Nitrogen is an essential requirement during plant growth. Applying nitrogenous fertilizers at specific stages of plant development improves yield. Urea and Calcium Ammonium Nitrate (CAN) fertilizers are common nitrogenous fertilizers, but growers are often confused when choosing between the two.
Nearly 50% of urea is nitrogen, while CAN fertilizer contains about 28% nitrogen. Urea is cheaper than CAN and with comparable yields. However, the nitrogen in urea is less stable and is easily lost into the atmosphere. On the other hand, CAN production releases toxic substances into the atmosphere.
Choosing between urea and CAN is more than just comparing the nitrogen content in each or their comparative yields. You must consider how they differ in efficiency, ease of application, and carbon footprint. I’ll explain all the differences between urea and CAN fertilizer in this article.
Urea vs. CAN Fertilizer: What’s in the Mix?
Urea and CAN are both nitrogenous fertilizers. Globally, urea is more readily available and widely used than CAN.
Urea contains 46% nitrogen, whereas CAN fertilizer contains about 28% nitrogen. So, a kilogram of urea contains more nitrogen than a kilogram of CAN.
CAN consists of equal amounts of fast-acting nitrate-nitrogen and slow-release and stable ammonium nitrogen. It also has calcium and magnesium.
Urea vs. CAN Fertilizer: Application and Effects
There are considerable differences in when and how urea and CAN should be applied to soils and how plants use each type of fertilizer. Knowing about these differences will help you choose a fertilizer that best suits your growing conditions and aligns with your efforts to grow your crops.
Applications on Different Types of Soils
CAN fertilizers are applicable to all soils, but they’re especially beneficial for acidic soils because they have almost neutral pH values. As a result, they don’t acidify the soil.
On the other hand, excessive urea can alter the pH value of the soil drastically, which in turn can reduce crop productivity.
Availability of Nitrogen to the Plants
The nitrogen in urea tends to get lost through volatilization, where ammonia in the urea escapes into the atmosphere.
The efficacy of urea decreases if it’s applied on alkaline soils and those with a high organic matter content. Nitrogen loss through volatilization is greater in these types of soils. So, more urea needs to be applied to achieve yields comparable to those obtained by using CAN.
Volatilization doesn’t occur in most other nitrogen fertilizers, such as CAN. Additionally, CAN contains calcium and magnesium that improve nitrogen uptake by the plants’ roots. Therefore, CAN is more efficient than urea in this respect.
Tip: I’ve written in-depth articles about why plants need nitrogen, phosphorus and potassium. Check them out!
Application at Different Stages of Plant Development
Plants don’t need nitrogen during all stages of their development.
For instance, corn is a heavy nitrogen feeder, but it requires nitrogen midway through the growing season, especially about a month before flowering.
The corn plant won’t take up any nitrogen fertilizer applied as top dressing during the early stages of growth. The fertilizer will sit on the topsoil.
If you apply urea, the unused fertilizer will soon release ammonia into the atmosphere. As a result, valuable nitrogen will be lost, and the fertilizer will lose its efficacy. However, there isn’t much loss of nitrogen if you use CAN, even if the fertilizer isn’t used right away by the plant.
Timing of Application
Plants can’t use urea right after it’s applied to the soil. It has to break down into ammonia nitrogen before the plants can uptake the goodness of the fertilizer. The breakdown generally takes a week from the day of application.
In the meantime, most of the nitrogen in the urea might volatilize if the soil is alkaline or the conditions are dry.
To reap the benefits of urea, you have to coordinate its application with sowing and planting times. You have to irrigate the soil well before applying urea or apply it a few days before heavy rain is forecast.
On the other hand, CAN can be applied at any time. The plants absorb it almost right after using it.
Yield Performance
According to an experiment on wheat, urea and CAN fertilizers produce comparable yields. Another experiment found that the fertilizers have no noticeable difference in grass yield in a temperate climate. So, it’s safe to say that yield performance isn’t a decisive factor when choosing between the two.
Urea vs. CAN Fertilizer: Cost of Application
As mentioned, urea has a high concentration of nitrogen (46%) compared to CAN fertilizer (28%). However, volatilization decreases urea’s utilization to about 30%.
So, you have to use a greater amount of urea and apply it more frequently.
Urea costs less than CAN fertilizer and has comparable yield performance. However, this cost advantage is only possible if you apply urea correctly and ensure no nitrogen loss.
Urea vs. CAN Fertilizer: Environmental Impact
With increased environmental awareness, more people scrutinize manufacturing practices before buying products. They want to know the carbon footprint of what they are consuming.
The environmental impact of urea and CAN fertilizer is also under the scanner.
Release of Nitrous Oxide Into the Atmosphere
Nitrogenous fertilizers release climate-warming nitrous oxide (N2O) into the atmosphere. Increased N2O in the atmosphere contributes to greenhouse gas pollution and depletes the ozone layer.
CAN fertilizers emit the maximum amount of N2O into the atmosphere among all nitrogenous fertilizers. Therefore, urea is more environmentally-friendly than CAN fertilizer.
Leaching Into Nearby Water Bodies
Urea comes with its own set of environmental concerns. It’s highly mobile in soil and tends to run off into nearby water bodies. Increased and indiscriminate use of urea is a major source of water pollution.
CAN fertilizer can be quickly absorbed by plants. So, dangerous materials won’t leach into nearby water bodies and pollute them.
Release of Nitrogen Into the Environment
Nitrogen is good for plants but bad for the environment.
Countries with targets to reduce ammonia emissions may need to reconsider their urea usage. Moreover, authorities need to educate the farming community about the correct way of applying urea so that nitrogen isn’t lost.
The adverse environmental effects can be reduced considerably by applying urea correctly. This entails improving injection methods, atmospheric conditions, dose, soil pH, and irrigation frequency.