Grazed grass is the cheapest feed available to dairy farms to maximise profitability.
Maximising grass growth rates and increasing utilisation rates, particularly at
the shoulders of the grazing year in the spring and autumn is a key priority. Each
additional day at grass in the spring is worth 2.70 additional profit per cow.
So How Can We Increase Spring Grass?
Soil fertility is one of the key pillars to growing early spring grass. Phosphorus (P) is one
of the major elements in driving early grass, 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 is
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
1) Phosphorus is critical to kickstart grass growth in spring
2) Phosphorus availability in soil is lower in cooler soil temperatures in spring
Therefore, it is essential to get phosphorus fertiliser out early in the spring to help
spring growth. Teagasc recommends applying a minimum of between 50 75% of the
total P 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, but the efficiency of their use by the grass can be affected by high levels of
lock-up by the soil, especially in low P 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.
So 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 available in Ireland from Grassland AGRO. TOP-PHOS is a new and
unique chemical form of phosphorus compared to standard P fertilisers, and has been
recognised within the EU REACH regulations as being different to the traditional forms
of P 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 the
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
P to the grass. TOP-PHOS also contains stimulants that are designed to increase root
mass to improve P efficiency and to increase soil microbial activity to release P from
the soil reserves.
So How Does TOP-
PHOS Help Spring
availability in soils is
the cooler soil
availability of P and
will therefore increase
spring grass growth,
as more of the P
applied can get to
the grass faster to
On-farm Irish trials in
2017 evaluating the
benefits of TOP-PHOS
for spring grass
growth showed an extra 0.4 tonnes of grass DM per hectare in the Jan to early April
period where TOP-PHOS was used as the source of P compared to standard P 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, thereby simplifying the remainder of the spring fertiliser rounds to straight
nitrogen (e.g. Urea or CAN). This has the advantage of making fertiliser management in
spring more simple and straightforward.
For more information on how TOP-PHOS can help you grow more grass this spring,
contact your local Grassland AGRO technical advisor
or Dr. P.J. O'Connor on 086 3237894
Get more from
in 2018 with TOP-PHOS
Dr. P.J O'Connor
Figure 1. The effect of using TOP-PHOS compared to
standard P fertiliser on spring grass yield.
2nd Option GrasslandAgro 200x283.indd 1
CALF REARING FOCUS
ARE VITAL TO CALF PERFORMANCE