Effects of long-term monocropping, rotation cropping, and fertilization on energy and fuel requirements for fall moldboard plowing in a clay-loam soil

With recent increases in energy costs, information on energy inputs is becoming a more important aspect in management decisions on selection of crop production systems. The effects of long-term (45-55 years) monocropping, rotation cropping, and fertilization on tillage energy (implement draft and tractor fuel consumption) were determined for a Brookston clay-loam soil in southwestern Ontario, Canada. Treatments included fertilized and unfertilized monocrop (continuous) corn (Zea mays L.), and a four year fertilized and unfertilized corn - oat (Avena sativa L.) - alfalfa (Medicago sativa L.) - alfalfa rotation with all phases of the rotation present in each year. The corn and second year alfalfa plots were moldboard plowed each fall after crop harvest, and then spring-tilled (disc, harrow) prior to planting; oat and first year alfalfa plots were not fall plowed or spring-tilled. Moldboard plow draft and tractor fuel consumption were measured annually from 2004 to 2014 using an instrumented tractor and the same plow and settings. Monocrop unfertilized corn consistently exhibited the greatest plow draft and tractor fuel consumption. Draft averaged over ten years was 13.0% higher for unfertilized than fertilized rotation corn, and 15.5% higher for fertilized than unfertilized second year alfalfa; fuel consumption was 10.4% higher for unfertilized than fertilized rotation corn and 5.1% higher for fertilized than unfertilized second year alfalfa. These differences were attributed to treatment-induced changes in soil strength. Both plow draft and fuel consumption were lower in rotation corn relative to monocrop corn, while plow draft was greater in fertilized alfalfa relative to unfertilized alfalfa due to greater root growth. This study demonstrated that long-term cropping systems can have substantial impacts on the energy required for tilling a clay loam soil.