Our Pioneer Agronomist Aric Bos forwarded a report prepared by Andy Bootsma, an Honorary Research Associate with Ag Canada in Ottawa. The report was entitled Decadal Trends for Crop Heat Units in Ontario and Quebec from 1951 to 2010. It is a look at the average temperature data from selected locations in Ontario and Quebec in 10 year intervals. If you want to download the full report here is the link.
The report can be summarized quickly using the following two charts.
The data reveals that the average growing season is 12 days longer and 344 CHU warmer in the first decade of 2000 than it was in the 1960's.
My own experience is a reflection on this trend. In 1995, I planted a 2750 heat unit hybrid and was told by the crop insurance inspector at the time it was one of the highest yielding fields in the area. It was a cheap attempt on his part to butter my bread, but the fact remained that in 1995 this maturity was a common choice in this area. Choosing to plant a 3000 heat unit hybrid for grain on our farm was considered to be taking too much risk from a maturity point of view.
This coming spring 18 years later I have decided to plant a 3100 heat unit hybrid. This is because the risk of lower yield with a shorter season hybrid is now geater than the risk of wet, immature corn with a full season hybrid.
Our hybrid maturity selection criteria has changed. Going forward, our hybrid and soybean variety selection criteria will continue to change as we adapt to the changing environment. Decadal change. I think I got it. Mr. Young would be proud.