# HYDRUS-1D Simulation of Soil Water Dynamics for Sweet Corn under Tropical Rainfed Condition  
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1 Department of Biological and Agricultural Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia; [EMAIL_ADDRESS] (M.L.); [EMAIL_ADDRESS] (H.C.M.); [EMAIL_ADDRESS] (A.W.)  
[PERSON]  
1 Department of Biological and Agricultural Engineering, Universiti Putra Malaysia, Serdang 43400, Malaysia; [EMAIL_ADDRESS] (M.L.); [EMAIL_ADDRESS] (H.C.M.); [EMAIL_ADDRESS] (A.W.)  
[PERSON].  
3 Malaysian Agricultural and Research Development Institute (MARDI), Serdang 43400, Malaysia; [EMAIL_ADDRESS]  
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andenvironment [7]. That is why devising water management strategies depend on information relating to crop water requirement (represented as evapotranspiration). Measuring other water balance components such as deep percolation, runoff in field conditions is also a big challenge [8]. The response of the water balance components also varies with climate geographically. The significant differences between regions necessitate a need to evaluate responses of water balance components in various geoclimatic regions. Rainfall is the most investigated components of water balance. A significant regional variation in rainfall has also been recorded [9]. Climate change also has a significant effect in altering rainfall patterns in humid tropics [10]. Therefore, in a tropical region like Malaysia, the change in rainfall patterns is more crucial than in temperature due to climate change.  
Simulation models are recognized as a valuable tool to assess water transport and the extent to which management practices affect crop yield and the environment. However, the validation of simulation models for local conditions is crucial [11]. Among different available models, a software package HYDRUS-1D [12] has been widely used for simulating water flow and solute transport in soils, to analyze flow and transport processes in agricultural fields. Several researchers have applied HYDRUS-1D to evaluate water balance successfully. As compared to other models, HYDRUS-1D has the flexibility of accommodating different boundary conditions and the capability to consider the root uptake of water and nutrient simultaneously. The model is capable of simulating soil water and solute dynamics under different management practices [13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. All these researchers validated HYDRUS-1D as a reliable tool for such investigations.  
It is necessary to improve agricultural water management and to develop new strategies to increase agricultural productivity [23]. The heavy rainfall results in the solute loss to increase manifold in the tropical climate. Therefore, the study was carried out to quantify water losses (surface runoff and leaching) from the field that results in fertilizer loss in Malaysia. Quantifying the water balance components under rainfed conditions can be useful to improve irrigation management and to assess the scale of fertilizer loss for sweet corn production. The study can further be used to link rainfall intensity with fertilizer loss. Besides, HYDRUS-1D has rarely been used for sweet corn production in tropical environment. The model validation through the field experiments in quantifying water losses is worthwhile for sweet corn production. Indeed, heavy rainfall in Malaysia can potentially meet crop water requirements. However, the duration and frequency of rainfall are uncertain that can affect the water availability to plant. Therefore, the objectives of the study were (1) to simulate the soil water dynamics under rainfed conditions, and (2) to evaluate the HYDRUS-1D model for the rainfall potential to meet the water requirement of sweet corn in the tropical region.