mohammad alavi; jahangir abedi; behrooz mostafazadeh
Abstract
Due to shortage of water, use of wastewater for irrigation is becoming more important. Also, using natural and non-toxic materials that increase fertilizer application efficiency and decrease nitrate leaching has gained increasing attention. The aims of this study were to investigate the effect of two ...
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Due to shortage of water, use of wastewater for irrigation is becoming more important. Also, using natural and non-toxic materials that increase fertilizer application efficiency and decrease nitrate leaching has gained increasing attention. The aims of this study were to investigate the effect of two sizes for particles, i.e. 1-1.68 mm and 53-63 μm, and two application rates (20 and 60 grams per kilogram of soil) of natural zeolite of clinoptilolite (Cp) and surfactant-modified zeolite (SMZ) on soil nitrate and ammonium leaching and wheat plant performance under irrigation by treated urban wastewater. The experiment was conducted in 2015-16 growing season. The experimental soils were placed in Polyethylene columns with 11 cm inner diameter and 65 cm height. The treatments were factorial combination of the variables in completely randomized design with three replications. The results showed that the total amount of released NO3-N from columns modified by SMZ and CP were 32% and 21% lower as compared to the control treatment. Also, these amendments improved wheat plant growth. There was no significant effect on nitrate leaching due to the particle size of the two soil amendments. CP and SMZ amendments are eco-friendly materials and results of the study showed that they were effective in controlling soil nitrate leaching and improving wheat plant growth.
Ali Javadi; b m; m sh; m m
Abstract
In order to design or evaluate an irrigation system, the infiltration phenomenon and its variations should be determined accurately. In saline and sodic soil and water conditions, the importance of this issue will become greater. The main objective of this study was to estimate the coefficients of different ...
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In order to design or evaluate an irrigation system, the infiltration phenomenon and its variations should be determined accurately. In saline and sodic soil and water conditions, the importance of this issue will become greater. The main objective of this study was to estimate the coefficients of different infiltration equations (Kostiakov, Kostiakov-Lewis, Horton, Philip, and U. S. Soil Conservation) and to evaluate the performance of these equations under different qualities of irrigation water, initial soil moistures, and constant water head. Using a laboratory method, infiltrations were measured in soil columns for constant water head. Then, by applying the cumulative infiltration and drainage outflow data to HYDRUS-1D model, soil hydraulic parameters were determined by the inverse solution. To determine the coefficients of infiltration equations, the outputs of the HYDRUS-1D model including cumulative infiltration verses time were corrolated. The values of root mean square error (RMSE), standard deviation root mean square error (SDRMSE), normalized root mean square error (NRMSE), percent relative absolute error (AE) and percent relative error (RE), were used to evaluate the performance of each infiltration equation and to rank the equations. The equation that had the highest rank was considered as the best and more stable equation. The Horton equation with RMSE, SDRMSE, NRMSE and AE of 0.043, 0.018, 0.006 and 1 and the Kostiakov equation with the values of 0.234, 0.175, 0.025 and 4, were the most and the least suitable eqations, respectively. The evaluation of the performance of infiltration equations using statistical indicators showed that the Kostiakov-Lewis and the Kostiakov infiltration equations were the best and the worst equations, respectively. Comparison of NRMSE values showed that in most cases, under deficit irrigation, infiltration equations estimate infiltration more accurately. For a given treatment, the errors of Kostiakov-Lewis and Philip infiltration equations increased as the amount of irrigation water increased, and as the end of the season approached. The rest of the equations did not show any especial trends. To measure infiltration, it is necessary to consider the effects of irrigation water quality, initial soil moisture, and water heads, because these parameters influence the coefficients of infiltration equations and, consequently, the irrigation efficiency.