When What We Believe To Be True????

If you ask 100 agronomists about early spring soil temperature vs soil depth, I would guess 99 of them would say that the closer you get to the soil surface, the warmer the soil temperature.  If you ask 100 farmers the same question, I would guess 90 of them would agree because I tend to think farmers are smarter than agronomists.  Regardless, there would be general agreement that in April, soil will be colder at 2-3" than it is at 1" or 1/2". 
My own random use of a soil temperature probe in April has made me wonder whether this was really true, but I am a believer that corn should be planted at 2" deep, (more on that later) so I did not care what the temperature was like at 1".
As food for thought, along comes a study presented in the Pioneer Agronomy Journal discussing soil temperatures vs soil depth during the months of April and May.

Fascinating stuff.  During the month of April the soil temperature was the same at 2" as it was at the shallower .4".  Could it be that what we believe to be true is false?  The relationship was the same no matter whether the soil was tilled or not.  Tilled soil was slightly warmer than no-tilled which makes sense, but in April the depth made no difference.  It was not until May when the air temperature warmed to 25-28C that the shallow soil began to warm faster.  Why would the soil not be warmer at .4" in April?
Two reasons.  Sunlight intensity and air temperatures are lower in April.  The second reason is the deeper soil acts as "insulation".  In April the soil is usually drying slowly and moisture is migrating up from lower depths.  This water is still cold and it keeps the shallow soil from warming as quickly as we think it should.

Now the practical stuff.  What impact does this have on planting depth decisions when we plant in April?  As I said before I am a firm believer in planting at 2" deep regardless of conditions.  The only time I would go deeper would be in extremely dry seedbeds, but I would never go shallower.  Here's why.



All crop advisers recommend a planting depth for corn at 1.5 to 2 inches for two reasons.  It is easier to maintain good seed to soil contact to allow uniform moisture uptake by all kernels.  The second reason is to support a strong nodal root system which develops at 3/4 of an inch.  The nodal roots develop into the main root structure that absorbs water and nutrients for the entire growing season.  A strong nodal root system is obviously impacted by planting depth.

This clearly shows the nodal roots getting off to a good start.  Note how they start to grow at about 3/4 inch below the soil surface.

The seed on the right which was planted at 1" is going to struggle with nodal root development and will be slow to grow.  As farmers we make more mistakes planting crops too shallow than we do planting them too deep. 
Considering soil temperatures do not support shallow planting in April, we have no excuse not to get our seed into the 2" zone.





Re-Cycled Ideas

A friend and customer asked me a question last week beginning with the preposition "I was looking on the internet".  I had to resist rolling my eyes because that phrase usually leads to a dumb question.  But he continued and asked me what I thought about twin row corn.  This is a concept that has been around my whole career and it seems to re-surface every few years.
The concept is simple enough.  Just modify your standard 30" corn planter to plant two rows instead of one row as shown in the picture below.

The theory behind this is to give each plant more room to capture sunlight because they are not as crowded as they would be if they are all crammed together in one row.  This is to have a more positive yield effect as we increase plant populations. 
(Excuse me for a second while I digress.  I believe this is why the concept keeps getting re-cycled.  When I began my career 28,000 population was considered high, now we are talking 36,000 plants per acre.  At every incremental step over the years, somebody tries to prove the value of twin rows.)

At a plant population of 36,000 the space between plants is 5.8 inches as shown in the schematic diagram below.

Using twin rows 8" apart centered on 30", the interplant spacing for 36,000 poulation is 9.9" to 11.6".  This is almost double the room for each plant in the the twin over the single row.  Common sense tells us this should result in healthier plants and more yield. 

But I know that common sense and corn plants do not always agree, so what does the research tell us? 
Both Pioneer and John Deere looked at this concept in 2010.  They co-operated together on some of the trial locations.  Pioneer likes to sell seed and John Deere likes to sell equipment, so it is reasonable to conclude they would be interested in the concept and it is also reasonable to conclude they would both be interested in a positive research outcome. 
Both companies came to the same conclusion.
In 31 locations across the corn belt in 2010, Pioneer found the overall advantage to 8" twin rows over 30" rows to be negative .7 bu/acre. 
John Deere reviewed the scientific literature on twin rows from 1980 to 2008 and discovered a .7 bu advantage in favour of twin rows.  Hardly a rosy picture for those that believe in the twin row concept.
And as my friend, Peter Johnson, said at the Southwest Ag Conference, "combining twin rows at night, with all those tassles jiggling in front of the cab will make you want to quit farming".
So my friend was not asking a dumb question after all.  It was just a question that has been asked many times before. 



Back to Work

I have been negligent in keeping up with this blog for the past 4 months, but 2011 will be different, I promise. 

January is meeting month in the crop service industry.  Every week there are multiple days devoted to spreading the latest word on crop and business management.
There was the Southwest Ag Conference, the CCA Annual Conference and the Pioneer Agronomy Conference, plus a couple of other Pioneer events.  I learned some new things from all these meetings and have a boatload of knowledge to pass along.

But more importantly this past month has been a memorable month for two other reasons.

I was shocked on January 12 to receive the CCA Award of Excellence for 2010.  It is indeed an honour to be recognized by your peers for your contribution to agriculture.  I must thank my nominator, Pat Lynch for pushing my name forward.  It means I have a responsibility to strive to make myself better and help my customers even more in 2011. 

I also want to recognize the other nominees for the award.

Shannon Bieman from Snobelein Farms, Larry Hale from FS Partners and Bob Thirwell from Dekalb.  These three had very impressive credentials and deserved to win as well.  Just to be included with them is honour enough, to win is unbelievable.

On January 16 a much bigger award was presented.  Brian and his wife April made Cathy and I grandparents for the first time. 

 

Hayden Brian Barker arrived at 7:50 am on Sunday, January 16. 

This beats the CCA award hands down.