Soil nitrate test well worth the cost this growing season

Debra Murphy, 2016.

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) will not be performing soil nitrate tests for public extension this growing season.

Which begs the question: will it pay for farmers and agronomists to draw tests in corn fields anyway?

The answer — if the field saw any manure or red clover the in past year to 18-months — is YES.

On this week’s Wheat Pete’s Word, host Peter Johnson shares that agronomists are pulling nitrate nitrogen samples in the corn crop and some levels are coming back unbelievably high wherever there was an organic nitrogen source.

Whether it was red clover, or fall-applied or even spring-applied manure some fields are coming back with 300, yes, 300! pounds per acre of available nitrate nitrogen.

These fields in question did have some starter nitrogen applied, somewhere between 40 to 60 pounds of N, as is good practice with corn. But it looks like Ontario conditions have been very conducive to N mineralization out of red clover and manure, and it could mean saving some pounds of (very expensive N) in the top-dress pass this year.

Manure N release can be highly variable, so Johnson says that if soil tests come back in the 35 or 40 parts per million range, you might still add 30 or 40 pounds of nitrogen to account for that variability. Higher than that and you may not need to add any additional N, potentially.

The bottom line is, if you had red clover or manure applied to any corn fields this year, pull those nitrate samples and adjust accordingly.

Interested in more discussion on the N decision in corn? Tune in Monday, June 13, at 8 pm E for The Agronomists!

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