NVZ extension will shake up slurry disposal

23 November 2001

NVZ extension will shake up slurry disposal

Slurry disposal methods and

grazing cows were debated

at the British Grassland

Society winter meeting.

Marianne Curtis reports

NITROGEN vulnerable zones are likely to extend dramatically and dairy producers in these designated areas will have to modify slurry and fertiliser policies to comply with legislation.

Chairing a session at the British Grassland Society Winter Meeting, held in Malvern, Worcs, Rob Robinson, agriculture policy manager at the Environment Agency, said a DEFRA consultation paper covering NVZs was expected before Christmas. "It would not surprise me if there were dramatic proposals for extending NVZs in this paper."

Speaking at the meeting, Paul Lewis, of Harper Adams University College, Shropshire, outlined management changes required to comply with NVZ legislation. "NVZs are designated in areas where nitrate from agricultural land is causing water source pollution. Producers in these zones must comply with a programme to reduce and prevent pollution caused by nitrate loss.

"NVZs cover 600,000ha and involve 10,000 farmers. The programme imposes restrictions on timing and rate of fertiliser and manure applications, together with safe storage of slurry and effluents." Full fertiliser records must also be kept.

To assess the impact of NVZs on dairy farm management, research was carried out by Harper Adams on five west midlands farms with a dairy enterprise (see table). The management, labour and financial implications of NVZ designation were assessed in the study.

"Farm A has a small dairy herd on 24ha of grassland and is constrained to its existing stocking density by lack of slurry storage, a muck-for-straw exchange and very small organic nitrogen capacity surplus. Muck-for-straw exchanges allow muck to be exported to a neighbour outside the zone in exchange for another commodity, such as straw," he said.

"Farm B can support its existing stocking density without using its muck-for-straw arrangement and its labour profile is unaffected. But greater slurry storage capacity will be required for winter, having a financial impact on this unit."

A high stocking density and high organic nitrogen production made compliance difficult for farm C, said Mr Lewis. "This unit overcomes this by a muck-for-straw exchange where nearly 100% of poultry manure is exported. Winter slurry storage capacity is just adequate, for a normal winter period."

Lastly, farm E has a large dairy herd, together with a substantial arable contribution and has 86ha outside the NVZ area. It was not affected by the stocking density limits imposed by NVZ organic nitrogen limits, said Mr Lewis.

"When trying to comply with NVZ legislation, smaller intensive units are limited by land area or lack of adequate slurry storage. Large mixed units are less affected unless heavily stocked." But it was possible to apply for grants to assist with extending slurry storage capacity, added Mr Lewis.

Farm enterprises in Harper Adams NVZ study

A* B C** D E

Cropping (ha)

Grass 24 27 58 24 73

Arable 0 10 148 0 47

Total (ha) 24 37 273 24 206 (120 in NVZ)


Milkers 58 75 190 70 265

Followers 50 50 110 35 140

Beef 0 0 60 12 0

Slurry storage (litres) 0 0 4.5m 0.9m 2.23m

*All farms have clamp silage except A which has big bales. **Farm C also has 80,000 hens and 112 sows.

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