Soil inorganic N processes

The following processes are computed on a daily basis in the soil inorganic N module:

  1. Plant uptake rates for NO3 and NH4 are computed in the individual plant modules. These amounts of N taken up are integrated into soil state variables in the inorganic N module.
  2. Fertilizer event: Urea, NO3 , and NH4 are placed each day to user-specified depths.
  3. Tillage event: Soil NO3, NH4, and urea are mixed within the tillage depth with specified mixing efficiency.
  4. Volatilization of NH4 in oxidation layer to ammonia gas (NH3).
  5. Hydroloysis of urea to NH4.
  6. Mineralization and immobilization due to organic matter decomposition.
    1. Addition of mineralized N to NH4 pool .
    2. Subtraction of immobilized N from NH4 (preference) and NO3 pools.
  7. Nitrification of NH4 to NO3, N2O and NO gases.
  8. Denitirification of NO3 to N2O and N2 gases.
  9. Movement of NO3 and Urea with soil water drainage and upflux.