Types of Fertilizers

Each field, each plant, each seed needs nutrients to grow.  Fertilizers play a large role in giving seeds nutrients and growing strong healthy plants.  With all of the types of fertilizers, which one is best?  That answer depends on which plant is needing fertilized and at what stage of life the plant is at.

NPK Ratio in Fertilizer Types

Nitrogen, Phosphorus, and Potassium are the most common building blocks in fertilizers.  When you pick up a bag of fertilizer, the ratio will be displayed on the bag in a series of three numbers, such as 10-5-5. These numbers correspond to the 'N', 'P', and 'K' ratio of the fertilizer.  In this case, the example fertilizer would have 10% nitrogen, 5% phosphorus, and 5% potassium.

What is so important about NPK?

Without enough nutrients, seeds and plants will fail.  With the wrong combination of nutrients, plants won't mature correctly and may not produce the anticipated crop yields. Keeping a good balance of nutrients for the crop's needs will provide the best yield with healthy plants.

Nitrogen (N)

- Proper nitrogen levels will promote healthy growth of leaves. Nitrogen is largely composed of chlorophyll, which allows plants to absorb sunlight and turn it into useful energy.

Phosphorus (P)

- Proper phosphorus levels allows for healthy root growth as well as promotes proper development in the flowers and produce a plant grows.

Potassium (K)

- Proper potassium levels encourages strong and healthy stems and stalks, encouraging plants to grow healthfully and rapidly.

Micronutrients in Fertilizers

Along with the larger known nutrients, many micronutrients play a role in various types of fertilizers.

Micronutrients support the growth, development, and overall health of plants in the fields.

Micronutrients commonly used in agriculture today include boron, chlorine, copper, iron, manganese, molybdenum, and zinc. With high-yield crops, these nutrients can get depleted from the soil quickly and need to be replenished for proper plant health.
Fertilizers contain micronutrients which are utilized in various phases of a plant's growth

Granular Fertilizers

Granular fertilizers are dry fertilizers that are made into a pellet form, often times blended together to get the desired ratio of nutrients needed for the fields. Using this method a farmer can control the exact amount of Nitrogen, Phosphorus, and Potassium that is added to the fields.

Applying Granular Fertilizers

Granular fertilizers can be applied via broadcasting directly onto the field, planting in a band with the crops, or applied adjacent to the crops as a sidedress where it is cultivated into the soil.

Liquid Fertilizers

Liquid Fertilizers have the advantage of being able to be applied to both the ground or to the plants themselves, also called foliar application.  Application through the ground will result in the roots absorbing the nutrients whereas application to the plant allows the plant to absorb the fertilizers through the leaves and have the nutrients more readily available for immediate use.  Foliar application can allow a farmer to make mid-season corrections to add vital nutrients to plants if it happens they did not get the correct mixture at the beginning of the season and need a boost.

Applying Liquid Fertilizers

Liquid Fertilizers can be foliar applied or ground applied.  With ground application, the liquids can be broadcast as well as used in a band during planting and as a mid-season sidedress.

A visual of how broadcasted granular fertilizer appears with a stalk of corn.
A visual of fertilizer being applied with the sub-soil band method.
A visual of liquid fertilizers being applied with the dribble band method.

Urea Spread with Fertilizers

Urea is a high nitrogen fertilizer, replacing ammonium nitrate as a fertilizer on many fields today. It can be applied in a granular or a liquid form, either being broadcast out or spread with prilling towers that spread the liquid over the fields.

UAN, or liquid urea ammonium nitrate, provides more flexibility regarding in-season applications than dry urea. UAN can be subsurface injected or surface banded within the row. Subsurface injection of UAN strongly reduces the potential for ammonia volatilization because urea hydrolyses occurs below the soil surface. Banding UAN on the soil surface does not eliminate ammonia volatilization, but reduces the risk of ammonia volatilization considerably (figure 2, Jones et al., 2013). The reduction in ammonia volatilization risk with banding UAN occurs because banding physically reduces the amount of N fertilizer exposed to the urease enzyme.

Field with low Urea rate stripes


For more about Urea Fertilizer and our research see our post about it here.


High Nitrogen Fertilizers

Nitrogen is arguably the single most important compound for healthy plants, from the roots to the leaves to the crops. Nitrogen that allows plants to absorb sunlight through photosynthesis by promoting chlorophyll formation in leaves. When a plant has enough nitrogen, the leaves will be a bold green.  It is easy to spot nitrogen deficiency as leaves will turn a yellow color before full maturity.  Urea is one example of a high nitrogen fertilizer, containing 47% Nitrogen.

High Phosphorus Fertilizers

High phosphorus fertilizers are often referred to as the "bud and bloom" fertilizers. These fertilizers promote strong bud development during the reproductive cycle.  Along with encouraging healthy blooms, phosphorus is necessary for healthy root and stem formations. While a plant can get too much phosphorus, it is very rare.  Plants often thrive with access to high amounts of phosphorus.

Potash Fertilizers

Potash is a common element that naturally occurs in our soil and is commonly available.  Potash is named after a process to gather potassium from wood ash soaked in old pots. The modern process is a bit different, but the name stuck around.  Potash provides plants the potassium they need, allowing plants to better absorb water from the soil and better synthesize the nutrients into essential sugars. The elevated potassium often yields better plant health and more flower development during the reproductive cycle.