Urea is the cheapest way to give crops nitrogen, but only if it ends up in the soil. It contains 46% nitrogen, more than any other solid fertilizer. Left on the surface in warm, dry weather, part of that nitrogen turns into ammonia gas and escapes into the air. Used well, urea is simple, efficient and good value.
This guide covers when to apply it, how much to use, how to stop losses and which fertilizers you can mix it with.
How urea works in the soil
Plants cannot use urea directly. Once it touches moist soil, an enzyme called urease converts it to ammonium. Soil bacteria then turn ammonium into nitrate. Plants take up both forms.
The weak point is the first step. If the conversion happens on the soil surface instead of in it, ammonia can be lost to the air. Most of the advice below is about getting urea into the soil quickly.
When to apply urea
- Apply when the crop needs nitrogen. Most crops need the most nitrogen during fast growth, not at sowing. Splitting the dose matches that demand.
- Choose cool weather when you can. Losses are lower on cool days. Many guides suggest applying when temperatures are below about 15 °C.
- Apply before light rain or irrigation. About 10 to 15 mm of water moves urea into the soil. Heavy rain right after application can wash it away, so avoid spreading before a storm.
- Avoid wet leaves. Granules that stick to wet foliage can scorch it.
How much urea to use
The right rate comes from a soil test and your crop’s yield target. As a general guide:
| Crop | Typical urea rate | How to split it |
|---|---|---|
| Field crops such as wheat and maize | 50 to 80 kg per acre | Part at sowing, the rest at early and mid growth |
| Paddy rice | 75 to 100 kg per acre | Two or three splits, timed with tillering and panicle start |
A quick conversion: 100 kg of urea supplies 46 kg of nitrogen. To get your urea rate, divide the nitrogen your crop needs by 0.46.
How to apply urea step by step
- Check the soil and weather. Moist soil and a cool day are ideal.
- Spread it evenly. Use a calibrated spreader or careful hand broadcasting so no strip gets too much or too little.
- Get it into the soil. Water it in, apply before light rain, or work it in with shallow tillage within a day or two.
- Keep it away from seed. Urea placed with or too close to seed can damage germination. Keep a gap of at least about 5 cm, for example when banding beside maize.
- Split large doses. Two or three smaller doses cut losses and feed the crop when it needs it.
Reducing nitrogen loss
If you cannot incorporate or water in the urea, a urease inhibitor can help. It slows the first conversion step and gives rain or irrigation more time to move the urea into the soil. Urea treated this way usually costs more, so it makes most sense on surface applications in warm weather.
Other simple steps:
- Do not spread on dry soil with crop residue in hot weather.
- Do not spread on waterlogged or flooded fields where it can run off.
- Store bags in a dry, covered place. Urea absorbs moisture and cakes.
Can you mix urea with other fertilizers?
Yes, with some care. Urea absorbs moisture from the air, and some mixes become sticky or lose nitrogen.
| Mix urea with | Result |
|---|---|
| SOP (sulphate of potash) | Mixes well |
| DAP or MOP | Can be mixed, but use within 2 to 3 days |
| Calcium nitrate, ammonium sulphate nitrate, superphosphate | Avoid. The mix gets wet and sticky |
For background on potassium and phosphorus fertilizers, read the top 3 fertilizers and our NPK fertilizer guide.
Granular or liquid urea?
Granular urea is the most common form for broadcasting on field crops. Urea dissolved in water can be used in fertigation or as a light foliar feed. Each has its place. See liquid vs granular urea for a full comparison.
Common mistakes
- Spreading on the surface in hot, dry, windy weather
- Putting the whole season’s dose on at once
- Placing urea in contact with seed
- Mixing it with incompatible fertilizers and storing the mix
- Guessing the rate without a soil test
Buying urea in bulk
Agromer trades urea 46% N with major producers on spot and contract terms for importers, distributors and large buyers. To get an accurate offer, tell us the quantity, packaging, destination port and delivery terms. For price trends, see what urea costs today, and for product details, our urea fertilizer page.
Frequently asked questions
What is the best time to apply urea?
Apply it when the crop is growing fast and needs nitrogen, ideally on a cool day before light rain or irrigation. Splitting the dose into two or three applications works better than one large dose.
How much urea should I use per acre?
It depends on the crop and soil test. Field crops such as wheat and maize often take 50 to 80 kg per acre, and paddy rice 75 to 100 kg per acre, usually in splits.
Should urea be watered in after application?
Yes, if possible. About 10 to 15 mm of water moves urea into the soil and reduces ammonia loss. Shallow tillage does the same job.
Can urea burn plants?
Yes. Too much urea, granules on wet leaves, or urea placed against seed can damage plants. Spread evenly, keep it away from seed and apply the right rate.
Can I mix urea with DAP?
Yes, but use the mix within 2 to 3 days because it can absorb moisture and cake. Avoid mixing urea with calcium nitrate or superphosphate.
Why does urea lose nitrogen?
On the soil surface, urea converts to ammonia gas, which escapes into the air, especially in warm, dry and windy conditions. Getting it into the soil quickly prevents most of this loss.