Death comes to us all. Life's but a walking shadow | It seems to me that my question had to do with the effect of early season drought on yield whereas yours is about late season drought on seed fill (& yield). I think most everyone recognizes the importance of late season seed fill on yield. For example, for your two examples the 60,000 kernels/bu x 250 bu/a is 15,000,000 kernels per acre and the 110,000 kernels/bu x 145 bu/a is 15,900,000 kernels per acre. Clearly you had about the same number of kernels per acre going into the final period.
My question concerns the effect of early season drought (or water stress) on final yield. I looked at four agronomy factsheets from major universities and they all say the same thing. Early season moisture stress reduces yield by about 5-10%. They define stress as 4 consecutive days of wilting. I don't think they're talking about just rolling up but getting that tight roll with the gray color. Two of the factsheets say about the same thing. The yield reduction can be traced to the reduction of kernel rows and row length even before any ear is formed.
The reason why I raised the question is because in June about half of Iowa and Nebraska very substantial dryness as did parts of Illinios. Parts of Mich & Ohio are still dry. People here are talking about a 2014 type yield, 171 bu/a. In order to achieve this not only must kernel fill be perfect but the total number of kernels must be near the maximum potential.
If you look at the current 30 day precipation maps for much of the corn belt it's apparent that moisture conditions are more than adequate at present except for possibly northeastern Ohio and southern Mich. My question is simple. Was there enough early season stress over a wide enough area to trim total yield? Granted there wont' be much difference between a yield of 168 bu/a and 172 bu/a on the price but 5% of 168 is 8.4 bu. and that may be enough to sober up even the most diehard bears. |
When ear size is determined
