Simulation of Soil Moisture by HYDRUS-1D Model under Wheat Cultivation

To achieve the goal of high yield, deep understanding of physiological, agronomic and environmental factors is necessary to improve the performance and sustainability of agricultural systems. This may not be practical unless the plant complex systems and the type of response to inputs and environmental conditions are known as important factors. In modern agricultural methods the uses of different models are important for management, optimize productivity, accurate understanding of the system and obtaining a precise formulation of the standard. In order to simulation of soil moisture under different water conditions on wheat(Chamran cultivar) a field experiment was conducted at the Agricultural Research Center- Ahwaz. In this experiment, three irrigation levels include I1 ( no water stress ), I2 (stop irrigation at the heading stage and I3(stop irrigation at the milky grain stage) and five levels of nitrogen fertilizer namely N1(no nitrogen fertilizer), N2=40, N3=80, N4=120 and N5=160 kg/ha were used as treatments. In this research, HYDRUS-1D was used as simulation model. Analysis of results for sensitivity of model showed that soil moisture coefficient of model under saturation condition θs is more than other coefficients and a slight change in coefficient caused a large change in output variation of model. The minimum effect was observed in α, I and θr coefficients. Meanwhile, results indicated that model was estimated moisture content less than reality condition. Also, the amount of moisture on the basis of simulated model was estimated less than the real moisture. The model efficiency that reflects to quality and observed data was estimated between 0.67 and 0.90. This was due to high efficiency of simulated model for soil moisture.