One of my earliest memories of growing corn was driving tractor while picking rocks on my uncle's farm. I was 6 years old and could barely push in the clutch. After getting me going in granny gear and pointing me down the field, my only job was to drive straight and stay off the corn. However, I ran over lots of corn and thought I had caused the death of numerous seedlings that day, but my cousin said not to worry. I don't remember what happened when we reached the end of the field, but I do remember I was demoted quickly from tractor driver and promoted to rock picker.
Running over corn happens when side-dressing with a manure hose application system. However, little is known about what growth stage different corn hybrids can be dragged with a manure hose before plant population and grain yield is affected.
In a paper published in Agronomy Journal, field studies were conducted in 2019 and 2020 in Minnesota. Plots were dragged in both directions along the row with a manure hose from the first through sixth leaf collar growth stages (vegetative growth stage V1 through V6) and compared to a non-dragged control.
Dragging corn at V1 to V3 did not significantly damage the crop. Dragging corn at V5 and V6, and sometimes V4, reduced yield and increased grain moisture. Dragging at V4 reduced plant population and yield by 41% in 1 of 4 site-years, while dragging after V5 significantly reduced yield by 21–79% and in most cases, increased grain moisture. These results suggest that when using a manure drag hose application system to side-dress corn, side-dressing should be completed before V4 to avoid damaging the crop.