Meanwhile, a customer was speaking to me earlier in the week about how his corn crop was making grade 2 without the presence of a distinct black layer. How can that be, he asked. He had the impression that no black layer meant that in addition to high moisture, low test weight would automatically go hand in hand.
I was weighing off some corn plots early last week before the snow shut down harvest that were planted during the last week in May.
As exhibit A, I present a picture of the grain sample from P9675AMXT, a 2850 CHU hybrid.
As exhibit B, I present a sample of P0157AM which is 200 CHU later than P9675AMXT. Keep in mind both samples came from the same field, planted May 26.
Two things to keep in mind.
1.Test weight and moisture are not automatically correlated. One needs to be careful making assumptions. Black layer is a terrific tool for evaluating when hybrids make it across the frost safety date, but is less accurate at predicting test weights. Immature corn at moisture levels above 40% will have low test weight because it has not converted the liquid sugars inside the kernel to more dense and heavier starch. The reason corn did not dry back in the infamous fall of 1992 was due to the kernels containing a high percentage of sugars and very little starch. Natural occurring yeasts that function in the presence of oxygen started to ferment the sugars, converting them to alcohol which increased moisture levels in the grain. Those same yeasts have a tough time fermenting starch. You have to limit oxygen to make well developed grain corn ferment which can only be done by putting it in a silo or a big pile.
This year starch conversion while not fully complete as indicated by the generally reduced test weights and lack of clear black layer, is much closer to normal.
2. Genetics matter. P0157 has a higher than average test weight score than P9675 which is only average for test weight. That is likely the biggest reason for seeing the results we did in this case. In fact, P0157 was the highest test weight of all the hybrids in this plot, 6 of them being earlier in maturity than P0157. Of course not all P0157 in every field is making grade 2. In addition, samples from only one plot should never be interpreted as gospel, but I think it proves a point. One of the biggest contributors to making grade in a year like this one is the relative genetic disposition of each hybrid for test weight. The comparative maturity of hybrids to each other is secondary, which seems odd in a cool year, but that is how it works.
I actually believe what we are seeing has a lot to do with the hybrid's ability to function in cold temperatures. Just as some hybrids handle heat and drought stress better, others handle cold stress better. The challenge as always is to identify genetics that function well in all environments.
The final word in case you were wondering is P9675AMXT ran 162 dry bu/ac and the P0157AM ran 168 bu/ac. Incidentally, P0496AMXT, a 3100 CHU hybrid was the highest yielding hybrid at this location and the only other hybrid in addition to P0157 whose sample made grade 2.
Genetics and of course the persimmon, make a difference.