Soil Compaction in Alfalfa Fields Ronald T. Schuler, Professor Extension Agricultural Engineer Biological Systems Engineering University of Wisconsin- Madison
Soil Compaction Causes include combinations of: Wheel Traffic Tillage Precipitation Types Surface Subsoil
Loam soil by volume Non-compactedCompacted
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Contact Area-Size-Diameter (Firestone) TireSizeTire Dia.Area(in 2 ) Radial Tires Flat3”Sinkage 18.4R R R R Bias Tires
Contact Area-Size-Width (Firestone) TireSizeTire WidthArea(in 2 ) Radial Tires Flat3”Sinkage 16.9R R R Bias Tires
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
6 psi 18 psi Impact of Tire Pressure
Inflation pressure-slight tire bulge with the proper pressure on radial ply tires 18 psi 6 psi Bulge
Top View: Measured soil-tire interface stress (psi) distribution of an 18.4R38 tire
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias ply Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Radial vs. Bias Ply Tires Contact Area
At Proper Inflation Pressure, Radials have greater Contact Area
Tractor Manufacturer Recommendations Tire Size – Pressures-psi Axle Load (lbs) Radial Bias
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Impact of soil moisture on compaction (depth and sinkage) Hard dry soilNormal Wet soil Depth, In.
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Wheels should follow in same track Wheel alignment-harvester and wagon
Wheel alignment- tractor and wagon
Small Square Baler-Bottom Feed Wheels aligned-tractor, baler and wagon
Mid-Size Rectangular Baler Wheels aligned-tractor and baler
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Sickle Cutterbar-Roll Conditioner 14-foot width
Self-propelled mower-conditioner
Front self unloading wagon
Wheel Alignment –harvester and wagon
Dual rake merging two windrows
Merger - Picks up one windrow and places it on the adjacent one
Merging three windrows into one
1 Mower-conditioner-pull or self-propelled 2 Mower conditioner width, feet 3 Rake-to rake, merge or do not rake two windrows together 4 Area covered by wheel traffic if uniformly distributed 5 T-M/A – ton miles per acre System Comparisons-three cuttings per year Type 1 Width 2 (ft) Rake 3 Area 4 T-M/A 5 Pull13None Pull16None Pull13Rake Pull16Rake Self-Prop16Rake Self-Prop16Merge Pull13Merge Self-Prop13Merge(Dbl) Self-Prop16Merge(Dbl) 2.332
Compaction Issues Tires Size Inflation pressure Tire design, radial vs. bias Machinery Avoid wet soil Wheel alignment Machine selection Machine weight
Tractor ballasting criteria Towed Load wt. vs.Max.Speed Towing machine wt.mph 1 to to 110 More than 2 to 1Do not tow
Concluding Remarks Select appropriate tire Use proper tire pressure Align wheels Reduce traffic of large equipment Use safe towing machine weight
The End