What’s the best fertiliser for your ground?

Soil temperature is now 9 degrees here in Tyrone and grass is beginning to jump; quite timely as we need to be closing off silage ground now and applying fertiliser to grass.

I have been asked several times this week which fertiliser is best to apply on silage ground – there is no ‘one fits all’ fertiliser, start by looking at your soil analysis, is your pH on target, is the P/K index high 3s?

The next step is to identify what quality of silage you need, based on what animals it will be fed to next winter and early spring.

First cut silage must be exceptional quality if we are going to feed lactating cows in autumn and spring.

P and K indices on our silage ground are both index 3. As the nutrient requirements of a ‘high quality’ first cut are; 80 units N, 20-30 units P and 80 units K, we will apply 2000 gallons/acre of slurry and 125kg/acre of 24-4-13+S compound.

Where soil samples show high potassium (index 4), reduce the amount of applied chemical K, similarly if soils show low levels of K we must apply additional K. Bulky, first-cut silage will require an additional 20 units N, 5 units P and 20 units K per acre.

The changes in land entitlements this year has resulted in some farmers having difficulty in securing land on a long-term lease.

If it is the case that you have land rented for one year only, it would be advisable to take a soil sample to see how deficient the soil is, if ph is very low (below 6.0), apply 100kg granular calcium/acre – this is highly soluble and will be used up by the end of the year.

Acidic soils lock up P very rapidly, by not raising the ph therefore, we can lose a lot of any applied P into the land owners future soil bank. The gran lime will help to keep more of the soil P and chemical P available.

Second rotation
The second rotation is either about to begin or started this week and finally we can stop focusing on the grass budget and go back to the grass wedge and cover/cow, which we want to have between 160-180kg/cow.

It is easy at this time of year to become overly focused on milk yield as cows are peaking, instead focus your attention on input costs.

Grazing covers of 1,200-1,400kg/ha will have the same production output as grazing 1,800-2,000kg with 2kg meal, this is owing to lower energy in higher covers.

Grass that is well managed and grazed at the target pre grazing cover of 1,200-1,400kg will support 25L of milk, whereas poorly managed grass may not support 22L.

Grazing down to 3.5cm is crucial if we are to maximise grass quality in the subsequent rotation when breeding has begun and we want to maximise cows energy intake.

The increased growth rates allows supplement to be either greatly reduced or removed altogether; phase out supplement over 3-5 days depending on how much you are feeding. Magnesium levels are low in lush grass, owing to low uptake so mag supplements must be given.

Maiden heifers need to be on high quality grass to increase weight gain and conception rates to service next month. Maidens and calves will need an eight-in-one vaccine when going to grass.

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]

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