A kinetic model for root ion absorption named as the evapotranspiration-integrated model was newly proposed in order to analyze the characteristics of ion absorption by crop roots in soil-based culture. The validity of the evapotranspiration-integrated model for simulation of the day-to-day dynamics of soil salinization was examined based on experiments with a large-sized soil column system cropped with maize plants, where the salinized nutrient solution was supplied as found in crop fields under desertification. The simulated time courses of salt accumulations in plants and soil were expressed reliably based on the specificity of ion types in root absorption: Cl-, Na+, Mg2+ and Ca2+ more highly accumulated in the root zone soil than in plants because of the root low absorption of these ions. Accumulation of the major essential ion of K+ was extremely higher in plants than in the root zone soil because of the root high absorption of K+. These results indicate that the evapotranspiration-integrated model is applicable for evaluating selective and active ion absorption by crop roots in the soil salinization process, which is considered to contribute to sustainable management of crop rotation systems.
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