‘We can grow 300-400kg more grass by just getting slurry right’

Irish farmers can grow another 300-400kg/DM/year more grass by just getting the slurry right, the audience of this year’s Teagasc Virtual Dairy Conference heard this morning (Tuesday, November 24).

In the first of four webinars in this year’s conference, which focused on making better use of nitrogen (N), the topic of nitrogen use efficiency (NUE) was centre stage.

The panel discussion featured Teagasc specialists Dr. Laurence Shalloo, Dr. Elodie Ruelle and Dr. Owen Fenton, and was moderated by Teagasc head of knowledge transfer Dr. Stan Lalor.

Dr. Shalloo outlined the technologies that are currently being used to drive efficiency: “Probably the most important factor affecting NUE is grassland management.

If we look at the National Farm Survey, we estimate that farmers are growing approximately 10t of grass and in terms of Pasturebase, we know that farmers are growing an average of 13t. So there’s a 3t difference there for a similar level of nitrogen.

“In terms of precision grassland management, a better focus on grass covers and grazing residuals, and measuring will be the first step.

“Coming into that then will be sward renewal and soil fertility.

“It’s so big that it’s very hard to pinpoint what an individual response will be to getting lime right, or getting phosphorus (P) right, or getting potassium (K) right, because every farm is different and everyone will be in a different status. But the benefits are going to be huge in that light.”

Turning to slurry, Dr. Shalloo said: “The next technologies we talk about are using slurry better.

When we talk about using slurry better, we’re talking about using spring slurry and using low emission slurry spreading [LESS] technology, like your trailing shoe, your dribble bar or your injector.

“The figures we estimate are that we can grow another 300-400kg more grass by just getting the slurry right; by having it in the spring and using low emissions spreading technology,” the specialist highlighted.

On another technology, Dr. Shalloo said:

“There’s clover; we’ve a lot of studies done on clover over the last 10 years both in Clonakilty and in Moorepark.

Basically what they are showing is, if you take it on the round, and you summarise the data together, clover will give a response of somewhere between 1.5 and 1.6t DM per year.

“That is not straightforward, it’s not simple; there’s a serious amount of management needed with the clover but it’s fairly consistent across the studies.

“We have to reduce chemical nitrogen and so on to get it to stay in the swards but there is significant evidence now to say that clover will certainly deliver in terms of that,” the Teagasc expert said.