When it comes to feeding your crop, you want nutrients readily available when they’re needed. After selecting nutrient rates, your next decision is the vehicle you’ll use to fertilize your crop.
According to Michigan State University and Penn State University Extension, granular and liquid fertilizers provide the same total amount of nutrients; the differences lie in crops’ access to nutrients, crop safety, consistency and ease of use. In terms of price comparison, granular urea cost 9% more than anhydrous ammonia and 6.5% more than liquid UAN in early February, according to Pro Farmer Inputs Monitor. During harvest 2016, prices for all forms were more similar and only started to diverge in early December.
- Easier to store
- Slow-release granules help feed crops longer into the season
- More efficient for preplant application
- High salt content can burn leaves and steer roots away from nutrients
- Immobile nutrients such as phosphorus can’t get any closer to the roots because they can’t be carried like liquid in water
- Each granule holds a nonuniform amount of nutrients
- Easier to handle when blending and applying
- Provides uniform application
- Can be used for both starter and in-season application
- Option for one-pass in season by blending with crop protection products
- Can be expensive to convert equipment to handle liquid fertilizer
- More susceptible to volatilization and loss
Special Considerations for Anhydrous Ammonia
While anhydrous ammonia (NH3) can serve as an excellent source of nitrogen, many factors need to be in place for it to be effective. Penn State University Extension provides some recommendations and points of caution.
Be mindful of your soil composition. “If rocks or terrain cause the injection knives to come out of the soil, NH3 will immediately be lost to the atmosphere,” Penn State says. If you have rough and rocky field conditions, it might be best to look into other options.
Soil moisture can affect row closure behind the knife. If it’s too dry the soil won’t close and you’ll lose nitrogen to the atmosphere. Additionally, NH3 needs water to convert to NH4 so it can be absorbed into soil particles.
These special considerations for your soil might make application timing trickier than using other nitrogen fertilizer options. However, if you hit the right conditions, anhydrous ammonia can help provide crops nitrogen when they need it in a relatively easy-to-use form.