Soil nitrate tests taken over the last week have showed elevated soil nitrate levels. This is true for sites that had received either manure or fertilizer N. The number of fields sampled to date is not large, so these results must be taken with some level of caution. But, the nitrate levels are nevertheless some of the highest we have ever seen for this time of year and are mostly above the threshold where you would consider applying any more N via sidedress or top dress applications.
Why Elevated Nitrates?
Soils often lose nitrogen when they sit in saturated conditions or when rainfall is high enough to force N down and out of sandy soils. It is fair to say that in many areas, (at least east of Manitoba!) that April, May and the first few days of June produced relatively few situations where high rainfall caused N losses out of the system. This may be at least a partial explanation as to why we are seeing relatively high N levels and why applications of manure or early applications of fertilizer are contributing significantly to soil N supply. Further sampling over the next 10 days will verify this trend.
If you have received significant rainfall (more than .75 inches , 20mm) in the June 6-8 window you will need to wait 1-2 days before a soil N test will again give reliable results.
For growers looking to get some direction on sidedress N rates the soil N test can be a useful tool, especially when the results are integrated into a spreadsheet that includes corn yield expectations and prices of both corn and nitrogen as in the Maizex N Tracker: http://www.maizex.com/maizex-n-tracker-2022
If you have any questions about the status of nitrogen in your fields, please reach out to your local Maizex Representative or email or call Greg Stewart (firstname.lastname@example.org), 226.820.2203.