Autumn Grassland Management on a Dairy Farm

By Michael Donoghue, B&T Dairy Adviser, Teagasc, Galway/Clare

Although it is only late August thoughts are turning to autumn and potentially housing cows. 3 things will determine when cows will be housed on your farm.

1. Weather
2. Soil Type
3. Grass Supply

The first one cannot be influenced. Soil type in the longer term can be managed at least to some extent thought a combination of drainage, good access (roads & multi access points) and in the short term by on/off grazing etc. Grass supply however is very much within a farmer’s control. Putting the correct amount of grass on the farm before October is critical to your housing date and that grass has to be mainly grown now.

The table below sets out targets to successfully build up enough autumn grass for a farmer stocked at 2.5 LU’s/ Ha (1 cow/acre). Different stocking rates will require different targets but the rotation length will be the same, contact your local advisor for details.

The key to achieving these targets is extending the rotation up to 35-40 days by the beginning of October, start of last rotation. Ways to extend the rotation include.

• Reduce stocking rate, so only milking cows are on the milking platform.
• Sell/ move milking cows that can be dried/ culled i.e. high SCC, bad feet, not in calf.
• Apply fertiliser or slurry to maintain grass growth (roughly 20 units of N/ acre).
• Graze swards clean and don’t damage them.
• Feed extra ration or high quality bale silage (this will reduce demand).

Occasionally we can get very strong growth in September and grass can run ahead of target especially on lighter stocked farms. If this happens action will be required as very strong grass can lead to poor utilisation and severe sward damage if the weather turns, this in turn affects spring performance. Options here will include

• Reducing meals, be careful of grass tetany if going below 2-3 Kgs.
• Increasing stocking rate for a short time.
• Cutting bales, the earlier this is done the better, as regrowth will be slow.

Once we get to the first week of October the main priority is spring 2024 grass supply. Grass that will be graze in February and early march needs to be grown in October. So minimise damage, graze swards as clean as possible and don’t re-graze from the 5^th of October. This date will vary a few days either way depending on growth and soil type.

A couple of last important points that need to be considered as we head into the autumn

• 14^th September is the last day for spreading chemical N and P
• All slurry has to be spread by end of September
• N statements from DAFM should be available shortly, check yours as banding may have significantly changed your Kg of N/ Ha figure
• Get your tax accounts done asap as some farmers have significant tax bills after last year’s high milk price, but that bill with have to be paid with a poor milk price this autumn