Table 3: Transport, sorption, and root parameters used in the NST 3.0 model to describe P uptake by smooth brome for the 0–120, 0–30, 30–60, and 60–120 cm soil depths.

ParameterUnits0–120 cm0–30 cm30–60 cm60–120 cm

Diffusion coefficient in watercm2 s−1
ΘVolumetric soil water contentcm3 H2O/cm3 soil 0.256 0.25 0.26 0.26
Impedance factorUnitless 0.243 0.23 0.25 0.25
Water uptake at rootcm s−1
Initial solution concentration mol cm−3
Buffer powerUnitless 73 28 98 92
Maximum influx at high concentration mol cm−2 s−1
Solution concentration when influx is 0.5  mol cm−3
Solution concentration when influx is zero mol cm−3
Root radiuscm0.01140.01350.0090.0117
Half distancecm0.5050.2550.3470.914
Initial root lengthcm m−32,486,3791,464,477793,155228,747
Root growth ratecm d−13,5728,6311,622464

From Edwards and Huffman [18].