Urea - Ammonium Nitrate 32% w/w

Solutions of UAN are widely used as a source of N for plant nutrition. The NO3- portion (25% of the total N) is immediately available for plant uptake. The NH4+ fraction (25% of the total N) can also be assimilated directly by most plants, but is rapidly oxidized by soil bacteria to form NO3-. The remaining urea portion (50% of the total N) is hydrolyzed by soil enzymes to form NH4+, which is subsequently transformed to NO3- in most soil conditions.

Solutions of UAN are extremely versatile as a source of plant nutrition. Due to its chemical properties, UAN is compatible with many other nutrients and agricultural chemicals, and is frequently mixed with solutions containing P, K, and other essential plant nutrients. Fluid fertilizers can be blended to precisely meet the specific needs of a soil or crop.

UAN solutions are commonly injected into the soil beneath the surface, sprayed onto the soil surface, dribbled as a band onto the surface, added to irrigation water, or sprayed onto plant leaves as a source of foliar nutrition. However, UAN may damage foliage if sprayed directly on some plants, so dilution with water may be needed.

UAN makes an excellent source of N nutrition for plants. However, since half of the total N is present as urea, extra management may be required to avoid volatile losses. When UAN remains on the surface of the soil for extended periods (a few days), soil enzymes will convert the urea to NH4+, a portion of which can be lost as ammonia gas. Therefore, UAN should not remain on the soil surface for more than a few days in order to avoid significant loss. Inhibitors that slow these N transformations are sometimes added. When UAN is first applied to soil, the urea and the NO3- molecules will move freely with water in the soil. The NH4+ will be retained in the soil where it first contacts cation exchange sites on clay or organic matter. Within 2 to 10 days, most of the urea will be converted to NH4+ and no longer be mobile. The originally added NH4+ plus the NH4+ coming from urea will eventually be converted to NO3- by soil microorganisms.

Abbreviations and notes: N = nitrogen; NH4+ = ammonium; NO3- = nitrate; P = phosphorus; K = potassium.

 

Chemical Properties

 

Properties                                                         28% N                                30% N                              32% N

Composition (% by weight)

Ammonium Nitrate                                              40                                       42                                    44

Urea                                                                        30                                        33                                    35

Water                                                                      30                                       25                                    20

Salt-out temperature (˚C)                                  -18                                     -10                                   -2

(Crystal precipitation temperature)

Solution pH                                                            - - - -                          approximately 7                    - - - -

 

    Guaranteed Analysis  32-0-0

 

Total Nitrogen (N)           32.00%

Ammoniacal Nitrogen    8.60%

Nitrate Nitrogen               8.60%

Urea Nitrogen                14.80%

pH                                    6.3 - 7.3