Green Alliance urges nutrient efficiency

In a move to push nutrient pollution and management up the political agenda, Green Alliance has published a booklet on "closing the loop" on nitrogen and phosphate cycles.1 The continued failure to manage nutrient cycles, it maintains, adds to the greenhouse effect, generates pollution and wastes resources.

The imbalance in human management of the natural cycles for phosphorus and nitrogen is akin to the imbalance in the carbon cycle which is responsible for climate change, Green Alliance argues in the booklet.

It is a clear ploy to tie nutrient management to carbon management - now by far the leading environmental issue. But there is sense in the argument, and the current profligacy with nutrients runs counter to sustainable resource management and has substantial environmental costs.

Nitrate fertiliser production, for instance, is highly energy intensive. Phosphate reserves are limited and their extraction has costs in terms of energy, transport and pollution.

While fertilisers are being manufactured and applied to farmland, water companies are spending millions of pounds annually on removing nitrate from tap water and phosphate from sewage.

"Something is not quite right here," said the Green Alliance’s Jiggy Lloyd at the booklet’s launch. "The nutrient cycle is greatly inflated in the developed world and the total circulation is enough to meet our needs. Yet we keep topping it up. Why is that?"

The launch of the report was supported by Lord Rooker, minister of state for farming and food, and Environment Agency board member Ted Cantle.

The booklet is structured as a series of essays by prominent specialists on aspects of nutrient management - the water industry, sludge recycling, farm management, composting, and the implications for energy and biodiversity.

Its recommendations for policy objectives include:

Safeguard sewage sludge disposal to farmland by making the safe sludge matrix statutory. The matrix, which specifies voluntary standards for sludge treatment and application for various crops, was agreed by the water industry in 1999 as a response to retailers’ fears over the microbiological safety of sludge use on land. It is adhered to by all water companies and the government has promised for some years to make it statutory (ENDS Report 333, p 43 ). The idea has the enthusiastic support of Water UK and the industry. They believe the move would further build confidence in sludge spreading among retailers, allowing them to endorse the use of treated sludge by farmers and growers.

Develop a certification scheme similar to the safe sludge matrix for the use of waste-derived composts in agriculture. This would allow retailers to buy in to the use of composted waste and ensure an outlet for biodegradable municipal waste.

Consider a levy on detergent and industrial phosphate to deter discharges to the water environment. The proceeds could be used to fund phosphate recovery from sewage by water companies.

Devise economic means of distributing farm-waste nutrients from the west of the UK, where livestock farming produces an abundance of manures, to the east, where there is a paucity of nutrients for arable production.

A levy on inorganic nitrogen fertilisers should be considered to promote the use of organic alternatives. However, the use of nitrogen fertilisers is already in decline.

Nutrient management needs to be considered at farm-scale and nutrient planning should be required as a condition of single farm payments.

‘Precision agriculture’ needs to be widely adopted, where livestock feeding regimes and field fertiliser applications are much more closely tailored to needs.