Sins of Planting

BY Dairyland Seed Agronomy Team

2024 Planting

Variable weather conditions and frequent doses of rainfall may have resulted in some crops being planted in less-than-ideal conditions. This spring gave us short planting windows between the rain events and, in order to get fields planted before the next rain, several fields were planted while they were still a little sticky. This can cause several problems that last throughout the growing season.

Sidewall Compaction

Planting into wet soils can cause smearing of the seed furrow sidewalls, sidewall compaction from the disk openers, and an open seed trench. When sidewall compaction or smearing occurs, the furrow does not fall properly around the seed which doesn’t allow for proper seed-to-soil contact and inhibits horizontal root growth (Figure 1). This results in uneven emergence, stunted plant growth and nutrient deficiencies from restricted root growth. Although there may be adequate nutrient levels in the soil, the restricted nodal roots will reduce the plant’s ability to take up water and nutrients.

Figure 1. (Left) Soil that was too wet to plant, leaving the seed trench open and the seed exposed. (Right) Sidewall compaction restricting nodal root growth. Note the roots of the corn plant are running horizontally along the seed trench.

Figure 2. The roots on the left are from a plant that experienced sidewall compaction. The roots are concentrated directly underneath the stalk and do not branch out horizontally. The roots on the right show a normal root mass.

When the roots experience sidewall compaction and grow vertical instead of spreading horizontal, you end up with roots that are shown in Figure 2. This has several names but is commonly referred to as hatchet roots, tomahawk roots, or mohawk roots. The combination of uneven emergence, stunted plants and reduced ability to gather water and nutrients results in a loss of yield potential. Some tips for reducing sidewall compaction are to reduce the downforce pressure, avoid shallow planting and utilize a spiked closing wheel to till the sidewall.

Soil Crusting

If soil conditions are a little too wet during planting, then you can see some soil crusting where wheel tracks run over the row. However, soil crusting is more likely to occur after a heavy rain and if the weather turns hot and windy. This dries the soil rapidly and creates a thick crust on the top layer, making emergence much harder for the seedling. Corn seedlings that are struggling to emerge can have deformed mesocotyl elongation and leafing out underground. The corn plant can also partially leaf out underground and emerge with tightly rolled leaves (Figure 3). Soybeans emerge by pushing up with the hypocotyl that carries the cotyledons to the surface. When soybeans experience soil crusting the hypocotyls become swollen and can break off while trying to push through the crust. Swollen hypocotyls can result in a weak plant and broken hypocotyls result in plant death (Figure 4).

Figure 3. Shows examples of a corn plant leafing out from soil crusting/compaction.

Figure 4. Swollen hypocotyl on soybean seedling trying to push through soil crusting/compaction.

Light rainfall along with warm temps and low wind can help to alleviate soil crusting and help the seedlings emerge. In some situations, rotary hoes can be an effective tool for breaking up the crust layer and allowing seedlings to push through. Rotary hoes can damage seedlings so be sure to consider how much potential damage might occur from using the rotary hoe before making your choice. The population of emerged seedlings, depth of seedlings trying to emerge and soil conditions should all be considered when deciding to use a rotary hoe.

If you have any questions on sidewall compaction or soil crusting, please reach out to your local Dairyland Seed dealer, DSM or Agronomist.