Changed N-uptake models to be more consistent for both mineral uptake and for the organic uptake on Nitrogen.
First of all the uptake is related to a root density function for both mineral and organic uptake. See switch “Root Density Influence” and
two parameters: NUptRootCoefOrg and NUptRootCoefMin. The parameters are made proportional to the root density in an exponential function that reduce the uptake efficiency from unity to zero depending on the root density.
The mineral uptake model was changed so that the competition between different plants is correctly related to the root distribution for each plant. Previous model was using the relative demand for the entire root system to differentiate the uptake from one single layer. The new model is using the relative demand of the actual plant to the other plants for each specific layer.
The compensatory uptake by plants using the parameter NUptFlexDegree as regulating the degree for all plants in a common way has been complemented by a table “Plant Specific Flexibility Uptake” to specify different values for different plants. A Switch Flexible Uptake is introduced to make choice between the two options.
The Organic uptake was corrected to being independent on soil discretization by removing the relative distribution of roots from the maximum supply function for each layer. The previous model was unfortunately sensitive to number of layers and root distribution. Many layers with roots was an disadvantage for the organic uptake efficiency.
PEJ/DG/LK