The Influence of Corn Plant Population, N Rate and Simulated Landscape Position On Net Energy Yield and Profitability.

            To improve profitability and reduce the reliance on non-renewable energy sources, economic resource utilization and life-cycle analysis must be conducted simultaneously.  The objective of this study was to determine the impact of N rate, population level, and simulated landscape position on corn (Zea mays) profitability and net energy return.  The field experiment was conducted in 2005 and 2006.  The experiment contained 2 N (0 and 224 kg N ha^-1) rates, 2 population levels (76,500 and 149,000 plants ha^-1), and two simulated landscape positions (upper backslope and lower backslope).  The experimental design was a randomized split block. The energy balance and efficiency for corn grain used in ethanol production was calculated using the Nebraska Biofuel Energy Simulator (Bess) Model version 2008.3.1.  A partial economic analysis was conducted where seed, N fertilizer, and corn values were $312 (100,000 seeds)^-1, $1.25 (kg N)^-1, and $158 (Mg grain at 15.5% moisture)^-1,  respectively.  Fertilizer application and planting costs were not considered.  Results showed that: 1) increasing the population level increased yields, the energy return while reducing profitability; 2) applying 224 kg N ha^-1 increased yield, total energy input, and reduced the energy return; 3) that landscape position has a large impact on both financial and energy returns; and 4) economic and energy efficiency assessments may provide conflicting results. 
Keywords: Energy ratio, Energy use efficiency, Life cycle analysis, Ethanol