Anyone using Urea Nitrogen 21-0-0? It's very cheap. If I understand it right it needs to be incorporated into the soil or it will convert and dissapate on the surface.

Pros and Cons?

Charles Urea is 46% Nitrogen, therefore the formula for urea is 46-0-0. If the fertilizer you have is actually 21-0-0 than what you have is not Urea but rather Ammonium Sulfate. Urea can be used, but is not available to the tree until it is converted to NO3 by bacteria, which takes a couple days. When Urea is used one must insure that it is a quality grade having a low biuret content, as biuret is toxic to citrus. - Millet

Thanks Millet and of course you are right. I had two thoughts in my head at once when I posted. One was fertilizer ammonium sulfate for my blueberries the 21-0-0 to help with the acidity needed for them and the other was can I use the urea nitrogen 46-0-0 on the citrus safely. Is the biuret level listed on the package.

I did a bit more research and found that with our sandy soils it probably is not worth using. This is based on our frequent rains which leach it quickly through the soil and the three step breakdown process before it can be taken in by the plant. By the time it reaches a usable state it will be below the root zone.

What prompted all this thought is my desire to not have to buy the small bags of specialty fertilizer. I believe some of you are using the larger bags and then supplementing the trace. With my long growing season I was thinking of small feedings of 8-8-8 monthly or maybe the AS 21-0-0 if I can work out the cut ratio. Does anyone else use this approach?

Darkman,

I'm using three separate water soluble fertilizers mixed into the same tank. My blend contains 30-10-10, 10-5-40, and ammonium sulfate. All of this is mixed into a 250 gallon tank and injected into the irrigation with a mazzei. I'm fertilizing my blueberries, citrus, and nursery with this blend. Occasionally I will put humic and fulvic acids to everything in ground. I'm considering injecting endo mycorrhiza to my citrus to help with the nitrogen conversion.

There are products that can be applied with urea that help with volatization and loss through rainfall. Two such products are Agrotain and N-Fixx.

Charles, a good suggestion , in your situation would be to use a 3 to 4 month slow release fertilizer which would release nutrition every time it rains or when you water.

babranch, you really don't need to add mycorrhiza, as it is already every where. You can find a mycorrhiza discussion on this site by Dr. Manners explaining the abundance of mycorrhiza. It is blown by the air currents every where. If you have dirt you have mycorrhiza. - Millet

Millet,

I am planning on growing a couple thousand citrus in soilless media in a greenhouse. Since they aren't in native soil, would it be beneficial to apply mycorrhiza to these plants? The plan was to do a root dip as they were transplanted from seedling beds to the pots.

With your method of growing the seedling, adding mycorrhiza probably be beneficial. After all, the cost would be very minimal. I don't know if mycorrhiza is affected by pH or not. If you did nothing the pots would probably become infected with mycorrhiza in a more or less short period period of time. - Millet

I use it regularly once a year in spring. I guess it can not harm them.