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New NVZ rules spur on N-rate rethink

10 September 2011

New Nitrate Vulnerable Zone regulations come into force on January 1, 2009, and follow a year of sustained fertiliser price rises.  Growers are urged to review application plans and make use of published research material to help inform judicious savings.

New regulations have been issued by Defra governing the use of fertilisers and manures.  With fertiliser prices at least double last year’s value, the changes to the Nitrate Vulnerable Zones (NVZs), and actions that must be taken within them, underline the need for businesses to review applications made to potato crops.

With nitrogen fertiliser trading at a staggering £410 per tonne and compound blends up to £600/t, research material that delivered benefits to levy-payers when prices were at £84/t and £110/t respectively, is now more relevant than ever.

The areas of England now designated as NVZs has risen from 55 per cent to around 70 per cent.  The Regulations also make changes to the Action Programme, specifying actions farmers in NVZs must take to reduce and prevent nitrate leaching and run-off to waters from manures and fertilisers.  These come into force on January 1, 2009.

The main changes in the revised Action Programme relate to:

  • A whole farm limit of 170kg/ha for nitrogen from livestock manures, which now applies to all land
  • Closed periods for spreading organic manures, which will be longer and apply to all soil types
  • Manure storage capacity requirements, which have been amended to reduce the risk of manures being spread when conditions are unsuitable
  • The introduction of forward-planning rules to ensure nitrogen applications from manures and fertilisers are more accurately directed to crop needs

Environment Minister Phil Woolas has acknowledged that the regulations will impact on farmers.  “Farmers have a key role to play,” he said.  “The significant amount of nitrogen entering waters from agriculture is one problem that needs to be tackled if Defra’s environmental objectives are to be achieved.”

The changes come at a time when fertiliser prices are rising sharply.  Nitrogen (N) fertiliser has sold out till January, with merchants now asking a staggering £410/t.  Phosphate and potash are three to five times more expensive than they were 12 months ago.

“We’re urging growers to review their application plans,” notes AHDB Potatoes Rob Clayton.

“If you make your next fertiliser order based on outdated rules of thumb about crop requirements and uptakes you are likely to be spending unwisely.”

RB209, the industry’s fertiliser ‘bible’ that gives guidance on application rates, is currently being revised.  AHDB Potatoes is overseeing revisions to the potato section and the new RB209 is due to be published in time for the 2009 crop.

“But there’s much you can do now to plan your applications for the new season.  There are big cost as well as compliance benefits to be gained from looking closely at your crop’s requirements,” continues Dr Clayton.

Much of the research on which RB209 recommendations will be based has been published and is available to levy payers through the AHDB Potatoes website

Pivotal work at Cambridge University Farm has refined understanding of how the crop’s nutrition requirements develop during the growing season, for example.  The report, Potassium, magnesium and nitrogen nutrition of Estima is available here.

The report contains detailed analysis of N uptake related to leaf area index (LAI).  Up to 94 days after planting, each unit of LAI was found to be associated with 45kg of total N uptake per ha.  Results of experiments that study the relationship between potash and calcium, the crop and the soil are also included.

“While this report is not hot-off-the-press, it has helped shape our understanding of crop requirements, forms the basis for other on-going research and informs some of the changes growers will find in the new RB209.

“Through the revised RB209 and other on-going activities, AHDB Potatoes is working with the research community to bring the practical benefits of this research to growers.

“But those with the analytical skills to interpret the research themselves will find valuable information they can tailor to their own situation – once you factor in recent changes to fertiliser prices and nitrate compliance, that adds up to quite a competitive advantage.”

Maps showing the revised NVZ areas can now be viewed at  Defra is urging growers to apply good practice in their use and management of nutrients.  An updated Code of Good Agricultural Practice will be published later in the autumn which includes guidance in this area.

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