Active plant uptake

An active plant uptake of trace elements can optionally be chosen in the model (see switch ActiveUptake). This uptake is calculated for the leaf, stem and roots separately, and is a function of the allocation of assimilates to each pool. Thus, active trace element uptake from the mineral pool to the leaf, S_{TEMin→TELeafA}, is calculated as:

                                      (2.64)

where Δz is the layer thickness, C_TEMin is the concentration of trace elements in the dissolved phase, c_AUmax is a maximum concentration parameter, s_AUeffL is an efficiency parameter for active uptake to leaves, and C_a→Leaf is the allocation of assimilated carbon to leaves. The C_TEMin / c_AUmax ratio is never allowed to exceed unity. (See viewing functions Active uptake function and Active uptake leaf function.

The same equation is used analogously to calculate the active uptake to stem, S_{TEMin→TEStemA}, and roots, S_{TEMin→TERootsA}, by exchanging s_AUeffL to s_AUeffS or s_AUeffR, and C_a→Leaf to C_a→Stem or C_a→Root , respectively.

The total active uptake of trace elements, C_{TEMin→TEPlantA}, is the sum of the active uptake to the leaves, stem and roots.