As slurry spreading zones begin to open, it coincides with periods of varied weather conditions nationwide, from heavy rain to freezing temperatures.
Environmental scientist at Meath County Council (MCC), Finbarr Quigley said that farmers “need to be cautious” and that the ending of the closed period for spreading “does not signify a green light”.
Biodiversity officer, Ben Malone said that spreading nutrients, which are intended for land can often end up in watercourses, “damaging” biodiversity when weather conditions are not correct and soils are wet.
He said that when there is an “influx of nutrients” that shifts the freshwater ecosystem away from natural conditions mixed with phosphorus or nitrates, and it can cause a “eutrophic impact”.
“There’s a number of factors at play, which creates quite a dire situation ecologically speaking for aquatic life,” Malone said.
He said the increase in nutrients transforms habitats for species that are familiar with low nutrient conditions, such as mayflies, which need highly-oxygenated environments.
In contrast, it then provides the optimum conditions for some species, leading to an abundance of creatures such as detritivores, like water hoglice or gammarus, according to Malone.
He added that biomass is created, which has its own timespan for breaking down, leaving a loss of oxygen within the environment.
Advice
Quigley advised farmers to avoid spreading if possible at this time of the year during wet soil conditions.
He said spreading slurry in the middle of January or beginning of February, when there is usually low growth levels is “not the best use of the resource”.
“Paying attention to slurry management is not just to appease enforcement agencies, but for a farmers own benefit.
“I would advise farmers not to completely empty tanks at this time of the year for that reason,” Quigley said.
He advised that if farmers do find themselves having to spread, then to stay “even further away” than the buffer zones would indicate.
“Farmers know their land better than anyone else and know the driest parts, so they should definitely aim for those parts,” he said.
He said that “not everyone is aware”, but farmers should have 18 weeks of slurry storage on farm prior to spreading.
“If all your tanks were empty at the start of this closed period back at the beginning of October, that should bring you up into February before spreading,” Quigley said.
He added that if farmers are rushing to spread, then it “tends to indicate” that there is an “issue with storage” on the farm.
The Department of Agriculture, Food and the Marine (DAFM) has requested Teagasc to complete research on whether the current 0.33m³/cow/week requirement for farms is accurate.
Ongoing research from Teagasc is monitoring around 100 farms and the level of slurry being produced on these farms.
Quigley advised farmers to chat to advisors and receive a storage assessment to ensure they have that 18 weeks storage as a minimum.
Slurry spreading
For spreading at other times of the year, Malone said that is still important farmers understand the water flow plan on their land.
He said this can be done by figuring out where water might congregate, and then put in place measures to intercept pathways.
Malone advised that this could be done by increasing buffer zones and planting trees or letting rough grassland grow.
“By planting trees, you’re not only improving water quality, but also adding to ecological connectivity by creating a new carbon sink,” he said.
He added that during droughts there are also concerns for biodiversity, as there might be the same level of nutrients reaching the catchment.
With low levels of water, there may be an increase in concentration, leading to further impacts from nutrients leaked into the streams, according to Malone.