Urea is the most concentrated solid nitrogen fertiliser available at 46% N, which makes it the cheapest way to move nitrogen per tonne. It also has a failure mode that costs growers real yield every season.
What happens on the surface
Urea must convert to ammonium before a plant can use it. The enzyme urease drives that conversion, and when it happens on a warm, moist soil surface the intermediate product escapes to the atmosphere as ammonia gas. Losses of 10–30% of applied nitrogen are common on surface applications in the wrong conditions, and they can run higher on high-pH or high-residue soils.
How to keep the nitrogen
- Incorporate it — even shallow cultivation largely eliminates the loss
- Water it in — roughly 10mm of irrigation or rainfall moves urea into the soil
- Apply ahead of rain — the cheapest option when the forecast cooperates
- Use a urease inhibitor — worth the cost on warm, moist, high-residue surfaces
- Consider ammonium sulphate instead — lower analysis, but it does not volatilise, and it brings sulphur
If you are unsure which suits your situation, tell us the crop, timing and application method in your enquiry.
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