You are in a different situation - irrigated pivot and shank tpye machine in the fall - than most of my customers and experience. I beleive there is a good chance, depending on your soils and climate, rainfall annual weather etc that your corn was deficient in N and that a significant portion of the fall N you applied was just gone with the water table by the time the plant needed it. "Deep placement" of N in some soils and weather just gives it a head start. jmho.

What we find is that strip tilling into cornstalks in the spring (not fall) with our Pluribus units leaves almost 100% of the residue on the surface yet clears a trip to warm and get fit to plant.

I don't see any evidence that corn residue left untouched on the surface - just scooted to the side - uses a significant amount of soil N to break down. It appears that most of our Dawn strip tilled corn residue breaks down under the canopy the next summer - using atmospheric N to break down at a slower rate and in the process releasing CO2 ( fuel for photosynthesis) at a time when there is a canopy above to use it.

There is a reason plants look green after cultivation and with residue breaking down underneath. (Credit to Dr Jerry Hatfield, USDA soil labs). Dr Hatfield (and others incl Univ of IL) have measured the CO2 concentration under a corn canopy through the day and season and it is amazing data.

Here is a photo of some Iowa strip tilled continuous corn taken by the customer in July. Note how the residue is turning gray and how green the corn looks. Contrast this to the photo of last years c on c residue as the new crop emerges. These photos were by the same customer, the same year but not likely in the same spot.

I know folks apply 28% to residue just to break it down....why?

jmho.

Jim at Dawn

(Dawn Striptill Corn on Corn E IA 5-8-05 hp095 first corn emerges.jpg)

(Dawn Striptill Corn on Corn E IA 7-25-05 hp175 cust photo -last yr residue + spring cleared strip.jpg)

Dawn Striptill Corn on Corn E IA 5-8-05 hp095 first corn emerges.jpg (87KB - 63 downloads)

Dawn Striptill Corn on Corn E IA 7-25-05 hp175 cust photo -last yr residue + spring cleared strip.jpg (81KB - 67 downloads)