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Washington State University Extension

Irrigated Agriculture

Cold Springs Reduce Strip-tilled Corn Yields

By Andrew McGuire

I have talked to several growers who are concerned about how cold springs have reduced their strip-tilled corn yields when compared to corn with full width clean tillage. While we can hope for average spring temperatures, there are a few other things that should be considered.

  • Crop rotation. When corn prices are high, the temptation to grow corn-after-corn is high. However, consider that cold soil problems, and dealing with high amounts of residue are much greater problems in corn-after-corn than corn following a low residue crop.
  • Remove residue. If you have decided that continuous corn is worth the effort, but still want to do strip-till, consider removing some of the residue. In our arid climate, residues do not decompose quickly and so maintaining residue cover is not hard, especially with continuous corn. If there is a market for it, baling off some corn stubble could be at least part of the solution.
  • Strip-till earlier. This will only work with a two-pass system, but strip-tilling as soon as the soil is thawed could give it more time to warm up before planting. The challenge here, especially with corn-on-corn, is that loose residue can blow back over the rows. With early strip-tilling, adjusting the machine to leave a raised berm would both allow the soil to warm better and keep some of the loose residue off of the row. Fall strip-till would also be something to consider for next year.
  • Narrow row corn? This might not work well with strip-till, but recent reviews of the research on the effects of planting corn with row spacing less than 30″ (20″ or 15″) has come to the conclusion that it gives the most consistent benefits north of 43° N latitude (Lee, C.D. 2006). The presumed reason is that in Northern latitudes, narrow rows help the corn canopy reach maximum light interception earlier than wider rows. This directly affects yield potential. In southern locations, the time and growing degree days are sufficient for corn in 30″ rows to reach maximum light interception before flowering. The narrow rows may also help northern grown corn take better advantage of our longer days around the June solstice.

Those are my ideas. Do you agree, disagree, have other ideas?

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