1. Soil Compaction in Alfalfa Fields Ronald T. Schuler, Professor Extension Agricultural Engineer Biological Systems Engineering University of Wisconsin- Madison

3. Soil Compaction Causes include combinations of:  Wheel Traffic  Tillage  Precipitation Types  Surface  Subsoil

4. Loam soil by volume Non-compactedCompacted

6. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

7. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

8. Contact Area-Size-Diameter (Firestone) TireSizeTire Dia.Area(in 2 ) Radial Tires Flat3”Sinkage 18.4R3465.1 320720 18.4R3869.0 340740 18.4R4273.0 350760 18.4R4677.0 365780 Bias Tires 18.4-3465.4 284653 18.4-3869.3 300675

9. Contact Area-Size-Width (Firestone) TireSizeTire WidthArea(in 2 ) Radial Tires Flat3”Sinkage 16.9R3816.9 255660 18.4R3818.4 340740 20.8R3820.8 390870 Bias Tires 16.9-3816.9 252629 18.4-3818.4 300675

10. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

11. 6 psi 18 psi Impact of Tire Pressure

12. Inflation pressure-slight tire bulge with the proper pressure on radial ply tires 18 psi 6 psi Bulge

13. Top View: Measured soil-tire interface stress (psi) distribution of an 18.4R38 tire

14. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias ply Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

15. Radial vs. Bias Ply Tires Contact Area

16. At Proper Inflation Pressure, Radials have greater Contact Area

17. Tractor Manufacturer Recommendations Tire Size – 18.4-34 Pressures-psi Axle Load (lbs) Radial Bias 5500 616 6000 716 6500 716 7000 8 16 7500 916 8000 1016 8500 1216 9000 1316 9500 1416 10000 1516

18. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

19. Impact of soil moisture on compaction (depth and sinkage) Hard dry soilNormal Wet soil 0 4 8 12 16 20 24 28 Depth, In.

20. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

21. Wheels should follow in same track Wheel alignment-harvester and wagon

22. Wheel alignment- tractor and wagon

23. Small Square Baler-Bottom Feed Wheels aligned-tractor, baler and wagon

24. Mid-Size Rectangular Baler Wheels aligned-tractor and baler

25. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

26. Sickle Cutterbar-Roll Conditioner 14-foot width

27. Self-propelled mower-conditioner

28. Front self unloading wagon

29. Wheel Alignment –harvester and wagon

30. Dual rake merging two windrows

31. Merger - Picks up one windrow and places it on the adjacent one

32. Merging three windrows into one

33. 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 4.050 Pull16None 3.444 Pull13Rake 3.235 Pull16Rake 2.733 Self-Prop16Rake 3.132 Self-Prop16Merge 3.032 Pull13Merge 3.437 Self-Prop13Merge(Dbl) 2.827 Self-Prop16Merge(Dbl) 2.332

34. Compaction Issues Tires  Size  Inflation pressure  Tire design, radial vs. bias Machinery  Avoid wet soil  Wheel alignment  Machine selection  Machine weight

35. Tractor ballasting criteria Towed Load wt. vs.Max.Speed Towing machine wt.mph 1 to 120 2 to 110 More than 2 to 1Do not tow

36. Concluding Remarks  Select appropriate tire  Use proper tire pressure  Align wheels  Reduce traffic of large equipment  Use safe towing machine weight

37. The End