Urea 46-0-0 Fertilizer FAQ

Urea (CO(NH₂)₂) is the most concentrated solid nitrogen fertilizer available, containing 46% nitrogen — nearly double that of ammonium nitrate (34%). It's a white, odorless, granular material that's 100% water-soluble.

How it works:

1. Application: Urea granules are applied to soil
2. Hydrolysis (Days 1-2): Soil moisture and the enzyme urease convert urea to ammonium (NH₄⁺)
3. Nitrification (Days 3-14): Soil bacteria convert ammonium to nitrate (NO₃⁻)
4. Plant Uptake: Roots absorb both ammonium and nitrate forms

This is one of the most common questions from growers. Here's a direct comparison:

Biuret is a byproduct formed during urea manufacturing when two urea molecules combine under heat. All commercial urea contains some biuret.

Why it matters:

• Soil application: Biuret levels under 2% are completely safe for all crops
• Foliar application: Biuret above 0.25% causes leaf burn and phytotoxicity

Our urea contains less than 1% biuret — well within the safe range for soil application on all crops. However, this means it is not suitable for foliar spraying.

No. Synthetic urea is manufactured from ammonia and carbon dioxide — it is not approved for certified organic production under USDA NOP standards.

Organic nitrogen alternatives:

• Blood Meal (12-0-0): Fast-release, high nitrogen
• Feather Meal (12-0-0): Slow-release, longer lasting
• Fish Emulsion (5-1-1): Liquid, fast-acting
• Alfalfa Meal (2.5-0.5-2.5): Mild, adds organic matter
• Composted Manure: Variable NPK, slow release

Related products:

Timing depends on your crop and conditions:

• Cool-season lawns (fescue, bluegrass): Early spring (soil 55°F+) and early fall
• Warm-season lawns (bermuda, zoysia): Late spring through summer
• Vegetables: At transplanting and during rapid vegetative growth
• Field crops: Pre-plant incorporated or side-dressed at growth stages
• Fruit trees: Early spring before bud break

Surface-applied urea can lose up to 40% of its nitrogen to the atmosphere as ammonia gas. Prevention is critical:

1. Water in immediately: Apply 0.5 inches of irrigation within hours of application
2. Apply before rain: Natural rainfall moves urea into soil
3. Incorporate mechanically: Till or rake into top 2-4 inches within 24-48 hours
4. Avoid hot/windy days: Volatilization accelerates above 85°F
5. Consider urease inhibitors: Products like NBPT can reduce losses by 40-50%
6. Split applications: Multiple smaller doses are more efficient than one large application

Yes, if misapplied. Urea has a relatively high salt index and the ammonia released during conversion can damage plant tissue.

How to prevent fertilizer burn:

• Never exceed recommended application rates
• Keep granules at least 2 inches away from seeds and transplant stems
• Water immediately after application
• Never apply to drought-stressed plants (the salt can dehydrate them further)
• Split large applications into 2-3 smaller doses
• Avoid application when temperatures exceed 85°F

Yes — urea is an acid-forming fertilizer.

The conversion process works like this:

1. Initial reaction: Urea + water → ammonium + CO₂ (temporarily raises pH around granule)
2. Nitrification: Ammonium → Nitrate releases H⁺ ions (lowers pH over time)

The net effect over a growing season is soil acidification, especially with repeated applications.

This is the #1 physical complaint with urea storage. The cause is simple: urea is hygroscopic — it actively pulls moisture from the air.

What happens:

1. Urea absorbs humidity from the air
2. Surface granules partially dissolve
3. When humidity drops, they re-crystallize and fuse together
4. Result: rock-hard clumps or a solid brick

Prevention:

• Store in original sealed bag until use
• Keep in a cool, dry location (not a humid shed or garage)
• Store off concrete floors (use pallets or shelving)
• Reseal opened bags tightly or transfer to airtight containers

Urea is chemically stable, but extreme heat degrades it over time:

Properly stored urea has an indefinite shelf life. Unlike some fertilizers, urea doesn't "expire" in the traditional sense.

However, quality can degrade if:

• Exposed to moisture (causes clumping)
• Stored in extreme heat (breaks down prills, may increase biuret)
• Contaminated with other materials

Signs your urea may be degraded:

• Strong ammonia smell (indicates breakdown)
• Yellow or brown discoloration
• Powdery dust instead of firm prills

Some combinations work well, others create problems:

Related products for complete nutrition:

Yes! Urea is 100% water-soluble and excellent for fertigation systems.

Solubility: 108 g per 100 mL water at 68°F (very high)

Mixing tips:

• Dissolve urea in water before adding to tank
• The dissolution process is endothermic — the solution will cool down
• Use warm water to speed dissolution of large quantities
• Filter solution if any particulates remain

Once properly watered in, treated areas are generally safe.

Safety timeline:

• During application: Keep pets and children away from the area
• After watering in (0.5" water): Once granules are no longer visible and the lawn is dry, it's generally safe to return
• If granules are still visible: Wait until they dissolve or are watered in

Why the concern? Urea itself has low toxicity, but in the stomach it can be converted to ammonia, which is irritating to the digestive tract. Large ingestions require medical attention.

Responsible urea use protects water quality and the environment:

• Don't over-apply: Excess nitrogen runs off into waterways, causing algae blooms
• Maintain buffer zones: Keep applications 25+ feet from streams, ponds, and wells
• Avoid application before heavy rain: Prevents runoff before soil absorption
• Calibrate your spreader: Ensures accurate application rates
• Sweep up spills: Don't wash granules into storm drains
• Follow local regulations: Some areas restrict fertilizer application timing

Be patient — urea requires conversion time. Unlike nitrate fertilizers that work within days, urea typically shows results in 7-14 days.

Timeline expectations:

1. Days 1-2: Urea dissolves in soil moisture
2. Days 2-4: Urease enzyme converts to ammonium
3. Days 5-7: Initial greening begins
4. Week 2+: Full response visible

If you still don't see results after 2 weeks:

• Cold soil? Below 50°F, conversion is very slow — wait for warmer weather
• No watering? Urea may have volatilized — nitrogen was lost to air
• Other deficiencies? Nitrogen alone won't help if phosphorus, potassium, or micronutrients are limiting
• Soil pH extreme? Very low or high pH affects nutrient availability

This is likely fertilizer burn. Common causes:

• Over-application: Applied more than recommended rate
• Drought stress: Applied to dry, stressed turf
• Hot weather: Applied during high temperatures (85°F+)
• No watering: Granules sat on leaf blades and burned them
• Overlap: Double-coverage from spreader overlap

Recovery steps:

1. Water heavily and immediately (1+ inch)
2. Continue watering daily for several days to flush salts
3. Most lawns recover within 2-4 weeks
4. If damage is severe, overseeding may be needed

A slight ammonia smell is normal during the first 24-48 hours as urea converts to ammonium. However, a strong, persistent smell indicates volatilization loss — your nitrogen is escaping into the atmosphere.

What's happening:

• Urea is converting to ammonia gas (NH₃) on the soil surface
• This nitrogen is lost and won't benefit your plants
• Losses can reach 40% of applied nitrogen in worst cases

Fix it now:

1. Water immediately with at least 0.5 inches
2. This moves remaining urea into the soil where it's protected

Next time: Always plan to water in urea within hours of application, especially in warm weather.