Kelly Robertson Farms

Late last evening I spent some time in the corn field.  According to my GDU clock, I have accumulated 2,703 GDU’s (Growing Degree Units. An excellent primer on GDU’s for corn is here at OSU)since 19 April.  This corn field was planted on 18 April, so I know I should have  few more GDU’s than that.  That should be enough to bring this corn to physiological maturity, or black layer. 

Dan Davidson does a great job of defining black layer here at his DTN Blog.  Suffice it to say that when the black layer, a layer of “dead cells” forms at the base of the kernel, all water and dry matter accumulation quits in the kernel.  The black layer can be seen when you split the kernel open as noted in the pictures I took below. 

Now that the corn has black layered it is time to see what our expected yield is going to be.  Using the formula I described on Monday, I went out and counted ears per 17.5 ft of row for corn planted in 30 inch rows.  I averaged 30 or 30, 000 plants per acre.  Not bad because I dropped 32,000 seeds, so I ended up with 94% of my dropped population.  That’s better than the advertised or guaranteed % germ on the sack!  Not bad. 

Next, I counted the average number of rows per the sampled ears.  Again, I chose the odd numbered ears starting with the fifth ear in my sample. One sample set is shown below.  Here is a big hint: while your average number of rows can be an odd number, when you count the rows on each ear they will be an even number.  If you ever come across an ear with an odd number of rows, let me know……….we will make a fortune!  My sample came up with 17 rows on average.

Then you count the number of kernels long the ear is.  I cheat a bit here.  I don’t count the first 5 butt kernels or the last five tip kernels.  Don’t ask me why, I just don’t.  I don’t feel they are representative of the rest of the sample.  In my sample set I got 31 average kernels per length of ear.  Again not too bad.

At this point we can estimate yield.  30,000 ears per acre that are 17 rows around and 31 rows long equals (30,000 X 17 X 31) 15,810,000 kernels per acre.  Divided by 90,000  kernels per bushel and that (15,810,000/90,000) gives us 175 bushel per acre.  I will take that this year!

The one problem I see is that there is not much kernel depth as noted below.  This is the effect of the hot weather on the corn crop.  Corn likes night time temperatures of 67-70 degrees.  This allows the corn to better move water and dry matter into the grain.  With the high night time temps we have had (80+ now for 6 weeks) the fill has resulted in shallower grain depth. 

As a result, I would knock off 15% of my yield estimate for shallower grain depth, and now say that 150 bushel an acre will be my yield.  But rembember, I fudge a bit, not counting the butt and tip kernels, so I expect it to be a bit better than my reduced guess.

One thing to notice is that there are ears in the field that look like this one below.  Here we see that the ear has robbed water and dry matter from the tip kernels (the last to fill) to the lower kernels to make sure the plant fills and  reproduces.  This will cut yields in a lot of fields this year. 

Well, so much for my yield tour here at my own farm.

Today, I will be speaking at the Brookside Labs Consultants meeting in St Louis.

I think some of you get the idea that I am against applying fungicide on corn.  I am not against it.  I have recommended it.  But again, as a general rule, if one knows their hybrids and scouts, they may very well not need to apply a fungicide.

The key is to know your hybrids.  This involves researching them and talking to not just the salesman, but to the agronomist or to the plant breeders of the company from whom you buy your corn seed.  That also means looking at the research that they have that will, in most cases, show what the response to such applications has been over multiple sites. 

Then once you know your hybrids, it becomes a matter of placement and scouting those hybrids that will need, or might, need a fungicide application.  Knowing and scouting,  the two keys to a successful and profitable fungicide application.

In my mind, its all ROI.  Return on Investment.  If it costs me $30 to do something, then it had better have a very good chance of making me at a minimum $30 or there is no reason to even consider it.  Just because “it’s the thing to do” or “everyone is doing it” is not an agronomic reason to do anything.

So guys, spray away!

Here are some pictures of the corn crop here on Robertson Farms.  The weather has been lousy for taking pictures the last few days so bare with me………..

First, is Matthew standing, yes standing in the corn field planted on 13 April.  This field has tile drainage in it and is pretty hot, fertility speaking. 

Next is some shots of the corn planted on 19 April.  7 days makes a lot of difference this year it seems. 

And my wife’s favorite shot, “tunnnel vision”. 

We feel real fortunate this year. We have a good crop of corn growing:  The ground worked great, planted better than it has in years,  no major problems other than a low place or two were the stand is thin, we didn’t have to replant, weed control is excellent thus far and we had no trouble getting the N applied side-dress, no insects and no disease so far.   

We got our part done, now is up to the Good Lord to finish it out.