The Agronomists, Ep 71: Greg Stewart and Elizabeth Karpinchick on in-crop N for corn

We're back with another episode of The Agronomists, and as always, we're excited to be here.

Today's show — hosted by Lyndsey Smith — features Greg Stewart of Maizex Seeds and Elizabeth Karpinchick of Tone Ag. The trio discusses in-crop N applications in the corn crop (and more).

The Agronomists is brought to you by ADAMA Canada, the Pest & Predators podcast, and RealAg Radio. Click here to view all the previous episodes.

SUMMARY

• Soil nitrate testing is important
• The number for broadcasting N is different than what you will put down with the planter. Keep that in mind
• What is the earliest that that top up starts, and how late would you recommend someone still top up some N on the corn crop

CLIP 1: Corn School: Cool weather calls for more sidedness nitrogen

• In Ontario we don't pull samples in the fall
• Why would we be seeing relatively high soil nitrate tests in Ontario?
• April and May wasn't all that warm in southern Ontario, but it wasn't necessarily all that wet, either
• We are using the soil nitrate test to gauge where we are at. It works to give us a * guide *
• For those acres that have a history of manure, or have a good red closer stand, there are some really high nitrate tests coming off. Do we trust this enough to pull back our nitrogen?
• If you've got really high nitrates, you've got to trust those and pull back. There's enough research to support this
• High organic matter soils is where you often see high N tests
• If you're going to sidedress, it's not worth it for 10 pounds
• If we're soil testing, we're doing it for a reason....we have to somewhat trust the process. Not blindly, but still
• Consider plant factors — yield expectation, plant tissue N status, NDVI
• Weather factors — rainfall, temperature, crop heat units
• Cropping system factors — previous crop, tillage systems, manure additions
• Soil temperatures — soil texture, soil organic matter, soil N status
• Nitrogen factors — price of corn/nitrogen, source of nitrogen, application method/timing

CLIP 2: How do you apply N, let me count the ways?

• Is this the perfect year for split applications trials in Manitoba? Depends where you are — there's a lot of different soil types
• Sometimes we get so excited about the concept of splitting N applications...it doesn't always pencil out
• This year is really the year of nitrogen
• We're seeding in June — should we be cutting down on fertilizer prices?
• Tissue tests for N top ups? Do you use them? Could be used, but a soil nitrate test gives you more information
• There's a window for adding N, but then the crop gets so big, we simply don't have the toils
• How late can we go in and it still be effective?
• You can actually put it on right up to tasseling
• How late can you put manure on corn? There's a lot of rules in different places — so you have to pay attention to those