This week’s conference organised by the Agri-Food and Biosciences Institute (AFBI) under the heading ‘‘shaping livestock farming for 2030’’ saw another warning issued to the local dairy industry that it must do more to tackle excess phosphorus coming on to farms.

This time it was Dr Conrad Ferris from AFBI Hillsborough delivering the stark message – unless things change, farmers are at risk of tighter rules around slurry spreading and manure management. These rules come under the nitrates action programme (and associated phosphorus regulations), preventing slurry spreading in winter months and limiting each farm to 170kg of manure nitrogen per hectare per year (farms can apply for a derogation of up to 250kg).

The most pressing current issue relates to phosphorus concentrations in local lakes and rivers, which has been on the decline, but the most recent results suggest that decline has now halted and may even be heading in the wrong direction.

“When quality doesn’t improve, legislation will force change,” said Ferris.

He was also dismissive of the suggestion that with Brexit coming, some of these rules might somehow just drift away.

So unless there is change, Ferris outlined a number of potential options. These include extending the closed period for slurry spreading, banning farmers from spreading slurry on fields with a phosphorus (P) index of 3 or more (70% of fields on intensive dairy farms) or imposing phosphorus balance limits on all farms.

In the last three years, increased concentrate feeding and more use of P fertiliser on local dairy farms has raised the average P surplus above 10kg P/ha/yr.

“Derogated farms (308 farms in 2017) can survive below 10. Why not all farms?” asked Ferris.

He maintained that the problem is compounded by the lack of soil testing, meaning that slurry is not being properly targeted at fields low in P, and in some cases P fertiliser is being bought and used when not required.

Concentrate feed

Ferris also maintained that there remains further scope to reduce P in concentrate feed. It has been moving downwards, from 5.7g/kg in 2005 to 5g/kg in 2015, but research at AFBI has suggested it could go as low as 3.8g/kg of fresh material.

However, where the industry really needs to focus its efforts is on more efficient use of concentrate feed.

Analysis of data highlights that there is a wide range of concentrate being fed across individual farms to achieve the same milk yield per cow.

“We need more quality grazed grass and quality grass silage going in – there are significant economic and environmental gains,” said Ferris.

Environmental controls in the Netherlands

Where the NI dairy industry doesn’t want to end up is in a similar situation to the Netherlands where there has been a large surplus of phosphorus (P) on farms which has resulted in strict environmental controls.

In order to try to stay within phosphate limits, the Dutch are embarking on a cull of 160,000 dairy cows (over 6% of the total herd). If this does not work, the herd might have to be cut even further in future years. The problem is not just dairy-related, with the Dutch also having an intensive pig and poultry sector, but the high-input system of milk production has left some questioning the long-term viability of the industry, given its dependence on concentrate feed.

“Only half of our animals are grazing. Housing is also leading to more ammonia (causing acidification and loss of biodiversity). People want to see cows out. Supermarkets only want milk from cattle grazing outside. It really has become an issue in the Netherlands,” said Dr Theun Vellinga, from Wageningen University, speaking at the AFBI conference.

Exports won’t solve P issue

To date, the answer for some farms operating above the 170kg manure nitrogen limit has been to export slurry to other farms.

However, Conrad Ferris does not believe this will solve the problem of excess phosphorus as the amount of land available across NI is limited (already high in P, or too wet, too steep, etc).

The other idea floated by the expert working group tasked with developing a new land use strategy in NI was to grant aid technologies to remove P off farms. “I don’t believe that is a NI-wide solution,” said Ferris.

It was left to Brian Ervine from DAERA to sum up the thinking.

“More forage and less concentrate going into cows would solve a lot of the problem on NI farms,” he said.