Modeling Phosphorus Capture by Plants Growing in a Multispecies Riparian Buffer

Table 1

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

Parameter		Units	0–120 cm	0–30 cm	30–60 cm	60–120 cm
𝐷𝑒	Diffusion coefficient in water^†	cm^2 s^−1	8.9𝐸−6	8.9𝐸−6	8.9𝐸−6	8.9𝐸−6
Θ	Volumetric soil water content	cm^3 H2O/cm^3 soil	0.32	0.32	0.33	0.31
𝑓	Impedance factor	Unitless	0.33	0.33	0.35	0.32
𝑉𝑜	Water uptake at root	cm s^−1	7.45𝐸−7	7.45𝐸−7	7.45𝐸−7	7.45𝐸−7
𝐶li	Initial solution concentration	𝜇mol cm^−3	9.39𝐸−3	2.69𝐸−2	6.45𝐸−4	6.45𝐸−4
𝑏	Buffer power	Unitless	314	45	477	421
𝐼max	Maximum influx at high concentration	𝜇mol cm^−2 s^−1	1.64𝐸−8	1.647𝐸−8	1.647𝐸−8	1.647𝐸−8
𝐾𝑚	Solution concentration when influx is 0.5 𝐼max	𝜇mol cm^−3	8.7𝐸−4	8.7𝐸−4	8.7𝐸−4	8.7𝐸−4
𝐶min	Solution concentration when influx is zero	𝜇mol cm^−3	1.0𝐸−6	1.0𝐸−6	1.00𝐸−6	1.00𝐸−6
𝑟𝑜	Root radius	cm	0.023	0.0241	0.0217	0.0217
𝑟1	Half distance	cm	1.05	0.213	0.378	2.578
𝐿𝑜	Initial root length	cm m^−3	3,041,322	2,094,524	663,672	283,126
𝑘	Root growth rate	cm d^−1	4,812	6,631	6,816	991

^†From Edwards and Huffman [18].