Fertilizers: The Basic Materials

The formulation of N, P2O5, and/or K2O in a bag of fertilizer is made from a small set of basic fertilizer materials. The fertilizer is either a single basic fertilizer material or a blend of basic materials. Dry fertilizers also contain fillers, carriers, and/or other materials to help improve the flowability of the fertilizer, make the nutrient analysis possible, or condition the fertilizer to have special traits.

Consider the major basic fertilizer materials in the table below. Take notice of the nutrient analysis, major uses, and traits and consider the link between fertilizer materials and application methods.

Material N-P2O5-K2O Analysis

Major Uses


Anhydrous Ammonia 82-0-0

Sidedressing N in corn. Used to make other N fertilizers, like urea.

Most concentrated N source, liquid under pressure, highly caustic – if exposed can “burn” plants and people.



Topdressed N on perennial grasses and included in blends (e.g. 19-19-19).

$, volatile, hydroscopic (absorbs water from the air), can cause high pH near seed, concentrated N source, salt toxicity potential.

Ammonium nitrate


Used to topdress, in starter, and in blends.

$$, hydroscopic (absorbs water from the air), salt toxicity potential, cannot purchase in bulk.

Ammonium sulfate



Mild N source for starter fertilizers. Also supplies sulfur Used in blends.

$$$, reduces soil pH, flows well thru planter, less salt toxicity potential.

Diammonium phosphate (DAP)


Used in blends for broadcasting and banding.

Can cause high pH near seed.

Monoammonium phosphate (MAP)


Used in blends for broadcasting and banding.

Easy on seeds, but do we need the P in the field? More mild in starter blends than DAP.

Muriate of potash


Used for topdressing K on legumes and included in blends.

Salt toxicity potential.

The nutrient content of fertilizer materials is always presented in the percentage of N, P2O5, and K2O, in that order!

Fertilizer Blends

The basic fertilizer materials, above, are often combined to make blends of N, P2O5, and/or K2O that are tailored to crop needs.

Due to the concentration of the N, P2O5, and/or K2O in the basic fertilizer ingredients, the blend with the highest possible concentration of N, P2O5, and K2O is 19-19-19. So a 25-25-25 blend is impossible to formulate.

It's best to call your area fertilizer suppliers to find out what basic fertilizer materials are carried and what blends can be made. Many fertilizer plants can custom blend a N - P2O5 - K2O fertilizer to meet your crop needs, so be sure to ask the local plant about that option. What are some common blends made from the basic ingredients?

First take a look at some common dry fertilizer blends:

Corn planters and sprayers can be configured to apply liquid fertilizers, as well. Some common liquid blends are:

The density of the fertilizer solution is needed to determine how much liquid fertilizer to apply per acre, because the N, P2O5, and K2O ratio is based on a weight basis and not a volume basis.

Consider the example...

The 30-0-0 liquid fertilizer blend has a density of 11.3 lbs/gallon. If 20 lbs of N is desired per acre, how many gallons of the fertilizer should be applied per acre?

Step 1. Calculate: lbs nutrient/gallon for the fertilizer

(0.30) x (11.3 lbs/gallon) = 3.4 lbs N/gallon

Step 2. Calculate: gallons/acre application rate

(20 lbs N/acre needed) / (3.4 lbs N/gallon) ≈ 6 gallons/acre

Try out another example, below.

Click to the next page to see how fertilizers can help to meet crop nutrient needs on dairy farms.

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