GrowthWatch: Slurry and fertiliser – when and where?

By Teagasc’s Seán Cummins and James Fitzgerald

The deadline for chemical fertiliser nitrogen (N) and phosphorus (P) applications is fast approaching, with midnight on September 14 being the cutting off point for spreading this year.

When it comes to the final round of fertiliser, there are a number of questions farmers need to ask. Firstly, is an application of fertiliser warranted and how am I for grass?

Where farm covers are running high, and farms are relatively lowly stocked, the economics of spreading chemical N at this time of year may be questionable in some cases.

However, where the farm is running on target – or even slightly below target – for grass, there may be scope to spread chemical N before the deadline closes.

When a decision is made on whether or not to spread, the paddocks on the farm that are most likely to respond to additional N must be targeted first. These will be the paddocks with a high perennial ryegrass content that are green and leafy to the base.

[grass_growth_map from=”2020/09/02″ to=”2020/09/09″]

The field conditions must also be examined and spreading should only occur where ground is trafficable and free from surface water – an issue still on some farms in the south west of the country.

Where slurry is still present on farm – and looking at the weather ahead – there may be an opportunity to empty the tanks while ground conditions are still manageable.

Remember, slurry is a source of N – and along with a boost of potassium (K) and P – it will help to keep grass growing over the coming weeks.

Excellent graze outs are also being achieved, and with the availability of the Low Emission Slurry Spreading (LESS) technology – ground on which it has been applied will be available once more for grazing before housing.

The average farm cover is running at 1,372kg DM/ha, but our stocking rate is 3.9LU/ha. In a normal year, we’d take out bales, but any of the heavier covers are reseeded paddocks – on their third grazing – and we’re splitting and achieving very good graze outs.

I’m not too keen on going in and taking bales of these paddocks in their first year of production.

Growth rates have been excellent over the last few weeks, sitting at 80kg DM/ha and that has been helped by the reseeded paddocks and the kinder weather conditions we’re experiencing.

Before the fertiliser deadline, I hope to apply 20 units of N to any of the grazed out paddocks or those on the block with a cover below 1,000kg DM/ha, that are green and leafy to the base.

We also still have a tank of slurry present in the yard and this will be applied to any of the paddocks that are showing low indexes of P and K.

We reseeded another three paddocks after silage approximately 11 days ago through stitching and a very good establishment has been achieved.

If conditions allow, we will apply a post-emergence spray of Pastor Trio in the coming weeks, once the seedling weeds are the size of a 50c coin.

All calves on the farm are currently being supplemented with 1kg/head/day of concentrate at the minute. We introduced meals during the wet weather to calves and will continue until housing in late November / early December.

We like to build a bank of grass during the months of September and October to try and maintain the calves grazing as long as possible as we are farming very dry land.

The stocking rate has been steadily falling as the majority of the 30-month bullocks, spring lambs and cull ewes were sold off.

This has led to the reserve of grass on the farm for late autumn grazing and building, even in spite of some low growth rates recorded over the last couple of weeks.

Left to sell at the moment are eight bullocks which are at grass and the last 13 spring lambs. The next sale after that will be the 15 spring of 2019-born bullocks which have been picked out and housed for finishing.

This has helped reduce the demand for grass further which will help extend the grazing period for the sheep well into the winter.

The calves are split into a heavier and lighter bunch for more accurate meal feeding and balancing grass demand on two different blocks.

One bag/ac of SulCAN is being spread at the moment for the last round of fertiliser before the deadline and samples of the silage made this year will be taken and sent for testing in the coming days to assess how this year’s silage cutting went and to plan ahead for the winter feeding period.