Different forms of nitrogen in turf management

Nitrogen, a pivotal nutrient for turfgrass growth and health, comes in several chemical forms, each with its own unique properties and effects on turf management.

Understanding these forms—such as ammoniacal nitrogen, urea nitrogen, ureaformaldehyde, and others—is essential for tailoring a fertilisation strategy that meets the specific needs of your turf. #

Let’s delve into the characteristics, benefits, and considerations of these nitrogen forms.

Nitrate Nitrogen (N-NO3)

Nitrate forms of nitrogen are chemical compounds that contain nitrogen in the nitrate ion (NO3-) form. Nitrogen in the nitrate form is readily available for plant uptake, meaning it can be absorbed and utilised by turfgrass quickly.

There are several different forms of nitrate fertilisers commonly used in turf management products. Some of the most common forms include:

• Potassium nitrate (KNO3): Potassium nitrate is a dual-purpose fertiliser containing both potassium and nitrate nitrogen. It is commonly used in greenhouse and hydroponic systems, as well as in specialty turfgrass applications.
• Calcium nitrate (Ca(NO3)2): Calcium nitrate is a water-soluble fertiliser that provides both calcium and nitrate nitrogen to plants. It is often used as a source of readily available nitrogen for high-value crops and turfgrass.
• Magnesium nitrate (Mg(NO3)2): Magnesium nitrate is a water-soluble fertiliser that provides both magnesium and nitrate nitrogen to plants. It is often used in hydroponic and fertigation systems, as well as in greenhouse production.
• Ammonium nitrate (NH4NO3): Ammonium nitrate is a fertiliser containing both ammonium and nitrate nitrogen. It is less commonly used in turf management due to its higher potential for volatilisation and leaching.

These different forms of nitrate fertilisers offer highly soluble and quickly available nitrogen combined with other important nutrients making them an attractive choice for use in liquid or soluble fertiliser products.

Ammoniacal Nitrogen (N-NH4)

Ammoniacal nitrogen is found in ammonium sulphate and other ammonium-based fertilisers. It’s quickly available to plants because it’s positively charged (NH4+) and binds to negatively charged soil particles, reducing the risk of leaching. Once absorbed by the turf, ammoniacal nitrogen can be directly used for protein synthesis.

Advantages:

• Rapidly assimilated by plants.
• Less prone to leaching than nitrate forms of nitrogen.
• Acidifies the soil, which can be beneficial in alkaline soils.

Urea Nitrogen (N Urea)

Urea is a synthetic organic compound containing a high percentage of nitrogen. It’s a highly concentrated form of nitrogen, making it cost-effective for transportation and application. Urea is converted into ammonium in the soil by the urease enzyme, and then further converted into nitrate, for plant uptake.

Ureaformaldehyde (N-MU)

Ureaformaldehyde, also known as methylene urea (MU), is a type of slow-release nitrogen that breaks down in the soil over time. The breakdown rate is influenced by microbial activity, temperature, and moisture, making it a slow-release nitrogen source. MU provides a more prolonged, steady release of nitrogen, which reduces the risk of nitrogen leaching.

Other Forms of Nitrogen

Beyond these common types, there are other forms of nitrogen used in turf management:

Isobutylidene Diurea (IBDU) is a slow-release form of nitrogen (similar to MU), but the release of nitrogen from IBDU fertiliser occurs through a process called hydrolysis, where moisture in the soil gradually breaks down the granules of the fertiliser, releasing nitrogen into the soil over an extended period of time.

Organic forms of nitrogen for use in turf management include both plant-based and animal-derived sources. Here are some examples:

Plant-Based nitrogen sources:

• Alfalfa Meal: Alfalfa meal is derived from dried alfalfa plants and is a natural source of nitrogen. It releases nitrogen gradually as it decomposes, providing a steady supply of nutrients to turfgrass.
• Soybean Meal: Soybean meal is a byproduct of soybean oil production and contains nitrogen in an organic form. It breaks down slowly in the soil, releasing nutrients over time to support turfgrass growth.
• Cottonseed Meal: Cottonseed meal is made from the crushed seeds of cotton plants and is rich in nitrogen. It provides a slow-release source of nutrients for turfgrass, promoting healthy growth and vigour.

Animal-Derived nitrogen sources:

• Dried Blood: Dried blood is a natural fertiliser made from dried animal blood and is high in nitrogen. It releases nitrogen gradually as it decomposes, providing a long-lasting source of nutrients for turfgrass.
• Hoof and Horn Meal: Hoof and horn meal is made from ground-up hooves and horns of animals and contains nitrogen in an organic form. It breaks down slowly in the soil, releasing nutrients over time to support turfgrass growth.
• Bone Meal: Bone meal is produced by grinding animal bones and is rich in phosphorus and nitrogen. It provides a slow-release source of nutrients for turfgrass, promoting strong root development and overall turf health.

These organic nitrogen sources offer several benefits for turf management, including improved soil health and reduced nutrient leaching. Incorporating organic fertilisers into turf management programs can help promote more sustainable and environmentally-friendly practices while maintaining healthy turf.

Selecting the right nitrogen form

The choice of nitrogen form depends on several factors, including the desired speed of response, the risk of environmental loss through leaching or volatilisation, soil pH, and cost. For example, quick-release forms like ammoniacal nitrogen and urea nitrogen are suitable for rapid green-up or recovery, while slow-release forms like ureaformaldehyde are better for long-term nutrition and reduced maintenance requirements.

Incorporating a mix of nitrogen forms can also be an effective strategy, providing both immediate green-up and phased release. This balanced approach can help maintain turf health, support environmental stewardship, and manage costs.