The curse of nitrogen fertiliser

Introduction

The manufacture of nitrogen fertiliser uses large amounts of oil and natural gas. The gases released when nitrogen fertiliser is taken up by the soil are even more damaging as green house gases than the carbon dioxide released from the fossil fuels burnt during the production process. Nitrogen fertiliser has been one of the key elements of the Green Revolutions that have taken place in most agricultural zones over the last half century where supplies of water are adequate during the growing season.
Replacing nitrogen fertiliser with nitrogen from legumes is a feasible alternative but it will require farming and dietary changes.

Part 1. The nitrogen story.

Part 2. Legume farming systems.

Part 3. Dietary changes.

Part 4. Action Plan

The nitrogen story

Green Revolutions around the world

Green Revolution is a term normally associated with the spectacular increase in grain production and yield in India and other Asian countries. In Europe and the northern temperate regions generally there has been a similar Green Revolution with an equally spectacular increases in grain yields during the second half of the 20th century.

On the demand side these increases have been encouraged by the high subsidies paid to farmers in Europe, Japan and USA for agricultural commodities.


On the supply side there have been many improvements in cereal agronomy but the Big Three are:

* a good supply of water (either reliable spring rain in the northern temperate regions or irrigation in India and other parts of Asia),

* large quantities of nitrogen fertiliser

* and crop varieties that are capable of converting this nitrogen into high yields. Older varieties converted the nitrogen into tall straw growth. The crop fell under the weight of the grain and the flattened crops produced less recoverable grain. Dwarf straw varieties can support increased yield.

There have been other fertilisers besides nitrogen, herbicides and fungicides but the Big Three are the most important elements of the Green Revolutions.

Nitrogen fertiliser consumption 1960 to 2006

Nitrogen fertilisers contain different amounts of the element nitrogen (chemical symbol N). The various N fertilisers have all been converted to N content in the table below. Figures in millions of tonnes.

Source: International Fertiliser Industry Association.

Year

Developed world

Developing world

1960-61
8.55
2.28
1970-71
23.13
8.61
1980-81
35.79
24.90
1990-91
35.39
42.16
2000-01
29.07
52.12
2005-06
27.17
63.69
Carbon dioxide footprint 2005-06
182 million tonnes
427 million tonnes

How green is green?

The Green Revolution tag was developed before the recent era of green awareness and is quite misleading in environmental terms. It is a production revolution and has a high environmental cost. The nitrogen fertiliser comes from carbon-based fuels and the intensive cereal cropping has reduced soil organic matter. Considerable quantities of soil carbon have been oxidised and released into the atmosphere.

Country

1961

2000

Countries with adequate soil moisture during the growing season - where nitrogen is an effective fertiliser. Source: FAO data base.

United Kingdom

Wheat & barley

7.6 million tonnes

23.2 million tonnes

India

Wheat

11 million tonnes

76 million tonnes

Dryland farming countries where soil moisture during the growing season is unreliable. Because of the highly variable yields the figures have been averaged. That is 1961 is the 5 year average and 2000 is also the five year average. Source: FAO data base.

Algeria

Wheat

1.3 million tonnes

1.6 million tonnes

Australia

Wheat

8.2 million tonnes

20.6 million tonnes

Measuring the Green Revolution

Production figures are a crude measure of the Green Revolution but yield figures can be equally misleading.

* UK figures are for wheat and barley because there seems to have been a shift out of barley into wheat over the forty year period. Yield figures are misleading because marginal arable land has been taken out of production through the EU funded set-aside program.

* Indian production increases are not due to the Green Revolution alone. More land has been irrigated and marginal land brought into production.

Economic factors

* The Algerian figures are a fairly conclusive proof of the failure of the Green Revolution in the dryland farming regions of North Africa. Algeria is a good example because there has been no lack of resources on the supply side and farmers have been paid good prices. While political instability (the curse of Africa) has caused considerable disruption to the farming economy at times the Algerian government has provided fertilisers, machinery and research in generous amounts. Levels of mechanisation in Algeria are higher on some indicators than Australia.

The Algerian examples makes a strong case for a good farming system as the bedrock needed for supply and demand economics to have a substantial effect. That is pouring high prices for outputs and low prices for inputs into a farming system that is fundamentally unsound will not have the effect of increasing production as predicted by economic theory.

* While the Australian figures look impressive - almost but not quite as good as UK - there has been a substantial increase in the area sown to cereals. The production figures cover the whole continent and while most of the wheat is produced in the southern half with a dryland climate similar to Algeria some is produced in the northern summer rainfall belt.

The Australian production increase was achieved with very low levels of subsidy. There was a small subsidy over some of the period on phosphate fertiliser but none on nitrogen. The price paid to farmers for wheat was close to the world price. While there were a few years when prices were high, the general trend over the 40 years was a reduction in price when measured in real terms. The level of subsidy paid to Australian farmers overall has averaged about 4% of returns compared to figures of 40 to 50% in Europe. This 4% may even be too high for wheat as subsidies in Australia were biased towards crops grown under irrigation for domestic consumption rather than dryland crops or livestock products for export.

Australia has also seen a large increase in livestock production. While wheat prices were generally poor during the second half of the 20th century the price of wool was truly disastrous The second half of the century saw the nemesis of the industry and the final destruction of the saying that Australia rides on the sheep's back.

Limits to the Green Revolution based on Nitrogen

The water element of the package seems so obvious that it is often forgotten but where reliable water is lacking the Green Revolution package has usually failed. I have called these areas “dryland.” They are rainfed but quite different to the rainfed areas of the temperate regions as there are substantial water deficits during parts of the year and even during parts of the growing season. For example London and Tunis have a similar annual rainfall but the pattern of rainfall and temperature make the growing season completely different.
North Africa and West Asia are two areas with Mediterranean climates (winter rain and hot dry summers) where the nitrogen/dwarf varieties package has failed in spite of 50 years of effort. The summer rainfall areas of Africa, Asia and South America with less than about 700 mm rainfall have an unreliable pattern of soil moisture during the growing season and have also failed to respond to the Green Revolution package based on nitrogen fertiliser and dwarf varieties
The reason for the failure is well understood scientifically and by farmers. The combination of nitrogen and crop varieties with a high yield potential produces more tillers. A tiller is a shoot that produces a seed head full of grain - at least when there is adequate water. Extra tillers and a dry spring produce many empty heads and the yield is less than a traditionally grown crop that has fewer tillers but where the plant finds enough moisture to fill the grain.
The Green Revolutions based on nitrogen and dwarf varieties have been so successful that the agricultural establishment in FAO and other similar institutions have failed to look for alternatives and wring their hands in despair about any improvement in yield for these dryland regions.

A deeper shade of green revolution

The cereals growing zone of southern Australia experienced a Green Revolution during the second half of the 20th century that was quite different from the rest of the world. Cereal yields increased dramatically. Livestock production increased even more dramatically - but not from grain feeding but from legume pasture. The soil organic matter increased and atmospheric carbon dioxide was fixed in the soil.
This Green Revolution was based on legume pastures either in rotation with cereal crops or alone.
Australia is remote and the experience has been largely ignored by the rest of the world.

Others (Conway 2008) have referred to this type of Green Revolution as "Double Green" because it has the production increases of the traditional form plus environmental advantages.

The figures in this table give some indication of the transformation of yields and sheep numbers in South Australia due to the use of legumes. In 1970 Algeria was still waiting for a Green Revolution. (Chatterton 1992)

South Australia

Algeria

1970's

Post Green Revolution

1930s

Pre Green Revolution

1970s Pre Green Revolution

Wheat Production - tonnes

1,327,000

888,000

1,270,000

Wheat Yield - Kg/ha

1,139

735

624

Sheep Numbers

18,961,000

8,500,000

8,357,000

Nitrogen pathways

The nitrogen (N) fertiliser used in agriculture starts as oil or natural gas. It is transported to the chemical factory where it is converted into ammonia, urea or nitrates. The nitrogen itself comes from the air but large amounts of energy are required to convert it into compounds that can be used by soil bacteria and plants. Obviously there is a large carbon footprint from the fertiliser factory. Nitrogen fertilisers are measured in terms of their content of the element N. For example urea, a common N fertiliser, contains 46% of the element. To manufacture one tonne of N in fertiliser form produces 6.7 tonnes of carbon dioxide.

The nitrogen fertiliser is then transported around the country and finally delivered to the farm producing an additional carbon footprint. It is applied to crops and pastures with machines that run on fossil fuel. Most of the nitrogen is used by the plants and soil bacteria but the nitrogen compounds are highly soluble and some are leached into the ground water. The N pollutes rivers and eventually has to be removed at considerable expense from drinking water. More energy is required to remove the nitrogen compounds.

The conversion of the fertiliser by soil bacteria into plant nutrients can release nitrous oxide which is even more serious as a green house gas than carbon dioxide. Some experts indicate a figure of 310 times (Melchett 2007).

Nitrogen fertiliser has allowed farmers to grow cereals without a rotation. They can use a monoculture of cereal crop after cereal crop. The effect is to reduce the level of soil carbon. Soil carbon is another term for organic matter in the soil. It is in a constant cycle of destruction and renewal but during a cereal crop destruction is more dominant than renewal. Carbon levels have fallen in farmed soils but more so when monoculture is practised.

While there is much public debate about the release of carbon from the soil and rain forests of Brazil there is a similar effect, if not so sudden and dramatic, in all the cereal monocultures of the temperate regions. The release of soil carbon in the form of carbon dioxide adds to the green house gases in the atmosphere. Melchett (Melchett 2007) claims that between 1850 and 1990 changes to farming throughout the world have released soil carbon that is equivalent to 50% of the increase in carbon dioxide levels in the atmosphere. This is a startling figure as it means that farming changes are just as important as industrialisation.

Cost - benefits of nitrogen fertiliser

Costs

Benefits

Price - the price of nitrogen fertiliser now generally reflects the price of oil and gas in the developed world. In the 1950s and 1960s subsidies were common. In many developing countries the price of N has become a highly charged political issue and governments still subsidise the price directly or indirectly through cheap fuel. No subsidies are available for legume based farming systems anywhere in the world to compensate for the cheap nitrogen. Generally N fertiliser prices (without subsidies) have doubled over that last 1 to 2 years.

Carbon footprint - following the collapse of the European carbon trading scheme the environmental cost of carbon dioxide emissions is not reflected in the price of N fertiliser.

Distribution - the distribution of N fertiliser to farms and onto fields is not measured separately from transport and farming costs generally.

Release of nitrogen compounds - during the conversion of the fertiliser in the soil into plant nutrients there is a release of nitrogen compounds which are more polluting as green house gases than CO2. Figures indicate it is 310 times more polluting.

Water pollution - Nitrogen compounds also pollute ground water and runoff water. This is due to the high solubility of the fertilisers and N flush when they are first applied. N from legumes is tied up in organic compounds and is released more slowly. It rarely pollutes rivers or water ground supplies.

As far as nitrogen fertilisers allow the use of monocultures of cereals they encourage the depletion of soil carbon.

Nitrogen fertiliser increases the yield of cereal crops provided water supply is adequate.

The effective response is good for wheat, maize, barley, rice etc. grown under irrigation or in temperate climates where the spring rainfall is both adequate and reliable.

In dryland farming areas the effective response from nitrogen is erratic. In some seasons the use of nitrogen can reduce yields. While institutions such as ACSAD and ICARDA claim that there is a positive return over a long period many farmers find the risk of yield reduction too great and are reluctant to use N fertilisers.

While the effective response is good for cereals with adequate moisture there is a world surplus of cereals and large quantities are fed to animals. The efficiency of conversion is high with chickens, lower with pigs and much lower with ruminant animals such as cattle.

On pasture the effective response of nitrogen is low. About 70% of the nitrogen applied merely replace that available from legumes. The pasture then has to be converted into animal products. Further inefficiency occurs during conversion.

Climate, economic and social change

Proposals for reducing carbon dioxide production come as two extremes and a range of intermediate options.

One end of the spectrum, proposed by some members of the Bush administration, is to wait for the hydrogen economy. They contend that some form of clean energy will be found that will produce endless supplies of non-polluting hydrogen which will then replace natural gas and oil. The source of the clean hydrogen is presently unknown but if found the hydrogen economy will produce only the minute changes to our economy and way of life. People need not turn down their central heating or turn up their air conditioners. They can drive their gas guzzlers knowing they are not globe hotters. Somewhere down the pecking order the chemical companies can produce more and more nitrogen fertiliser.

At the other end of the spectrum are the deep, deep greens who see the solution to global warming in a return to a pre or early industrial age.

Most of us are in between. That is we are seeking non-polluting forms of energy (renewables etc.) but realise that they will be insufficient to maintain current energy consumption levels. We will need to change the economy and our way of life to reduce consumption. We will need to turn up the air conditioning and reduce the heating as well as drive more economical cars and insulate our houses.

Nitrogen used in farming is an excellent example of this mixed approach. Renewable sources of nitrogen already exist but they are unlikely to provide enough of the nutrient to maintain current levels of production - at least if we wish to maintain our current high levels of meat consumption. We will need to switch to renewable sources of N and change consumption patterns to cope with the reduced availability of meat and dairy products.

Alternatives to fossil fuel based nitrogen

The alternative that seems to be favoured by policy makers in Europe and USA is to ignore the nitrogen problem and encourage the production of an energy surplus from agriculture. Currently agriculture is a consumer of fossil fuels but these policy makers are seeking to produce energy crops such as biomass, ethanol and bio-diesel.

While the surplus energy is not necessarily used for the production of nitrogen fertiliser it can be regarded as such when considering the overall energy balance of agriculture.
Using grain for energy production begins with with a large input of energy into the growing of the crop. Nitrogen fertiliser is part of this negative energy balance. The next stage is transport from the fields to the chemical complex. The grain is then treated with enzymes to convert the starch to sugar. The sugar is fermented into a beer and the beer is distilled into super strong vodka. It is hardly surprising that the output of energy is barely more than the input. While the technological optimists claim that this is only a transition to greater efficiency there is a law of physics about the latent heat of steam that is difficult to bypass. The fermented beer is about 90% water. The water must be removed by distillation if the ethanol is to be burnt as a fuel. Removing the water requires energy and while some can be recycled through heat exchangers the process will inevitably consume considerable amounts of energy.
In addition to the obvious problem of producing returns greater than the costs there is the polluting effects of using even more nitrogen fertiliser to grow the bio fuel crops as well as the existing food crops. More intensive cropping will also deplete the soil carbon at a faster rate.

One can see the appeal of such a policy as it creates more economic activity, more employment and more GDP but to paraphrase J.K. Galbraith there is a limit to how much we can open doors for each other. He was making the point that opening doors for each other adds to the GDP but does it add anything to our well being? The churning of nitrogen into farming and to produce fuel for more nitrogen fertiliser production is a similar category of useless activity that produces no overall benefits in terms of reducing carbon dioxide emissions. When all the side effects are counted in it does positive harm.

Legume farming systems

Legume nitrogen will not replace fertiliser nitrogen.

There have been some attempts by agricultural scientists to develop farming systems based on a green manure. A legume crop is grown as a manure alone and turned into the soil. It provides nitrogen for the following cereal crop. A green manure will replace virtually all the nitrogen fertiliser.

These systems have generally been rejected by farmers as too expensive - a complete season is used to produce the fertiliser - and instead farmers have used the legumes directly for animal or human food. The surplus nitrogen for the next crop is less but the systems are more profitable.

What are legumes?

Legumes are a large family of plants that are able to fix nitrogen gas from the atmosphere into proteins. Strictly speaking they do not carry out the fixation - it is done by bacteria that live in a symbolic relationship with the plant in nodules on the roots.

In farming terms there are three main groups of legumes.

* There are annual and perennial legumes such as clover, lucerne, vetch and medic that are used in pastures or fodders. These produce excellent feed for grazing livestock and a surplus of nitrogen that is returned to the soil. If grown in rotation with cereals they can provide a large part of the nitrogen requirements of the following cereal crop.

* There are grain legumes or pulse crops. These include peas, beans, chick peas, lentils and various types of dal. The legume crop with its bacterial companion produces sufficient nitrogen for the crop to grow without any additional nitrogen fertiliser from a bag but most of the nitrogen is removed with the crop and the surplus provides only a small proportion of the amount needed by the following cereal crop.

* There are various trees and fodder shrubs that fix nitrogen but the rate of fixation is usually low. They have been used in some tropical and sub tropical farming systems.

Encouraging the development of legume farming systems

Creating the economic environment

High fossil fuel prices have increased the price of nitrogen fertiliser (they have doubled over the last 1-2 years) but at least as far as cereals are concerned the price of grain has increased as well. There is not currently an incentive for farmers to reduce nitrogen usage.

If the European carbon trading scheme can be salvaged and carbon credits return to a sensible price level this will add to the cost of carbon rich nitrogen fertiliser. Nitrogen fertiliser uses 6.7 tonnes of carbon dioxide in the production process alone. Nitrous oxide gas released when N fertiliser is used is 310 times more polluting than carbon dioxide. Taxes or trading need to reflect its high level of green house gas production.

The reorganisation of the European farm subsidy system has shifted the emphasis from production of the barely edible to conserving the environment. This has proved to be extremely costly in terms of administration as the environment is defined as the population of birds, bees, animals and trees. Measuring their conservation is a complex and costly business. One way to cut through the administrative complexity would be to pay farmers to increase their soil carbon levels. Soil carbon levels can be measured cheaply and easily.

Management skills for legumes

Changing a farming system not a simple process. While legumes were used more widely half a century ago that farming knowledge has now been lost. Restoring it is not simple as government advisory services around the world have been dismantled as part of the movement to reduce government and its share of the national income. We now rely on the corporate sector to educate farmers on the benefits of fertilisers, herbicides, insecticides and other products of the chemical industry. There is not a corporate sector for legume seeds on anything like the scale of the chemical industry (most of it is owned by the chemical industry in any case) and it does not have the resources to mount an education campaign to teach farmers the techniques of legume based farming.
There are other complications. Farmers can keep their own legume seed. While this saves them considerable costs it reduces the market for the seed industry. Other legumes (specifically medic pastures) reseed naturally and do not require further purchases of seed. The industry will never reach the size and strength where it can fund farmer training programs nor will it be able to development significant income on the basis of plant patents.
Governments are unlikely to restore their advisory services so we will need to look for alternative sources of funds.
The Australian model could provide some ideas. Traditionally Australian farmers have funded a great deal of agricultural research and development through product levies on grain, meat and wool. These could be used to fund legume research and development but with the added twist that the polluters would pay for the development of the non polluters. A nitrogen pollution tax would be one source of revenue but others could be found (such as a water pollution tax) that would shift the economic advantages away from nitrogen towards legumes.

Cost - benefit for legumes

Cost

Benefit

Seed - Grain legume crops require seed as do cereal crop. Legume pastures require seed but many are perennial or regenerating. Seed is only required when the pasture fails due to poor management or extreme drought.

More phosphate - Legume pasture will require more phosphate fertilisers than the natural weed pastures they replace.

Opportunity costs - Legumes will not replace all the nitrogen supplies by fertilisers. Cereal production will be reduced.

Release of nitrogen in the soil and uptake by plants reduced by low soil temperatures.

In dryland farming areas a win-win situation with increased cereal production and more livestock from increased pasture output.

Grain legumes - Provide high quality human food and a healthier option than eating large quantities of meat.

Slow release of nutrients from soil organic matter produced by legume pastures means that the following cereal crops do not have reduced yields in a dry spring.

Slow release of nutrients means there in not the release of nitrogen compound into the atmosphere. This happens with heavy applications of N fertiliser.

Build up of soil carbon under legume pastures.

Legume pastures produce a surplus N for the following cereal crop.

Dryland farming regions

In the dryland farming zones of the world the nitrogen fertiliser based Green Revolution has failed. This has not been accepted by the agricultural research establishment who still wrap the failure in euphemisms such as “limited success” and hope that even more complex technology can somehow produce results. There is also a tendency to blame farmers for being risk averse yet it is their livelihood they are risking in a climate they know well to be unreliable

Legume based systems have succeeded. They are simple. They are low cost. They are win-win systems that produce more cereals and livestock as well as being environmentally friendly.

Introducing legume based farming systems into dryland regions will be difficult as technological fixes have gone out of fashion within the development class. The titles of projects tells it all. In the 1950s agricultural projects were excessively technical. "Improved fertiliser use in .... " "New cereal varieties..." were the run of the mill projects. They rammed the Green Revolution and other western farming ideas into developing countries whether they were suitable or not.

The reaction has been a complete reversal and projects are now titled "Integrated community development based on farmer participation and social ..." Beside having much longer titles the projects have excluded all reference to improved technology.

There needs to be some balance between the two approaches. Technology needs to be appropriate and farmer participation is essential.

A good example of the current opposition to technical fixes for agricultural development comes from a World Bank Report on the Horn of Africa. The report stated that roads built over many decades with development funds had fallen into disrepair and were almost useless. Communities would have to develop means of maintaining roads in future. Further expenditure on roads would be wasted unless an appropriate management structure was developed. The road technology was not doubted and the community would need to change.

Another part of the report admitted that a lack of pasture was the major limiting factor in animal production and that animal production was the major source of rural income. Research had shown that legume pastures had performed well. They had improved animal production and reduced erosion. When taken out of the research centre they had failed because of poor management by flock-owning communities. The reaction was that the legume technology had failed and no further effort should be put into it. This seems an extreme reaction given the way that communities had be told in no uncertain terms to adapt to the road technology.

What the World Bank should have identified was something in between. In the 1950s the flock-owners were told to establish American ranches (under various disguises) as the only method of managing legume pastures but now they are told that nothing should change. There is a middle way where new grazing management regimes can be developed that allow the legume pastures to flourish and which are compatible with the local economy and culture. This is an unfashionable approach. Farming improvement has to be completely within the existing culture, traditions and tenure arrangements.

Winter rainfall dryland farming areas.

Here success with legumes has been greatest but the potential area for expansion is limited. The winter rainfall or Mediterranean zone covers a fringe of West Asia and North Africa (the region of the world with the greatest food deficit), the southern tip of Africa, southern Australia and some parts of South America.
Legume based farming systems for these areas have the technology and the practical techniques but have so far only been implemented on a large scale in Australia.

Summer rainfall dryland farming areas.

These are much more extensive in Africa, Asia and South America. Much of legume technology exists but there is a complete lack of practical farming techniques and no mechanism to develop them.


Temperate and irrigated regions where the Green Revolution has succeeded.

Unlike the dryland regions of the world legume-based farming will not be win-win. There will be some “costs” to off set against the environmental benefits of reduced nitrogen use but these costs may be regarded as changes rather than costs.

Pastures and livestock

About 70% of the nitrogen fertiliser applied to pastures is wasted. It is only the low cost of fossil fuels over the last half century and the subsidies paid by governments in Japan, USA and Europe that has kept such an inefficient system of production in existence.
If one starts with a good pasture based on a mixture of grasses and clovers (or other legumes) and then applies nitrogen fertiliser the effect is to encourage the grasses and reduce the clovers. There is no net gain in output. More and more nitrogen is applied until all the clover has disappeared. After this further application of nitrogen will produce increased output. The first 70% replaces the legumes and the last 30% increases output. The output is then converted into animal products that in the case of Europe are often dumped on world markets or controlled by quotas on output.
A return to clover and other legume based pastures would seem to be the most obvious solution to environmental pollution and high input costs.

New Zealand has over the last 25 years been a continual embarrassment to Ministers of Agriculture in the developed world as it has been able to produce milk, butter, cheese and meat from legume pastures and export them at low prices (NZ exporter have to pay the freight to Asia and other markets) without any subsidies. NZ farmers have received good returns without any help from fairtrade organisations. New Zealand has provided a model of efficient, environmentally friendly farming while the rest of the developed world is trying to justify its subsidies and high pollution levels.

Crops

Changing the great cereal monoculture areas is more complex.

* One option is to adopt the rotations of the dryland farming regions - that is a year of legume pasture followed by a year of cereal crop. Obviously production of cereals would fall by half as only half the area would be sown.

The surplus nitrogen from the legume pasture would provide perhaps half the nitrogen needed for a high yielding cereal crop.

Benefits:

75% reduction in nitrogen fertiliser. (Half the area sown with half the amount of N)
More livestock production from pasture.
Higher levels of soil carbon.

Costs:

50% reduction in cereal output.

* Another option is a grain legume and cereal rotation. Instead of growing cereals and oil seed crops year after year with large amounts of nitrogen, grain legumes could be grown in alternate years. They would not require nitrogen fertiliser. The cereals or oil seed crops would need nitrogen if yields are to be maintained.
At present the range of grain legume crops in northern temperate regions is rather limited but it should not be difficult for plant breeders to extent the climatic range of lentils, chick peas and the various dals as they have done with many other crops.

Production changes.

A legumes based farming system will produce:

* Less cereals and oil seed crops as the area sown will be perhaps half.

* More grain legumes such as beans, peas, chick peas etc.

* Less animal production from existing pastures fertilised with N.

* Additional animal production from short term pastures grown in rotations with cereals.

The most substantial change is the reduction in cereal grain. This in turn would mean a reduction in meat production particularly from chickens and pigs. These animals products would be replaced by grain legumes.

Nitrogen fertiliser consumption.

* All nitrogen on pastures would be eliminated.

* Area sown to grain legumes would not require nitrogen fertiliser.

* The area sown to cereals would require less nitrogen if sown after legume pasture but almost the same amount if sown after a grain legumes crop.

Changing cereals into legumes

We have been promised for a number of decades that GM technology will produce cereals crops that fix nitrogen from the air in the same way as legumes. There seems to be a considerable problem in safeguarding the commercial returns from such technology and the release date is continually postponed for another decade. It may prove impossible to develop these nitrogen-fixing cereals in such a manner that they can be commercially exploited by the biotech companies and public breeding may be necessary. An internationally funded program should be developed immediately as the savings in N fertiliser would be enormous.

Another option is Nitrogen-use-efficient cereals. These use nitrogen from the soil (either from legumes or fertiliser) more efficiently. They have already been developed to a stage where commercial varieties are expected in the 2015-16 season.

Neither of these technical fixes should be seen as an alternative to legume farming. They will make it more efficient.

Changing the diet

A legume based farming system will not produce the same amount or mix of output as the current nitrogen-fertiliser based system. It will be necessary to change the diet and food culture to coincide with the legume based farming system.
There have been many changes in the diet of the northern European population over the last half century and further changes to include more grain legumes and less chicken and pig meat would seem to be feasible. Already 25% of the UK population claim to be vegetarian or would be vegetarian if it were easier. The so-called Mediterranean diet is also being promoted on the grounds of health and taste. This includes less meat and more grain legumes compared to current UK diets.

Recent dietary changes in Europe.

The cheap chicken - a supply led change

It is claimed that Chicken Tikka is now the national dish of the UK. While there is wonder that the Indian Tikka recipe could appeal to British taste buds the real dietary transformation is the chicken not the tikka. Chicken meat has swept through the world as the cheapest and commonest meat.
It has been a supply led change in diet. In 1950 chicken was expensive and a relative luxury. The availability of cheap grain produced under the subsidy systems of USA and Europe plus the breeding of broiler chickens that converted this grain efficiently into meat created a cheap and plentiful supply.
The cheap chicken is now under threat from higher grain prices and concerns about the welfare of the animals. Consumers are also turning to foods that have more flavour than these young, force-fed birds.
Grain legumes as a substitute for a part of the cheap chicken market seems entirely feasible.

Vegetable oil and fat - creating a demand through corporate advertising

In 1950 most of northern Europe used animals fats - butter, lard, suet and dripping. Now they have disappeared except for butter. The disappearance has been so complete that even the names of the fats other than butter are no longer known by people born after 1960.
The change was corporate led. Large food corporations became involved in the production of margarine and vegetable cooking oils and their powerful marketing skills (partly based on some doubtful health claims) swept aside the small producers of butter and other animal fats.
The food market is now a corporate battle ground and the weak players have all been gunned out of the water. Chicken producers will not give up their market share as easily as the butchers did their cooking fats. However the food corporations can obtain good profits from grain legumes once they have been put into small packets and converted into a more expensive “instant” form. Already in India - a country with a very strong food culture based on grain legumes - the middle class are buying these instant mixes rather than the raw ingredients.

Finland - government led health campaigns

The government of Finland has undertaken a successful campaign to reduce coronary heart disease. The campaign included dietary changes.

The official forecasters of world food requirements take no account of these campaigns. They predict that attempts to reduce obesity or alter the composition of the human diet will fail. Their forecasts are based on present trends continuing unaltered. If calorie intake has increased it will continue to increase. If the share of meat and dairy products in the diet has increased it will continue to do so at the same rate in the future. This may be the case in developing countries for some time but in the developed world it is unlikely.

The Mediterranean Diet

A few times per month

A few times per week

Daily

Red meat

Sweets

Cheese and yoghurt

Eggs

Olive oil

Poultry

Fruit, vegetables, beans, lentils and other grain legumes

Fish

Bread, pasta, rice, couscous, other cereal grains and potatoes.

Physical activity

Wine in moderation (usually red)

The above chart is an idealised version of the Mediterranean diet in the sense that it has virtually disappeared on the north shore as the populations eat more meat and less fish. It is still found on the southern shore of the Mediterranean but the fish component is under threat. It was drawn up by scientists at Harvard University who may not have been aware that pasta is made from eggs as well as flour and that the average Italian consumes eggs daily with their pasta.

Action plan

World farming:

1. Expansion of legume based farming systems first developed in Australia to other countries with a Mediterranean climate.

2. Development of similar systems for dryland farming in the dry tropics.

European farming:

1. Measures to place the real environmental cost (carbon dioxide, nitrous oxide and nitrates in water) onto nitrogen fertiliser.

2. Reform of the Single Farm Payment scheme to provide incentives for increased soil carbon.

3. Plant breeding research to extend the range of grain legume crops suitable for northern temperate regions.

4. Farmer training to develop management skills in legume farming to be funded from nitrogen taxes and levies.

Diet

1. Dietary and cooking advice to encourage people to use more grain legumes instead of meat from grain fed animals.

References

Chatterton Brian and Lynne (1992) Fodders for the Near East: annual medic pastures. FAO Rome

Chatterton Lynne and Brian (1996) Sustainable Dryland Farming. Cambridge University Press, Cambridge, New York and Melbourne.

Conway, Sir Gordon (2008) "How we feed the world?" Gerald Lacey Memorial Lecture delivered on 16th May 2008 at the Institution of Civil Engineers.

Melchett, Peter (2007) "One planet agriculture - the strengths and weaknesses of organic food and farming." Paper given at Soil Association Annual Conference 2007 Friday 26 January 2007.