Applying fertiliser based on the specific needs of each field or crop helps farmers make the most of every granule – avoiding waste, improving nutrient uptake, and minimising environmental impacts.

With fertiliser application windows closed across much of the UK’s Nitrate vulnerable zones (NVZs) through winter, autumn is a great time to review nutrient plans ahead of spring when spreading resumes.

By planning ahead and using precision techniques to target nutrients when and where they’re most needed, farmers can not only meet NVZ regulations but also make best use of inputs.

The risks of inaccurate fertiliser application

When fertiliser isn’t applied accurately, the consequences can be significant for crop performance, causing inefficient nitrogen use, and negative effects on the environment.

Underapplication of fertiliser can cause soil mining where nitrogen stores in the soil are depleted, resulting in stunted crop growth.

Over-applying fertiliser can cause leaching – when soluble nutrients are washed out of the root zone by heavy rainfall, leaving crops with reduced nutrient stores and compromising yields.

Soils that are light or sandy, or regions with high rainfall, are especially vulnerable to leaching – not just for nitrogen but for other mobile nutrients such as sulphur, affecting ecosystems and compromising water quality.

To avoid bad nitrogen use efficiency, soil testing can determine specific nutrient requirements to ensure fertiliser is applied accurately, while the Nitrate Vulnerable Zone (NVZ) rules in the UK also help mitigate this risks.

As a reminder, spreading fertiliser is prohibited between 1 October – 31 January, and from 1 August – 31 December on sandy or shallow soils that are more prone to leaching.

[Box out] For more on the benefits of precision farming techniques, read our blog on enhancing crop yields and environmental sustainability.

Soil testing to identify nutrient deficiencies

Understanding specific soil needs is essential to be able to implement precise fertiliser applications when NVZ closed periods end.

The winter period presents a perfect opportunity to conduct regular soil testing before the busy spring arrives.

Testing is critical in providing accurate data on nutrient levels, pH, and soil fertility.

By identifying imbalances in key nutrients such as nitrogen, phosphorus, potassium, sulphur, and trace elements, farmers can fine-tune fertiliser rates to match crop demand and soil reserves – ensuring inputs are both environmentally efficient and economically effective.

Read our recent blog and learn about soil nutrient supply and why it is important.

Planning for optimal fertiliser application timing

Timing is one of the most important factors for achieving efficient and precise early spring fertiliser applications.

Optimal application timings differ between crop types – each has distinct growth patterns and nutrient demands.

For instance:

• Winter wheat benefits from a split nitrogen application, with the first dose best applied in early spring as the crop begins to tiller and enter vegetative growth – helping to promote strong growth in the early days.
• Barley matures more quickly than wheat – making it essential to apply fertiliser carefully to avoid excess nitrogen late in the season, which can negatively affect grain quality.

In addition to crop variety, soil conditions and weather patterns also play key roles in determining the best timing for fertiliser applications.

Striking the right balance between nutrient availability and crop needs at each growth stage is vital in maximising yield potential and quality.

Variable-rate fertiliser application

Incorporating soil test data into precision farming practices enables variable-rate fertilisation when the spreading season arrives in the spring.

This technique involves applying nutrients at differing rates across the field based on the specific soil requirements of each zone.

This targeted approach ensures that areas with nutrient deficiencies receive the necessary inputs, while areas with sufficient nutrients are not over-fertilised.

The result is improved nutrient use efficiency to maximise crop yields.

By applying fertiliser only where it is required, farmers can also help maintain balanced soil PH levels and reduce the risk of nutrient run-off.

Variable-rate fertilisation is typically integrated through precision farming systems that combine GPS guidance, yield mapping, and soil or crop sensing technologies.

These tools enable precise, real-time adjustments during spreading, ensuring inputs are applied accurately and consistently across the field.

While in the NVZ closed period, winter is a good time to be servicing, calibrating and updating system software to ensure everything is ready for the spring application window.

For more on optimising nutrient use, read our blog on precise fertilisation.