E. C. Burt

Energy Reduction in Sweep Tillage Systems

Conservation farming systems are rapidly increasing in popularity. As these changes ntake place, there is an obvious need to maximize the efficiency and effectiveness of the more ncommon conservation farming tools. Chisel-sweep systems have an advantage over many nconservation tillage tools because they maximize the residue left on the surface for erosion ncontrol while providing the tillage necessary for weed control and seedbed preparation. The naccumulation of residue within the confines of the tillage tool is a common problem. The proper nclearance vertically between the soil surface and the supporting framework for the tillage device nis necessary for the passage of residue. A coulter directly ahead of the wingtips of each leading nsweep, operating at the same depth as the sweep, reduced draft of the sweep-coulter system nup to 45% as compared to the draft of a sweep plus coulter system with the coulter operating ndirectly ahead of the sweep center. Coulters directly ahead of the wingtips of sweeps permit npassage of the sweeps through heavy residue without problems of residue clogging, although nthere is a tendency for more residue buildup on the sweep shanks when wingtip coulters are nused.

TIRE OPTIONS AND CONSEQUENCES FOR FOUR-WHEEL DRIVE TRACTORS

General principles are presented to assist agricultural operators in the selection of tires and wheels for four-wheel drive tractors. For improved traction, all wheels should be powered since it takes more energy to tow or push a wheel than to self-propel it. Wheels of greater diameter are desirable because of their longer footprint. Tandem drive provides increased traction efficiency because the second wheel runs in the first wheels compacted footprint. Radial ply tires slightly longer footprints give improved performance. Equal dynamic load on front and rear axles and equal slip of front and rear wheels are recommended. Dual wheels can be advantageous when flotation is a problem since more soil surface is used to support tractor weight, although using duals to reduce soil compaction is usually counterproductive. The first pass of a wheel in loose soil generally causes about 80% of the sinkage plus sufficient compaction to restrict crop root growth. A traffic control system which establishes permanent traffic lanes is beneficial; compacted traffic lanes improve traction and flotation, and guide water flow into crop-growing areas where it is needed. If traffic is kept off a tilled area, annual primary tillage is not necessary. The effect of total tractor load on soil compaction is discussed.