Ask the Quality Silage Experts: Nitrate Forage Testing

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Q. Should I invest in forage testing for nitrates this year?

A. If your forage crop is at risk for elevated nitrate levels, we always recommend you send a sample to a commercial lab for analysis.

Here are some common risk factors:
•    Overapplication of nitrogen during growing
•    Insect and disease damage to the plant’s leaves 
•    Frost-damaged grasses, including corn and sorghum plants
•    Crops that experience drought; in particular, immediately after a recovery rain
•    Cloudy weather around harvest

If these conditions sound familiar, we recommend testing for nitrate levels. Adjustments during harvest and ensiling can help limit nitrates in the forage. Right now, your best bet is to test your silage and adjust the ration, as the crop is already harvested and ensiled.

Nitrates accumulate in the bottom portion of the plant, so raising the cutter bar during harvest to leave 12" or more of stalk in the field can be effective in reducing nitrate levels in the resulting silage. This may lead to a yield reduction, but the material harvested will have higher quality (proportionally more grains and leaves) as well as a lower nitrate risk.

Bacterial fermentation during ensiling can reduce nitrates by 40% to 50%, so the risk of poisoning is considerably lower. Using research-proven quality forage inoculants can help ensure silage has safe nitrate levels – in addition to helping retain dry matter and maximizing nutrient preservation and stability at feedout. 

Remember: Crops with high nitrates can also be dangerous for people. Producers should watch out for hazardous silage gases in these crops. Shortly after ensiling green plant material, oxygen is used up, and the nitrates in the plant may be released as nitric oxide (NO). This gas escapes from the silage and combines with oxygen in the air to form toxic nitrogen dioxide, a lethal orange-brown gas that smells similar to laundry bleach.

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The Quality Silage Experts

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