Control tire tracks to avoid soil compaction

    With the wet, slow start we’ve had to the growing season and spring work this year, there have been quite a few fields sprayed under excessively wet conditions. While time pressures may make this unavoidable — the work does have to get done, and timing is often critical with applications of crop protection products — the sort of severe compaction that happens under these conditions can have long-lasting negative effects on yield.
    If equipment tracks are 3’6” deep on the surface, deep soil compaction has also happened. Experiments have consistently shown yield losses of 10% to 25% in wheel tracks, resulting from soil compaction when equipment is run on overly wet fields. Worse yet, the negative effect of deep compaction usually lasts five or more years, even after the visible surface compaction has disappeared.
    The area of a field covered by wheel tracks is seemingly minimal in any one pass, but over the course of even a single growing season, a surprisingly large percentage of the field can be covered. In a controlled traffic or tramway system, where all equipment always drives in the same set of tracks, about 10% to 15% of field area is dedicated to wheel tracks, and the remaining area is untouched. In a more typical field where equipment traffic is not restricted to designated tracks, up to half (or more, for some crops) of the field area can be covered by at least one tire pass over the course of a growing season. Although extremely difficult to put a hard number on, this adds up quickly, and soil compaction can lower whole-field yields significantly over time. Compaction is important, and should be avoided if at all possible. A few considerations may help reduce the risk:
    — Wait for better conditions. The worst compaction occurs when soils are just dry enough to operate on. As they dry, the risk falls relatively quickly. Even an additional day of drying can make a big difference if you can spare the time. Of course, this is not always feasible, but when it is, a bit of patience can pay off in spades.

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