Description of SOIL_LAYERS variables

[HGarre]

For some variables in the SubGroup SOIL_LAYERS it is unclear whether the amount of nutrient was measured per Mg of soil solution or per Mg of total soil
e.g. NO3_soil_by_layer: Description: NO3[N], for a given soil layer

[Jeff-White-AZ]

These are all meant to be per Mg of total soil. Ideally, the measurement should be accompanied by soil bulk density in order to calculate a true nutrient balance based on soil volume.
If there is interest in similar measurements for the soil solution, we would welcome suggestions for the most commonly used variables and how the method used to obtain the solution is best documented.
Again, thank you for this feedback. We have seen that there is a general need to provide more detailed definitions of terms.