POLY4 is a natural polyhalite mineral fertiliser that provides a sustained release of potassium, sulphur, magnesium and calcium.Its gradual nutrient release helps feed grass throughout the growing season,supporting grass yield, quality and livestock performance.
POLY4 ANALYSIS: 14% K₂O – 48% SO₃ - 6%MgO - 17% CaO
Why does grassland need balanced nutrition?
UK grassland is under increasing nutritional pressure.
* Sulphur deficiency is now a recognised risk.
* Two-thirds of UK grassland soils are deficient in calcium.
* High silage yields can quickly reduce soil potassium levels.
* Less than one in ten soils are on target for both phosphorus and potassium.
* Slurry nutrient content and availability can vary considerably.
When nutrients are limiting, nitrogen cannot be used as efficiently. This can mean lower grass growth and protein production,increasing reliance on bought-in feed and potentially affecting livestock performance. *Source: AHDB Nutrient Roadshow 2026 – Lancrop.
Sulphur is essential for efficient nitrogen utilisation
Without sufficient sulphur, grass cannot make full use of applied nitrogen. POLY4 provides a gradual supply of sulphur throughout the growing season, helping grass convert more nitrogen into protein and supporting efficient nutrient use. For best results, aim for an N ratio of 10:1 or lower.
POLY4 is particularly suited to farmers looking to:
* Improve nitrogen use efficiency
* Support grass protein production
* Maintain grass quality
* Reduce unused nitrogen
* Produce more forage from every hectare
UK field trials have demonstrated positive results from POLY4 fertilisation programmes.
Across five UK grass trials from 2014–2022, POLY4 programmes delivered:
+11% Dry Matter Yield
+4% Crude Protein Yield
The trials compared POLY4 fertilisation programmes with standard NPS programmes, with equal amounts of nitrogen and phosphorus applied to treatments within each trial. Global trials have also reported: +10% Higher Nitrogen Use Efficiency Based on 68 global trials comparing POLY4 fertiliser programmes with NPK programmes across various crops.
UK grassland trials have shown that POLY4 can deliver an additional 730 kg of dry matter (DM) per hectare, alongside a 4% increase in crude protein yield.
Based on typical forage and feed values, this could equate to an estimated £122–£185 of additional forage value per hectare.
What does this mean in practice? The estimate is based on a typical productive grass silage system with:
* Baseline yield: 12 t DM/ha/year
* POLY4 response: +0.73 t DM/ha
* Baseline crude protein: 16%
* Grass silage value: £120–£180/t DM
* Additional dry matter value: £88–£131/ha
* Additional protein value: £34–£54/ha
Giving an estimated additional forage value of £122–£185/ha.
More grass Supports fresh weight and dry matter production, helping maximise forage production.
Better feed value Higher crude protein yield and good grass quality can contribute to the nutritional value of forage.
Efficient nutrient use A balanced supply of sulphur, potassium, magnesium and calcium supports nutrient uptake and nitrogen utilisation.
Ideal for clover and herbal leys Provides sulphur without additional nitrogen, making it suitable for legume-based and multi-species systems.
Supports rooting The balanced nutrient supply supports root development and nutrient uptake, helping grass cope with weather-related stress.
Soil-friendly nutrition POLY4 has a low salt index and neutral pH, with no acidifying effect.
