The new version include a change in the organic transformation from litter to humus to avoid negative values of Nitrogen in the remaining litterpool when no nitrogen is available. The previous version was not testing for nitrogen and occationally the nitrogen values may have been negative numbers. This is now avoided.
The switch Displacement of organics between layers have been updated and modified. Previous options with a delayed dispacement has been removed. Instead new options have been added that allows the displacement to include only the uppermostlayer have been added.
Current definition of the switch is with 5 different levels.
Static – No Displacement of organics will be made (This means that the state variables are fixed to the original compartments as defined in the start of the simulation)- default
At Year Shift – Dispacement of all excess compared to the start of the simulation will be made downward to the adjacent compartment. If the state of the compartment is a deficit compared to the start of the simulation the dispacement of this amout is upwards toward the layer where the deficit appears. The result of this is that changes of organics is propagating from the top to the lowest layers. This may be a good assumption for an organic soil profile where the entire soil profile will growth upwards like a typical undrained wetland. A drained wetland with decreasing organics will instead loose the thickness of organics from the bottom.
At Year Shift only top layer – Displacement will then only be from the toplayer to the adjecent second layer of the profile. This may be a good solution to form a thicker organic layer in the second layer instead of the uppermost layer when if we have a typical forest soil with an organic top layer (O). In this case the the organic layer will expand or shrink in the second layer. Good solution if you have a compartment size of the uppermost layer that is similar to the height of the O-layer in the simulated profile.
The 2 options above can also be made with a higher frequency (week) instead of year.
Those options may be useful when making simulation during long periods. For simulation less then 50 years the static option is recommended. Optionally the simulation can be made in a serie where new initials values are introduced as the result of the prior simulation. In this case a manual flexible setting can be assumed together with also possible change in the soil physical properties.