Grass advice: Decisions with the final round of fertiliser
Deciding which fertiliser to use at this time of the year will depend on soil fertility and previous fertiliser used this year.
There can be a big difference between soil fertility and nutrient availability if weather has been cold or very wet, owing to reduced root depth by the plant which in turn compromises nutrient availability.
This is why I have said in previous articles that a compound fertiliser can lift growth rates substantially, dependent on weather and soil temperature, even on farms that have good P and K indices.
Autumn calving herds will have a lower average farm cover (AFC) target of 850-900kgs, irrespective of stocking rate as they will have 100% of the grazing platform closed by early November.
High pre grazing covers (>1600) are much more difficult to graze out for fresh calvers and so by grazing lighter covers and housing earlier.
Research in Johnstown Castle has found that they can turn cows out in spring with a high percentage of paddocks at 1000-1100kg covers.This is a must for cows going out at peak demand.
In periods of poor growth/low soil temperature, straight nitrogen will not give growth a huge boost.
We need to be very careful about which fertiliser we use now in the final round as the only nutrient we can use after mid September will be slurry.
Before spreading the final round of fertiliser we must think forward to when paddocks will be grazed next and closed off.
E.g. a paddock grazed today will be grazed again in early October and then closed. The AFC and cover/cow will influence how much fertiliser we need to spread.
Lowly stocked farms that are achieving good growth rates may need to spread very little. The first grazed paddocks in spring are those that are closed 3-4 weeks after start of closing in autumn.
Remember – first grazed paddocks in spring will have covers around 800-1000kgs as we need low covers that are green to the base to re-train the cows to grazing down to low residuals.
Paddocks closed first will be grazed in late February; we need to think about which paddocks are best to turnout cows onto, based on proximity to the parlour and soil type when closing up paddocks this autumn.
Cathal McAleer is a grassland consultant working with individual farmers and facilitating discussion groups throughout Ireland.
You can contact Cathal on 087 160 2491 / 0044 7749 531679 or by email:[email protected]