The prospect of the closed period for slurry applications being replaced with a system which allows more flexibility during the winter months has been ruled out by DAERA.
A report published by the department last week states that the current closed period is “the most effective strategy” for minimising environmental risks associated with spreading slurry.
Agriculture Minister Edwin Poots had favoured a system where slurry could be applied during the closed period if soil moisture levels and weather conditions were suitable.
Scientists from Agri Food and Biosciences Institute (AFBI) initially said a more flexible approach could be possible, but it would require costly investment to secure timely and accurate data.
Phosphorus levels in waterways is the main environmental issue relating to slurry spreading
However, the new report, which was prepared by DAERA officials and AFBI researchers, states that a system where spreading is based on soil moisture and rainfall conditions “will not sufficiently mitigate the risk associated with slurry applications”.
The document points to research from AFBI’s farm in Hillsborough, Co Down, where over a nine-year period soil conditions during January were only suitable for slurry applications 3% of the time.
Phosphorus levels in waterways is the main environmental issue relating to slurry spreading, but DAERA state that “mismanagement and overuse” of phosphate fertilisers is also a key factor contributing to the issue.
The latest figures indicate that 56.1% of rivers and lakes in NI were at either “high or good” status for phosphorus during 2019, down from 66.3% over the 2012-2015 baseline period.
The document states that the decline in water quality is a “serious cause for concern” and phosphorus levels in waterways have been listed as a priority for the NI Executive.
Restrictions on phosphorus inputs on all livestock farms in NI is floated in the DAERA report as a potential measure which could help limit run-off into waterways.
At present, only farms that operate under a nitrates derogation are required to calculate a P-balance.
Derogated farms are required to keep their P-balance below 10kg/ha/year
This involves subtracting the total phosphorus exported off the farm through the likes of milk and livestock sales, from phosphorus imports, such as purchases of concentrate, fertiliser and straw.
Derogated farms are required to keep their P-balance below 10kg/ha/year, but the new report states “there appears to be a case” for lowering this requirement to 8kg/ha/year for derogated farms whilst rolling the same requirement out across all intensive dairy farms.
It is also suggested that a P-balance limit of 5kg/ha/year could be introduced for all beef and sheep farms, as well as less intensive dairy farms.
According to the report, this could be achieved on these farms by “eliminating some or all” of the phosphorus input through chemical fertiliser.
The authors state that for intensive dairy farms to achieve P-balance below 8kg/ha/year, extra steps beyond cutting out phosphate fertiliser would be necessary.
“Reductions in the concentration of phosphorus in concentrate feeds may also be needed, and in cases where farm phosphorus surpluses are over 15kg/ha/year, reductions in total concentrate imports may also be required,” the report reads.