While this week’s storm will do nothing for soil temperatures and grass growth, getting fertiliser out on grazing ground early in the year is important as a means to kickstart grass growth.

Even on farms stocked at less than 2.0 LU/ha, the advice is to apply 0.5 bags of urea per acre (23 units) in the month of March as a first fertiliser application of the year. Farms stocked at 2.5LU/ha or higher can go with a full bag in the coming weeks where poor ground conditions prevented any spreading in February.

Urea works best at soil temperatures above 50C. If we spread it below this, it is not wasted – the response is simply delayed. In fact, urea is more stable than CAN in the soil even if rain comes shortly after spreading.

In the coming weeks, aim to spread urea when ground conditions allow and there are no heavy rainfalls forecast in subsequent days.

In terms of silage ground, we should absolutely not skimp on nitrogen (N). Regardless of soil fertility, we should be looking to get 100 units of N in late March/early April when ground is closed. Unless soil P and K status is at index 4, we need to include slurry or compound fertilisers in this.

Where ground is at index 1 or 2 for P or K, go with 3,000 gallons of slurry immediately after closing and a week in advance of fertiliser spreading.

Where P is index 1, we need 32 units of P applied and index 2, 25 units of P, respectively. Slurry at 3,000 gallons/acre reduces the need for P by around 10 units and we can look to compounds like 24-2.5-10 spread at a rate of 3 to 3.5 bags/acre.

It is likely K that will be deficient in a permanent silage field and slurry and farmyard manure are of big value here. Depending on dry matter, cattle slurry can have a K units/acre equivalent value of 15 to 30 units/acre per 1,000 gallons.

One tonne of farmyard manure/acre will deliver 12 units of K. An index 1 or 2 soil needs 130 units of K/acre pre silage-cut. Three thousand gallons of slurry will reduce the need for chemical K by 90 units.

Grazing

During the grazing season, from April onwards, it is advisable to switch to compound fertilisers on areas of the farm deficient in P or K. Deficiency on grazing ground is generally in P and spreading products like 24-2.5-10 here to build P up will be a slow process.

Instead, use 18-6-12 at a rate of one bag per acre either following grazing or in a monthly block-spread. At a recent grass walk in Grange, Teagasc’s John Maher remarked that every animal leaving a beef farm was the equivalent of a bag of 18-6-12 walking out the gate, highlighting the need for a CAN ban on some farms.

In terms of muriate of potash 0-0-50, the ship has probably sailed for this on suckler farms as a quick-fix for correcting low K levels. The fact that K locks up magnesium means that the risk of predisposing animals to grass tetany is too high, particularly in early lactation when cows will be under big stress and the weather is generally unsettled.

While many chose to put lime on the back burner until the end of the grazing season, that strategy will have backfired for most in 2017. The advice now is to aim to spread the farm in sections during the season after a tight grazing or silage cut.

Spreading 2t lime/acre on a dry soil should lift pH by approximately 0.5 units (5.8 to 6.3). On heavy soils, up to twice this amount might be needed but spreading more than 1t/acre to 1.5t/acre in one application here is not advised as it can act to soften the soil’s structure. Correcting lime (soil pH) alone in a soil with P and K levels on the floor will increase grass production by 10%.

Also, on a soil very deficient in lime, for every bag of CAN we spread we are effectively losing one-third (nine units of N).