Due to buying a new JD1790 planter too close to planting season to get everything ready to VR this is the first year I have not done VR seeding of corn after 4 previous seasons with VR.

Some observations:

I have been walking corn (20" corn is not a lot of fun to walk at 100 degree temps, although for some reason I seem to enjoy it - heat stroke maybe?) for the last two weeks. This is a very typical SE Ks summer in that we have had severe drought stress late. Corn looked like a record crop up untill roasting ear stage then rain was spotty to non-existant. I think we will run as low as 80 field average on some droughty upland that missed a rain up to maybe 170 in some bottom that got rain. Many fields will range at least between those two extremes and more. I saw some spots that look like 20-30 bpa and some that will go well over 200 (not in same field).

What I observed in the field is that my blanket rate populations on average were pretty much on target in any field that will make over 120 bpa (27-28k upland, 28-31k bottom). Average areas of the field had maybe one half to an inch tipped back on the ears. The deep soil high yielding areas had corn completely filled to the tip end indicating it could have stood higher population. Poor areas had the ear tipped back about a third and occasionally worse in the worst spots indicating a lower population could have been good. Walking all this corn, varying from almost phenominal for us to considerably below average (10 yr ave 120-130), has reinforced my conviction that in our soils, in our conditions, variable rate corn seeding has its place in our operation.

Variable rate might not have made a yield difference - maybe the hybrid had enough flex that even a perfect variable rate would have not changed the yield (although I believe it would have in the highest yielding areas). However it is my contention that if we would have obtained that perfect variable rate that would have resulted in ears that indicated an ideal population, had conditions been worse - or better - the built in flex that is available from the plant would have been in the ideal center position to have benefited from even more extreme conditions. If the ears have already reached their maximum ability to flex or beyond (reached maximum ear weight in the best ground or excessively aborted kernels in the hardest hit areas), they would have nothing left to have handled better or worse conditions than what were presented this year. That's my theory.

Also I have come to the conclusion that this year is an ideal year to base future VR maps from with only one year data. I know that it is generally accepted that several years of data are needed to base decisions from but I contend that one perfect year for the conditions that are being managed for is far superior than several years of data that may have other yield variables mixed in. For example this year we had ideal stands (no insects or weather related events thinning stands in parts of the field). Insects, disease or fertility was not an issue. The only thing affecting yield was water and that is what I want to use VR seeding to manage for and this year was about as good as it gets to identify the deep soil high yielding areas of the field as well as the shallow droughty areas. Therefore I contend that this one years data is better than the 4-5 previous corn crop data combined that I have since the almost exact conditions exsisted that I want to manage for and there was an absence of other yield limiting variables.

I realize all of this is subjective - no hard datamined facts! All biologically computed.

Looking for feedback - tear my theory apart. Where am I thinking wrong? Surely one year of data will not do!

John