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Requirements for Emergence

In your fields, you want to make sure that all of the plants emerge at the same time, providing you satisfaction of a job done right and setting high yield potential.  But what are the keys to getting emergence as consistent as possible?  There are 3 S’s of emergence- simultaneous, speedy, and safe.  Each of these S’s happen as a result of every seed that is planted having two things- uniform heat and moisture.  When heat and moisture are not uniform and the 3 S’s are not achieved, late emergence of some plants is the result which causes preventable yield loss.

 

Tillage Affects Emergence

Thinking through the process to achieve consistent emergence, we need to start with the soil conditions.  If a tillage pass is used prior to planter, great care should be taken to make sure that both moist and dry soil are not mixed in the seed zone.  A tillage pass a few hours ahead of the planter that knocks dry peaks of soil into more moist valleys left by the fall tillage pass can cause variances in moisture that seeds experience, and thereby impact emergence timing.  Equipping the planter with SmartFirmer can alert the operator to moisture variability where it exists.

Make Residue Your Friend, Not Your Foe

Previous year’s crop residue is a valuable asset in maintaining soil tilth and health, and it also needs to be managed correctly in order to ensure that it does not affect this season’s young crop.  When residue is in the seed zone there are multiple issues that can occur with the young plants. 1. Late emergence as the residue wicks away moisture from the seed and insulates the seed causing a lower temperature. 2. Seedling blights. 3. Nutrient deficiencies as microbes tie up nutrients as they feed on residue.  For these reasons, residue not only needs to be distributed evenly by the harvester, it’s breakdown managed by tillage or cultural practices, but also needs to be removed from the immediate area where the seed is being placed.  When residue is moved away from the seed zone, it is unable to affect emergence consistency and the health of the plant.

 

Row Unit Maintenance is Critical

Once residue is properly cleared, the disk openers now must create a trench for the seed to be placed in.  It is imperative that V- style opening disks have a minimum of 1.5 inches of contact throughout the full 360 degrees of their rotation so that no soil is left in the furrow, creating erratic furrow depth.  If running a row unit with a furrow forming point, be sure to use a firming point gauge to ensure that the point is not worn out of spec which would cause shallow depth.  Check gauge wheel arms to make sure there is not excessive wear on them and adjust the wheels so they gently scrub the disks as they turn.  If the gauge wheels can be pulled away from the disks leaving a gap, measures should be taken to make them tight as this gap will allow dry soil into the trench, causing late emergence.

Downforce- The Unseen Yield Robber

As growers become more and more aware of needing to focus on the agronomics of planting, many find out that downforce is a crucial aspect that affects emergence and yield, yet is typically overlooked.  Proper downforce settings on the row units create a proper amount of weight on the gauge wheels.  It is this weight on the gauge wheels that determines if the row unit is planting at the correct depth, as well as determining if the row unit is causing compaction which will rob yield from the plants.  A correct gauge wheel weight firms soil under the gauge wheels to allow the disk openers to create a trench and then hold that trench open while the seed is placed in it, and then lets the closing system do it’s job of closing the furrow.  Too little gauge wheel weight and depth is lost and sidewalls of the furrow collapse: too much weight and compaction is created.  Compaction can cause delayed emergence, but also has a bigger, typically unseen yield impact- restricted root growth.  As roots grow, they need to grow unrestricted and uninhibited.  Compaction created by too much gauge wheel weight will cause roots to turn, become smaller, and when that happens in growth stages V4-V8 of corn, it causes the kernels long and kernels around on the ear to be reduced.  This reduction in ear size is a significant loss in yield, but many times unknown to a grower because the plant looks healthy, even though the root system underground is sick.  Getting the correct amount of weight on the gauge wheels is challenging, because fields have so much variability in them from the lay of the land to manmade variability like wheel traffic

Where Do Seeds Settle?

The area immediately surrounding the seed in the seed trench needs to be 100% soil, not air.  Many seeds in the narrow trench created by the planter end up with an air pocket below them and need firmed into the bottom of the trench to eliminate this air pocket.  Even row units with a wider trench don’t end up with the seed firmed into the soil.  The goal is not simply seeds touching soil, but seeds touching soil firmly

Make Sure it's Closed Well

Closing the seed trench is the final step in ensuring that a freshly planted seed will be able to emerge with all 3 S’s of emergence- simultaneous, speedy, and safe.  Closing should be looked at in two aspects; closing the trench all the way to the surface of the soil, as well as ensuring that the soil right on top of the seed is firmed against the seed so that it can absorb moisture correctly.  Understanding if these two aspects of closing are happening requires digging a cross section of the seed trench to see if there are air pockets around the seed, and if any compaction has been created above the seed.