Combines working in wet conditions to harvest crops have formed a lot of ruts in fields this fall. Some of them are pretty big ruts. What can or should you do to best manage these ruts? Should you do tillage this fall to try to smooth out those ruts and relieve compaction, or wait until spring? Iowa State University Extension ag engineer Mark Hanna and agronomist Mahdi Al-Kaisi, a soil management specialist for ISU Extension, offer the following observations and guidelines.
Creating ruts in fields during harvest may be unavoidable this fall, but proper soil management will improve issues related to soil compaction, according to Hanna and Al-Kaisi. They are advising farmers to wait until spring when it's warmer and the soil is drier to try to correct the rut problems—as working wet soil this fall will create soil compaction.
About three-fourths of combine mass and virtually all of loaded grain tank weight is carried on the combine's front axle, they point out. With good yields, grain tank extensions, and a 12-row head, front axle load can be 18 to 20 tons.
The consequences of such wet conditions are significant soil compaction caused by this heavy equipment and yield reductions that will be realized next season. Compacted soil created beneath the rut may interfere with subsequent crop rooting and development. Ruts deeper than about 2 inches can also interfere with maintaining seed depth during planter operation next spring, unless these ruts are leveled.
Deep tillage this fall or next spring isn't likely to be effective
Using tillage to loosen the soil and relieve soil compaction requires soil to be dry enough so that soil shattering is effective. Because soil moisture has refilled the top 12 to 24 inches of the soil profile, deep tillage with a chisel plow or subsoiler this fall or next spring will use fuel and time – but is unlikely to loosen soil effectively between tillage shanks.
However, the full soil moisture profile in upper layers will freeze and thaw over the winter and help loosen soil, depending on air temperatures and snow cover. Entering the field this fall in wet moisture conditions for deep tilling or any type of tillage will be counter productive by creating much deeper soil compaction.
Ruts deeper than planting depth will need to be leveled before planter operation. A good strategy may be to wait until a week or two before planting next spring and use a light tillage pass, such as with a field cultivator, light disk, harrow, or soil finisher. If only a portion of the field is rutted, consider tilling only that area to avoid recompacting subsoil in other parts of the field.
Waiting until next spring is better idea than doing tillage this fall
Waiting until warmer weather next spring allows for some potential drying of the top 2 or 3 inches of soil and avoids further compaction of wet, plastic soil on the surface – which will happen with a tillage pass this fall. If compaction effects are observed during the 2010 growing season and soil is dry after harvest, tillage next fall may be considered deep enough to break through the compacted soil layer.
Summing up, Hanna and Al-Kaisi suggest you keep the following facts in mind when deciding what to do about ruts:
• Rutting creates compacted soil and an irregular soil surface.
• Avoid deep tillage this fall to correct the problem as wet soil does not shatter/loosen.
• Shallow tillage next spring will level ruts for planter operation.