17:15 〜 19:15
[AGE34-P12] Predicting Soy Bean Growth using Coupled Soil and Crop Model Accounting for Nitrogen Fixation Process
キーワード：気候要因、栄養分吸収、成長段階、作物モデル
In order to cope with the effects of global population growth on food security and the negative impacts of climate change on agricultural production, it is important to have a reliable model that can predict not only crop growth but also environmental impacts under different agricultural practices. This will enable us to make the best use of limited resources and to develop agricultural strategies that respond to climate change and environmental changes. In this study, we developed a coupled soil and crop model using HYDRUS, a widely used program for precise calculation of water, heat, and solute transport in saturated and unsaturated soil and iRGM (Tatsumi, 2021), a comprehensive crop growth model. After nitrogen fixation process for soybean growth prediction was introduced in iRGM, two models were coupled through root water and nutrient uptake, enabling precise calculations for both the above- and below-ground areas (hereinafter referred to as the coupled model). The coupled model enables accurate computation including mass transport in the soil by exchanging data between the two models at each time step through the processes of water and nutrients uptake by roots. Nitrogen fixation is the process of converting atmospheric nitrogen gas (N2) into forms that plants can use, primarily ammonium ions (NH4+) and nitrate ions (NO3-).
The objective of this study is to evaluate the performance of the coupled model with the recently introduced nitrogen fixation process (Boote, 2008) for predicting soy bean growth under different conditions. In this new coupled model with the nitrogen fixation process, carbohydrates are first distributed to the rhizoids and the potential nitrogen fixation is calculated. Then, water flow and heat transport in the soil are computed to determine the limiting functions for water and temperature. Finally, the actual nitrogen fixation, which is the multiplication of the potential nitrogen fixation and the limiting functions of water and temperature, is calculated.
In this study, a coupled model with a nitrogen fixation process was developed. Evaluation of processes other than nitrogen absorption from the soil is now possible. The coupled model was tested with actual field soy bean growth data.
The objective of this study is to evaluate the performance of the coupled model with the recently introduced nitrogen fixation process (Boote, 2008) for predicting soy bean growth under different conditions. In this new coupled model with the nitrogen fixation process, carbohydrates are first distributed to the rhizoids and the potential nitrogen fixation is calculated. Then, water flow and heat transport in the soil are computed to determine the limiting functions for water and temperature. Finally, the actual nitrogen fixation, which is the multiplication of the potential nitrogen fixation and the limiting functions of water and temperature, is calculated.
In this study, a coupled model with a nitrogen fixation process was developed. Evaluation of processes other than nitrogen absorption from the soil is now possible. The coupled model was tested with actual field soy bean growth data.