M Khorramian; S. Boroumand Nasab; F. Abbasi; S. R. Ashrafizadeh
Volume 37, Issue 2 , March 2015, , Pages 33-45
Abstract
This study was conducted to assess the ability of LEACHN model for predicting nitrate and ammonium in the soil profile under corn at the Safiabad Agricultural Research Center, over two growing years. Three irrigation levels (50, 75, and 100% water requirement) and three nitrogen fertilizer levels (150, ...
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This study was conducted to assess the ability of LEACHN model for predicting nitrate and ammonium in the soil profile under corn at the Safiabad Agricultural Research Center, over two growing years. Three irrigation levels (50, 75, and 100% water requirement) and three nitrogen fertilizer levels (150, 225, and 300 kg N ha-1) were applied through fertigation in three equal splits during the first irrigation, 6 to 8 leaves, and before flowering stages. The results of model calibration showed that nitrification and denitrification rates with 0.17, 0.004 per day and a dispersion coefficient equal to 200 mm provided the minimum mean bias error (MBE) and the maximum modeling efficiency (EF). Therefore, the MBE and EF values for nitrate varied from -2.09 to 3.89 and -0.1 to 0.88 respectively. However, model predictions for NH4 mobility through the soil profile were lower than that of nitrate mobility. Comparison between predicted and measured values did not show nitrate leaching below 60 cm in the soil profile in any treatments. Statistical indexes of MBE, EF, and coefficient of variation (CV) for soil moisture content predictions in different depths varied between 0.003 and 0.019, 0.24 and 0.73, and 5.8 and 17.9% respectively showing the high accuracy of model in prediction of soil moisture content.
E. Zangene Usefabadi; M. Behzad; S. Boroomand Nasab
Volume 34, Issue 1 , December 2011, , Pages 13-28
Abstract
Transmission of water through a magnetic field will cause some changes in water characteristics, affecting the overall behavior of water molecules including increasing solubility of some of compositions and decreasing water surface tension. This study was conducted with the aim of examining the effects ...
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Transmission of water through a magnetic field will cause some changes in water characteristics, affecting the overall behavior of water molecules including increasing solubility of some of compositions and decreasing water surface tension. This study was conducted with the aim of examining the effects of magnetic water on the level of remaining cations and anions of saline soil, in laboratory conditions, in a compeletly randomaized design. Soil with loam silt texture was poured in pipes with the height of 50 cm and diameter of 10 cm while the end of each pipe was closed with a filter paper and a plastic net. By passing water through the magnetic field with different intensities (6500 Gaousses in first magnetic treatment, 8000 Gaousses in second magnetic treatment), leaching was performed alternatively. At the end of the leaching experiment, the experimental soil was divided into three equal depths and amount of cations ana anions was measured. The result of chemical analysis showed that the avrage amount of the remaining sodium of the soil in the first magnetic treatment, 11.7 %, and in second magnetic treatment, 22.8 %, was lower than the controlled treatment. The avrage amount of the remaining potassium of the soil in the first magnetic treatment, 2.8 %, and in second magnetic treatment, 8.5 %, was lower than the controlled treatment. The avrage amount of the remaining calcium of the soil in the first magnetic treatment, 2 %, and in second magnetic treatment, 16 %, was lower than the controlled treatment. The avrage amount of the remaining magnesium of the soil in the first magnetic treatment, 6 %, and in second magnetic treatment, 13 %, was lower than the controlled treatment. The avrage amount of the remaining chlorine of the soil in first magnetic treatment, 14 %, and in second magnetic treatment, 14.7 %, was lower than the treatment. The avrage amount of the remaining sulfate of the soil in the first magnetic treatment, 2 %, and in second magnetic treatment, 5.8 %, was lower than the controlled treatment.