Finding an example of corn growing on compacted soil was relatively easy in early summer. Some fields were worked wet because there was no other choice if you wanted to get the field planted. Did those effects linger and impact yield, or did rains at the right time mask the effects of soil compaction?
Gary Steinhardt, Purdue University Extension soils specialist and the father of soil compaction studies, says the answer is all of the above, none of the above and anything in between. One of the best answers when it comes to soil compaction and the impact on crops is "it depends," he notes.RAIN BAILOUT? Rains at the right time during the year can mask the effects of soil compaction. Some believe that may have happened this year.
Here is Indiana Prairie Farmer's exclusive interview with Steinhardt that sheds more light on how soil compaction works, and why it is so elusive to pin down.
IPF: Is soil compaction more of a problem with corn or soybeans?
Steinhardt: Soil compaction almost never causes a yield impact with soybeans. When it comes to corn, there might be a yield impact and there might not be an impact in any one year. A lot of it depends upon the weather conditions.
IPF: This year, we saw short corn and yellowish corn in spots where soil compaction was created during the spring. In some fields those areas caught up; in some they didn’t catch up. What determines if corn affected by soil compaction early can catch up?
Steinhardt: A lot of it depends upon weather conditions during the rest of the season. If it rains at the right time, corn affected by compacted soils often recovers and yields nearly as well or as well as the rest of the field. Timing of the rain during the rest of the season is the key.
IPF: Why is timing of when it rains so important if soil compaction is an issue?
Steinhardt: Soil compaction can limit the ability of plant roots to take in enough moisture for good growth. If the soil receives enough rain at key times during the season, the plants may still get enough moisture even though the soil is compacted.
Think about it this way. Suppose you have a sandy loam soil. In some years plants run out of moisture during pollination or grain fill because it doesn’t rain enough. Those soils are very dependent on timely rains because the soil profile doesn’t hold as much moisture as a silt loam soil. That’s why many of those fields are irrigated.
If you happened to get a year when it rains in a timely fashion, then you may still harvest good yield on a sandy loam soil, even if you don’t have irrigation. The same happens with soil compaction. In dry years, the roots can’t take up enough water, and it causes plant stress. If you get a year like 2016 where many areas in the Corn Belt received timely rains, then the plants may receive enough moisture and produce a good crop in spite of compacted soils.