Nitrogen loss from agricultural fields results in contamination of ground and surface water resources due to leaching and runoff, respectively. Nitrogen transport dynamics vary significantly among agricultural fields of different climates, especially in the tropical climate. This study intended to evaluate the rainfall impact on nitrogen distribution and losses under tropical rain-fed conditions. The study was carried out in a sweet corn field for two growing seasons at the Malaysian Agricultural Research and Development Institute (MARDI) research field. The HYDRUS-1D numerical model was used to simulate nitrogen transport dynamics in this study. The observed nitrogen concentrations were used for calibration and validation of the model. Total nitrogen input to sweet corn was 120 kg/ha for both seasons. Nitrogen losses through surface runoff and leaching were dominating pathways. Surface runoff accounted for 35.3% and 22.2% of total nitrogen input during the first and second seasons, respectively. The leaching loss at 60 cm depth accounted for 4.0% (first season) and 18.5% (second season). The crop N uptake was 37.5% and 24.9% during the first and second seasons, respectively. Nitrate was the dominant form of N uptake by the crop that accounted for 83.6% (first season) and 78.5% (second season). The HYDRUS-1D simulation results of nitrogen concentrations and fluxes were found in good agreement with observed data. The overall results of simulation justified the HYDRUS-1D for improved fertilizer use in the tropical climate.

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HYDRUS-1D模拟雨育甜玉米生产中氮动态的模拟

农田中的氮损失分别由于淋溶和径流而导致地下水和地表水资源的污染。在不同气候的农业田间，尤其是在热带气候下，氮的运输动态差异很大。这项研究旨在评估热带雨养条件下降雨对氮素分布和损失的影响。这项研究是在马来西亚农业研究与发展研究所（MARDI）的一个甜玉米田中进行了两个生长季节的研究。在这项研究中，使用HYDRUS-1D数值模型来模拟氮的迁移动力学。观察到的氮浓度用于模型的校准和验证。两个季节向甜玉米的总氮输入量为120千克/公顷。地表径流和浸出造成的氮损失是主要途径。在第一个和第二个季节，地表径流分别占总氮输入的35.3％和22.2％。60 cm深度的淋失损失占4.0％（第一季）和18.5％（第二季）。在第一个和第二个季节中，作物的氮吸收量分别为37.5％和24.9％。硝酸盐是农作物氮吸收的主要形式，占第一季的83.6％和第二季的78.5％。氮浓度和通量的HYDRUS-1D模拟结果与观测数据非常吻合。模拟的总体结果证明了HYDRUS-1D在热带气候中改善了肥料的使用。在第一个和第二个季节分别输入总氮的2％。60 cm深度的淋失损失占4.0％（第一季）和18.5％（第二季）。在第一个和第二个季节中，作物的氮吸收量分别为37.5％和24.9％。硝酸盐是农作物氮吸收的主要形式，占第一季的83.6％和第二季的78.5％。氮浓度和通量的HYDRUS-1D模拟结果与观测数据非常吻合。模拟的总体结果证明了HYDRUS-1D在热带气候中改善了肥料的使用。在第一个和第二个季节分别输入总氮的2％。60 cm深度的淋失损失占4.0％（第一季）和18.5％（第二季）。在第一个和第二个季节中，作物的氮吸收量分别为37.5％和24.9％。硝酸盐是农作物氮吸收的主要形式，占第一季的83.6％和第二季的78.5％。氮浓度和通量的HYDRUS-1D模拟结果与观测数据非常吻合。模拟的总体结果证明了HYDRUS-1D在热带气候中改善了肥料的使用。硝酸盐是作物吸收氮的主要形式，占第一季的83.6％和第二季的78.5％。氮浓度和通量的HYDRUS-1D模拟结果与观测数据非常吻合。模拟的总体结果证明了HYDRUS-1D在热带气候中改善了肥料的使用。硝酸盐是农作物氮吸收的主要形式，占第一季的83.6％和第二季的78.5％。氮浓度和通量的HYDRUS-1D模拟结果与观测数据非常吻合。模拟的总体结果证明了HYDRUS-1D在热带气候中改善了肥料的使用。