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Fertiliser application ‘critical’ this spring

The wet weather of early spring 2020 has disrupted the spring rotation planner, writes Martina Harrington, Drystock Specialist, Teagasc.

That now needs to be adjusted to reflect the circumstances. The application of fertiliser will be critical, see the options.

Things are finally looking up in the east with cattle beginning to appear out on the driest of paddocks. The wet weather has really messed up the spring rotation planner and it now needs to be updated. If left as is with the end of our first rotation on 10th April or “Magic Day”, the first rotation will be very short.

That means if a paddock is grazed today and you want to go back and graze it @ 1250kg DM in 23 days, growth rates would have to be on average 54kg DM/day, this is unachievable. However, if the start of the second rotation was pushed out by 10 days, the average growth rate needed will be reduced. 

The spring rotation planner needs to be adjusted to reflect this. There will need to be a balance between getting paddocks grazed off to have grass for the second rotation and getting silage ground closed. You may need to leave some silage ground un-grazed and cut early to end the first rotation on time. This plan may need updating as you go along.


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The application of fertiliser will be critical, there are several different scenarios out there, but what should you do now?

No fertiliser applied at all: Apply 1.5 bags of 18-6-12 to the whole farm as soon as ground is travelable, check your nutrient management plan to ensure you stay within the limits. If 18-6-12 is not allowed, use protected urea.

Go on driest paddocks first and follow up with the wetter ones as they dry. The target is 27 units of nitrogen and the P&K will help give you an extra jump in growth. On heavily stocked farms, follow up with 23-30 units of Urea or protected urea in the following 3-4 weeks. Keep your slurry and apply to the silage ground after it is grazed.

Slurry applied on some ground, no fertiliser applied: Do the same as above, however, if possible, use the fields you applied slurry to as silage ground, so as not to waste the potassium. With a very short rotation we need all the push we can get. If you have high P soils you could apply 30 units of straight nitrogen to the fields that got slurry.

½ bag of urea applied to 50% of the farm in January: Apply 1.5 bags of 18-6-12 to all fields as they become travelable, as long as your nutrient management planner allows. Always watch your nitrates limits, if not use protected urea. The urea will have grown the grass that is there now but the 18-6-12 will grow the grass you will need in 3 weeks’ time.

The aim to have between 50 and 70 units of Nitrogen applied by the middle of April.

Heavy ground

While cattle are starting to head out in the east, the west is a week to ten days behind. This will push out the turn out date. Most paddocks have good covers due to early housing, so the reality that most of the silage ground will not be grazed this year and should be closed, fertilised and cut in Mid-May.

Turned out stock should graze 20-30% of the lighter covers (800-1000kg DM/ha) first and get through this fast and get it growing. This will also provide an area for slurry to be applied and then head into the heavier covers.

The problem here will be that the rotation will be short, but soil temperatures should be up and grass growth rates will be on the rise and very close to demand.

Fertiliser will be key. Apply 1.5 bags of 18-6-12 to all paddocks, including those with heavier covers. This will grow the grass you need in three weeks’ time, as long as your nutrient management planner allows. Always watch your nitrates limits, if not use protected urea.

As tanks are nearly full, spreading slurry with a dribble bar or trailing shoe may be the best option. Apply a further 23 units of nitrogen in the form of urea or protected urea on top of the slurry.

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