The Impact of US Biofuels Policy on Agricultural Production and Nitrogen Loads in Alabama
Table 3
Nitrogen load model calibration.
Parameter
Default values
SUFI-2 estimated values
Min
Max
New min
New max
Fitted value
valuea (sensitivity analysis)
RCN
0.00
15.00
7.098
21.327
14.212
0.000***
NPERCO
0.01
1.00
0.476
1.410
0.943
0.000***
BIOMIX
0.00
1.00
ā0.212
0.597
0.192
0.000***
UPDIS
0.00
50.00
14.000
24.700
19.300
0.001***
AI1
0.07
0.09
0.084
0.112
0.098
0.268
RSDCO
0.02
1.00
0.048
0.106
0.077
0.379
CDN
0.00
3.00
0.880
2.645
1.762
0.822
Statistical summary of the calibration procedure
Constituent
Period
-factor
-factor
NSE
Pbias
RSR
N organic
Mar-1999/Aug-1999
0.43
1.01
0.88
0.60
21.16
0.63
Nitrates and nitrites
Mar-1999/Aug-1999
0.68
0.79
0.85
0.53
42.49
0.69
Monitoring point: USGS 0357479650; RCN: concentration of nitrogen in rainfall; NPERCO: nitrogen percolation coefficient; BIOMIX: biological mixing efficiency; N_UPDIS: nitrogen uptake distribution parameter. ***99% confidence intervals. aprobability of the test statistic of the coefficients obtained by regressing the Latin hypercube parameters, generated during the calibration procedure and against the objective function values [23].
