Energy Use in Agriculture and a Precision Farming Approach to Minimize Impacts.

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 paper is discuss the benefits of conducting simultaneous analysis and to demonstrate how landscape positions impact profitability and energy efficiency.  Data used in this study was derived from corn (Zea mays) field experiment 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.  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.