Many fertilizers contain a blend of the three macronutrients: nitrogen, phosphorus, and potassium. However, other products, such as 46-0-0 fertilizer, only supply plants with one of the nutrients.
When used properly, 46-0-0 fertilizer (also known as urea) can help plants grow lush and green. But improper use can lead to fertilizer burn, nutrient leaching, and even plant death.
Stay with us as we explain all you need to know about 46-0-0 fertilizer.
The numbers in 46-0-0 fertilizer refer to the NPK ratio, or the amount of nitrogen, phosphorus, and potassium. You can read more about fertilizer numbers and NPK ratios in our article on the subject.
Since the first number in the NPK ratio refers to the amount of nitrogen in a product, a 46-0-0 fertilizer is loaded with nitrogen. However, it doesn’t contain any of the two other macronutrients: phosphorus or potassium.
So, what does nitrogen do? All sorts of things!
In general, it is a major component of amino acids, which are the molecules that act as building blocks for larger proteins. Without enough nitrogen, plants have a difficult time forming new tissue, creating enzymes, and completing plant processes.
Nitrogen is also a significant component of chlorophyll, the molecule that gives plants their green color and allows them to complete photosynthesis. Without enough nitrogen, plants may appear yellow and/or become stunted.
Supplying 46-0-0 fertilizer gives plants lots of nitrogen and helps prevent them from becoming nitrogen deficient.
Because 46-0-0 fertilizer contains nitrogen and few (if any) other nutrients, it’s best to apply it when plants need a big dose of nitrogen but not any other nutrients. However, it’s important to remember that plants need 18 elements to thrive, so you’ll often want to apply a fertilizer that contains more than just nitrogen.
With that said, there are some instances when it makes sense to apply 46-0-0 fertilizer. Lawns often benefit from a high-nitrogen fertilizer once their roots are well established.
You can also apply 46-0-0 fertilizer to grain crops including wheat, barley, and corn. However, you will likely also need to apply other types of fertilizers to supply other necessary nutrients.
While you can apply 46-0-0 fertilizer to vegetables in order to give them a big boost of nitrogen, it’s often better to apply a fertilizer that contains multiple nutrients.
The vast majority of 46-0-0 fertilizer is urea, also known as carbamide. Although urea naturally occurs in mammalian urine, urea is often produced in a lab by combining carbon dioxide and ammonia.
Since the urea fertilizer is synthesized in a lab, it is considered a synthetic product. Therefore, it is not organic and is prohibited for use in organic operations by the Organic Materials Review Institute (OMRI).
When it comes to choosing between types of 46-0-0 fertilizer, you have two main options: prilled and granular. I’ll describe the attributes of each product to help you select the best type for your needs.
Prilled 46-0-0 fertilizer is made up of small pieces of fertilizer known as prills. These prills quickly dissolve in water, which allows the nitrogen to become available for plant uptake.
As the name suggests, this type of fertilizer exists in granular form. These granules are not quite as water-soluble as the prills, so they take a bit more time to break down and release their nitrogen.
You can apply these granules on their own, or combine them with other types of fertilizer to form a custom blend.
Another type of 46-0-0 fertilizer is a liquid form. Before you opt for this form, you should ensure that you can properly apply it.
While you can apply many types of liquid fertilizers by spraying them on your plants, this isn’t the case with liquid 46-0-0. If you do this, the nitrogen will convert to ammonia gas and be lost to the atmosphere.
Instead, you must inject liquid urea into the soil if you want the nitrogen to become available to plants. Therefore, this type of fertilizer is only recommended if you have a fertilizer injector.
If you’re interested in applying a 46-0-0 fertilizer, follow these guidelines and tips.
Applying to Lawns
One of the most common uses for 46-0-0 fertilizer is applying it to lawns. The large amount of nitrogen encourages green growth and the lack of phosphorus and potassium discourages the formation of pesky seedheads.
You’ll only need to apply this fertilizer once a year.
The best time to apply 46-0-0 fertilizer to your lawn is in the late fall for cool season grasses or spring for warm season grasses. Applying during these cooler periods will limit the amount of nitrogen that is lost when the fertilizer converts into ammonia.
You should also try to apply the fertilizer a day or few hours before rain is predicted. The rain will help the fertilizer penetrate into the soil, which will help with the volatilization of nitrogen into ammonia and therefore prevent the loss of nitrogen into the atmosphere.
If you are not expecting rain around the time you need to fertilize, you can also use an overhead irrigation system or sprinkler to water the fertilizer.
Since this is such as nitrogen-rich fertilizer, you’ll need to be careful to not overapply it. Adding too much fertilizer to your lawn can result in fertilizer burn and cause more harm than good.
That said, how much 46-0-0 fertilizer should you apply to your lawn?
First, you’ll need to measure the area of your lawn. Using this area as a guide, weigh out two to three pounds of fertilizer for every 1,000 square feet.
Once you’ve measured the proper amount of fertilizer for your lawn, it’s time to evenly distribute it throughout your lawn. The best way to do this is by using a fertilizer spreader that you’ve calibrated to the proper distribution setting (somewhere between two and three pounds per 1,000 square feet).
Applying to Small Grains
Most small grains like wheat and barley require between 50-100 pounds of nitrogen per acre. The amount of nitrogen needed depends on the previous crop as well as the targeted yield.
One way to apply this nitrogen is with a 46-0-0 fertilizer. You can apply fertilizer in the fall before spring plantings, as long as the soil temperature is lower than 50°F. Another option is to band the fertilizer alongside the seeds at planting, just make sure the seeds and fertilizer are at least 1.5 inches apart.
Overall, you’ll want to apply 108 to 217 pounds of 46-0-0 per acre of small grains.
Applying to Corn
Urea, also known as 46-0-0 fertilizer, can be applied to corn to support this heavy-feeding crop. However, proper application is key to ensure that you are not wasting the nitrogen present in the urea.
First off, you should never apply 46-0-0 fertilizer when you plant corn seed. That’s because urea rapidly converts into ammonia, and this high concentration can cause germinating seeds to die.
Instead, the University of Minnesota recommends that you broadcast the fertilizer in the fall before you plant, or sidedress the plants when they are at least two inches tall.
You should utilize a soil test in order to determine how much 46-0-0 to apply.
However, in general, you can expect to apply between 200 to 250 pounds of N per acre if you are expecting a 200 bushel harvest. That means you will need to apply 435 to 543 pounds 46-0-0 per acre.
You can apply less fertilizer, but you should expect a smaller harvest if you do so.
Applying to Vegetable Gardens
In general, you should not apply 46-0-0 fertilize to vegetables. All vegetables require phosphorus and potassium as well as nitrogen, so a fertilizer with an NPK ratio like 12-12-12 or 6-2-4.
Read this article from Stephanie if you would like to apply fertilizer to your vegetable gardens.
Applying to Flowers
I would not recommend applying 46-0-0 fertilizer to flowers. While the nitrogen will benefit these plants, the high concentration can burn sensitive flowering plants.
Additionally, a fertilizer that also contains phosphorus and potassium is a better choice.
No matter what crops you’re applying 46-0-0 fertilize to, you should always follow fertilizer application best practices. By keeping these tips in mind, you’re likely to minimize nutrient runoff, which can help you save money and protect the environment.
The biggest thing to remember is that 46-0-0 fertilizer begins to break down quite quickly. As long as moisture is present, urease will break urea into ammonium and bicarbonate. This ammonium often then transforms into ammonia.
If the fertilizer is on the soil’s surface, the ammonia will evaporate into the atmosphere before plants can take it up. However, if the fertilizer is worked into the soil, the ammonium will be held on the soil until plants can take it up.
Therefore, it’s best to incorporate 46-0-0 fertilizer into the soil shortly after you apply it. You can incorporate it via tillage or irrigation.
You should also recognize that various factors influence the production of ammonia and, therefore, loss of nitrogen to the atmosphere. These factors include temperature, moisture, soil pH, and the amount of fertilizer applied.
Higher temperatures and higher moisture levels will lead to rapid production of ammonia. Therefore, the best time to apply 46-0-0 fertilizer is during cool and dry periods.
A high soil pH will also increase the rate of ammonia production. This is especially true if soils are low in clay and organic matter, both of which hold onto hydrogen ions.
The final factor that impacts ammonia production is the fertilizer application rate. Overapplication of 46-0-0 can result in nitrogen loss, so make sure to avoid applying more fertilizer than your plants need.
When urease reacts with water and urea molecules, it pulls hydrogen ions from the soil to form bicarbonate and ammonium. As the amount of hydrogen ions in the soil decreases, the pH rises.
Therefore, adding 46-0-0 fertilizer to the soil can lead to an increase in pH. In other words, the soil pH can become less acidic or more basic.
If your soil pH is already above 7.0, you may want to avoid applying urea. That’s because most plants grow best at a soil pH between 6.0 and 7.0. If the pH rises above 7.0, many plants have difficulty absorbing nutrients.
The rate of action of 46-0-0 fertilizer depends on soil moisture and temperature. As long as the soil is warm and moist, the nitrogen will become available to plants almost immediately.
If you want to get started with applying 46-0-0 fertilizer to your plants, check out these options. Along with the readily available options I’ve included below, you can also look out for 46-0-0 fertilizer at stores like Southern States and Tractor Supply Co.
Easy Peasy Urea
If you’re looking for a small amount of urea for your lawn or corn planting, Easy Peasy Urea is a good choice. The product comes in five pound bags, which means it’s easy to ship and transport around your garden and home.
This 46-0-0 is made up of prilled urea. The prill form means the fertilizer is water soluble and quickly converts to a form of nitrogen that plants can take up. However, it also means that you’ll need to be extra careful to keep this fertilizer in a dry place.
Easy Peasy Urea is relatively affordable, especially when you consider the high nitrogen content. However, if you need to fertilize a large area, you will be better off opting for a product that comes in larger bags.
Like with all types of urea, you’ll need to practice care when applying this product. Make sure you till or water after applying the material to the surface in order to prevent loss of nitrogen via volatilization.
If you need to fertilize a big lawn or large planting of grains, one suitable 46-0-0 option is YaraVera Urea. This product comes in 50 pound bags, which makes it a more economical option than Easy Peasy Urea.
Like with the Easy Peasy product, this YaraVera Urea comes in a prilled form. That means it easily dissolves in water and the nitrogen is readily available to plants.
If you’re looking to supply your lawn or crops with a large dose of nitrogen, 46-0-0 fertilizer is a good option. This product is also known as urea, and is an economical way to apply lots of nitrogen.
No matter which 46-0-0 product you choose, you should avoid overapplication, which can cause nutrient burn. And remember to till or water the soil after application in order to avoid nitrogen loss via volatilization.