## Nitrogen simulation

A discussion forum for Hydrus-1D users.
aliko
Posts: 14
Joined: Sun Jul 03, 2016 3:01 pm
Location: Brazil

### Nitrogen simulation

We know Hydrus is not a crop-based model, however, it has interesting possibilities for solute transport modelling for my work. So to simulate
150kg N/ha applied in the sowing day is it true to assume all that in the first 5 top cm of the soil profile as the initial condition. Assuming the depth of fertilizer application is 5cm so

(150 kgN/ha) * (1/0.05m) =0.3 mgN/cm3 soil --------------[Initial concetration in total concentration : mass solute/volume of soil]

then we put this initial condition in the first 5 cm and model the nitrogen transport and run under the climatic conditions and for any year of planting, we put this condition and zero nitrogen in top boundary condition. is it true?
Considering whole nitrogen is nitrate, so Kd is ZERO and all passive uptake.
I attached one simple model
Attachments
example.rar

Jirka
Posts: 4985
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

### Re: Nitrogen simulation

The initial concentration will depend also on soil water content. The solute mass in the soil profile is equal to the depth integral of water content multiplied by concentration, i.e., S=theta*c*depth. Note that the Balance.out file (Mass Balance Information) provides information about how much mass is in the soil profile. To get then the solute mass for one hectar, you simply need to multiply the local mass (in the soil profile) by the surface area.

I'm traveling in Tanzania (climbing Kilimanjaro and safari) and thus do not have time (and frankly, interest) to look at your project.

J.