Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2006
Publication Date: 10/1/2007
Citation: Rathke, G., Wienhold, B.J., Wilhelm, W.W., Diepenbrock, W. 2007. Tillage and rotation effect on corn-soybean energy balances in eastern Nebraska. Soil & Tillage Research 97:60-70. Interpretive Summary: Crop production requires significant inputs of energy. Management alternatives vary in energy requirements and as energy costs increase more efficient alternatives are desired. A long-term study comparing corn and soybean grown year-after-year or in rotation under six different tillage practices was used to calculate energy input and output. Nitrogen fertilizer requires a large amount of energy to produce and fertilized crops require higher energy input than crops that support N fixation. No-tillage systems require less energy input than other tillage systems. Lowest energy input was required for no-tillage soybean and highest energy input was required for moldboard plow corn. Corn yields are greater than those of soybean resulting in higher energy output for corn systems. Crop rotation and reduced tillage improve the energy efficiency of crop production systems. Improving crop N use efficiency will improve cropping system energy efficiency.
Technical Abstract: Data from a field experiment conducted in eastern Nebraska over 16 yr (1986-2001) were used to determine the energy balance of corn (Zea mays L.) and soybean (Glycine max L.) as affected by tillage treatments and rotation. Tillage treatments included chisel plow, tandom disk, moldboard plow, ridge-tillage, no-till, and subsoil tillage. Crop sequences were continuous corn, continuous soybean, corn in a corn-soybean rotation, and soybean in a soybean-corn rotation. The energy balance was assessed by comparing the parameters: energy gain (net energy output), energy intensity (energy input per unit grain equivalent), and output/input ratio. Changes in plant density, crop production practices, and machinery over the course of the study were taken into account in the analysis. Averaged across years, the no-till treatment provided significant energy savings compared to the other tillage treatments. The energy input was lower for soybean systems than corn. Hence, the lowest energy input was required for soybean with no-tillage, and highest for corn systems with moldboard plow tillage. Within a rotation the tillage treatment had a small effect on energy output with energy efficiency being more strongly affected by crop rotation than by tillage method. Moldboard plow tillage maximized the energy gain while reduced tillage (ridge-till, no-till) minimized energy intensity and maximized output/input ratio. Within crops and crop rotations, the highest energy gain and lowest energy intensity occurred in corn production. For both corn and soybean, the energy gain was greater for crop rotations than monocultures. The output/input ratio was greatest for rotated corn and lowest for continuous soybean. Crop rotation and reduced tillage improve the energy efficiency of crop production systems.