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Maintaining Grassland Productivity in Autumn

03 October 2018
Type Media Article

Glen Corbett, Teagasc, Tuam

It’s been an incredibly tough year to date for farmers throughout the country. There has been some respite west of the Shannon in the last month, but parts of the South East still have soil moisture deficit issues. The big challenge facing most farmers now is assessing fodder supplies on hand for this winter, (given that most yards were emptied in the Spring) and thereafter ensuring there is adequate fodder there for the planned stock-numbers until turnout in Spring 2019. There are a number of issues to cover when looking at the subject of maintaining grassland productivity this Autumn.

Fertiliser deadline Extension and Soil Fertility

If you still have fertiliser to apply you are probably aware that the chemical fertiliser and slurry spreading deadlines have been extended. Chemical fertiliser deadline was extended to the 30th September and slurry until the 31st October. The priority on all farms should be to maximise grass grown and utilised this Autumn, in the form of both grazing and silage making. With growth rates up to an impressive level of 57kg DM/ha in mid-September (Pasturebase Ireland), second/third cuts are progressing well and land is holding up. When the weather opportunity arises, take out these crops ortherwise there could be excessive tracking by machinery.

An application of 25-30 Units of N per acre (CAN based) should be applied if not done so already if you need to get grass growing. Apply this sooner in September rather than later (as deadline is approaching).Trial results have shown that Nitrogen applied in October has approximately only half the yield benefit of September applied N. Nitrogen applied will help build grass supplies as we approach the dates when we want to start to close areas of the farm (see more later in article on this).

If grass is growing well and you aren’t considering Nitrogen then perhaps you should consider a compound fertiliser (like 10-10-20) application in order to build up P’s and K’s on your farm. Again, this is an ideal time of year to soil sample your holding (prior to applying fertiliser and 1 soil sample per 5ha every 4 years minimum). Use soil sample results to assess P and K deficiencies and apply accordingly (ask adviser to help with this if need be). Take note of samples from silage ground in particular. On silage ground, obviously nutrients are depleted every year to a greater degree than on grazing swards. On silage grounds K levels in particular can drop to Index 1 easily if left to do so. Apply 50% Muriate of potash if K is your concern, there is no limit on K application.

Teagasc Soils specialist Mark Plunkett has said this week that one consequence of the year we’ve had is that lime application nationally is back by 50%. That’s a massive deficit. If pH isn’t in order (below 6.2) then you won’t see the full benefit of the compound you apply. It will particularly affect P uptake from fertiliser, P is the limiting nutrient in soil chemical reactions. Lime is great value for money and should be applied to bare ground and remember the important rule of thumb: slurry before lime is no problem, do not apply slurry on top of lime!

Closing Land/Paddocks

The principle behind closing land as we approach the winter makes sense and is based on extensive research work. We need to maximise the grass in the diet of all stock no matter what system you operate as grass is the cheapest feed available. As a general rule it has been shown that cattle grazing outdoors will achieve a kilogram of LW gain 8 to 10 times cheaper than trying to put a kg on them indoors. There is no point doing a great job with lambing ewes or calving cows next spring only to turn them out to fields that are bare. To ensure this doesn’t happen we must put some type of plan in place now. The following are the basic guidelines to getting this done:

  1. Close in order that you want to start grazing next Spring. Consider closing areas first that are close to the yard and/or sheltered
  2. Graze tightly before closing i.e. 4cm if possible. This will benefit regrowths.
  3. Do not regraze closed paddocks in late October. Leave that gate closed! Do not let stock roam the farm during the winter months.
  4. Target giving your land a 120 days rest period minimum. Target closing 20% by late October and 40% by mid-November for example in case of early March lambing flock.

The theory behind point 4 is that everyone knows that there is little or no grass growth in December and January. The growth won’t pick up until soil temperatures allow (over 6 degrees). So it’s really what is grown before the ‘dormant’ season for grass growth that’s important in having a supply ready for Spring. Put a figure on what 20% land area equates to in your situation, eg on a 50 acre farm that’s 10 acres. So have 10 acres grazed off tight and ready to close by late October. Proceed to close a further 20% land area every 2 weeks.

Farm Walks

The Grass 10 Teagasc Autumn Farm Walks this Autumn will involve helping to provide further information on topics covered in this article and other important related matters. The walks in our locality are as follows (1 beef and 1 dairy):

Ronan Joyce Carrowjames, Belcarra, Castlebar, Co. Mayo, F23 C560 Wed 26 Sept 2pm Dairy
Martin Kenny Cams, Cloverhill, Co. Roscommon, F42 E766 Wed 26 Sept 11am Beef


It’s essential to make the most of Autumn grass to reduce winter feed demand and to set up the farm for the Spring (as outlined). This in turn will help lower feed costs and shorten the winter period as much as possible.

We can’t control what the weather will bring; luckily it’s a lot better in 2018 than it was in 2017 as we approached the Ploughing. What we can control is what happens inside the farm gate in terms of Soil Testing, application of N-P-K and Lime, Fodder Budgeting/planning,   this should include a Reserve, very important this year as previous Reserves have been used up. Lastly closing in a timely manner so that grass is there when Spring 2019 arrives.

On a side note – Watch Out - Lush autumn grass like soft spring grass can be low in magnesium. Tetany can strike if magnesium is not been supplemented via buckets etc.