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| John,
Really appreciate reading your thought processes. I believe 1 year of data will get you 80% of your VRT solution, when you know your operation as well as you do, and we have this kind of year. Our weather has been somewhat similar (I think pretty true for big chunk of the western cornbelt).. here is some concerns I would have about doing what you suggest on our own operation:
1) This spring, we had some problems with sidewall compaction/stand establishment. Planting conditions were fairly good (we thought), but went several weeks after planting with heat and little/no rain. From walking our fields, I am concerned that we do not have good, consistent stands. That won’t hurt this year b/c dry weather reduced yields, but I do wonder if that issue may affect our yield maps, esp. our ability to use yield maps as a “water holding capacity” map..
2) We plant a range of hybrid maturities, 103 to 118 day. At this point, I really don’t think yield differences will be that great between them, we have picked up enough rain late to probably make the fuller season stuff equal the shorter season. And this is a total guess, but I suspect our fuller season corn will have more variability, so that needs to remembered. In other words, our earlier corn may not show much variability this year, even though the farms it is planted on may have higher than average variance.
3) I wonder if we can label a single year anything close to “typical”. For us, we have been border line dry most of the year with little water runoff, picked up a couple small rains early in July and corn hung on amazingly well until blast of heat and wind over the weekend. Then we got a good rain Thursday night, but too late for a lot of the corn. The big thing in our area is how rapidly some of the ears turned brown and dropped (even with still green stalks). So while our yield will be slightly below average and defiantly caused by drought stress, I am not sure how “typical” the year is. However, there are certainly areas of our fields we know will be very good corn and areas we already know will be bad. For us it is the giant 75% “normal soil”… where we have seen some strong yield patterns in the past, but have trouble with consistency year to year..
I guess the bottom line, this set of yield maps will be another learning experience, and I really can’t say yet whether I think they will provide extra special value or not..
One thought on your process.. You have established VRT seeding zones from years past I believe. I think it would be valuable to take those established zones, and compare to this years yield maps. I think it would be interesting to see how well they match up, and esp. if there are any glaring differences. By using only one set of maps for prior history (which should represent everything you think you know to date) it should keep the “information overload” syndrome at bay as well.
Good topic!
Darin
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Variable rate seeding observation
