheat indicated that the N rate of 270 kg/ha for Changhan No. 58 was better to avoid the risk of reduced production reduction due to lack of precipitation; however, under conditions of better soil moisture, the N rate of 180 kg/ha was more economic.
Materials and Methods: The study was a factorial experiment in a completely randomized design with three soil texture treatment, including silty clay loam, loam and sandy-loam soil and three fertility treatment, including without fertilizer, one and two percent fertilizer( It was conducted at the experimental farm in Jey and Qahab district of Isfahan. Reference evapotranspiration and actual evapotranspiration of maize were measured by evaporation pan method and volumetric soil water balance method using micro lysimeters, respectively. In order to accommodate the growing field conditions, a ditch with a depth of 25 cm, length of 240 cm and width of 300 cm were dug and micro-lysimeters were placed it in three rows (three replications) with a distance of 75 cm. After preparing the treatments, four seed Maize with variety of NS540 were planted at a depth of 3-5 cm on 5 August. To reduce the oasis effect on evapotranspiration, the same corn was planted in the vicinity of the project area with 500 square meters..
Results and Discussion: The results showed that using fertilizer caused increasing of crop evapotranspiration and crop coefficient of maize. Maximum of the ten-day average evapotranspiration of maize in the silty clay loam soil with two percent fertilizer was obtained 8.76 (mm/ day) on the fifth decade of growth and this value was found 45.5 percent higher than the lowest mean evapotranspiration value of the ten-day. Comparison evapotranspiration of maize in different soil fertility treatments showed that the greatest impact on increasing of maize evapotranspiration in SLF2, SCLF2, SLF2 treatments were obtained that was equal %19.1, %14.3 and %10.6, respectively (table 4). Most of the effects of fertility the crop coefficient of maize at the middle stage of growth was influenced more than other stages by the different treatments of soil fertility. Adding one and two percent of the fertilizer to treatment SCLF0 increased maize crop coefficient about 3.5 and 9.7 percent at development stage, respectively, That measured %6 and 11% for LF1 and LF2 treatments, respectively, and about 1.6 and 5.6% for SLF2 SLF1 treatment, respectively (Table 6). Comparison of maize middle crop coefficient in SLF2 and SLF1 for different soil fertility treatments showed that effect of increasing soil fertility on middle Kc of maize was more than other stages of plant growth (Table 6). The obtained results showed that the addition of one and two percent fertilizer to the silty clay loam soil increased, the middle crop coefficient 13.3% and 27%, respectively in.
Conclusion: Maximum and minimum effect of soil fertility on increasing crop coefficient of maize in the middle stage was equal to 37.8% in the loamy soil and 18.3% in the sandy loam soil with two percent fertilizer. The greatest effect of soil fertility on crop coefficient of maize was measured 8.37% in the middle stage of growth in LF2. The effect of soil fertility on crop coefficient of maize in loam and silty clay loam soils more than sandy loam soil, Because can be a further organic matter in these soils (loam and silty clay loam and also decreasing evaporation in sandy loam soil.
Y. Khoshkhoo; parviz irannejad; ali khalili; Hassan Rahimi; A. Liaghat; P. Erik Jansson
Abstract
In this research calibration and uncertainty analysis of COUP model with focus on soil temperature simulation for 3-hours time scale have been performed for Hamedan synoptic station. The Generalized Likelihood Uncertainty Estimation (GLUE) was used for this object. In order to simulate the soil temperature, ...
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In this research calibration and uncertainty analysis of COUP model with focus on soil temperature simulation for 3-hours time scale have been performed for Hamedan synoptic station. The Generalized Likelihood Uncertainty Estimation (GLUE) was used for this object. In order to simulate the soil temperature, 22 parameters were chosen and by using the Monte Carlo stochastic sampling method from the uncertainty space of the parameters, 25000 scenarios were produced and model simulations were implemented. For separate behavioral and non-behavioral simulations, 3 criteria including Nash-Sutcliff, Mean Bias Error, and Root Mean Square Error were considered and acceptable thresholds for each criterion were defined. With applying the acceptable thresholds, 253 behavioral simulations were detected and used for calibration and uncertainty analysis of the model. Based on posterior parameter distributions some parameters were recognized as sensitive parameters. The median of behavioral simulations was considered for model calibration and the uncertainty analysis of the model was performed based on 90% confidence levels of behavioral simulation errors. The results showed that calibration of the model has considerably improved the performance of the model in comparison to default parameter values. In addition, the uncertainty analysis showed that the uncertainty of parameters has been considerably decreased in most cases with application of the GLUE method. Other differences between simulated and observed values were attributed to other sources of model uncertainty.
Mohammad Ghorbanian
Abstract
Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. ...
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Many numerical and analytical models have been developed for estimation of soil water distribution in order to increase water use efficiency in drip irrigation. Accurate solution of well-known soil water equation, Richard’s equation, in these models cause more accurate estimation of soil wetting front. The purpose of this study was to evaluate finite difference and finite element methods to numerical solution of Richard’s equation for simulating soil water flow around dripper via comparing HYDRUS-2D and SEEP/W numerical models. Experiments were carried out to collect required data to investigate the advance of moisture front inside a Plexiglas box filled with a silt loam soil in central laboratory of water researches in University of Tehran. Wetting front advance at different time intervals were plotted on the transparent Plexiglas box walls. The wetting front around the emitters, for pressures 1.5 and 2.2 meters (equivalent to 4.5 and 6.3 liters per hour, respectively), were measured. Comparison of two simulation models, HYDRUS-2DandSEEP/W, showed that HYDRUS-2D model (finite difference solution method) with higher determination coefficient and lower root mean square error coefficient had better performance to simulate wetted area dimensions for both surface and subsurface drip irrigation.
A. Sadeghilari; Hadi Moazed; AbdAli Naseri; A. Mahjobi; A.M. Liaghat
Abstract
In arid and semiarid regions, controlled drainage is the next logical step towards improving water management in irrigated agriculture and reducing the environmental impacts of subsurface drainage flow. Controlled drainage has been practiced in humid areas for a long time. In this research a controlled ...
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In arid and semiarid regions, controlled drainage is the next logical step towards improving water management in irrigated agriculture and reducing the environmental impacts of subsurface drainage flow. Controlled drainage has been practiced in humid areas for a long time. In this research a controlled drainage system in Khuzestan Province, Southwest Iran was tested as a strategy for continuous water table management with the benefits of optimizing water use and reducing unnecessary drainage and nitrogen losses from agricultural fields. To study the feasibility and performance of water table management, Field experiments were carried out on a 63.41 ha with 3 treatments on the farms under subsurface drainage of Imam Khomeini's sugarcane agro-industry. 3 treatments compared consisted of a free drainage treatment (FD) and tow controlled drainage treatment with water table controls set at 90 centimeter (CD90) and 70 centimeter (CD70) below the soil surface. Collected data during a sugarcane growing season included water table depth, drained volume, nitrate-nitrogen and ammonium-nitrogen concentration in the drainage water and groundwater. Controlled drainage had a significant hydrological and environmental effect during studding period. Compared with CD, the total drain outflow from CD70 and CD90 area were 62.48 and 48.98% less, respectively. Compared with CD, the total amounts of nitrate-nitrogen and ammonium-nitrogen in drain outflow were about 45 to 60 % and 50 to 65 % less, respectively. Nitrate-nitrogen and ammonium-nitrogen concentration in the both of drainage water and groundwater did not differ significantly in all of the treatment. These data suggest that controlled drainage can be applied at big scale in the Khuzestan Province with the most installed subsurface drainage in Iran, with advantages for water conservation and environment.
H.R. Javani; A. Liaghat; A. Hassanoghli
Abstract
Based on limited water resources, increasing population, the need for high volume production and waste disposal, it is necessary to increase the reuse of wastewater. Artificial recharge using one of the most important methods of wastewater re-use of this resource is valuable. Necessary in order to utilization ...
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Based on limited water resources, increasing population, the need for high volume production and waste disposal, it is necessary to increase the reuse of wastewater. Artificial recharge using one of the most important methods of wastewater re-use of this resource is valuable. Necessary in order to utilization of artificial recharge system was conducted. In order to simulate the physical conditions of artificial recharge ponds PVC cylindrical column of diameter 30 cm and height of 250 cm was used. Columns filled by Sandy loam soil and Mahdasht Alborz Province treated wastewater was used for artificial recharge system in the College of Agriculture, Tehran University. Two strategies using geotextile lining and coating materials are coarse debris on the soil surface and a bare soil, water infiltration into the soil to improve the approach was evaluated in terms of permanently flooded. Values of BOD5, COD coliform, fecal coliform, nitrates and phosphorus inputs and outputs of the column effluent were measured. The results indicate the high efficiency of columns of soil, covered with geotextile, the amounts of percentage removal of BOD5, COD, coliform, fecal coliform and phosphorus, average 84/7, 77, 99/5, 99/7 and 79/9 and efficiency of all columns in the nitrate removal was low. Using geotextile cover and building materials in addition to reducing transport emissions, the use of the soil as well as the filter increases. Also due to its low cost and ease of preparation, may change or modify these materials to improve soil penetration.
A.A. Zolfaghari; Mehdi Shorafa; M.H. Mohammadi; A. Liaghat; A. Hoorfar; manoochehr gorji
Abstract
Quantitative knowledge of soil hydraulic properties such as the soil moisture characteristics curve (SMC) is crucial for flow and transport modeling supporting hydrologic and agricultural engineering. However, many laboratory and field methods are currently available for direct measurement of the soil ...
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Quantitative knowledge of soil hydraulic properties such as the soil moisture characteristics curve (SMC) is crucial for flow and transport modeling supporting hydrologic and agricultural engineering. However, many laboratory and field methods are currently available for direct measurement of the soil hydraulic properties but, most or all of direct methods are too time consuming and costly. Thus developing of physically-based methods for predicting SMC is essential. In this study, an analytical method was developed to estimate Brooks-Cory model parameters using horizontal infiltration data. The new method was compared with Wang et al (2002) method. Sixteen soils with wide range of hydraulic properties were used to test the new method. The results showed that the new method estimates n and hd parameters smaller than those experimental values. Although, results showed that the new method properly predicts the measured SMC data. High coefficient of determination (R2=0.93) and low root mean square error (RMSE =0.03) confirmed the accurate predictability of new method. Mean RMSE of Wang et al (2002) method was 0.049. Therefore, results indicated that the new method is more accurate than Wang et al (2002) method for predicting soil moisture characteristics curve. The sensitivity analysis indicated that, for a given soil, the accurately estimation of SMC depends mainly on sorptivity parameter.
Y. Abbasi; A. Liaghat; F. Abbasi
Abstract
Suitable management of water and fertilizer is one of the important factors, affecting water and fertilizer efficiency and environmental pollution. In this study, nitrate deep leaching was evaluated in a furrow irrigated experimental field in Karaj. Experiments were conducted in randomized complete blocks ...
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Suitable management of water and fertilizer is one of the important factors, affecting water and fertilizer efficiency and environmental pollution. In this study, nitrate deep leaching was evaluated in a furrow irrigated experimental field in Karaj. Experiments were conducted in randomized complete blocks in free-drainage furrows having 162 m length in 12 experimental blocks. The first factor consisted of 60%, 80% 100% and 120% of required irrigation water and the second factor 60%, 80% and 100% of nitrate fertilizer requirement applied by fertigation method. Nitrogen requirement was determined based on soil analysis and applied in four stages of the crop growth: before cultivation, in seven leaves, shooting and earring stages in which the first part (before cultivation) was applied by manual distribution and other three parts by fertigation. To determine soil nitrate concentrations, soil samples were taken from depths 20, 40, 60, and 80 cm in all of treatments. After air-drying, soil samples were passed through 2 mm sieve. Then, nitrate concentration of samples were analyzed by spectra photometer. Nitrate losses through runoff were measured by sampling of outlet water. Accumulated nitrate in maize was determined by randomized sampling of plants in all treatments. Finally, to determine nitrate leaching, nitrate mass balance was made. Results showed that 120% water level treatment provided 12% water deep percolation from root zone, while 60% water level treatment resulted in 4.5% water deep percolation. Both water and fertilizer levels had pronounced effect on nitrate leaching. The highest nitrate leaching occurred in 100% fertilizer level treatment decreasing by water reduction level. In some cases such as 80% fertilizer level, water level of 60% and 80% didn’t have any effect on nitrate deep percolation. Therefore, water level selection in this situation depends on other factors such as yield. Considering maize as a plant with root depth to be about 80 cm, water and nitrate deep percolation was evaluated up to 80 cm soil depth for all treatments. 60% and 80% water levels did not provide nitrate leaching below the mentioned root zone depth.
H. Aryanpour; Mehdi Shorafa; A. Liaghat
Abstract
As far as soil moisture is a function of soil structure and texture any changes on these properties changes the soil moisture content. In this study for finding the soil moisture content at field capacity and permanent wilting point for cultivated soil, point pedotransfer functions of non cultivated ...
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As far as soil moisture is a function of soil structure and texture any changes on these properties changes the soil moisture content. In this study for finding the soil moisture content at field capacity and permanent wilting point for cultivated soil, point pedotransfer functions of non cultivated of the same soils were used. For this purpose 64 soil samples from cultivated and non cultivated were chosen in Abyek Qazvin area. Then available soil properties such as particle size distribution, bulk density, organic carbon, calcium carbonate, cation exchang capacity and PH of soils were measured. The soil moisture at FC and PWP. For non cultivated soil were determined by peresure plates. After that point pedotransfer functions were established. With using these functions the moisture of cultivated soils were predicted and compared with the measured ones. The results showed that this functions had overestimated moisture for FC and underestimated moisture for PWP. In fact cultivation reduses soil ability in moisture preservation. Correlation coefficient between measured and predicted moisture for cultivated soils at PWP was more than FC.
B. Ghanbarian Alavijeh; A.M. Liaghat
Abstract
Abstract
Saturated water content is one of the important parameters which its measurement is necessary in estimation of soil water retention and unsaturated hydraulic conductivity curves. In several researches, saturated water content is assumed to be equal to soil total porosity. In some others, its ...
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Abstract
Saturated water content is one of the important parameters which its measurement is necessary in estimation of soil water retention and unsaturated hydraulic conductivity curves. In several researches, saturated water content is assumed to be equal to soil total porosity. In some others, its value is estimated by pedotransfer functions using readily available parameters, such as bulk density and soil textural data. The objective of this study is to evaluate different presented methods in the literature in estimation of saturated water content. Since soil organic matter is considered as an effective parameter on the soil structure, in this study its influence in the estimation of saturated water content is studied. For this purpose, in the first case without considering the value of organic matter, different methods such as soil total porosity, Vereecken et al., Mayr and Jarvis, and Scheinost et al., were evaluated. In the second case, the measurement of organic matter was used in prediction of saturated water content. Then beside the other methods mentioned above, Wösten et al. model as well as two linear and nonlinear models of Rajkai et al. were evaluated as well. In the first and second cases 443 and 309 soil samples from three data bases e.g., Cornelis et al., UNSODA and GRIZZLY were used, respectively. The results showed that when organic matter increased, saturated water content increased as well. In the first and second cases, the smaller values of RMSE and AIC showed that the Vereecken et al. model predicted saturated water content more accurately than the other methods. The obtained results also indicated that models in which organic matter is considered as an input parameter could not estimate saturated water content as accurately as Vereecken et al. model estimated.
Keywords: Bulk density, Organic matter, Pedotransfer functions, Saturated water content
H. Molavi; M. Parsinejad; A.M. Liaghat
Abstract
Abstract
One of the ways to increase economic and environmental efficiency of drainage systems is water table management. Water table management consists of, controlled drainage and subirrigation. This study examines the effect of controlled drainage on yield, root distribution pattern and water use ...
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Abstract
One of the ways to increase economic and environmental efficiency of drainage systems is water table management. Water table management consists of, controlled drainage and subirrigation. This study examines the effect of controlled drainage on yield, root distribution pattern and water use efficiency of maize (SC 704) in Karaj. The experiment was performed as a randomized complete design with three replicates including three treatments: free drainage (FD) and controlled drainage with 40 cm (CD40) and 60 cm (CD60) controlled water tables. Lysimetric station is equipped with drainage system and water table control system. Irrigation intervals in all of the lysimeters were based on MAD = 0.65 in FD treatment. For all treatments, irrigation depths were determined based on deficiency of soil moisture from field capacity with 70 percent application efficiency. The results showed that 30 percent irrigation losses during implementation of treatments in CD treatments did not cause rise of the water table to the desired control levels, due to extra consumption of plant. So between two water table control treatments there was no significant difference. In free drainage treatment which drainage water discharge was facilitated lower plant consumption were noted. Effect of water table management on yield, irrigation amount, root dry weight and water use efficiency was significant (p
N. Nikamal Larijani; A. Hassanoghli; M. Mashal; A.M. Liaghat
Abstract
Abstract
By increasing the world population and more need to supply food, farmers attend to use of chemical fertilizers, organic manures and pesticides. Also, applications of these agents without attention to their side effects, cause more problems to human health and environment. Nitrate is one of ...
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Abstract
By increasing the world population and more need to supply food, farmers attend to use of chemical fertilizers, organic manures and pesticides. Also, applications of these agents without attention to their side effects, cause more problems to human health and environment. Nitrate is one of the most important elements of organic manures, which leach through soil to surface and ground waters by irrigation or precipitation. So, it’s necessary to monitor the behavior of it. The purpose of this study was to determine the nitrate transport through two different soil textures, loam and silt loam via application of organic fertilizers. In this study, experiments were carried out by cylindrical drained plastic lysimeters with 100 cm height and 60 cm diameter, filled by uncondensed soil up to 60 cm height. Three different organic manures (poultry, cow and sewage sludge) were used on top soil of lysimeters by the rate of 35 tone/ha (upon the average use amounts of farmer's). 24 lysimeters were prepared; 9 lysimeters for 3 types of manure with 3 replicates and 3 without manure used as control for each soil type. The results were analyzed by a factorial experiment in a completely randomized form statistical design. Irrigation was done by one week intervals, totally three times with well water. Five drainage water samples (100 ml each sample) were taken through the first pore volume drained after irrigating of lysimeters. It means that each pore volume divided to 5 equal parts for sampling. The results showed that the nitrate concentration in loam soil was more than silt loam soil in drainage water samples, so it can be attributed to the effect of soil texture. Also for both soil textures, sewage sludge treatment was caused the most nitrate concentration, and the least was monitored in control treatment. The amounts of poultry and cow NO3 in drainage water samples were between them, respectively. Considering the one week irrigation intervals and three consecutive irrigations which were done, the amount of contamination in both soils in the first week was highest and in the third week was the lowest; it can be related to nitrate leaching by irrigations done.
Keywords: Water pollution, Nitrate leaching, Lysimeter, Organic manure
M.R. Asgari; A.M. Liaghat; M. Parsinezhad
Abstract
Abstract
Although lateral drains play the main role in removal of excess water from soil profile in subsurface drainage systems, but it is assumed that perforated collectors can directly remove a part of drainwater from soils. This part of discharge in subsurface drains is not usually taken into consideration ...
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Abstract
Although lateral drains play the main role in removal of excess water from soil profile in subsurface drainage systems, but it is assumed that perforated collectors can directly remove a part of drainwater from soils. This part of discharge in subsurface drains is not usually taken into consideration in drainage design criteria, due to lack required information and its difficult estimation. If the level of collectors’ drain discharge is determined, drainage coefficient for laterals can be adjusted depending. Consequently the distance between laterals is increased and economic value of drainage system design is more justified. This research was conducted in drainage network of Amirkabir Agro-Industrial Unit with the purpose of determining collectors’ discharge level and lateral’s drainage coefficient adjustment. Therefore, measurement of water table, discharge of laterals and collectors in ARC2-14 farm having 25 hectare size was measured. Results obtained from field measurements indicate collectors directly discharge approximately 2.8 litter water per second or 2 mm per day or about 24% of total drainage discharge within the system. The actual drainage coefficient will then be reduced from 8.24 to 6.24 mm/day. This change will result an increase in lateral distance from 40 to 44 m.
Keywords: Drainage coefficient modification, Collector or collecting drainage, Constant flow
Z. Aghashariatmadary; M.A. Khalili; P. Irannejad; A.M. Liaghat
Abstract
Abstract
Angstrom-Prescott equation is one of the most commonly used methods for the estimation of global solar radiation (Rs) based on sunshine hours. The critical step in the application of this method's is the calibration of its coefficients for each region. Although the coefficients of the equation ...
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Abstract
Angstrom-Prescott equation is one of the most commonly used methods for the estimation of global solar radiation (Rs) based on sunshine hours. The critical step in the application of this method's is the calibration of its coefficients for each region. Although the coefficients of the equation have been calibrated in different parts of the World, the effect of different time scales has not been considered clearly. In this article, variations of the coefficients of A-P equation in different time scales and their effects on the estimation of global solar radiation are studied. For this purpose data for the 15-year period of 1992-2006 from the Tehran-North (Aghdasieh) station in daily and monthly time scales are used. The values of the coefficients derived from the daily and monthly data were clearly different, and the equation based on monthly data has higher coefficient of determination (R2=0.92) compared to that based on the daily data (R2=0.48). We also found that the daily total solar radiation incident at the surface can be estimated well by using the A-P equation derived based on monthly data.
Keywords: Calibration of Angstrom-Prescott equation, Global solar radiation estimation, North of Tehran station, Time scales
M. Navabian; A. M. Liaghat; R. Kerachian; F. Abbasi
Abstract
Abstract
Optimal management of water and nutrient could consider as effective on farm method to reduce pollution because agriculture is none point pollution. In this research, an optimal model was presented to reduce nitrate loss in furrow fertigation. The optimal model contains four simulation models ...
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Abstract
Optimal management of water and nutrient could consider as effective on farm method to reduce pollution because agriculture is none point pollution. In this research, an optimal model was presented to reduce nitrate loss in furrow fertigation. The optimal model contains four simulation models for predicting runoff, deep percolation, nitrate concentration in runoff and nitrate concentration in deep percolation. Genetic algorithm was used for model solution. Decided values were inlet discharge, cutoff time of irrigation, starting time and duration of fertigation. Simulation model’s ability to simulate fertigation event cause a comprehensive optimal model of fertigation in different climate, plant, irrigation and fertigation situations. Field experiment of furrow irrigation under continues regime was used to evaluate optimal model. Optimal decided values for inlet discharge, cutoff time of irrigation, starting time and duration of fertigation was determined 0.184 L/s, 595.2 min, 7.5 min and 162.9 min in plant conditions. These values were 0.21 L/s, 537.1 min, 6.5 min and 143 min in none plant condition. Optimal decided values cause 113.86 and 118.3 mg/L mean nitrate loss from farm as runoff and deep percolation under plant and none plant conditions, respectively. Optimal model was increased nitrate concentration in deep percolation or decreased nitrate concentration in runoff by increasing inlet discharge because plant increase nitrate concentration in deep percolation. Results show plant has effect on optimization then it is appropriate to determine optimal decided values under plant and none plant conditions.
Keywords: Furrow irrigation, Optimization, Fertigation, Water and nutrient management, Nitrate
M.J. Nahvinia; A. Liaghat; M. Parsinejad
Abstract
چکیده
در مدیریت آبیاری سطحی، تابع نفوذ از اهمیت زیادی برخوردار است. معادلات ریاضی که تاکنون برای نفوذ توسعه یافته اند، توابع تک متغیره ای از زمان فرصت نفوذ می باشند. در ...
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چکیده
در مدیریت آبیاری سطحی، تابع نفوذ از اهمیت زیادی برخوردار است. معادلات ریاضی که تاکنون برای نفوذ توسعه یافته اند، توابع تک متغیره ای از زمان فرصت نفوذ می باشند. در این تحقیق پیش بینی متوسط میزان نفوذ در آبیاری جویچه ای توسط مدل های شبکه عصبی و عصبی- فازی به عنوان مدل های تجربی و مدل رگرسیونی به عنوان مدل آماری با استفاده از رطوبت اولیه ی خاک و دبی ورودی به جویچه مورد بررسی قرار گرفت. به همین منظور از یک سری آزمایش های صحرایی که به روش آبیاری جویچه ای در پنج مزرعه آزمایشی گلمکان مشهد، توتون ارومیه ، صفی آباد دزفول ، دانشگاه بیرجند و موسسه اصلاح بذر کرج در طی دوره ی زمانی تابستان 1376 تا تابستان 1385 انجام شده بود و دارای طیف گسترده ای از نظر بافت خاک (سبک، متوسط و سنگین) بودند، استفاده شد. برای تعیین عوامل معادله ی نفوذ کوستیاکوف لوییس از روش بیلان حجم در آبیاری جویچه ای استفاده گردید. نتایج نشان داد که دقت مدل رگرسیونی در خاک های سنگین در مقایسه با خاک های متوسط و سبک بیشتر است. مدل شبکه های عصبی در خاک های متوسط (Silty Clay Loam) دقت مناسبی دارند و در خاک های سنگین (Clay Loam) تمایل به بیش برآورد و در خاک های نسبتا سبک (Silty Loam) تمایل به کم برآورد دارند. اما سیستم استنتاج فازی عصبی قادر است قابلیت تخمین را در تمام شرایط حفظ کند که این امر نشان از دقت بیشتر و قابلت تخمین زیاد سیستم استنتاج فازی عصبی دارد.
واژه های کلیدی: نفوذ، آبیاری جویچه ای، مدل رگرسیونی، شبکه ی عصبی ، شبکه ی فازی عصبی
F. Abbasi; A. Liaghat; H. A. Alizadeh; Y. Abbasi; A. Mohseni
Abstract
چکیده
در این تحقیق، به منظور مطالعه و بررسی اثرات کودآبیاری بر تلفات نیترات از طریق رواناب سطحی در آبیاری جویچه ای و همچنین ارزیابی یک مدل ریاضی کودآبیاری، 12 آزمایش ...
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چکیده
در این تحقیق، به منظور مطالعه و بررسی اثرات کودآبیاری بر تلفات نیترات از طریق رواناب سطحی در آبیاری جویچه ای و همچنین ارزیابی یک مدل ریاضی کودآبیاری، 12 آزمایش در دو سال زراعی 1387 و 1388در مقیاس بزرگ و در حضور گیاه ذرت روی جویچه های انتها باز در یک خاک لومی انجام شد. تعداد جویچه های هر آزمایش 5 عدد، طول جویچه ها 165 متر، فاصله بین جویچه ها 75 سانتی متر و شیب عمومی مزرعه 006/0 متر بر متر بود. کود مصرفی مورد نیاز مطابق توصیه کودی از منبع کود اوره و طی چهار تقسیم مساوی (قبل از کاشت، مرحله هفت برگی، مرحله ساقه رفتن و مرحله سنبله زدن) اضافه گردید. دبی جویچه ها با استفاده از فلوم WSC و غلظت نیترات خروجی از روش طیف سنجی اندازه گیری شد. از داده های سال اول برای تعیین بهترین زمان تزریق کود با هدف دستیابی به کمترین درصد تلفات نیترات استفاده شد. در سال دوم، تزریق کود فقط در زمان بهینه شده بر اساس نتایج سال اول انجام گرفت. نتایج نشان داد که بهترین زمان تزریق کود به سیستم آبیاری جویچه ای 20 دقیقه انتهایی آبیاری می باشد. تلفات نیترات از طریق رواناب سطحی در سال اول بسته به زمان تزریق کود بین 7/5 تا 0/42 و در سال دوم با اعمال مدت زمان تزریق بهینه بین 4/1 تا 3/12درصد متغیر بود. همچنین، نتایج نشان داد که مدل کودآبیاری مورد استفاده در این تحقیق قابلیت برآورد تلفات نیترات از طریق رواناب سطحی را دارد. ضریب تبیین (R2) بین مقادیر اندازه گیری و شبیه سازی شده تلفات آب در دو سال زراعی به طور متوسط 85/0 و برای تلفات کود به طور متوسط 80/0 بود.
واژه های کلیدی: کودآبیاری، تلفات نیترات، مدل ریاضی کودآبیاری، آبیاری جویچه ای
A. Shahidi; M.J. Nahvinia; M. Parsinejad; A. Liaghat
Abstract
Abstract
Various mathematical water uptake models have been introduced for plants response to combined drought and salinity stress. The reduction functions are classified as additive, multiplicative and conceptual models. In this study six different macroscopic reduction functions, namely; Van Genuchten ...
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Abstract
Various mathematical water uptake models have been introduced for plants response to combined drought and salinity stress. The reduction functions are classified as additive, multiplicative and conceptual models. In this study six different macroscopic reduction functions, namely; Van Genuchten (additive and multiplicative), Dirksen et al., Van Dam et al, Skaggs et al and Homaee were evaluated. The experiment was carried out at Research farm of Birjand University in a factorial split plot design with 3 replicates. The treatments consisted of four levels of irrigation (50, 75, 100 and 120%of crop water requirement), and three water qualities (1.4, 4.5, 9.6 dS/m) and two wheat cultivars. The results indicated that the additive model estimates relative yield less than the actual amount. In other word, the effect of combined stresses on wheat yield was less than the summation of separate effects due to salinity and water stress. The effect of drought stress on yield reduction was more than salinity stress. The results also revealed that reduction function of Skaggs et al and Homaee's models agreed well with the measured data when compared with other functions.
Keywords: Salinity stress, Drought stress, Reduction function, Wheat, Birjand
M. Mohammadi; A. Liaghat; H. Molavi
Abstract
Abstract
Different strategies are existed for adjusting with water shortage, of which the strategy of suitable policies adoption by determining optimum production function can be mentioned. Water shortage and quality degradation of soil and water resources is one of main factors of production reduction. ...
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Abstract
Different strategies are existed for adjusting with water shortage, of which the strategy of suitable policies adoption by determining optimum production function can be mentioned. Water shortage and quality degradation of soil and water resources is one of main factors of production reduction. Therefore, this study was carried out for determination of tomato sensitivity coefficients and its water-salinity-yield optimum function in Karaj. The experiment was performed as a complete randomized design with three replicates including two factors; Salinity and irrigation water. Salinity and irrigation water factors consisted of four levels (S1=0.7, S2=4, S3=8 and S4=12 dS/m) and three levels (W1=100, W2=75 and W3=50 percent of water requirement), respectively. The Soil texture was sandy loam. Yield data were fitted on different forms production functions (simple linear, logarithmic linear, Quadratic and Transcendental) and the optimum one was determined after sensitivity analysis. Then, the values of water use efficiency and plant sensitivity coefficients were determined. Results of sensitivity analysis showed that the quadratic production function is optimal production and it can be recommended. Investigation of the maximum values of error (ME) showed that the logarithmic linear and simple linear functions have had the highest error. In the irrigation treatments, W1S1 (control) and W2S1 (75% of water requirement) with 7.57 and 7.5 Kg /m3 respectively had the highest water use efficiency. However, water use efficiency decreases if the drought and salinity increases. The average value of Ky, in the condition of combined salinity and drought stress was 1.696. Moreover, Plant sensitivity values (Ks) decreases if salinity and drought increases and the lowest value of Ks were belong to W3S4 (0.57). The iso-yield curve showed that by increasing of irrigation amounts, water with higher salinity can be applied without yield change.
Keywords: Drought and salinity stress, Optimization of water use, Production function, Tomato sensitivity coefficientss
H. Noory; A.M. Liaghat; M. Parsinejad; M. Vazifedoust
Abstract
Abstract
In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different ...
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Abstract
In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different times of agriculture year of 2007-2008 were measured. The measured and simulated data were analyzed. The statistical comparison which was done base on the root mean square error (0.49 ton/ha), correlation coefficient (0.85) and modeling efficiency (0.84), for estimating the total crop dry matter of wheat and fodder maize showed that the estimated crop yield by SWAP agree well with observed values. Suitable values of statistical indexes obtained for estimating soil moisture and soil salinity by SWAP, indicated that considering suitable bottom boundary condition in SWAP which has important role on water and solute balance in soil, has affected on estimation of soil moisture and salinity considerably.
Keywords: Crop yield, Soil salinity, SWAP model, Water and salinity limitations
H.A. Alizadeh; A. Liaghat; F. Abbasi
Abstract
Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this ...
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Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this study was to investigate the effect of furrow fertigation on fertilizer use efficiency (FUE), water use efficiency (WUE), and corn yield. A field experiment was carried out in furrows which have 165m length and 0.006 (m/m) slope in Karaj. The corn Hybrid 370 double-cross was planted on June 2008. A factorial design based on randomized complete block design with 4 replicates. Four levels (0, 60, 80 and 100%) of the recommended fertilizer value and four levels (60, 80, 100, and 120%) of the irrigation water requirement were applied. These 16 treatments were compared with traditional fertilizer application method. Fertilizer treatments were accomplished in four critical stages of the growth (before cultivation, in seven leaves stage, shooting stage and Flowering stage) for fertigation treatments and two stages (before cultivation and seven leaves stage) for the traditional method. Results showed that effects of levels of different water and fertilizer on yield component were significant. Water use efficiency (WUE) was significantly affected by nitrogen rate. On the other hand, water treatments significantly affected fertilizer use efficiency. Increasing fertilizer increased water use efficiency. Increasing water levels to 100% of ETC resulted in increasing fertilizer use efficiency. Highest yield was obtained from the full irrigation treatments (W100%). Albeit the difference among W120%, W100% and W80% was not significant (P=0.05), because W100% was always higher than W120%, treatment of W80% recommends as optimum water level for arid and semi arid region. The maximum and minimum WUE was 2.24 and 0.66 (kg/m3) in W80%N100% and W100%N60%, and The maximum and minimum FUE was 29.85 and 8.52 (kg/kg) in W100%N100% and traditional method, respectively.
Key words: Fertigation, Fertilizer use efficiency, Productivity, Corn
H.A. Alizadeh; A. Liaghat; M. Noorimohamadeh
Abstract
چکیده
استفاده از کم آبیاری به منظور صرفه جویی در آب و همچنین اعمال حداقل ضریب آبشویی در طول فصل آبیاری و یا حتی در سراسر چندین فصل آبیاری باعث انباشته شدن املاح در منطقه ...
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چکیده
استفاده از کم آبیاری به منظور صرفه جویی در آب و همچنین اعمال حداقل ضریب آبشویی در طول فصل آبیاری و یا حتی در سراسر چندین فصل آبیاری باعث انباشته شدن املاح در منطقه ریشه میشود. طبیعتا وقتی از آبهای با کیفیت کم مثل پسابها و یا آبهای نامتعارف استفاده می کنیم وضع بدتر هم می شود. در چنین شرایطی گیاهان به طور همزمان تحت تأثیر تنش شوری و کم آبی قرار می گیرند. در زمینه چگونگی پاسخ گیاهان به تنش همزمان شوری و خشکی و سهم هر یک از آن ها در کاهش جذب آب مدل های ریاضی متعددی وجود دارد. مدل های جذب آب در شرایط تنش همزمان به سه دسته جمع پذیر، ضرب پذیر و مدل های مفهومی تقسیم بندی می شوند. از آنجایی که بیشترین مقدار آب مصرفی در مناطق خشک و نیمه خشک صرف تعرق می شود، کارآیی مدلهای شبیه سازی پیش بینی حرکت آب و املاح تا حد زیادی به توانایی آنها در پیش بینی تعرق بستگی دارد. در این مطالعه شش تابع کاهش جذب آب ماکروسکوپی وان گنوختن (جمع پذیر و ضرب پذیر)، دیرکسن و آگوستیجن، وان دام و همکاران، اسکگز و همکاران و همایی با استفاده از داده های گل خانه ای گوجه فرنگی مورد ارزیابی قرار گرفت. آزمایش در قالب طرح کاملاً تصادفی با هشت سطح شوری (75/0، 5/1، 5/2، 5/3، 5/4، 6، 8 و 10 دسیزیمنز بر متر) انجام شد. سطوح خشکی به صورت تغییرات پتانسیل ماتریک و در طول دور آبیاری اعمال می شد. نتایج نشان داد که در شرایط عدم وجود تنش شوری همه مدل ها برازش خوبی با داده های اندازه گیری شده داشتند. همچنین نتایج نشان داد در شوری های کم واکنش گیاهان به تنش همزمان شوری و خشکی جمع پذیر است در حالیکه در شوری های بالاتر از 5/3 دسیزیمنز بر متر مدل های ضرب پذیر برازش بهتری دارند. از میان مدل های ضرب پذیر مدل مفهومی همایی و مدل اسکگز و همکاران برازش بهتری دارند.
واژه های کلیدی: تنش شوری، تنش خشکی، تابع کاهش، گوجه فرنگی
Kh. Amadali; S. Nikmehr; A. Liaghat
Abstract
Abstract
Understanding distribution of physical and chemical soil parameters is very important in recognizing, planning, and soil and water resources management in precision agriculture. Regard to the problems related to direct measurement, finding solution to estimate these parameters are very essential. ...
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Abstract
Understanding distribution of physical and chemical soil parameters is very important in recognizing, planning, and soil and water resources management in precision agriculture. Regard to the problems related to direct measurement, finding solution to estimate these parameters are very essential. The purpose of this study was to evaluate the spatial variation of some soil parameters such as; soil salinity, pH and CaCO3 percentage using different methods of interpolation and then to select the most suitable method for estimation of the proposed parameters in the Boukan region with total area 2992 Km2. Totally, 183 soil samples were taken from 0-30 cm soil depth in order to cover whole studied area and the amount of salinity, pH and CaCO3 percentage were measured in all soil samples. Then, different interpolation methods (kriging, cokriging, weighted moving average with powers of 2, 3, 4 and 5 and TPSS with powers of 2, 3, 4 and 5) with ArcGIS and GS+ software were used to analyze data. The proposed methods were evaluated by MAE (Mean Absolute Error) and MBE (Mean Bias Error) statistics indexes. The results of this study showed that the cokriging method with minimum MAE 0.218, 0.156 and 7.353 for salinity, pH and CaCO3 percentage respectively, is the most accurate method.
Key words: Acidity, Boukan, Salinity, Cokriging, IDW
H.A. Alizadeh; B. Nazari; A. Liaghat
Abstract
Abstract
Determining saturated hydraulic conductivity (Ks) is one of the important soil characteristics that its estimation is important in soil and water studies. There are several methods for estimating Ks in unsaturated conditions. These methods include the inversed-auger-hole method, the double-ring ...
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Abstract
Determining saturated hydraulic conductivity (Ks) is one of the important soil characteristics that its estimation is important in soil and water studies. There are several methods for estimating Ks in unsaturated conditions. These methods include the inversed-auger-hole method, the double-ring infiltrometer and the single-ring pressure infiltrometer. The measurement of Ks by these methods requires large volumes of water and long period of time. The Simplified Falling Head (SFH) technique is for rapid determination of Ks, using small volumes of water and easily transportable equipments. The SFH technique appears hopeful and suitable for detailed and repeated sampling, also, over large areas. In this study, Ks was measured by SFH method, double-ring and single-ring pressure infiltrometers for evaluating SFH method. Results showed that in a loam soil, the SFH method estimate higher values for Ks, compared with the double-ring and the single-ring pressure infiltrometers (respectively 9.6% and 18.5%). Statistical analysis of the results of above methods showed that there is no significant difference between Ks values (P
