Zero Nitrogen Footprint

Brittany attracted a substantial amount of negative publicity in the European press, and particularly the British press, at the end of July 2011 due to several wild boar being found dead on the beaches to the east of St Brieuc. The death of the animals is thought to be linked to the seaweed deposited on the beaches at this time of year, which in turn is thought to be at least partly due to nitrogen pollution coming off the land. In this article, the CBJ investigates the concept of the Zero Nitrogen Footprint.

The issue:

Large amounts of seaweed are a traditional feature of some Breton beaches, and in times gone by local people used to collect it by the wagonload to use as a fertiliser on their fields.

However, it seems that the quantity of seaweed has increased significantly over recent years, at least partly because of nitrates being washed off the land and accumulating in the sheltered bays along the coast. The seaweed is unsightly, and therefore bad for the tourist trade, but more importantly in recent years it has been proved to be a health hazard. Large amounts of rotting seaweed exposed to the sun form a dry crust on the surface which traps toxic gases underneath. If a person or an animal breaks the crust, they can release a cloud of the gas into their face, with potentially lethal effects.

The seaweed has been linked to deaths of animals on the beach and to people employed by the council to clear it up.

Causes:

Assuming that there is more seaweed than there used to be, various inter-related factors are believed to be responsible:

Global warming: seaweed grows much more prolifically when seawater temperature increases by just a small amount.

Overfishing: if European sea water is being drastically over-fished – as many people believe to be the case – then one of the knock-on effects could be exponential growths in organisms further down the food chain, such as seaweed.

Nitrogen Pollution: The geography of the North Breton coast is such that water coming down to the coast in rivers is trapped in shallow bays and estuaries for relatively long periods of time. The areas around the Breton coast are home to some of the most intensive animal production in Europe. Modern, intensive animal farming gives rise to two forms of nitrogen pollution – run-off of nitrogen fertiliser from the fields, and liquid waste products from the animal sheds finding their way onto the land and into the water courses. Modern farming methods have already been identified as causing dangerously high levels of nitrates in Breton drinking water, and this, coupled with the widespread public distaste for modern forms of animal husbandry, explains why farming is assumed by most people to be the main cause of the seaweed problem. Further nitrogen pollution comes from poorly-treated sewage coming from towns and cities around the coast.

Solutions:

Discussions about what is to be done about the seaweed have focussed on two areas: clean-up operations and more farming controls, and both of these have proved to be contentious. So far, more health problems seem to have occurred amongst people working on the clean-up operation than to people on the beaches, and there do not seem to be any changes that can be made to the farming industry that are both affordable and effective.
In fact it seems that the only way to prevent farming from contributing to the problem would be to shut down all the animal sheds in the affected river basins and to stop the use of nitrogen fertilisers on the land.

To make sure that no nitrates were entering the sea due to human activity, it would also be necessary to stop any sewage from coastal developments entering the water system. In fact, it would be virtually impossible to simply eliminate nitrate pollution in this one corner of Brittany, without tackling the problem on a much larger scale.

Zero  Nitrate Footprint:

Various aspects of modern living are responsible for nitrate pollution: in the same way that fossil fuels consumption causes people in developed countries to leave a ‘carbon footprint’ they could also be said to be leaving a ‘Nitrogen Footprint’.

Anyone wishing to leave a zero carbon footprint simply has to avoid using anything to do with fossil fuels – oil, gas, coal, plastics, synthetic fabrics, etc. The analogous situation for nitrates is to avoid any product that uses either directly, or indirectly, nitrogen fixed from the atmosphere by the chemical process known as the Haber process.

The Haber process is a method for combining hydrogen with nitrogen at high temperature and pressure to produce ammonia. The ammonia is then converted into the nitrate fertilisers which are used in agriculture (it is also used in the production of explosives). The process was first demonstrated in 1909 by Fritz Haber, and was developed into an industrial process by Carl Bosch on behalf of the BASF chemical company. The Haber process made it possible for Germany to develop an armaments industry without having to import nitrates from abroad, and therefore was a significant factor in the events that led to the First World War, 1914-18.

During the war Fritz Haber worked on the development of chemical weapons – for which he was vehemently criticised by family members, including his wife who committed suicide during the war, and by fellow scientists.

Haber originally came from a Jewish family and left Germany in 1933, fearful of Nazi oppression. He died in 1934.

The Haber process has continued to be refined and developed over the past one hundred years, and it is estimated that it is now used to produce 100 million tons of nitrogen fertiliser every year. This requires 3-5% of the world’s natural gas production (the hydrogen in the process is derived from methane), and 1 to 2% of the world’s annual consumption of fossil fuel. It is also estimated that between one third and one half of the world’s population is dependent on foods grown on nitrogen fertilisers produced by the Haber process – or to put it another way, one third of the nitrogen in the protein present in human bodies today, was originally fixed from the atmosphere by the Haber process.

Just as there is nothing intrinsically wrong with the carbon dioxide produced by burning fossil fuels, there is also nothing intrinsically wrong with the nitrates produced by the Haber process. In each case, it is the quantity that is the problem – in the case of carbon dioxide, so much is being produced that its level is starting to rise in the atmosphere, and it seems to be causing global warming. In the case of nitrates, their level is rising in rivers, ground water, and some parts of the seas and oceans. These high levels have uncertain consequences for the health of animals, and can cause explosive growth in plants, such as the seaweed in Brittany, which is, of course, the reason why they are used as fertilisers.

The nitrates in the fertilisers enter the water system directly because they are soluble and they drain off the fields: they also enter it indirectly via animal waste products. Considerable sums are spent on treating human sewage – and this has significantly reduced the amount of nitrates entering the water system from towns and cities, but it is not considered commercially viable to institute the same level of sewage treatment on farms.

The Nitrogen Cycle

The nitrogen cycle is the term used to describe the complex process by which nitrogen circulates through the ecosystem. Nitrogen is an essential element for all living creatures; it is a component of amino acids, which are the building blocks of proteins, and also of nucleic acids, which are the building blocks of DNA. Although nitrogen is present in massive quantities in the atmosphere (the air we breathe is roughly eighty percent nitrogen) it is in a form that cannot be used by plants and animals.

In Nature, nitrogen is extracted, or fixed, from the air by lightning strikes, but more significantly by bacteria, which either live in the soil or in the roots of plants, principally legumes. The bacteria use the nitrogen in the air to make soluble nitrogen compounds, which can be taken up by plants and used to make proteins and their genetic material. Animals get their nitrogen by eating plants, and breaking the complex molecules back down to their components – amino acids and nucleic acids.

The nitrogen compounds from plants and animals are returned to the soil through the process of decay, and also by the breakdown of animal excreta. In a balanced system, the fixed nitrogen is held in the top, fertile layer of the soil, and cycled through plants and animals several times before it is eventually returned to the atmosphere by denitrifying bacteria. Thus the amount of nitrogen fixed by bacteria is balanced by the amount denitrified, and a constant amount remains in the biosphere, available to living things. If there is a localized build up of nitrogen products, they can seep down into the subsoil, into rivers, and eventually into the sea, a process which helps to balance out levels across different eco-systems – forests, coastal areas, and the ocean, for example.

It is estimated that the extensive use of the Haber-Bosch process over the past one hundred years has doubled the amount of ‘fixed’ nitrogen in the environment, with unknown consequences for the workings of the nitrogen cycle.

Understanding the Bocage

In order to understand why tampering with the nitrogen supply might not be a good idea, it helps to understand how the traditional countryside, known in France as the ‘bocage’, was designed to operate. In Brittany, the countryside was divided into small fields, each of which was little more than a quarter of an acre in size, surrounded by high banks planted with trees. This had the effect of creating a very stable soil structure – even when light ploughing was carried out for cereal production. The soil near the surface was rich in organic matter, constantly replenished by leaves from the trees, animal manure, and applications of compost, and the immediate under-soil was held in place by an intricate network of tree roots. There was very little opportunity for surface run-off of water, because of the banks, and drainage of water into the subsoil was reduced in summer, when the soil bacteria are most active, by the tree roots. This created an environment that allowed the maximum possible capture of nitrogen from the atmosphere, and the maximum retention of nitrogen released through processes of decay. The build up of nitrogen products in the fields led to the ground becoming more and more fertile, the more it wasfarmed.

Nitrogen Fertilisers

Of all the different elements present in fertilisers, nitrogen is the one that has the most spectacular effect on plant growth. When present in large quantities it causes the plant to grow at an exponential rate, creating a huge amount of green, leafy material in a short space of time. Adding nitrogen fertiliser can double or triple the yield from an area of ground:

However, it is now clear that there is a downside to what was once known as the ‘green revolution’.

• The nitrogen-induced growth pattern does not work well for traditional varieties, so new, short-stalked varieties have had to be bred.
• The rapid growth caused by the nitrogen, leaves the plants with weaker than usual cell walls, and they are therefore more susceptible to attack by aphids, caterpillars, etc. In order to protect the extra yield, farmers have to spray with insecticide and fungicide. These chemicals unfortunately have a detrimental impact on the ‘friendly’ organisms that form part of the natural balance in the bocage.
• Certain plants, most notably certain grasses, respond more to nitrogen fertilisers than others; when the fertilisers are applied to pasture land, these grasses flourish, and all the wild-flowers, etc. die out – with further detrimental effects upon insect and bird life.
• The addition of nitrogen to the soil, seems to have the effect of eliminating the natural nitrogen-fixing bacteria, which has a knock-on effect to all the soil-borne organisms, earthworms, insects, fungi, etc. The result is a degradation of the top soil, which in turn leads to a poorer level of nutrient retention, which leads to a further loss of soil organisms, more nutrient loss, and a cycle of reduced fertility. This means that over the course of time, more nitrogen has to be added, to provide the same results.
• Once the soil’s natural fertility has been lost, its ability to retain the applied nitrogen is reduced, and significant amounts of it find their way directly into underground water, rivers, and eventually the sea.

Animal Waste Products

One implication of the nitrogen cycle is that animal waste products (and in terms of biology this includes human waste) are part of the natural process of maintaining soil fertility. When applied to the surface of the soil in small amounts they are simply one element in the well-functioning nitrogen cycle: but if they find their way directly into the water course they become an environmental hazard. Unfortunately, parallel to the increased reliance on nitrogen fertiliser in the fields, modern agricultural techniques involve keeping animals in large sheds, with the result that huge amounts of waste products are produced in concentrated locations. Inevitably, these are not broken down properly, and a large amount of the nitrogen that they contain gets into the water system.

The Correct Response?

There are various ways to react to the facts relating to nitrogen usage in the modern world. One response, and this seems to be the most popular, is fatalism. Another, perhaps more understandable, response is anger – how can the people in charge have been so stupid as to have let something like this happen? This is, essentially, the sentiment that has underpinned the Green movement over the past thirty or forty years, but there is no sign that it has yielded any positive results.

Another response is to simply opt out of the modern nitrogen-fixing lifestyle: stop buying food that involves the use of nitrogen fertilisers, stop using nitrogen fertilisers in the garden, and reconstruct an area of bocage around your own home. Just because  Fritz Haber invented a way of fixing nitrogen from the atmosphere, we are not obliged to build our lives upon its products.