Energy Requirements for Conventional Tillage Following Different Crop Rotations

Energy savings can be made by improving tractor and implement performance during tillage. We studied therelationship between cropping history and energy requirements for moldboard plowing and seedbed preparation(two passes with a field cultivator) on a loam soil under nine previous management practices, ranging from 6-yearbromegrass (Bromus inermis Leyss.) to 6-year conventional-till corn (Zea mays L.). Soil bulk density ( b) and volumetricwater content ( ) were measured before tillage. Draft, specific draft, ground speed, wheel slip, fuel consumption and plowdepth were monitored during primary and secondary tillage using a 97 kW instrumented tractor. The b, and all of theprimary tillage performance variables were significantly influenced by cropping history. Plow depth increased withdecreasing b (r = 0.41*). Draft (r = 0.44**), specific draft (r = 0.40*), wheel slip (r = 0.40*), and fuel consumption (r =0.35*) increased with increasing , while ground speed decreased (r = 0.39*). The effects of previous management ontillage energy became less pronounced as number of secondary tillage operations increased. Soil fragmentation (Df) wasmeasured after tillage, and was similar for all of the treatments despite different amounts of energy expended.Conventional tillage operations following long-term forages increase the energy required to produce a corn crop relativeto continuous conventional-till corn.