Modeling Phosphorus Capture by Plants Growing in a Multispecies Riparian Buffer

Table 2

Transport, sorption, and root parameters used in the NST 3.0 model to describe P uptake by switchgrass 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	0.37	0.39	0.36	0.36
𝑓	Impedance factor	Unitless	0.42	0.45	0.40	0.40
𝑉𝑜	Water uptake at root	cm s^−1	8.43𝐸−7	8.43𝐸−7	8.43𝐸−7	8.43𝐸−7
𝐶li	Initial solution concentration	𝜇mol cm^−3	1.28𝐸−2	2.95𝐸−2	4.52𝐸−3	4.52𝐸−3
𝑏	Buffer power	Unitless	63	47	74	69
𝐼max	Maximum influx at high concentration	𝜇mol cm^−2 s^−1	2.30𝐸−8	2.30𝐸−8	2.30𝐸−8	2.30𝐸−8
𝐾𝑚	Solution concentration when influx is 0.5 𝐼max	𝜇mol cm^−3	3.22𝐸−5	3.22𝐸−5	3.22𝐸−5	3.22𝐸−5
𝐶min	Solution concentration when influx is zero	𝜇mol cm^−3	102𝐸−6	1.02𝐸−6	1.02𝐸−6	1.02𝐸−6
𝑟𝑜	Root radius	cm	0.009	0.0121	0.0075	0.0085
𝑟1	Half distance	cm	0.304	0.198	0.227	0.489
𝐿𝑜	Initial root length	cm m^−3	4,162,621	1,935,508	1,371,549	855,564
𝑘	Root growth rate	cm d^−1	8,484	10,506	10,306	4,641

^†From Edwards and Huffman [18].