I am sure my neighbours figured Barker had messed up again when part of our soybean crop was left unplanted for over 2 weeks. They are so used to seeing dumb things done at our place that they don't even ask any more.
This time, the mistake was done on purpose because Pioneer requested our participation in a planting date study. The field above was planted on May 11 with 92Y12, which is an early group 2 soybean and a full season variety for our area. A strip of 91Y61, a mid group 1 variety was also planted on May 11. If you relate more to heat units, 92Y12 is rated at 3050 HU and 91Y61 is rated at 2925 HU.
On May 26 we planted strips of both 92Y12 and 91Y61 for a second time. We now have both varieties planted side by side, two weeks apart. These strips will be weighed off this fall to evaluate the effect of planting date on these varieties. Other Pioneer sales reps have done the same and the intention is to summarize the results after harvest.
We have reached the summer solstice and the shorter days from now on will trigger the soybean plant to flower.
In fact, 2700 HU varieties like 91Y01 in the picture above are starting to flower, right on cue.
The theory is a bigger plant at flowering time will support more flowers and produce more yield. .
The May 11 planting date soybeans are clearly in the lead with 3 more fully developed trifoliates than the May 26 planting date. If the race was to end today the easy winner is the May 11 planting date. But the race is not over. It is only in the early stages. Weather during the reproductive stages of plant development carries the hammer.
The other theory we are testing in our our variey test plot and our IMPACT plot is the value of full season soybeans. In 2011, 92Y12's were 8-10 bushels better than earlier varieties planted on May 25. If the results repeat themselves we have to begin questioning our reliance in this area on early maturing soybean varieties. My buddy Peter Johnson may not be as impressed.