Competency Area 4: Nutrient Sources, Analyses, Application Methods
PO 26. Describe the physical form and analysis of each of the following nitrogen sources.
- Anhydrous ammonia
- Urea
- Ammonium nitrate
- Urea ammonium nitrate (UAN) solution
- Ammonium sulfate
- Anhydrous ammonia: NH3
- Fertilizer grade: 82-0-0
- Fertilizer with the highest analysis of N
- Stored as a liquid under pressure
- Injected in the soil as a gas
- Highly caustic: requires use of protective equipment, and subject to regulations (use, transport, etc)
- Urea: (NH2)2CO
- Fertilizer grade: 46-0-0
- Soluble, readily available N source
- Dry fertilizer product
- Contains the highest percentage of N for all dry fertilizers
- Significant N losses as volatilization of NH3 may occur when surface applied
- Hygroscopic: absorbs water from the air
- Can cause high pH near seeds
- Can potentially cause salt toxicity
- Ammonium nitrate: NH4NO3
- Fertilizer grade: 34-0-0
- Physical form: solid or liquid
- Hygroscopic: absorbs water from the air
- Can cause salt toxicity
- Urea ammonium nitrate solution (UAN): Urea + NH4NO3
- Fertilizer grade: 28-0-0 to 32-0-0
- Soluble, readily available N source
- Liquid fertilizer product made by dissolving urea and ammonium nitrate in water
- Urea portion is subject to NH3 volatilization
- Ammonium sulfate: (NH4) 2SO4
- Fertilizer grade: 21-0-0-24S
- Contains 24% Sulfur
- Soluble, readily available source of N and S
- Dry fertilizer productNH3 volatilization is not a concern unless applied to high pH soils (>7.5)
- Reduces soil pH
- Mild; low salt toxicity potential
