The Impact of US Biofuels Policy on Agricultural Production and Nitrogen Loads in Alabama

Table 4

Calibration of plant growth parameters.

Growth parameter	SWAT range	Calibrating values
	All crops	Corn	Cotton	Soybeans
LAI	0.500–10.000	6.000	4.000	3.000
LEC	0.000–2.000	0.650	0.650	0.450
RUE	10.000–90.000	39.000	15.000	25.000
HVSTI	0.010–1.250	0.489	0.128	0.194
Observed yield [𝑦] (t ha^−1)	Average 1990–2010	6.088	0.766	1.874
Simulated yield [𝑦] (t ha^−1)	Average 1990–2010	6.092	0.752	1.908
Bias	Average 1990–2010	+0.06%	−1.84%	+1.76%

LAI: maximum leaf area index (m²/m²); LEC: light extinction coefficient; RUE: radiation use efficiency (kg m²/ha MJ); HVSTI: harvest index (kg ha/kg ha). Bias is calculated as (𝑦−𝑦)/𝑦.