Solute Transport Hydrus 1D

[mazhar]

Dear Members,

We applied NPK 130:60:90/ha to Corn field in the form of compound fertilizer (15-15-15) as basal and urea as top dressing. The solute transport was subjected to natural rainfall over crop season. The water balance simulation results were quite good. For solute simulation, I need few clarifications;

1)After its conversion to mmol/cm3 the applied mass of basal fertilizer should be specified as the initial concentration cTop in the Time Boundary Condition or at the surface node in the Soil Profile? If it is specified in soil profile the rest of fertilizers application will be specified as ctop right??
2)If I consider solute application with surface water flux (rainfall). In this case, the concentration of solute can be obtained through (q*c*t) considering flux and time values of the day when fertilizer is applied, or subsequent flux have to be considered also?
3)I need to simulate three solutes (urea, nitrate and ammonium) while I have only rate of NPK and Urea application, how can I divide it to NH4 and NO3 cTop? I considered the applied N as urea (solute1) and assigned solute reaction parameters to ammonium (solute2) and nitrate (solute 3) for first order reaction with the help of literature but did not get any result for ammonium and nitrate mass.
Thank you.
Mazhar Iqbal

[Jirka]

1. Correct. If the basal fertilizer is in the soil profile at the beginning of the simulations, it should be specified as an initial condition. If it is applied during the simulation time, it should be specified as a boundary condition (cTop).
2. Correct. The concentration of solute can be obtained from the total solute mass S applied (=q*c*dt) considering water flux (q) and duration of application (dt).
3. I suggest that you look at multiple manuscripts (see below) when similar problem has been resolved. Note that nitrification rates that lead to daughter products (e.g., NH4 and NO3) needs be be given in the SinkWater1'. See Test3.

Hanson, B. R., J. Šimůnek, and J. W. Hopmans, Numerical modeling of urea-ammonium-nitrate fertigation with drip irrigation using numerical modeling, Agricultural Water Management, 86, 102-113, 2006.

Ramos, T. B., J. Šimůnek, M. C. Gonçalves, J. C. Martins, A. Prazeres, and L. S. Pereira, Two-dimensional modeling of water and nitrogen fate from sweet sorghum irrigated with fresh and blended saline waters, Agricultural Water Management, 111, 87-104, doi: 10.1016/j.agwat.2012.05.007, 2012.

Li, Y., J. Šimůnek, Z. Zhang, L. Jing, and L. Ni, Evaluation of nitrogen balance in a direct-seeded-rice field experiment using Hydrus-1D, Agricultural Water Management, 148, 213-222, doi: 10.1016/j.agwat.2014.10.010, 2015.

J.

[mazhar]

Sir, thank you for valuable input. The suggested articles are really helpful. If possible pls share the project file for 'Evaluation of nitrogen balance in a direct-seeded-rice field experiment using Hydrus-1D' any of above-mentioned articles

[Jirka]

I do not have them. You would have to contact Dr. Li Yong directly. J.

[mazhar]

Noted Sir

[Grant]

Hello Mazhar,

Were you able to contact Dr. Li Yong and request for a copy of the project file? If yes, hopefully you could share it with me.

Thank you in advance

[Ali.Ashrafi]

Hi all,
I have a question about the concentration results of observation nodes.
if I select the total concentration as the initial conditions, the results of concentration in observation nodes will be total or liquid concentration?

[Jirka]

Observation nodes always display the liquid-phase concentration, independently of the mode for input concentrations. J.