Hi Mariska,

I've seen that equation first in this publication on page 5:

Based upon this estimation of the average excretion, on the food supplied to the Swedish
population according to the FAO statistics and on statistical analysis of different foodstuffs,
relationships (Equations 1-2) have been developed between the food supplied according to
FAO and the excretion of N and P.
N= 0.13* Total food protein Equation 1
P= 0.011* (Total food protein + vegetal food protein) Equation 2

Source:
www.susana.org/en/knowledge-hub/resource.../library/details/187
Joensson, H., Richert Stintzing, A., Vinneras, B., Salomon, E. (2004). Guidelines on the Use of Urine and Faeces in Crop Production. Stockholm Environment Institute, Sweden

But maybe you already knew that and wanted to know if the Jönsson publication only cited someone else's work or if their publication is the original source? We could ask Hakan Jönsson about that?

Dear colleagues,

A brief question: in order to get an idea of the N and P content in urine, there is this rule of thumb to derive the concentration from the protein intake of people:

N = 0.13 x total food protein
P = 0.011 x (total food protein + vegetal food protein)

Does anyone know the original source of publication for this equation?

Many thanks in advance..!

Mariska.