Page last updated at 23:12 GMT, Tuesday, 8 July 2008 00:12 UK

Snared in a homemade 'NitroNet'

Mark Sutton
Mark Sutton

Farming and industry are producing too much of a substance we ought to be concerned about, says Mark Sutton; not carbon, but nitrogen. And he would like to hear your ideas on what society should do about it.

The nitrogen challenge for developed countries becomes clear: eat less meat

Over the last decade, you have surely heard many views as to why you should worry about carbon and climate change.

But the chances are you're not worrying about nitrogen.

In fact, there is a global nitrogen threat out there, yet the world seems not to notice!

It's an issue that has recently been highlighted by two reviews in the journal Science.

In many regions of the world, humans are producing too much nitrogen, creating a host of different environmental threats.

Most of this nitrogen is made for a reason - we need it to fertilise crops and feed ourselves. Without it, it has been estimated that around half of the world's population would not be alive.

Put these parts of the problem together and you get what we might call the "NitroNet" - a complex web of nitrogen interactions that are difficult to explain and even harder for governments to manage.

And here you can already see why people on the streets are not yet talking about nitrogen.

Complex web

There are many different nitrogen forms, from atmospheric ammonia, nitrogen oxides and particulate matter, to the greenhouse gas nitrous oxide and nitrates in aquatic systems.

Each has different effects: increased air pollution threatens human health and biodiversity, disturbance of the greenhouse gas balance, and loss of drinking and bathing water quality.

It is the kind of complexity that is not easy to chat about casually on a bus journey.

All this makes for a double challenge to the scientific community; to understand and deal with an extremely complex system, while distilling out the simple messages.

This is where the Science papers start to help.

Rice farming
Nitrogen fertilisers fuelled the Green Revolution in Asia and Latin America

One of the ideas they contained is that we can distinguish nitrogen into two main forms - unreactive and reactive.

There is plenty of unreactive nitrogen in the world; this is the N2 that makes up 78% of the earth's atmosphere. But it can't be used directly by most plants or animals.

By contrast, reactive nitrogen (Nr) is all the other nitrogen forms that can be used.

In natural conditions, reactive nitrogen is in extremely short supply. Biologically, it can only be made by special nitrogen fixing bacteria, typically associated with legumes like clover and beans.

A century ago, a serious shortage of reactive nitrogen in agriculture limited food production in Europe, and encouraged careful re-use of manures.

How much nitrogen do we really need for food production? And how can we weigh up the environmental costs and benefits?

Since that time, two major new sources have appeared.

Firstly, high temperature combustion in vehicles and industry now oxidises more N2 to Nr. This contributes to acid rain, photochemical smog and particulate air pollution, the last of which may, for example, reduce average life expectancy across south-east England by 8-12 months.

Secondly, development of the Haber-Bosch process has allowed industrial-scale manufacture of reactive nitrogen fertilisers.

The benefits of this process for global food production have been immense, with synthetic fertilisers being the foundation of the Green Revolution. But along with the benefits have come hidden costs, as the extra reactive nitrogen pollutes air, land and water.

Perhaps the most dramatic changes are seen immediately downwind of large livestock farms, where atmospheric ammonia can completely wipe out certain wild flowers, bog mosses and lichens.

Seasonal problem

One message from the developing scientific assessment is that there are clear choices to be made.

How much nitrogen do we really need for food production? And how can we weigh up the environmental costs and benefits?

For example, Nobel Prizewinner Paul Crutzen has recently argued that emissions of nitrous oxide from fertilised biofuel crops can outweigh the carbon benefits of avoided fossil fuel use.

Others have highlighted a possible benefit of nitrogen in making forests grow faster, absorbing more carbon dioxide from the atmosphere.

But the decisions get even harder when dealing with multiple nitrogen threats.

For example, policies to reduce nitrates in water have banned wintertime spreading of farm manures across much of Europe's farmland. The resulting focus on springtime manure spreading has intensified peak ammonia emissions, giving a new threat to biodiversity and air quality.

The recent "odour episode" experienced in London is not unrelated, and likely to be repeated.

Food for thought

Future policies will, I hope, emphasise a smarter overall management of Nr in agriculture. The big challenge, however, will be for governments to weigh up trade-offs between the different nitrogen threats, and make better informed choices in international agreements.

Exhaust from car
Car exhausts produce nitrous oxides as well as CO2

Yet, there is also a simple challenge for each of us.

The cascade of reactive nitrogen from fertiliser bag to food on our plate is extremely inefficient, with losses to the environment occurring at every stage.

Eating meat and dairy products adds an extra step to the food chain, massively increasing the Nr losses. This observation can help us in our search for clear messages.

At its very simplest, the carbon story might be summarised in three short words: use less fuel.

At this level, the matching nitrogen challenge for developed countries becomes clear: eat less meat.

Of course, we all know that both stories are more complicated. But for nitrogen, this is a message that needs to be shouted much more loudly.

According to World Health Organization guidelines, many of us eat more animal products than is good for us.

As we begin to untangle the NitroNet, we could even find some health benefits too.

Mark Sutton is based at the Edinburgh Research Station of the Centre for Ecology & Hydrology

He is co-chair of the UN's Task Force on Reactive Nitrogen (TFRN), director of the European Centre of the International Nitrogen Initiative (INI) and co-ordinator of the NitroEurope Integrated Project

In collaboration with the European Science Foundation, his team has developed the NitroNet online pollwhich you can use to register your views and priorities on the issue

The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website

Do you agree with Mark Sutton? Is reactive nitrogen something we should be concerned about, or at least thinking about? Should farming and industry be helped, or forced, to reduce their emissions? Would a mass switch to vegetarianism help?

To those that say 'we are Omnivores not Herbivours' i would counter (as a meat eater) that 'we are Omnivores not Carnivores.'The fact is that meat consumption in developed countries(and countries such as China and India that are starting to emulate them in transport and eating habits)has skyrocketed in the last hundred years. Whereas meat used to be eaten once or twice a week, in addition to the tradional Sunday roast, it is now rare in the US and Europe to find any meal that deos not contain meat, an increase in consumption that is obviously unsustainable!
Edward Salt, Nottingham, UK

SURE, eat less MEAT and CONSERVE HYDROCARBONS. Very SIMPLEM Difficult to Greedy Human.
Mohan.Dudani., Atlanta,USA.

I tend to agree with other peoples comments that human population is a large contributing factor to this and other issues we facing. I have long felt that the global population needs to contract but as pointed out by others here, it is a very sensitive subject and not one that is easily approached. Whilst a reduction in human population would reduce our impact on the planet, it would also have a detrimental impact to the life style of the remaining people, especially in the industrialised west where we have a large benefit infrastructure to support. Even if you don't take into account the benefits paid to the unemployed (working on the assumption that fewer people means fewer unemployed)there is still a heavy burden for the retired, disabled and children. A reduction in population wouldn't only mean fewer material goods would be bought and therefore manufactured, but also that there are fewer people paying taxes to support the people who have retired and need financial assit! ance. Any move to manage a population reduction would have to be very carefully considered, and would probably be political suicide for the political party that tackles it meaning that it is very unlikely to happen. More likely that we ignore the root cause of so many of the issues facing the World, and continue to try to patch up the issues with flimsey fixes.
Phil, London

Don't get me wrong, the effectiveness of "commercial grade" nitrogen fertilisers are probably better, but considering male urine is a huge source of nitrogen every healthy male could be contributing instead of factories "artificially producing" it. Oh but how could we pee on something we're going to then grown food in, that's so unhygenic, like using animal poop.... oh wait..... The Chinese have been adding urine to gardens for years
John Knight, Neath, South Wales

A simple way to reduce polution from vehicles would be to reduce the need for travel. A high proportion of working people in this country are employed in offices. If they were all given the option of working from home instead (even some of the time) we could see a vast reduction in commuting journeys. The technology exists to do this (and has done for about 10 years) but there is a marked reluctance by employers to implement such schemes. Where they have been implemented, productivity and job satisfaction has gone up and absenteeism and sickness have gone down. One of the worst employers for non-implementation are the Government and Civil Service who are still, in this day and age, suspicious of their employees. This has a general de-motivating effect on all those employed by these organisations. If enough people worked from home there could be an increase in local shopping and entertainment and we could see a modern re-birth of village shops and society. Martyn A. Main FRSA Specialist Instructional Officer Ministry of Defence
Martyn Main, Blandford Forum, Dorset, UK

The soil testing I have done on my garden soil shows that it is deficient in Nitrogen. This shows I am not one of those destroying the world.
Bruce Sinton, Gisborne, New Zealand

Unfortunately for those people who think controlling population is evil/wrong/whatever, I'm sure few people posting here would suggest lining people against a wall and shooting them is a good plan at the moment. Just wait until the population reaches crisis point...Then we will have war, then we will have people being lined up, then you WILL see the evil in humanity. If we dont start taking measures like suggesting to people that they dont need to have 6 children, and/or preventing them from doing so, you will be a particulary unhappy person in the future.
General Disarray, Norwich

As usual a load of hot air. When will people realise those that make decisions will only do so if there's plent of and $$ involved. The reason we have carbon and Nitrogen problems is due to short term lazy narrow focused thinking driven by greed. Unless the issue of being driven by $& is tackled then you can forget us seeing these solutions being deployed quickly or effectively. EVERY MAN FOR THEMSELVES. ABANDON SHIP

I believe the message is not "eat less mean". The true message is "you will have less meat to eat". And that's quite different. And we will have less water too. We already have less freedom. The dream of reason produce this kind of Democracy. But it seems people love that, so it's ok.
Fabio, Milan, Italy

I do find it interesting that you very rarely hear anybody mention the 'Precautionary principle' when it comes to convincing the doubters of climate change. All of the talk about climate change often has a negative result as many people are often blinded by science and fear the change required to avoid this crisis. So whenever I am asked whether climate change is going to happen or not I simply say " all the arguing is irrelivant. All we need to know is that if there is any possibity that climate change is going to happen, it is better to do something now and be wrong later, than do nothing and be right."
David Smith, Manchester

please note: I am not advocating killing anybody, so please don't waste your time telling me how evil I am. However, the human population of the planet is growing hugely, because of the amazing advances in medicine and agriculture that allows more people to live longer. This level of growth is not sustainable. Surely it is not too much to ask that we think about how much we consume and how many children we have? I have chosen to have none. I shall probably have a miserable, lonely old age. There will be economic consequences for a falling population; but actually we have little choice; either we cut our population, or the planet will do it for us.
bug, UK

"Third world countries need to learn about this stuff. Anyway, we've already solved this "complicated problem" as you call it in the good ol' US of A." That's funny. In about 30 years America will be a third world country. America has always been great at solving mass-production problems though (e.g. Penicillin). Maybe if the USA spent their war budget on developing this technology you speak of then they would be helping the world for once. I say we should make big cardboard cut outs of rhizobium and scare all the nasty Ammonia away.
Ciaron Dochartaigh, Belfast, Ireland

Trevor Barker of Guildford, UK - You are absolutely right. And since EACH average US citizen pollutes 4 times as much as Each average Chinese citizen, we should kill 4 Americans for every Chinese. The same holds true for the Brits who pollute "only" 3 times as much as the Chinese. Keep this up and the Chinese will soon own the world !! BTW, are you volunteering to be one of those killed off so that others can benefit more from the dwindling resources ?? Well done !! You will get your reward in heaven, I'm sure !!
Ishkandar, London

Nutrient enrichment of our biosphere is not any longer only noticeable in our open water (dead zones, red tides), but the increase of this reactive nitrogen in our atmosphere, due to increased use of synthesized fertilizer and the burning of fossil fuels, now causes green rain (rain with fertilizer) that is causing grasses and brushes to grow well during wet weather, but become a source of fuel during dry seasons and are making range and wild fires hard to control. Although reactive nitrogen also has an enormous impact on global climate change, it is hardly mentioned in the media, more then likely because the nitrogen cycle (unlike the oxygen, hydrogen and carbon cycles) are complicated and occur on land, in water and in the air. Last year Utah experienced very large range fires close to an area where they have CAFOs (Confined Animal Feed Operations) and where the manure is dumped into self contained lagoons and while the ammonia is stripped out of such lagoons, this can not be regulated by any State Agency. The fact that EPA does not consider nitrogenous (urine and protein) waste a pollutant and allows rivers still to be used as urinals, does not help either even discuss what the impact are of this general nutrient enrichment of our biosphere.
Peter Maier, Stansbury, UT, USA

I think we shouldn't even bother with green taxes and reducing carbon emissions until the U.S.A sign the kyoto treaty..compared to the pollution the states produce europe is completely minimal, so why does no-one ever challenge them on this? it seems to me that all global leaders are just too scared to tackle the real issue, instead they try and get more money out of the europeans who already make quite a big effort to be environmentally friendly. i do not know enough about these issues but i think someone who does should cover it fully and get an answer.
Brian Surgenor , Troon, Scotland

The panic focus on how to keep cars on the road but in a 'green' way e.g. biofuels, carbon taxes and the such-like, doesn't seem to have taken all avenues into consideration. What do cars do for us? The problem they fix is getting from A to B. So in essence it's just a means of moving faster than walking pace. I can't help but think that we have become blind in this area, mainly thanks to our complete reliance on cars. After all, who among us 'developed' countries could imagine our life without one? Whatever would we do? I think we need to seriously consider totally green transport methods - horseback and cycling being my two frontrunners. The technology for bicycles already exists, and you can't get much greener than a mode of transport that uses grass for fuel and produces nothing more harmful than fertiliser! Why is it so inconceivable that we return to the ways of old? It worked before, it still works now (just ask Mongolia; horse is the de facto mode of movement there!), and it can work again if we let it. Desperate times call for innovative thinking, and we seem to be doing very little of that by refusing to accept a world without cars.
Paul Marshall, Cambridge

With GB's recent comments on food waste, and the ever increasing bio waste from all types of industry as well as sewage, isnt it time to look at methane recovery from such sources as well as the ever present cow flatulence. The Schweppes factory at Wakefield use a bug digester to dispose of waste from its drinks manufacturing and at the same time produce methane for heating, surely better than letting it go to atmosphere. All it would take is a bit of effort and the will to succeed, the technology is already there. Pump the methane straight into the national gas grid and we also reduce our reliance on foreign gas.
Robert Penketh (Grim Northerner), Barnsley

While I fully respect people's decision to become vegan or vegetarian, I do wish they would cease making totally unfactual statements about how humans "are supposed to be vegan". Our hominid ancestors were largely vegetarian. Their digestive systems were correspondingly larger and more complex and their brains were smaller and less complex. As they evolved to eat more meat, initially carrion and eventually cooking it, their digestive system shrank as it no longer needed to digest huge quantities of vegetable matter and brains grew vastly larger and permitted a constant evolution that lead us here today. In the long term, no one at all knows what the entire human race turning vegetarian would do to our future evolution. Every part of our body is designed as an omnivore (teeth, brain, eyes, digestive system) and to argue against this seems ignorance and even folly of the worst sort.
Gary Sparkes, Bangkok

"This issue and the problem carbon climate change issue further highlight the rarely spoken solution of human population control. Reduce the total world population and balance will return. Why is this not seen as an answer??

Dennis McCarthy, Hatfield UK

As you seem to have worked out the answer, it seems the solution is clear! Then once you've ended your life for the good of mankind we're one closer to a manageable population. ... Oh, you mean killing 'other people' or banning 'other people' from reproducing, well isn't that typically self centred.
John, Northampton

Eat less meat is not the answer. It is a ridiculous claim. If animals were smarter than us & more advanced what do you think they would be eating??? HUMANS or bits of grass & leaves??? Idiots. Well here is my solution which concerns the fuel. It is incredible that people in similar style jobs travel between towns & cities when really they can find work in their OWN town / City. So what if its not some flashy marketing job most people can survive off 1000 - 1200 a month net easily. I now work 3 miles away instead of 50 miles. This will do more for the environment than simply not eating meat. You do the maths Veggies! That aside all thats really happening is your delaying the INEVITIBLE. This planet will die long before the sun explodes into a supernova. What do you plan to do then? Most people dont give a toss about the environment because they already pay their way in society & do the recycle bins every 2 weeks etc... & are not in control of what 'harmful' products are bought & sold in the world. Blame the government not us MEAT EATERS We all know what is ultimately gonna happen anyway........

Dave Knowles, Burnley

Not only nitrogen, but methane and the silliness of creating pills to stop cattle producing more. Remember the old Sunday Roast and fish on Fridays? By all means, eat your meat, but it isn't healthy for humans to eat so much of it. Eating more meat is no longer a sign of wealth, but a sign of ignorance. Better quality instead of quantity.
Sunday Roast, London

All this talk of population control like only having one kid per family is crazy.You lose the future workforce and soldiers.The solution would be to kill off the old.The cost and burden on society that the elderly produce make this the right solution.If thats the way you want to go.I think if everyone gives up on our bad habits we will be fine beside you could always put people in space?????
phil, florida

Inspired by the comment by "Mike G" I feel obliged to emphazise what Mr Sutton already said: Nitrogen in the environment form a complex (!) web consisting of nitrogen in different forms. No need to list them again here. NOx is by no means a new found hazard anywhere in the world. But what is less obvious for most people, certainly for Mike G, is that NOx is not the only gorm in which nitrogen is harmful. The Baltic sea is one example where the use of nitrogen as a fertilizer has gone terribly wrong. When nitrogen drains out into the sea from the fields, it over-stimulates algae growth, which then empties the oxygen supply. To quote the WWF: "As a result, the Baltic Sea is now one of the most threatened marine ecosystems on the planet."
Thomas B, Turku, Finland

it's obvious that mankind is out to destroy itself. The last couple of hundred years we did not make any progress. We're not advancing towards worldwide peace, we haven't made any sustainable technological "improvements". We gloat that we are more civilised, smarter, etc, etc..... It's a total LIE!!!! IN the last hundred years we had two devastating wars. The colonial powers ditched the countries they sucked dry to become so called "democracies". We have become people that morgaged our and our children's futures for socalled progress. The only progress we have made is to become so absurdly political correct that it's loathesome. We even pride ourselves into a godly stance regarding the way we manage our planet and it's resources, we're ALWAYS on the moral high ground on every bloody topic in every bloody country..... Yep! We have made good progress in destroying our planet and ourselves with it!!!
anthos, pacific islands

Possibly the biggest elephant in the room is peak phosphorus, as highlighted in the Times online article of just over 2 weeks ago. As prime phosphorus mineral sources are used up, what will that do to the cost of food and farming - the present bottleneck in supply is already hindering agriculture farming in some developing countries. An especial reason to tackle population growth, perhaps easier said than done.
Jim, London

I eat mostly vegetarian, no meats. In November my organic garden will be planted over with Fava/Broad Beans. These produce edible beans in February to April, fix nitrogen in the soil at the roots and tops can be plowed in. The Organic seed company, Seeds of Change say:- they are fairly cold hardy; they fix nitrogen when used as a cover crop and tilled into the soil before they go to seed which increases the fertility of the soil probably as rapidly as any known plant; they are vigorous, some growing up to 8 ft. tall; they are bushy and don't need to be staked or trellised; and the flowers are beautiful and fragrant. (Bees love them.) The beans, in the pod or shelled, are delicious. The larger-variety beans tend to be sweeter. Eating some and tilling some in, as an individual I can do this.
Jean Macfie, Hamilton, Georgia, U.S.A.

We have known of the problems with nitrogen pollution for years. There are a number of things the human race could do to limit the damage, but at the end of it the real issue is obvious. It's world population and human greed. Convincing people to only take what is necessary is incredibly difficult as its part of our nature to 'secure' our lives by making sure we have more than is required. Until we can reduce and control our population, the other solutions are futile.
General Disarray, Norwich

A big problem with reactive nitrogen compounds is that they are extremely water soluble. So most of what is applied to farmland ends up being washed away into the groundwater, and ends up as a pollutant. The solution to this is to combine reactive nitrogen compounds physically into something to make them dissolve slowly into the soil. I know the French were experimenting with making fertilizer glasses fifty years ago for that very purpose (I ran chemical analyses on their glasses). It would use much less fertilizer, need to be applied much less often, and would cause much less pollution.
Richard Vineski, Wappingers Falls, NY USA

I think it's pretty much a given that we need to phase out the ICE (Internal combustion engine). It is a technology that has outlived it's usefulness. Once done, That source of Nitrogen will go away. As for the Fertiliser, You can mix your crops with nitrogen fixing plants and minimise the issue. I'm convinced we have the solutions, we're just using them the wrong way. Monoculture is an ecological disaster.

Kenneth Spicer, Long Beach USA

The obvious way of dealing with the problem of animal-related Nitrogen emissions and pollution is not to farm animals! There are plenty of examples of 'stock-free' agriculture and horticulture, where 'green' manures are used in place of animal manures. There is a lot of information at - the Soil Association in the UK even has an organic certification scheme for stock free growers.
Martin , Solihull, UK

Bob Carter - maybe some real empirical science would be nice Here's a brief intro for you guys: and though I doubt you'll read this, maybe if you actually read some scientific documents, you would soon see how foolish your bias against 'climate skeptics' looks to the educated world
Bon Smith, Bracknell

It would seem obvious that solving technologically induced problems by adding more technology is counterproductive. The fact is, humans have overpopulated this world, and it is time either to let mother nature randomly select who will go, or we can make rational decisions based on which groups of people are least valuable to the human race. People are going to die, the only choice we have in this whole scenario is who will die. I think we should get together and make a decision about this. Let's stop regulating technology and start regulating the real problem, humans. Wiping a billion or two of us off the map would certainly do us all some good.
Nicholas Nickelman, Oregon, United States

Once again humans are involved destroying our planet for spurious reasons. If we cannot farm without chemicals then we should not be reproducing so much. But not to worry. The disaster waiting is not for the planet but for us. Eventually, when humans are gone, the planet will regenerate and hopefully animals will be able to be free.
joao, Sacramento California USA

While nitrogen based fertilizers pose some risks, the benefits far outway the risks. Mr. Sutton points out that "some studies" suggest that Nitrogen from livestock farms have reduced life expectancy by 8-12 months - what he doesn't mention is that the same technology has doubled life expectancy in the last 150 years - so, losing 8 months is not so bad... Additionally, to suggest that we are herbavors is fantasy. Man is an omnivore - we need both vegatables and meat to be healthy. While Vegans may tout their lifestyle, they must go to extremes to remain healthy and have the same energy level - no we are not herbavores, we are omnivores.
Larry Kealey, Sugar Land TX, USA

To all you advocaters of Human population reduction - Why not kill yourselves if you feel so strongly about this? If you truly believe that this is the answer then why not lead by example? I presume that none of you are willing to be one of the 3 billion, yet you would no doubt be quite willing to watch the systematic slaughter of 3 billion human beings just to make your life easier. Tell you what, let's start with some of the poorer afican nations, they're too poor and downtrodden to object, then the indians, they're getting to industrialised these days and taking all our precious resouces, as are the chinese, then once that's done let's kill the prison inmates, then the disabled and mentally handicapped, anyone who doesn't figure into this fantastic barren once populated world... does this remind you of anything? (think 1939-1945). Truly idiotic arguments from idiotic people, I'm sure you are all well meaning (well actually, I think you are sick) all full of great answers, but no meaningful suggestions for how it would be implemented, who would be executed... sorry murdered in cold blood for this great cause, and how we would decide who is worthy. Solve that problem, and I'll commit suicide with you!!!
doug, Glasgow

A correction: I said that here in Kenya the problem is not so much eating meat etc... That's true enough, but I didn't mention the problem of what happens to that meat after we've eaten it, our - let me use the word "humanure", oh happy coinage! - because we ain't got much sewerage here. Interested readers may like to Google the phrase "flying toilets". On reading the correspondence, my long-held and reluctant opinion that we have to ratchet back the global population if we are to avoid what looks like a good, old-fashioned Malthusian crisis begins to look like fact rather than my personal view. But oh, proper drains and sewage works would make it all so much more comfortable...
Edward Freeman, Nairobi, Kenya

What really frightens me is that a commenter here has suggested that the Earth needs to be depopulated of humans. And I have heard others say it as well, so I know that this commenter is not alone in their thinking. I'm almost afraid to ask what draconian measures they would use to depopulate the earth, and whether the commenter cares that many people in Africa and India are already starving to death from the surge in global food prices? Do they not care that increasing food prices from nitrogen regulation will effect more people? Are so many people blind to the plight of the third world that rather than letting them use fossil fuels for basic amenities such as electricity and running water, that we consider the plight of a dandelion? The commenter and indeed others who subscribe to this mode of thinking should be ashamed for ignoring and abandoning your fellow man to starvation, disease, and death.
Jeremy Blasongame, California, USA

Well the world is killing it self thats the true and i have to say its making a good job.
David Teixeira, Lisbon/Portugal

Personally I think its all hype and nothing to worry about. Do we actually have the audacity to think that we have that much of an effect on this world? We've done everything we can to destroy nature, cutting down the forests, mining, etc. The planet is fine. The planet has been here for 4 1/2 billion years. We think we are a threat? The planet has been through far worse than a few animals taking some resources; Plate tectonics, erosion, solar flares, asteroids, volcanoes, continental drift, reversal of the poles, gravitational stress, ice ages, floods, cosmic rays... and we think... we are going to make a difference? The planet is fine.
Robert, Texas, United States

Biochar is a modern form of the charcoal found in Amazonian Dark Earth, which is about 20% by volume carbon in an activated charcoal form. It improves the soil by trapping nutrients in a form which keeps them from leaching, but keeps them available biologically. It is this soil which is hypothesized to account for the huge native population of the Amazonian basin when the first Spanish explorers arrived. When they returned a few years later, the population had drastically reduced--and the knowledge of the usefulness of the process was lost as the remaining population reverted to slash & burn and hunter & gatherer economics. Potentially, this practice could eliminate most if not all of the added nitrogen fertilizers in use today. Of course, many farmers still use too much fertilizer by acting according to the company sales literature--which is geared not to optimize cost-benefits but to optimize the profits of the manufacturer. In Wisconsin, over fertilization has led to highly polluted algae-choked rivers and lakes.
Charles Barnard, Menomonie, Wisconsin

Let's not forget to reduce waste!!Civilized society is wastefull on a grand scale. I just ordered an Apple laptop & watched the tracking of it's delivery. I'm astonished! Point of origin=Shanghai,sent via jumbo jet to Anchorage,Alaska then again to Oakland,Ca.,again to Ontario,Ca.then local FedEx delivery. We all know there are people capable of building that laptop on this side of the globe but it's X amount of $$ cheaper to build it on the other side. The same with so much of our productivity. How wastefull to use supertankers & jumbo jets to distribute goods around the globe when we CAN build them localy. Think about the size of the fuel tank for each vessel as well as the exhaust exuded from the backside of the 4 engines of that jet or supertanker. Yuck!! We can do better but the Wal-Mart syndrome is rampant. Save me 10 cents please and the heck with the small "mom & pop" businesses.
Phillip Mieszala, Ridgecrest,California

The 3 short words regarding Nitrogen also equally apply to Carbon. Eat Less Meat - means less animals producing both Nitrogen and also methane. It also means less crops are used for animal feed, which in turn needs less Nitrogen to grow, which in turn means less oil consumed to make it. When the oil runs out things will change, and it will probably fix some of the nitrogen issue too.
Garry, Cambridge, UK

Why cant we stop Co2 (Cars), and make hydrogen cars that can really blow down the Co2 that's realsed into the arctica, We need to help the polar bear's (Facing extinction) from Co2, We realise ton's of Co2 is pumped into the air every day, Thank you.
azad, london

Yes, yes and yes. Yes - extremely. Many forms of nitrogen based pollution are recognised as extremely detrimental to health and causal in a wide range of terminal diseases. In addition many other effects can at present only be suspected because they are insufficiently researched or too difficult to isolate. The rivers have run pea soup green for decades because of the use of nitrogenous fertilizers, with devastating consequences on our freshwater ecology. Worse still, they have by now reportedly contaminated all our aquifers such that supposedly potable water is arguably unsafe to drink. The water companies don't tend to publicise this for obvious reasons, while spending millions annually trying to ameliorate it. But once a contaminant is present in an aquifer it is impossible to remove it, and even after treatment traces will remain in the public supply to the detriment of everyone's health. Yes - absolutely. For all those reasons. It is scandalous that such indiscriminate use of chemicals with such dire public health consequences was ever allowed. It needs to be curbed urgently. Likewise it is time we woke up to the reality that every car driver is actively assaulting the health of every person they drive by, as well as the surrounding ecology and the built environment. To pretend that a conscious action more harmful than smoking is a benign, positive, respectable and responsible thing to do is to remain utterly in denial over this crucial and literally inescapable issue. A day will come when car drivers are treated with the opprobrium currently reserved for smokers - and with greater reason when these costs are added to their too often vain and frivolous contribution to climate change. Yes - indisputably. Thank you for yet another irrefutable argument for an essential step equally demanded of us by climate change, the equity of food distribution, morality and spiritual arguments.
the pensive prognosticator, chesham uk for now

Um, where have you been for the last 30 years? We've already waged an aggressive campaign against harmful nitrogen emissions into the environment, well, we have here in the US. NOx emissions are controlled by low-NOx burners on equipment, and other NOx controls like Exhaust Gas Recirculation valves in our cars. CARB has mandated maximum NOx emissions for quite a while. In the farming sector, we have stringent water runoff quality restrictions imposed by the EPA. If you're still having problems with this stuff in other countries, simply adopt the US's environmental quality standards for it, and you'll be in much better shape. At any rate, it is true that NOx emissions are much more dangerous than the inoccuous CO2, considering the ecological implications of the acid rain and other things. Third world countries need to learn about this stuff. Anyway, we've already solved this "complicated problem" as you call it in the good ol' US of A.
MIke G, New York, NY, USA

Surely the problem is that there are simply too many humans on the planet? Too many humans emit too much carbon dioxide for the planet to absorb. Too many humans require more food than the planet can produce without ruining many of its ecosystems. Too many humans use unsustainable quantites of the planet's finite resources. The solution: ultimately, we must reduce the human population. The other measures simply affect how much we need to reduce it by.
Trevor Barker, Guildford, UK

Of all the hype about 'Green' issues no-ne has taken up the fact that adding 20% water to food which is then taken by road around Europe is an easy target to cut pollution and waste. Sve the energy by not injecting water, save fuel by not transporting unwanted water in the products and save pollution by not having the water run out of the food when it is opened up. Is this too clever for the so called greens or are they frightened of the big companies and the Megalomaniac Eurocrats?
Derek, Sunderland

A timely concern, but one that economics may well solve for us within a decade. Since according to the World Energy Group we reach peak oil production in 2006 and are now seeing the beginnings of the economic consequences, the era of "cheap oil" is over - yet with nitrogenous fertilizers already making up over 60% of the overheads of intensive arable farms, it is only a matter of time and simple economics before our spendthrift approach to nitrogen becomes untenable. Result: we will have to eat less meat.
Andy McKee, Dorchester, UK

We waste a huge amount of fertility each and every day, by flushing our human waste products down the lavatory and into the ecosystem. If we were to compost our own poo (humanure) and return this to the land, along with farmyard manure and compost from food wastes and garden trimmings there would be far less need for the use of chemical fertilizers. As oil becomes ever more expensive and hard to obtain we will need to manage soil fertility without these crutches anyway. It's far better if we embark on this serious process now, while we still have the crutches in place!
James, Taunton

Amen and amen, but rather than thinking about Nr losses between the bag and the plate, why not think about farming systems that don't require it, then we can miss out the CO2-expensive step of the Haber-Bosch process as well as see the benefits to our rivers, ground-water, flora, atmosphere etc.
David, Lincoln, uk

This issue and the problem carbon climate change issue further highlight the rarely spoken solution of human population control. Reduce the total world population and balance will return. Why is this not seen as an answer??
Dennis McCarthy, Hatfield UK

The analogy with carbon is a bad one. We can measure the build-up of carbon dioxide in the atmosphere over the last century. On the other hand, Mark is offering no evidence that there is a dangerous build-up of nitrogen compounds anywhere in the environment.
James Allwright, Basingstoke, UK

I hadn't thought of acid rain as a source of high energy reactive nitrogen for plants. That's a good idea. Obviously, what we need to do is develop plants, or at least weeds, that can make good use of the more available reactive nitrogen and carbon dioxide to grow better. I've heard that some weeds have already stepped up to the challenge and become more proliferic with the greater availability of carbon dioxide.
Ralph M. Lake, Reston Virginia USA

Well said Mark Sutton! This issue does need more publicising. It may not be very easy for many people in our society but our diets ought to be largely vegan (not even vegetarian), with meat being consumed as a treat. I recommend Michael Pollan's book 'The Omnivore's Dilemma' for more information on this topic.
Clare, Liverpool

In mainstream Horticulture the use of fertilisers is always highlighted as a necessity. I have just started research on soil food web and no-dig methods of cultivation and found that there are indeed ways in which to grow crops without relying on man-made chemicals. The only catch is that this kind of agriculture/horticulture demands more knowledge and a nurturing attitude towards nature from the food producers. This is of course incompatible with extensive farming. I believe sustainable agriculture could be a reality if only mankind would realise we are overcrowding the planet and therefore cannot work with nature. Politicians should start discussing population control on the mainstream media and should stop listening to the Montsanto lobbyists.
Mara, London

I've been vegan for over 17 years now, mostly through compassion for animals, but also, out of respect for the environment. Animal farming also, vastly contributes to carbon levels and in fact, puts more carbon into atmosphere than cars, also huge quantities of methane as well as nitrogen. Humanity must at some point accept that we are designed to be herbivores - a vegetarian diet without dairy products is better for health, mind, body & spirit and better by-far, for the environment. Meat & dairy production is a filthy, inhumane business; when will we learn?
Deborah Mahmoudieh, Dinnington, Sheffield, England

Well, well, more bureacrats telling us to live poorer lives and, fancy that, to inrease the amount of our taxes that are paid to the bureacrats to produce yet more garbage reports telling us to ... (repeat ad infinitum) Wouldn't it be nice if there were some competent journalists who would make the effort to expose these people, instead of just copy-typing their press releases.
Freddy, London

I do agree. As a nature reserve manager I have seen losses of wild flowers in woodlands, grasslands and heathlands and increases in more competitive plants - the result is an increasingly bland and homogenous array of plants in our most special natural places. I think that generally the more intensive the farming system, the bigger the problem. So extensive, possibly organic, systems shoud be better. Cars and industry create more widespread nitrogen pollution and so curbs on fossil fuel use should also benefit N pollution. Ultimately the answer lies with the consumer - we need to lose our dependency on economic growth and learn to balance our environmental budget. The hardships that people fear might just be compensated for by the rewards of living a more natural life.
giles strother, Oxford

Nitrogen and phosphate run-off from farms and factories is a well documented and very real problem. A recent topical example being the algal blooms off China's coast.
David, Cheshire

If the article is correct then it seems there are 2 obvious ways to reduce this. Telling people to be vegetarian seems unlikely to do much, given how angry and irrational people get in defence of their daily burger. Firstly, remove subsidies for meat & dairy food production & ban the import of food (including animal feed) grown on land that is currently rainforest. The price of meat will then better reflect its actual cost and rise, suppressing demand. Secondly enforce mileage standards on cars to reduce the amount of petrol burned, and have government sponsored research to support future technologies like plug-in hybrids, hydrogen fuel cells etc.
Mark Richardson, Durham, UK

maybe reactive nitrogen is something we should be concerned about. It looks like a small increase in nitrogen oxides could switch the oceans from a sink to a source of ozone. Please read the following article:
Salvatore Sisinni, Ciampino - Italy

Here at IBERS in Aberystwyth, we take nitrogen use efficiency very seriously. Over the past decade we have been breeding new forages that require less nitrogen and also reduce emissions from ruminants by improving protein digestion efficiency.
Dr Richard Hayes, Aberystwyth, UK

Trouble is now most of Europes soil is technically desert we have no choice to keep using nitrogen if we are to feed the population and make 'green' fuels. A mass switch to vegetarianisim wouldn't change much as more upland areas where soil is poor will need to be used to produce crops which would in turn need more nitrogen!!!
Penske666, Sheffield

Mark Sutton - you are concerned that we have yet to wake up and think about another symptom gone wrong - I am concerned that we have yet to wake up and think about the fundamental problem behind all these symptoms - Human Activity levels Human Activity = (Indivudual Impact x Number of individuals) Nitrogen is only one more "dot" to join up, along with Carbon, deforrestation, loss of biodiversity, over fishing, drinking water, food prices . . blah blah blah. These "the" things are simply dots to join up to complete the picture; the picture is Human Activity. I agree with Mark Sutton "without this stuff, half the people would die" - well, we are destroying all this stuff - and in the next 20 - 25 years. This is all going to hurt like hell; this isn't some acedemic exercise for the Grandchildren; this is real mincing machine time for us ! Now - the problem is this; how to "think" our way down to soft land 6 billion people, and MANAGE it down to 3 billion people. Our present mind set is "more more more" - more economic growth, pays for more people, who inturn buy more shoes, which in turn provides more economic growth. Now; if the entire mind set of governments and economists, and business; is more more more; then they are simply digging us deeper and further into the hole ! So; the population was 3 billion in 1973 - and funnily enough, the economy was fine for 1973 . . so there is nothing economically wrong with having 3 billion people on the planet; so that bit is OK . . so how do we do the economics of planning a strategic retreat back to those numbers ? Zero the bith rate; leave natural mortality to do it's stuff and wait; obviously there is a limit to how long you can shut down human fertility; 20 years seems about a maximum; after that we loose infrastucture, bith problems etc; 20 years is about tops; then at 20 years, couples who want to have kids, have 1 kid, then we shut it all down for another 20 years and so on. The only tricky bit is to convince the politicians and the economists that it's OK to sell fewer airline tickets next year, and it's OK becasue there are fewer people to pay for; so it will balance out - it's OK. So; I'm mad; I'm crazy to suggest such a thing; I'm a dictator, I'm a deranged crack pot ??? Read Mark Sutton article again; this is happening, and half the population is going to die - and 20:2:1 is happening; in Japan, they are worried because due to the sheer stress, pressure and cost of living on a tiny cramped little island; the people have stopped breeding; the average couple (2 people) are having 1.7 kids. The Japaneese economists are fretting about this because there will be fewer consumers to buy things . . . but where is the problem; only in their minds; natural bilogy has had enough; so the economists will have to "evolve" to the new facts of life. This is happening; as it gets tougher and more stressful people - any animal will - stop breeding; few people need fewer shoes - simple as that ! Mark Sutton says "half the poeple would die"; and he seems to feel this other symptom of our present levels of Human Activity is in crisis. So what do you want to do; lie in the gutter waiting for the ecosystem to collapse beneath you - or do you want to act like the smartest monkey in the jungle ? - like the people who flew to the moon, and tore down the Berlin wall with our bare hands ? What's it going to be - squabble as the ship sinks beneath us - Ot have a sensible, practical, plan; to come out of this a wiser, fitter, leaner, smarter species; living in balance on a green fresh healthy planet ? Evolution doesn't operate a pension policy; no deck chair on the beach at the end of it. We screw this up - and that's it !
Steven Waker, Penzance

I'm glad to hear that someone is working on this at the UN level. Here in Kenya the problem is not eating meat - livestock are farmed extensively rather than intensively, on the whole - but rather high fertilizer inputs to high-value crops such as roses. I assume that the Nitrogen Task Force are also working with the treaty bodies that aim to prevent land-based pollution of the seas. Our marine parks in Kenya are under threat from this. What are the possibilities and problems of returning to the careful husbanding of organic nitrogen we used before we could make artificial nitrogen fertilizers? Are we in a cleft stick of our own making here, if we reduce nitrogen use to that level we can't grow enough food, if we continue as we are going we kill off our environment? I ask in all seriousness.
Edward Freeman, Nairobi, Kenya

Reactive Nitrogen is certainley something that we should be thinking about, as Mark clearly states society is at a loss as what solutions would decrease or at best manage our use of RN effectivley. Direct action is required ASAP but any bright ideas will be thrown around the European parliment untill they become as useless as some of this Nitrogen. And while countries are killing their peoples income with green taxes, it would be interesting to know exactly how much of these taxes (%) go to solving the RN problem.
Paul Mc Williams, Derry, N Ireland

Talking about excess nitrogen, my company has been approached by a group of chicken farmers who want to get rid of 40,000 tons per year of chicken poop. If anybody has any ideas for an environmentally-friendly use this manure mountain, please let me know!
David Smith, Singapore

The fundamental problem of a high population and population growth is the issue that needs addressing. Population growth is not sustainable. If this is addressed, then managing the pollutants is achievable. The only country to addres this is China. When will the rest of the world realise this? Look at the population growth in India, South America and the Far East. Even Europe and N.America are not doing well. The Leaders are too scared to make radical changes of any kind.
Mr B, Oxford, UK

Surely the increased reactive nitrogen threat is a double edged sword by its direct proportional link to increased methane production - a more effective destroyer of the greenhouse gas balance than CO2.
Allan Riley, Leeds

It's unfortunate that society is running into yet another problem to add to our long list already, from global warming to war. However, what does appear even more apparent after reading this article is the need for all of us to reduce our dependence on meat, and for me this means I most definitely need to return to being a vegetarian. Thank you for article. I'll be sending links to friends and colleagues. Sincerely, Will Fuqua
Will Fuqua, Nashville, TN

For heaven's sake! A bit of bog moss loss downwind of the odd livestock farm and a contribution to a spot of acid rain in Norway hardly ranks up there with the deforestation of the Amazon. Nitrogen pollution needs to be tackled by good management and appropriate effluent treatment but it isn't worth becoming a vegetarian for.
Gillian, cmb

Humans have been pushing their luck for too long. It should be obvious by now that we have over extended our lease on life on this planet by about a factor of 6. Mark has brought Nitrogen to the discussion which has so far been about Carbon. I am sure there is going to be more. And I am also pretty sure that applying more technology to solve the problems which were created by technology in the first place is only going to make things worse. Perhaps unravelling the complex artificial and all too superficial life that we humans have created for ourselves and going back to the basics and starting over smarter and wiser might be the only real solution. In the meantime, can the leaders decide once and for all to stop fighting amongst ourselves; get over dumb issues like who are superior and who should have nukes or deserves a better living standard and look at the real issue, which is the question of the survival of life on this planet?
Suresh, Edmonton, Canada

One interesting observation: The major European car companies i.e. Damler, VW, BMW, etc have had a terrible time getting their high efficiency Diesel cars approved for use in the U.S. because unlike the emission control laws of Europe, U.S. laws are very strict regarding the emission of nitrous oxides. In fact, cars sold here are less efficient than the same model sold in Europe specifically because the devices mandated to control nitrous oxides make the engine run colder, which as any college physics student can tell you, makes it less efficient.
Walter Moore, Indianapolis IN

Farming and industry should be forced to reduce their nitrogen use. More Vegetarianism would help. Nitrates destroy water courses, the Barrier reef. We can no longer indiscriminately just pour nitrates onto the land, just like we can no longer pour CO2 into the atmosphere. Are there any intelligent people out there, or are they all ostriches?
james Harrap, Brisbane Australia

Discussions surrounding impacts of Nitrogen use,esp., in fertilizers on the environment is long over-due. One has only to look at the impacts upon our steams, rivers and estuarine environments to see the devastating impacts! As for the solution, in an ever increasing world of agricultural demand upon land-use - Who knows? It is likely to be a similar answer to the CO2 issue, it's to late to do anything without radical reduction in global population. Not popular, but innevitable!
Andrew Card B.Sc Hons, Kingsbridge, Devon UK

Discussions surrounding impacts of Nitrogen use,esp., in fertilizers on the environment is long over-due. One has only to look at the impacts upon our steams, rivers and estuarine environments to see the devastating impacts! As for the solution, in an ever increasing world of agricultural demand upon land-use - Who knows? It is likely to be a similar answer to the CO2 issue, it's to late to do anything without radical reduction in global population. Not popular, but innevitable!
Andrew Card B.Sc Hons, Kingsbridge, Devon UK

Is it true that rotating crops that need and use nitrogen could be rotated with crops like beans and hemp to enrich soil without fertilizers? Virginia
Virginia Whitehead, Santa Maria, CA

There are many ways to reduce N2O emissions - one of the most potent greenhouse gases - from agriculture. One of those looked at by scientists is the use of biochar, a carbon-rich soil improver obtained from the pyrolysis of agricultural residues. First field trials in Australia have shown that biochar-amended soils reduce N2O emissions five to tenfold. The good thing about this N2O-emission reduction technique is that you simultaneously sequester carbon in soils and obtain renewable combustible gases from the pyrolysis process that can be used to replace fossil fuels. In short, this carbon-negative and N2O-reducing farming concept might be something to look into.
Laurens Rademakers, Brussels, Belgium

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