LECHM برآورد رطوبت در محدوده توسعه ريشه چغندرقند با استفاده از مدل

The estimation of moisture in sugar beet root development limit using LEACHM model

The growing interest in simulation of water movements in soils is in response to the need for development of solutions for various agriculture and environment management problems, such as irrigation. In order to be able to adopt models for simulation, it is important that the capabilities of these models and credibility of their results are tested. In this study results from LEACHM simulation model are compared with the measured soil water data. This experiment was conducted at the farm of Khorasan Agricultural Research Center during growing season of 2001. The experiment was laid out in a completely randomized block design, adopting split plot method. Main factor consists of three water levels; I1: without water stress, 12: continuous water stress and 13: early water stress. Subplots consist of 3 different nitrogen levels 80, 160 and 240kg/ha viz. A sensitivity analysis was performed to identify the input parameters of LEACHM, which most influence on the water content variations. Sensitivity analysis results showed that bulk density has an important effect on soil water content. Simulated soil water contents water in close agreement to measured values. Mean Bias Error (MBE), Relative Error (RE) and Coefficent of Variation (CV) water changed irrespectively between 1:09 to 2.81, 6.46 to 13.02 and 11.58 to 16.16 percent. Generally, the model overestimated measured water contents. According to the results, this model can be used for predicting the irrigation time and quality of water stress, by estimating and measurement some characteristics of soil, plant and climate.