Effects of winter wheat N status on assimilate and N partitioning in the mechanistic agroecosystem model DAISY

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Nitrogen (N) management in modern farming needs to balance the interests of yield quantity and quality with environmental impact of reactive N lost to the atmosphere and aquatic environments. Mechanistic agroecosystem models are useful tools to analyse the combined effects of management options and natural conditions, including soil fertility and climate, site-specific optimal N application rates and environmental impact. An important component of the system description is the crop module, including the responses to N status and N stress. To improve the description of crop growth response to N status in the DAISY model system, we implemented an empirical model for N status effects in winter wheat on the partitioning of assimilated dry matter and N between leaves and stems, originally described by Ratjen and Kage (Journal of Agronomy and Crop Science, 2016, 202, 576s). To our knowledge, this mechanism has not been included in any of the most widespread and commonly used mechanistic agroecosystem models. We tested and compared the model performance
with and without the new N status response against data from a two-season
winter wheat experiment in Denmark, where crop growth and partitioning of dry
matter and N were measured. Implementation of the new N status response function improved model performance and ensured a more robust crop growth description, especially in scenarios with periods of low crop N status or N stress. The mechanism mimics an adaptation strategy, where the crop balances N stress and growth potential by dynamically adjusting the leaf-stem ratio and thereby N demand. This behaviour opens a discussion regarding the empirical concept of a biomass driven critical N curve.
TidsskriftJournal of Agronomy and Crop Science
Udgave nummer6
Sider (fra-til)784-805
Antal sider22
StatusUdgivet - 2020

ID: 241583489