Timely advice as the end of the slurry spreading closed period approaches

Date published: 26 January 2026

Applications of slurry and manure can only resume from this date if ground and weather conditions are suitable to allow the uptake of nutrients from the slurry. For example, avoid spreading on wet or frozen ground. Care should also be taken to observe the increased buffer zones and reduced application rates required by NAP during February.  

It must also be noted that nutrient applications whether via organic manure or chemical fertiliser must only be made where there is a crop need.

The closed period for spreading is 16 weeks. The legal requirement for 22 or 26 weeks storage has been designed to allow the flexibility to retain slurry in store until conditions are suitable for spreading.

Climate change is affecting our weather patterns. Heavier rainfall incidents can increase run-off from land adding further nutrients to water bodies. Warmer temperatures are affecting water conditions which further increases the risk of blue-green algae forming blooms during the summer and autumn months.

Increased buffer zones

During the month of February NAP states that buffer zones should increase from:

• 20 metres to 30 metres for lakes
• 10 metres to 15 metres for any other waterway
• 3 metres to 5 metres for any other waterway if using Low Emission 

Slurry Spreading Equipment (LESSE) in fields with an incline of less than 10% or where the adjoining field is less than 1 hectare in size or not more than 50 metres wide.

Reduced application rates

During February and the first two weeks of October, the maximum single application of slurry must not exceed 30 m³ per ha (2,700 gallons per acre). This has been reduced from 50 m³ per ha (4,500 gallons per acre).

During February, grass growth is limited by lower soil temperatures and shorter day length, so the nutrient requirement is lower. A maximum single application of slurry to 30 m³, may still be exceed the nutrient requirement of the grass plant at this time. This adjustment will help reduce the risk of surplus nutrients being lost into waterways.

Spreading conditions

Outside of the closed period, you should only apply slurry when ground and weather conditions are suitable avoiding areas that pose a high risk of nutrient loss to waterways. Never apply nutrients to waterlogged soils or frozen ground. Avoid applying them to land that is flooded or liable to flood. Refrain from applying if heavy rain is falling or forecast within the next 48 hours. 

Applications also cannot be made on steep slopes where there is a risk of water pollution.

Soil temperature

Spreading when soil temperatures are consistently above 6℃ is advised. This means that grass is growing and has the potential to take up nutrients. Nutrient uptake will be greater when soil temperature rises to 8-10℃ and soil biology really starts to convert nutrients into plant available forms.

The timing of slurry application significantly affects nutrient uptake by plants and the potential for losses to water. Focusing slurry applications later in the spring when grass growth is higher will increase nutrient use efficiency.

Where to spread

Avoid spreading in paddocks with high connectivity to the drainage network. Wait until later in the spring when the risk of nutrient loss to water is lower.

Spreading on sloping land

Care should be taken on all sloping land near a waterway and a risk assessment carried out to determine if you can spread fertiliser (including organic manures) on it. 

The following factors must be considered in making these risk assessments:

• type and amount of fertiliser being applied,
• time to incorporation of organic manures (land other than grassland only),
• proximity of waterways,
• soil conditions and
• forecast weather condition.

Completing a Nutrient Management Plan

If you have taken advantage of the Soil Nutrient Health Scheme (SNHS) you should use your soil results as the basis for a Nutrient Management Plan. To complete a Nutrient Management Plan for your farm, use the CAFRE Crop Nutrient Calculator available at: https://www.daera-ni.gov.uk/services/daera-online-services. Enter your crop details and soil analysis results; the calculator will identify the crop requirement. Choose the appropriate manure type and chemical fertiliser to be applied. The Crop Nutrient Calculator report can then be printed off or saved and used as your fertilisation plan.

Organic Manure (Slurry) Analysis

The nutrient value of organic manures (cattle slurry and manure, pig slurry, poultry litter and increasingly anaerobic digestate) can be highly variable. It is beneficial to know the nutrient content of your own farms organic manures to allow for accurate nutrient management planning (NMP). This helps to minimise spend on chemical fertiliser and nutrient leakage to the environment.

Organic manure analysis will provide figures for, percentage dry matter, pH, nitrogen (N), phosphorus (P) and potassium (K). Magnesium, copper, zinc, sulphur and calcium are also included. Sampling and analysis can be carried out at any time of year but is particularly useful in early spring ahead of the main slurry spreading period. This will allow planning of any chemical fertiliser inputs required to optimise crop growth. 

Organic manure sampling kits and sampling instructions are available at DAERA Direct offices. 

The measures contained within the NAP are designed to improve nutrient efficiency within the farm and improve water quality. These important management practices and legal requirements apply to all farms in Northern Ireland. The aim is to improve nutrient utilisation of organic manures and chemical fertilisers while also reducing the likelihood of nutrient run-off into waterways. Nutrients lost from spreading slurry in the wrong conditions in February and March will be transported to Lough Neagh and other lakes. This occurs at the worst time, as the nutrients promote algal growth in the spring and summer.