Northeast Region Certified Crop Adviser (NRCCA) Study Resources

In This Section

• PO 27 Health & indicators
• PO 28 Compaction
• PO 29 Compaction in Northeast USA
• PO 30 Long-term intensive crop production
• PO 31 Soil compaction factors
• PO 32 Variable susceptibility
• PO 33 Root/shoot growth, crop yield
• PO 34 Strength & water content
• PO 35 Penetrometer
• PO 36 Degradation from compaction
• PO 37 Soil compaction prevention
• PO 38 Soil compaction remediation
• Summary

Competency Area 4: Soil health and compaction

PO 29. Understand the processes and management practices that cause soil compaction and their relative significance under Northeast conditions.

1. Equipment traffic and load distribution
2. Timing of tillage and traffic as it relates to soil water conditions
3. Tillage methods

Equipment traffic and load distribution

Surface compaction is primarily caused by surface pressure, which can be the result of animal hoofs, tires inflated to high pressures, steel wheels, etc. The threat of this type of compaction is primarily within the top 12 inches of the soil. Subsoil compaction is primarily due to axle load. When axle load exceeds 10 tons the threat of subsoil compaction is great.  If the load can be distributed over a larger footprint area, surface compaction is reduced. If the load can be distributed over multiple axles, subsoil compaction is reduced.

Timing of tillage and traffic as it relates to soil water conditions

When soils are tilled or trafficked in their plastic state they are highly sensitive to compaction, while the soils are sensitive to rutting in their liquid state. In the friable state soils are less sensitive to compaction.

Tillage methods

The moldboard and disk plows are probably the two tillage tools that pose the greatest threat to soil compaction because they are the most likely to cause formation of a plow pan. In-furrow moldboard plowing is the worst because, in addition to the tillage tool causing compaction, the tires or animal hoofs cause direct subsoil compaction.