جستجوی مقالات مرتبط با کلیدواژه « مدل های شبیه سازی » در نشریات گروه « آب و خاک »

In the recent years, growth simulation models have been attracted for agricultural engineers in order to predict different crop yields. However, growth simulation of medicinal crops has been rarely studied. In current research, for the first time, the performance of SALTMED model in predicting peppermint yield under different deficit irrigation and salinity conditions was studied. Treatments of water deficit included (100% irrigation requirement (as control), 20 and 40% water deficit) and salinity treatments (control, 2, 3 and 4 dS/m). Calibration of model conducted using control treatment data. After insuring the results, validation of model conducted using other treatments data. Results indicated that model accuracy for predicting peppermint yield was relatively good. The coefficient of determination of model during calibration and validation were 0.953 and 0.801. Studying the separate results showed that the model predicted maximum yield of water deficit levels with higher accuracy than salinity levels. Maximum simulated yield of 20 and 40% water deficit levels were 2.75 and 2.83 ton per hectare while the yield of 2, 3 and 4 dS/m obtained as 2.1, 2.06 and 2.05 ton per hectare.

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.

The propose of this study was evaluation of CropSyst Model on growth simulation and yield stimation of canola under different irrigation treatments. Canola (Talaye) was sown under 5 treatment and 4 replicants in completed randomized block designs at the college of Agriculture, Shiraz Universityduring 2007-2008. During the growth season dry mass and LAI was meseaured frequently, then model was calibrated by the resukts. Obtained results showed very good esyimation by the simulation model, as the correlation coefficient square between dry mass and LAI in defferent treatments were more than 0.99 and 0.95, respectively. Also correlation coeficient between meseaured and simulated crop yeild was 0.96, that shows the accuracy of model in simulation on crop parameter. Also the model was valuated by independent data. Obtained results showed the accuracy of model simulation in dry matter as the correlation cofficient was achieved 0.9. Also LAI simulation in all treatments had good reults, as generaly is reliable in canola investigations.