Looking to grow more spring grass?

Maximising grass growth rates and increasing utilisation rates, particularly during the shoulders of the year, are key priorities.

How can we increase spring grass?

Soil fertility is one of the key pillars to growing early spring grass. Phosphorus is one of the major elements in driving spring growth; along with the other elements, such as soil pH, nitrogen and sulphur.

With soil fertility – particularly phosphorus levels – being in focus in recent years, it’s important not to take phosphorus for granted when it comes to spring grass.

Having sufficient phosphorus in the spring fertiliser programme is essential for two reasons:
  • Phosphorus is critical to kick-start grass growth in spring;
  • Phosphorus availability in soil is lower in cooler soil temperatures in spring.

Therefore, it’s essential to get phosphorus fertiliser out early in the spring to help spring growth. Teagasc recommends applying a minimum of 50-75% of the total phosphorus for the year in the early spring period in advance of spring growth.

For years, traditional phosphorus fertiliser ingredients being used in NPK blends have remained very similar, with little advancement in improving the efficiency of fertiliser phosphorus.

These traditional forms of phosphorus fertilisers help to drive this spring growth. However, the efficiency of their use by the grass can be affected by high levels of lock-up by the soil – especially in low-phosphorus index soils, low pH soils and soils with high iron and aluminium levels.

A new form of phosphorus, called TOP-PHOS, is now available that can help overcome these issues to grow more grass in spring.

What is TOP-PHOS?

TOP-PHOS is a brand new form of phosphorus fertiliser which will be available in 2018. It is a revolutionary new phosphorus technology that has been developed by Groupe Roullier and is available in Ireland from Grassland AGRO.

TOP-PHOS is a new and unique chemical form of phosphorus, compared to standard phosphorus fertilisers; it has been recognised with EU REACH Regulations as being different to the traditional forms of phosphorus used in standard fertilisers.

TOP-PHOS is a new fertiliser ingredient called Complex Super Phosphate (CSP). It is a water-soluble phosphorus fertiliser and is, therefore, available quickly for uptake by grass.

However, unlike standard forms of phosphorus, the chemical make-up of TOP-PHOS protects it from being locked up by the soil.

This maximises the availability of phosphorus to the grass. TOP-PHOS also contains stimulants that are designed to increase root mass to improve phosphorus efficiency and to increase soil microbe activity to release phosphorus from soil reserves.

How does TOP-PHOS help spring grass?

Phosphorus availability in soils is always challenging; particularly in the cooler soil temperatures in spring.

TOP-PHOS increases the availability of phosphorus and will, therefore, increase spring grass growth, as more of the phosphorus applied can get to the grass faster to kick-start growth.

On-farm Irish trials in 2017, evaluating the benefits of TOP-PHOS for spring grass growth, showed an extra 0.4t of grass dry matter production per hectare in the January-to-April period where TOP-PHOS was used as the source of phosphorus compared to standard phosphorus fertiliser.

This results in a return of €72/ha of spring grass grown by using TOP-PHOS.


TOP-PHOS also has the advantage of allowing greater flexibility when designing a spring fertiliser plan, as it is a fertiliser containing both phosphorus and sulphur in the same product.

A single application of TOP-PHOS – in early spring – can help to simplify the overall spring fertiliser programme by getting both phosphorus and sulphur out together. This simplifies the remainder of the spring fertiliser rounds to straight nitrogen (urea or CAN). This has the advantage of making fertiliser management in spring more simple and straightforward.

More information

For more information on how TOP-PHOS can help you grow more grass this spring, contact your local Grassland AGRO technical advisor or Dr. PJ O’Connor at: 086-3237894. Click here for more information