Use of protected urea in arable and grassland systems

Restrictions on the application of unprotected (uninhibited) urea fertilisers to 15 January to 31 March have increased interest in protected urea, especially outside of this period. Learn about this nitrogen source and its use in arable and grassland systems.

Learn about the urea restrictions and requirements (Red Tractor website)

Ensuring optimal crop yields while simultaneously considering environmental sustainability is a paramount challenge for modern agriculture. The spotlight has shifted towards more innovative and efficient farming practices, and one such advancement is the utilisation of protected urea.

Following the decision to restrict the application of unprotected (uninhibited) urea fertilisers to the period between 15 January and 31 March, we explore the benefits of employing urea fertilisers to enhance agricultural productivity while minimising environmental impact.

Nutrient efficiency

Urease inhibitors, also known as protected urea, are substances that are added to urea-based fertilisers to slow down the hydrolysis of urea into ammonia.

The main goal of using urease inhibitors is to reduce ammonia volatilisation, which is the process by which ammonia gas is released into the atmosphere from urea-based fertilisers after they are applied to the soil, particularly under dry or warm conditions.

Ammonia emissions can contribute to air pollution, ecological damage and reduced fertiliser efficiency, so controlling these emissions is of environmental and agricultural importance.

Urease inhibitors work by inhibiting the activity of the enzyme urease, which is naturally present in soil and catalyses the hydrolysis of urea into ammonia and carbon dioxide. By slowing down this hydrolysis process, urease inhibitors aim to keep more of the nitrogen in the urea-based fertiliser in the ammonium form, which is less volatile and more readily available for plant uptake.

The efficacy of urease inhibitors in reducing ammonia emissions can vary depending on factors such as the type of urease inhibitor used, environmental conditions, soil properties and application methods.

Research has shown that urease inhibitors can be effective in decreasing ammonia emissions from urea-based fertilisers, but the extent of reduction may vary.

Studies have demonstrated that urease inhibitors can reduce ammonia emissions by around 10–50% in various conditions. However, it is important to note that while urease inhibitors can mitigate ammonia losses, they might not eliminate emissions.

Other best management practices, such as proper fertiliser application timing, incorporation into the soil and optimising fertiliser rates, also play a role in minimising ammonia volatilisation.

It is worth keeping in mind that research in this area continues to evolve, and new formulations of urease inhibitors or alternative methods to reduce ammonia emissions may emerge over time.

When changing to using urease inhibitors to manage ammonia emissions, it is advisable to consult with a FACTS qualified adviser or extension services in your region for the most up-to-date and region-specific information.

Environmental preservation

Environmental sustainability is a pressing concern in modern agriculture. Fertilisers, when not managed properly, can lead to nutrient run-off into water bodies, causing pollution.

Nitrogen released into the atmosphere, such as ammonia, can damage sensitive habitats when deposited. Safeguarding of natural resources aligns with sustainable farming practices and contributes to the preservation of ecosystems and water and air quality.

The adoption of protected urea promotes a more harmonious coexistence between agricultural activities and the natural environment.

Benefits to human health

When released, ammonia can mix with other gases in the air to form fine particulate matter. This can travel long distances and, when inhaled, can have a negative impact on human respiratory health.

With the potential to reduce ammonia emissions, protected urea can have a positive impact on air quality and thus can benefit human health. The less fine particulate matter there is to inhale, the better our health.

Crop yield enhancement

The primary goal of any agricultural practice is to enhance crop productivity. Protected urea plays a pivotal role in achieving this objective. By releasing nutrients at a controlled rate, it ensures a consistent supply of nitrogen to plants throughout their growth cycle. This results in improved root development and enhanced photosynthesis.

The use of protected urea versus unprotected urea can have varying yield implications for arable crops and grassland, depending on several factors including soil type, climate, management practices and the specific crops being grown.

In arable crops, the reduced ammonia volatilisation associated with protected urea can potentially lead to improved nitrogen use efficiency and higher crop yields. By minimising nitrogen losses through volatilisation, more of the applied nitrogen remains available for plant uptake, leading to better growth and potentially increased yields.

Like arable crops, the use of protected urea in grassland management can potentially result in improved yield. Grasses are responsive to nitrogen application, and by reducing nitrogen losses through volatilisation, more of the nitrogen becomes available for grass growth, leading to higher forage production.

It can also contribute to improved forage quality. Nitrogen is a critical nutrient for protein content, and better nitrogen utilisation can result in higher protein levels in the harvested forage.

Versatility and convenience

Protected urea fertilisers come in various formulations suitable for different crops and soil types. This versatility ensures that farmers can tailor their fertiliser application to meet the specific needs of their plants.

In conclusion, protected urea offers a host of benefits that span from nutrient efficiency and enhanced crop yield to environmental preservation, improved human health and economic advantages.

As agriculture strives to strike a balance between productivity and sustainability, these fertilisers emerge as a potent tool for achieving this equilibrium. By optimising nutrient utilisation, reducing environmental impact and increasing profitability, protected urea fertilisers demonstrate the potential of science-driven innovations in modern agriculture.

As the global population continues to grow, the adoption of such practices becomes not only desirable but essential in ensuring food security for generations to come.

Factors to consider

  • Nitrogen management: Regardless of the type of urea used, proper nitrogen management practices are crucial for maximising economic returns. This includes accurate application rates, timing, incorporation techniques and soil pH
  • Crop type and yield response: The economic impact will heavily depend on the specific crop being grown and how it responds to nitrogen fertilisation. High-value crops with strong yield responses to nitrogen might justify the use of protected urea due to potential yield increases
  • Fertiliser costs: The cost differential between protected urea and unprotected urea plays a crucial role in economic decisions. Farmers need to compare the increased cost of protected urea
  • Local conditions: Soil type, climate and management practices can influence the effectiveness of protected urea and its economic impact. It is important to consider how these factors interact in your specific agricultural context
  • Application method: Ensure that you have the appropriate equipment and expertise. Application rates, timing and methods may need to be adjusted compared to conventional fertiliser

Changing to protected fertiliser can offer advantages in terms of nutrient management and environmental sustainability, but it’s essential to carefully evaluate the specific needs and conditions of your farming operation to determine whether this fertiliser is the right choice for your crops and goals.

Before adopting a new way of working, consult with a FACTS qualified or a trusted adviser.

Further information

Access the Nutrient Management Guide (RB209)