Hoegemeyer - the right seed

Much of the region has been blessed recently with moisture in some form – snow, sleet, hail, ice, and even rain.  For most of us, the drought isn’t over yet, but this last weather system has helped relieve some of the deficit.  Prior to the recent rains, I did some soil probing in a field near Columbus, NE.  Throughout the field there was adequate moisture in the top 12-15 inches of the profile.  The soil below this layer was quite dry.  This same field has received over 2 inches of rain since then, and I’d expect that the moisture has made it deeper into the profile now.  Rain events that yield 1, 2, or 3 inches at a time will be important for recharging the full soil profile.  Why?  Look no closer than your coffee cup.  You’ll notice that water climbs ever so slightly up the side of your cup.  This is called adhesion.  The water is actually binding (loosely) to the cup.  Water also likes to adhere to soil particles.  When the top layers of soil are dry, new rainfall will first bind to the soil near the surface because adhesion is stronger than gravity.  Only after the top layer of soil reaches field capacity will water begin to percolate down through the profile.

Your soil profile not only needs moisture from above, it also needs help in terms of management.  I’ve noticed how nearby fields have absorbed the recent rains with different levels of success.  Some fields showed signs of ponding and runoff.  Other fields soaked up every drop.  It’s not that the fields with no runoff were dryer (all of our fields needed rain).  The difference is that some fields were able to absorb the rain at higher rates than others.  Decisions on tillage, how much residue to leave, and compaction are making an impact on the amount of moisture that will available to the 2013 crop.

One comment on soil temperature…
Keith Glewen, UNL extension agronomist, forwarded some recent soil temperature data from the Mead, Nebraska area.  Temperatures at the 4” depth had been on a slow climb up to the 50 degree mark in early April, followed by 4 straight days in the low 50’s starting on April 6 and ending on April 9.  The soil temperature for April 10?  41.5 degrees.  As you make early-season planting decisions, always remember that soil temperatures closely follow air temperatures.
 

Every year we emphasize the importance of planting depth.  Why?  Because it’s important!  Corn plants require a minimum of 1.5” of firm, settled soil to establish a proper root system.  Seed placed shallower than this will ultimately lead to rootless corn.  Rootless corn means standability problems throughout the growing season and harvest, and will likely reduce yield.  This season’s weather has already allowed for multiple tillage passes, leading to a dry, fluffy seedbed in some cases.  This type of seedbed is prone to shallow planting depth because equipment and rain eventually packs the soil back down.  Although we normally recommend a planting depth of 2” to 2.5”, setting the planter at this depth in fluffy soil could lead to only a 1” final depth after the soil settles.  Always check your planting depth – especially after any change in fields, soil conditions, or residue situations.  When checking your depth behind the planter, be sure to step down the soil firmly before digging to get a better feel for what the true depth will be after settling.

Planting into dry soil can leave seed sitting in the ground without ample moisture for germination.  A corn seed needs to be able to imbibe at least 30% of its weight from the surrounding soil in order for germination to happen.  Soil is never uniformly dry (or wet) so germination can be uneven in dry conditions.  Uneven germination leads to uneven crop development which has shown to have detrimental effects on yield.  For most fields, soil moisture cannot improve without a little help from up above.  Even farmers with center pivot irrigation prefer rain over “watering it up”.  So, what can be done if the planting bed is dry and irrigation isn’t an option?  Two choices: 1) wait for a rain before planting, or 2) plant deep.  Soil shallower than 2” is prone to excessive and uneven drying and planting seed into this shallow zone should be avoided.  Some agronomists recommend planting corn up to 3” deep.  3” may be the right depth in some situations, but excessive in others.  Our general recommendation is 2” to 2.5” is ideal, and up to 3” might be justified in very dry conditions.