Many growers in or near the Mn Red River Valley dont think they have variability in their fields because the soil types dont change or are very similar. Or if they believe there is some variability, why bother because the weather trumps everything.
I made a vrt seeding map and bet this guy a $1000 my vrt would beat his flat rate.
Pic 1 is lidar elevation. 4 feet max change.
Pic 2 is my zone map from sat images, fsa color naip, and his corn and bean yield maps. Red is poor to dark green is best zone.
Pic 3 is my vrt rx from 22k up to 34k with field avg of just under 31k.
Pic 4 is map off of his jd2630 after planting. He made some passes at his normal 34k flat rate.
Pic 5 is soil type map
Pic 6 is the soil test from last fall lol3 is poor zone, lg5 is medium zone dg7 is best zone
Pic 7 is 10 ears each side on the guess row. Left side 28k and right side is flat 34k
Pics 8 and 9 show plant spacing.
The 2 dots represent where these pics are taken. Its in zone 6 which is the second best zone. Much of zone 1 and 2 drowned out from a short wet spell in mid june. Then zone 7 got somewhat drought stressed shortly after until mid july, but not as bad as zone 3-5 that got a double whammy of too wet early, restricted root depth, then too dry
Stalk diameter and leaf width are larger on vrt side compared to 34k flat. All 10 ears on 34k side are at 2nd position down. 28k vrt side has 4 of 10 in top position and 6 in 2nd. When you remove leaf above the ear, the stalk has a very small groove on all 10 at 34k indicating the plant aborted the top ear very early. On the 28k vrt side 4 were in the top, 4 of the ones in the 2nd position had a very large and deep groove above indicating a very late decision to abort the top ear. The other 2 had a smaller groove, but much larger than the 34k ones.
We vrt applied P and K by deep bander last fall based on yield goals and zone soil samples. Applied a vrt blend of urea, ams, and esn broadcast preplant this spring.
Overall total P and K dollars were about the same to a little less as before when he just flat rated on this field. (Other fields are $25-50/acre less) Nitrogen dollars were more because we used a higher yield goal and he didnt want to side dress so we used esn for some of our needs. Seed averaged about $15/acre less. We will see what the combine says overall, but where this pic is taken, the yield difference is showing about 40 bu better on the vrt side.
So yes mother nature has the ultimate say, but with proper management, we can influence plant growth and minimize the negative stresses on our crops.
His Central agronomist cussed him out for doing vrt and going so low on population. His coop supplier and applicators fought me the whole way, saying their equipment couldnt do what i wanted and thought i was cutting them out of fert sales (but i actually had him spend more total than had he just flat rated like normal) His friends made fun of him(and me) for doing this "extra work"
All in all im pretty happy with the results. We are 1/3-1/2 starch line. The ear leaf and 2-3 below it are still green, so i think we nailed the N amounts about perfect.