What Is 46-0-0 Fertilizer Used For?

What You Need to Know

46-0-0 fertilizer, known chemically as urea (CO(NH2)2), is the most concentrated solid nitrogen fertilizer commercially available. With 46% nitrogen by weight, it delivers nearly five times more nitrogen per pound than a typical 10-10-10 formula, making it the most cost-effective way to supply nitrogen when phosphorus and potassium are not needed.

Urea is the most widely produced fertilizer in the world, accounting for more than half of global nitrogen fertilizer use. Its high analysis means less product needs to be transported, stored, and applied to deliver a given amount of nitrogen. A single 50-pound bag provides 23 pounds of actual nitrogen, enough to fertilize approximately 23,000 square feet of lawn at a rate of 1 pound of nitrogen per 1,000 square feet.

For lawn care, 46-0-0 is an excellent choice when soil tests indicate sufficient phosphorus and potassium but low nitrogen levels. This situation is common in established lawns that have received balanced fertilizers for years, building up phosphorus reserves while nitrogen is continuously consumed and leached. Apply urea at a rate calculated to deliver 0.5 to 1 pound of actual nitrogen per 1,000 square feet per application.

To calculate the application rate, divide the desired nitrogen amount by 0.46. For example, to apply 1 pound of nitrogen per 1,000 square feet, you need approximately 2.17 pounds of urea per 1,000 square feet (1 divided by 0.46). Set your spreader accordingly and calibrate before application.

Urea has one significant management requirement that distinguishes it from other nitrogen sources: it is highly susceptible to volatilization losses. When urea granules land on a moist soil surface, the enzyme urease converts the urea into ammonium carbonate, which can rapidly break down into ammonia gas that escapes into the atmosphere. On warm, moist days with no rainfall or irrigation, volatilization losses can exceed 30% of applied nitrogen within 48 hours.

To minimize volatilization, follow these practices. Water the lawn with at least 0.25 inches of irrigation immediately after application to dissolve the granules and move nitrogen into the soil. Alternatively, apply urea just before a predicted rainfall of 0.25 inches or more. If watering is not possible, apply during cool weather when volatilization rates are naturally lower. Some urea products contain urease inhibitors such as NBPT that slow the conversion process and reduce gas losses, providing a wider application window.

For agricultural and pasture use, urea is typically broadcast at rates of 50 to 200 pounds per acre depending on crop needs and soil test results. It can also be dissolved in water for liquid application through fertigation systems, though care must be taken with solution concentrations to avoid seedling damage.

In vegetable gardens, urea can be applied as a side-dressing for heavy nitrogen feeders like corn, cabbage, and leafy greens. Apply at a rate of 1 to 2 tablespoons per plant, placed 4 to 6 inches away from the stem in a shallow trench, then covered with soil and watered. Direct contact between urea granules and plant tissue causes severe burn due to the high nitrogen concentration.

Urea is also the primary nitrogen source used in liquid fertilizer blends, such as UAN (urea-ammonium nitrate) solutions used in commercial agriculture. When dissolved in water, urea produces a slightly acidifying effect on soil over time, which can be beneficial in alkaline soils but may require lime applications in already acidic soils.

Store urea in a dry location, as it readily absorbs moisture from the air and can cake or dissolve in its container. Keep bags sealed and elevated off concrete floors, which can contribute moisture through condensation.