Tyrone Dairy: Wind for spraying, slurry and harvest in Mid Ulster

Mid Ulster, including Co. Tyrone, is characterised by undulating farmland, often with mixed dairy and tillage operations. The topography is generally rolling, with some higher ground to the west and south, but largely open to the prevailing westerly and south-westerly airflows. This exposure means wind is a consistent factor in agricultural operations, particularly for activities sensitive to drift or requiring specific drying conditions.

Key operations influenced by wind include:

• Spraying: Herbicides, fungicides, and insecticides require low wind speeds to prevent off-target drift, which can damage adjacent crops, watercourses, or non-target organisms.
• Slurry Spreading: While less sensitive to drift than spraying, strong winds can make slurry application uneven and increase odour nuisance to neighbours.
• Harvesting (Silage/Hay): Drying conditions are critical. Moderate, consistent wind can aid drying, but strong gusts can lead to crop lodging (flattening) and make machinery operation challenging.
• Polytunnel/Structure Management: High winds can damage polytunnels, sheds, and other temporary structures, requiring proactive management or securing.

The Wind Agent provides height-matched wind forecasts and gust predictions, allowing farmers to plan these activities with greater precision against their own operational limits.

The prevailing wind direction in Ireland, including Co. Tyrone, is from the south-west and west. These directions generally bring moist, mild air from the Atlantic, often associated with frontal systems. While these are the most frequent strong wind directions, they are also often the most consistent, with less local turbulence compared to winds crossing complex terrain.

Wind from other directions can have specific implications:

• Northerly/Easterly: Often associated with colder, drier air, especially in winter. These winds can feel more biting and, if strong, can lead to rapid drying of topsoil.
• Southerly: Can be strong, but may also bring more stable, settled conditions in summer.

Understanding the dominant wind patterns helps in planning field layouts, shelterbelt planting, and scheduling wind-sensitive tasks. The wind rose chart illustrates the frequency and strength of wind from different directions, providing a climatological context for daily forecasts.

Effective spraying requires not only low wind speeds but also specific atmospheric conditions to ensure droplets reach their target and are absorbed efficiently. One key metric for this is Delta T, which is the difference between the dry bulb temperature and the wet bulb temperature, multiplied by 100. It is a measure of the drying potential of the air.

• Optimal Delta T: Commonly cited by agricultural extension services as being between 2 and 8. In this range, droplets are less likely to evaporate too quickly (high Delta T) or remain wet for too long (low Delta T), which can affect efficacy and increase drift potential.
• High Delta T (e.g., >10): Indicates very dry air. Droplets can evaporate rapidly, leading to 'off-target' drift of concentrated chemical particles. This is common on warm, sunny, breezy days.
• Low Delta T (e.g., <2): Indicates very humid air. Droplets may remain on the plant surface too long, increasing the risk of wash-off by dew or light rain, or poor absorption.

The Wind Agent provides Delta T forecasts alongside wind speed and direction, offering a more complete picture for optimising spray timing. Always consult product labels for specific environmental requirements.

Gusts are transient, rapid increases in wind speed, typically measured over 3-second intervals. While average wind speed might be within acceptable limits, a strong gust can cause significant issues, particularly for mature crops or during harvesting.

• Crop Lodging: Strong gusts can flatten cereal crops, making them difficult or impossible to harvest efficiently, leading to yield losses. This risk increases as crops mature and become heavier.
• Machinery Stability: Operating large machinery, such as combine harvesters or slurry tankers, in gusty conditions can be hazardous, affecting control and increasing the risk of accidents.
• Polytunnel Integrity: Polytunnels and other temporary structures are vulnerable to sudden increases in wind pressure from gusts. Regular monitoring of gust forecasts allows for timely securing or adjustment of these structures to prevent damage.

The Wind Agent's Shear Glass provides gust forecasts at various heights, allowing farmers to assess the risk of lodging or structural damage at the relevant operational height. The exceedance fan can show the probability of gusts exceeding a set limit.

The meteogram provides a detailed forecast of wind speed, gust, and direction for the coming days at the Tyrone Dairy location. This allows for immediate assessment of conditions for planned activities such as spraying, slurry spreading, or harvesting.

Key elements to observe on the meteogram:

• Wind Speed and Gust: Compare these directly against your operational limits for specific tasks. For instance, if your sprayer's limit is 10 mph, observe when the forecast mean wind or gust approaches or exceeds this value.
• Direction: Note any shifts in wind direction, which can influence drift patterns or the effectiveness of shelterbelts.
• Precipitation: The presence of rain can affect spray efficacy and drying times for hay or silage.

Use this information in conjunction with your own experience and local knowledge to make informed decisions for your farm operations. The Agreement Spine can show how different models agree or disagree on these forecasts.

The climate band chart illustrates the typical range of wind speeds for each month of the year at this location, based on historical reanalysis data. This provides a valuable context for understanding whether current or forecast conditions are typical or unusual for the season.

• Windiest Months: Typically, the period from October to March experiences higher average wind speeds due to the passage of Atlantic depressions. This often means fewer suitable days for wind-sensitive operations.
• Calmer Months: Summer months, particularly June to August, generally exhibit lower average wind speeds, increasing the window of opportunity for spraying and harvesting.
• Seasonal Planning: Understanding these patterns can assist in long-term farm planning, such as scheduling crop rotations, maintenance, or capital investments that are sensitive to weather windows.

By comparing the current forecast against the climatological norms, farmers can gain a better perspective on the likelihood of encountering favourable or challenging wind conditions at different times of the year.