09-03-24 Modification of Microbial based Nitrification model

The microbial biomass growth and death rates are changed to be linked to the Nitrogen mass balance of the system. Previous assumption made microbial biomass as an independent component. The death rate function is changed to be simplified and are now only dependent on a rate coefficient and the square root of the biomass. Previous assumptions also linked the death rate similar as the growth rate to environmental conditions as temperature, moisture and pH.

A number of default values have been adjusted for the microbial based function to correspond with robust behavior for the Hogiwald forest in Germany and not to the original DNDC model.