Nitrate Vulnerable Zones

With a planned expansion of Nitrate Vulnerable Zones, we highlight some of the key proposals growers should be aware of.

The current Nitrate Vulnerable Zone (NVZ) measures were introduced in December 2002 to cut nitrate losses and comply with the EU Nitrates Directive. However, these have not fully achieved their environmental objectives, which has meant DEFRA has had to take a fresh look at the areas designated as NVZs and at the measures in the existing NVZ action programme.

The biggest change for those growers who currently operate outside the designated NVZ areas could be that they may soon find themselves within one. The proposal is to increase the area covered from 55 per cent to about 70 per cent of England. This change is because additional waters have been identified as being affected by nitrate pollution. DEFRA is also seeking views in the consultation on whether to apply the action programme across the whole of England.

Secondly, for those growers who use manures, there are a number of key proposals. The most important is that the whole farm livestock manure N loading limit be set at 170kg per hectare of total N per calendar year. The limit for arable land in NVZs has already been lowered to 170kg per hectare from 210kg per hectare. This took place from December 2006. As is currently the case, this amount will be averaged across the whole farmed area. The requirement that no more than 250kg per hectare of organic manure total N should be applied to any field in any calendar year remains unchanged from current measures.  

Longer closed spreading periods are also proposed for high available N organic manures (slurry and poultry manure) and the closed periods will apply on all soil types. The proposals are detailed but, in essence, these would be for between three and five months, depending on rainfall and soil type. The longest period runs from 1 August to 31 December.

Previously, closed spreading periods of two to three months were confined to sandy or shallow soils. Closed periods are intended to minimise leaching loss.

Finally, for manures a minimum manure storage capacity is also included — 26 weeks (pig slurry and poultry manure) or 22 weeks (cattle and other slurry). This is to allow farms to have sufficient storage capacity to bridge the closed periods with a buffer at either end in case of bad weather.

Next, the document proposes that nitrogen applications (fertiliser N plus crop available manure N) must balance the crop N requirement allowing for soil N supply. It also proposes that the average nitrogen application rate across the farm for a particular crop must not exceed the maximum (Nmax) allowed rate. This calculation must allow for a minimum value of manure N efficiency. However, there are no N maximum rates for field vegetable crops although one is proposed for potatoes at 270kg per hectare.

Manufactured nitrogen fertilisers it proposes must not be applied to arable land between 1 September and 31 January, except for specified crops. Maximum rates are also specified. These figures are given in brackets below during the closed period.

Examples are:

•    Broccoli, cabbage, cauliflowers (100kg N per hectare);
•    Leeks, onions, parsley (40kg N per hectare);
•    Asparagus (50kg N per hectare).

Other proposals include:

•    The banning of the use of high-trajectory, high-pressure application techniques for spreading organic manures;
•    A requirement for a written risk assessment to identify suitable locations for organic manure applications — in other words a manure management plan;
•    A requirement to incorporate within 24 hours organic manures with high available N applied to bare soil or stubble;
•    A requirement for natural regeneration or sown cover crops where ground would otherwise be bare over-winter, except following crops harvested after 1 September;
•    An expansion of current requirements for records of all field-level N fertiliser and manure applications, compliance calculations and manure imports/exports to be kept for at least five years.

Full details can be found at Comments on the proposals can also be made by calling 020 7238 6732, or writing to: Nitrates Consultation, Zone A/B, 2nd Floor, Ergon House, Horseferry Road, London, SW1P 2AL. The consultation period ends on 13 December.

Help and support

The ADAS-run Environment Sensitive Farming project will be holding free events on this and related topics. Visit for dates and venues in your region. Additionally, a range of technical support documents and tools to help decisions, calculations and record keeping will available. Transitional arrangements for some measures are proposed to allow time for farmers to comply. However, DEFRA has said no new central-government money will be available for building new or additional manure storage.

Related consultations

DEFRA also issued two other consultations on the same day:
•    A proposal to consolidate the air, water and soil codes into one overarching code of good agricultural practice;
•    Options for tackling other types of diffuse pollution of water from agriculture required under the Water Framework Directive.

Details at

Helen Riby is part of the DEFRA-funded Environment Sensitive Farming team

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