When Bob Nielsen harvested plots at the Southeast Purdue Ag center near Butlerville recently, the seed specialist saw an inkling of what might become an issue for those who grow or want to grow corn after corn. While he hasn't confirmed what he saw yet, eyeball observations show that it took about 14 pounds more N to reach top economic yield on corn after corn vs. rotation corn.
That's not a shocker. Most people growing second year or longer corn without rotation realize that they need to apply approximately 30 pounds per acre more, just to make up for what's usually supplied by a previous soybean crop. That residual, basically manufactured by the nodules in the soybean roots, is not available if corn was the previous crop.
What was more surprising was that it appeared that continuous corn yielded less, and considerably less, than first year corn. However, it was not a side-by-side comparison, Nielsen notes. The second year corn field that they used for their nitrogen trial was directly across the road from the first-year corn field that they evaluated for nitrogen results. He is not aware of any major differences in how the fields have been handled that might affect yield, but intends to pursue it with Don Biehle, manager of SEPAC.
SEPAC utilizes primarily no-till in its cropping systems. The corn after corn plot was no-tilled, Nielsen confirms. Past track record for no-till corn following corn is not impressive, especially compared to success stories for no-tilling corn into soybean stubble as first year corn.
One of the worst years for no-till corn following corn in Indiana occurred in 1988. That year featured a lack of moisture and lots of heat fairly early in the season. The fall-out from that year discouraged many people from trying or continuing with no-till corn, especially no-till corn back into corn.
Exact causes of the yield meltdown that year were never fully categorized. The bottom line thinking has been that especially in dry, stress years, corn after corn doesn't tend to perform as well as when corn follows another previous crop, especially soybeans.
Nielsen will be following up on these observations and making more comments at a later date. If you have already harvested second year corn, either in conventional or no-till settings, let us know about your results. Contact: email@example.com with any information that you might be willing to share.