The ammonic nitrogen, referring to the ammonium ion which carries a positive electrical charge (NH4+), is one of two forms of nitrogen that can be absorbed by plants.
The other is the nitrate ion (NO3–) which has a negative charge.
Most nitrogen fertilizers either belong to the pure ammonium type or contain nitrogen in both the ammonium and nitrate forms.
Each of the two forms of nitrogen has advantages and disadvantages over the other.
The same applies to fertilizers that supply nitrogen in either or both the ammonic and nitrate forms. It is therefore important to familiarize with such fertilizer types.
Below is a list of fertilizers grouped according to the form of nitrogen that they contain.
The list also provides information on common fertilizer grades, chemical formula, formulation, and other descriptions.
Nitrogen fertilizers in which all nitrogen contained are in the ammonic (NH4+) form
1. Anhydrous ammonia [NH3, 82-0-0] – liquified gas; contains 82% nitrogen (N).
2. Urea [CO(NH2)2, 46-0-0] – dry, granular or prilled form; contains 46% N.
3. Aqua ammonia or ammonium hydroxide [NH4OH, (20-41)-0-0] – liquid; contains 20-41% N.
4. Ammonium sulfate [(NH4)2SO4, 21-0-0-24S] – dry, crystalline; contains 21% N and 24% sulfur.
5. Ammonium thiosulfate [(NH4)2S2O3, 12-0-0-26S] – dry, crystalline; contains 12% N and 26% sulfur.
6. Diammonium phosphate or DAP [(NH4)2HPO4, 18-46-0] – dry, granular, or crystalline; contains 18% N and 46% phosphorus pentoxide (P2O5, commonly referred to as phosphate) equivalent to 20% P.
7. Monoammonium phosphate or MAP [(NH4H2PO4, 11-52-0] – dry, granular; contains 11% N and 52% P2O5 (22.7% P).
8. Ammonium polyphosphate solution [(NH4) 3HP2O7 + NH4H2PO4, 10-34-0 or 11-37-0] – liquid, contains either 10% N and 34% P2O5 (14.8% P) or 11% N plus 37% P2O5 (16% P).
Nitrogen fertilizers that contain nitrogen in the ammonic (NH4+) and nitrate (NO3-) forms
1. Ammonium nitrate [(NH4NO3, (33-34)-0-0] – dry, granular or prilled form, contains 33-34% N; one-half nitrogen in ammonium form, one-half nitrate.
2. Ammonium nitrate solution or AN 20 [NH4NO3 + Water), 20-0-0] – liquid contains 20% N; one-half of nitrogen in the ammonium form, one-half nitrate.
3. Calcium ammonium nitrate solution or CAN 17 [NH4NO3 + Ca(NO3)2 + water, 17-0-0] – liquid, contains 17% N and 8.8% soluble calcium; one-third of nitrogen in ammonium form, two-thirds nitrate.
4. Urea ammonium nitrate solution or UAN [NH4NO3 + CO(NH2)2 + water, (28-32)-0-0] – liquid, contains 28-32% N; one-half of nitrogen in ammonium form, one-half nitrate.
COLLEGE OF AGRICULTURAL SCIENCES. 2013. Table 1.2-11. Description of fertilizer materials. Penn State Extension. Retrieved Jan. 27, 2013, from http://extension.psu.edu/agronomy-guide/cm/tables/table-1-2-11.
[IPNI] INTERNATIONAL PLANT NUTRITION INSTITUTE. 2013. Nutrient source specifics. Retrieved Jan. 28, 2013, from http://www.ipni.net/specifics.
THORUP RM. 1984. Ortho Agronomy Handbook: A Practical Guide to Soil Fertility and Fertilizer Use. San Francisco, CA: Chevron Chemical Company. 454 p.