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Planting Into Wet Soils

Written collaboratively by Anthony Bly, Sara Bauder, and Eric Barsness.

It is evident that there are high chances of planting into wet soils this spring. This is not a good decision when normal soil conditions appear to be attainable, but this year we may not have a choice. Side-wall compaction (Figure 1) occurs when the planter or drill disc openers smear the sides of the trench that is opened for seed placement. Soils with moisture contents near and around field capacity have the greatest potentials for side-wall compaction.

Side-by-side pictures showing the bottom part of a corn plant in soil with half of the roots exposed to show the seed trench (side-wall) compaction. The corn roots appear to be pancaked (stacked in a similar vertical plane) and struggling to grow out of the seed trench.
Figure 1. Corn plant roots with noticeable side-wall compaction.

Soil texture (% sand, silt and clay) will also influence the susceptibility of compaction depending on soil moisture content (Figure 2). Fields with variable soil textures will cause differing levels of side-wall compaction; this makes it very important to know how to adjust planter settings.

Even if the planter has automatic adjustments, one should still have concern for the degree of change the planter can have. Wet soils do not need as much downforce as dry soils unless compacted. Damp residues will require more downforce to cut through. If there was ever a year to have new disc openers on your planters or drills, this could be the one.

This graph has soil texture on the horizontal axis and increasing soil water (0-45) on the vertical axis. The lines show boundaries between unavailable water, plant available water and oversaturated soil conditions. The lower boundary (red) separates unavailable water and plant available water and runs from 5% water in sand to about 30% in clay. The upper boundary (blue) separates plant available water and over saturated soil and runs from 10% in sand to about 43% in clay.
Figure 2. Soil texture and % water content when field operations should occur to prevent soil compaction. The pink zone roughly estimates the combination of soil texture and water level when detrimental soil compaction could occur.

Planter Adjustments from the Front to Back

  1. Proper hitch height. Review planter or drill owner’s manual for recommended height.
  2. Residue managers or furrow openers. Operating too deep will uncover wetter soil and make the subsequent planter process much harder to perform. In wet soils try running residue managers higher and permit the openers to cut residues.
  3. Cutting residues. It is important to have sharp or newer disk openers adjusted with correct spacing.
  4. Proper down pressure on disk openers. Openers should consistently penetrate the soil to desired planting depth without excessive pressure. Check pressure on depth gauge wheels. One should just be able to turn gauge wheels with some force when planter in the soil.
  5. Seed firming. A good seed firmer is very important. Keeping the seed in the trench but placing it at the bottom of the trench is very important for even emergence.
  6. Side-wall and furrow closing. With properly firmed seed, furrow closing is not as important, however the seed trench should not open when the soil dries. The concept is to remove the side-wall and place crumbly soil over the correctly placed seed. Seed furrow closing wheels that have notched or spiked design reduce compaction as compared with smoother designs. This is especially important as bare soil within the row is increased with residue managers.
  7. Drag chain. This is older technology, but in some soils a drag chain can consistently pull a small amount of soil and help crumble it over the seed.

Despite the soil conditions when planting seeds, the correct planter or drill adjustment is very important. Now is the time to consider these planter adjustments because the windows of time available for in-field planting operations could be limited.