Table 2.

SPARROW calibration results of sources of nitrogen, delivery and decay variables.

Parameter	Units	Coefficient Units	NWLS Estimate	Confidence Interval		Standard Error	p-Value	Bootstrap Estimate
				Lower 90%	Upper 90%
Sources
Nitrogen applied to corn/soy	kg·N/year	Fraction	0.195	0.178	0.216	0.011	0.000	0.194
Nitrogen applied to hay	kg·N/year	Fraction	0.086	0.068	0.110	0.013	0.000	0.086
Nitrogen applied to other crops	kg·N/year	Fraction	0.006	−0.005	0.012	0.008	0.452	0.006
Atmospheric Deposition	kg·N/year	Fraction	0.110	0.057	0.159	0.030	0.000	0.110
Point discharge	kg·N/year	Fraction	0.727	0.534	0.912	0.142	0.000	0.729
Urban Land	km2	kg·N/km2/year	1210	863	1606	224	0.000	1207
Forests	km2	kg·N/km2/year	28.68	3.05	55.91	15.14	0.059	28.57
Land-to-water delivery
Average Daily Temperature	Celsius	Celsius	−0.069	−0.087	−0.049	0.012	0.000	−0.069
Annual Total Precipitation	cm/year	cm/year	0.016	0.014	0.018	0.001	0.000	0.016
Wetlands	km2	km2	−0.007	−0.010	−0.003	0.002	0.003	−0.007
Aquatic loss
Reach water time of travel	days	days−1	0.051	0.038	0.067	0.009	0.000	0.050
Reservoir residence time	days	days−1	0.002	0.002	0.003	0.001	0.000	0.002
Summary Statistics
Number of sites		1003
RMSE		0.57
Adjusted R2		0.92
Yield R2		0.87
Shapiro–Wilk		0.92
p-value		0.00