NDR - nutrients load


I am doing some trials with the NDR model and I have a question related to the nutrient load values for the biophysical tables. I have load data (N and P) that come from literature and from local agricultural models (all in kg/ha).

My question is: should I implement any adjustment or correction to the values in the biophysical table (to pixel size or, correct for nutrient retention from downstream pixels )?



Hi @Guille -

Do your load values represent the amount of N or P applied, or do they represent the amount that is running off of the agricultural pixel? If it is the amount of N/P applied (for example, fertilizer application rates), you should adjust the value based on the retention efficiency of that land cover type, so the result is the amount of N or P leaving each pixel of that particular land cover class, after the vegetation has retained some. This is described with an example in the Data Needs section of the User Guide.

If your load values already represent the amount of N/P that is leaving each pixel (so, they are already “export coefficients”), and they are in kg/ha/year, you do not need to implement any adjustment to the values, they can be used in the model directly.

~ Stacie


Yes, my data represent the applied amount of N and P, and, it actually comes from fertilizer application rates. Always grateful for your help Stacie!

Thanks a lot!