Posts Tagged ‘Nitrogen’

Nitrogen benefits and environmental costs,

December 12, 2012

More from IFS in Cambridge (se below)

In an introductory lecture prof Tim Benton mentioned that the European Nitrogen Assessment has made the estimate that the costs for the nitrogen losses from agriculture outweighs the value of the nitrogen fertilizer.

How can that be? Imagine that half the agricultural production suddenly disappeared.

I have to confess that I have not scrutinized the source, but I make an example of my own.

We have a cereal production giving 6 tons per hectare, today worth about  SEK 9000 , of which half is caused by the 100 kg nitrogen  (N) given as fertilizer.  The leaching of nitrate is 25 kg N.

What is the value? The cost for the nitrogen is 1000, it has produced 4500 in added value.

What is the environmental cost? The Swedish society has programs for reduced leaching, costs 50 to  100 per kg leaching reduced (artificial wetlands or catch crops). If the value 50 is used the cost for leaching is 1250.

Some comparisons:

The market value of the fertilizer is 1000, the cost for the leaching is 1250 or more.

With lower yields and prices an added value of the fertilizer use could be 2500. If we assume the leaching costs 100 per kg N this value will also be 2500.

We see that there are different ways to arrive att the introductory statement. It should be observed that the fertilization itself has caused an additional leaching of around 5-10 kg N.

It is the prices that are decisive for the outcome. Food prices are low, environmental work expensive. If fertilizer use and agricultural production are reduced the value of food increases and the relations will be different.


International Fertiliser Society: Meeting Challenges through Innovation

December 9, 2012

Conference Cambridge Dec 2012.

What challenges?

The growing world demand for food. Scarcity of land and water. Ecological limits are almost reached. We must produce more with less environmental impact. Sustainable intensification.

Some believe that organic agriculture is the solution. But the production is too low. We need increases, not reductions. We need an ecologically better general agriculture.

What innovations?

Higher and more reliable yields. The ambitious English project Wheat 20-20 (20 tons/ha year 2020), a combination of plant breeding and agronomic development.

Better adaptation of inputs and resources. More efficient phosphorus fertilization, for instance placement (common in Sweden) and maybe foliar or seed application as complements.

Focus also on potassium and magnesium. Deficiencies, also shortterm, reduce stress tolerance and yields.

Cover crops. They reduce nitrate leaching and in addition provide organic matter and are positive for life in soils. They function also as break crops in rotations.

Manure is a great problem. Theoretically a good solution is to move animal production back to crop producing farms. Go back to mixed agriculture. But that does not work in our economic reality.

Two ways are worked on: to improve the manure efficiency at farm level and to process manure to marketable or at least transportable products which can be removed from the farm. However, it is not an easy problem to solve.

The longterm nitrogen efficency of manure is low. The most efficient method, injection,  has a longterm efficiency of 55% compared to mineral fertilizer. In practice the efficiency today is only half of that.

A problem mentioned is that economic realities often do not permit use of improved agronomic measures. This a big problem for the world development.

Recycling. Phosphorus should have priority.

November 24, 2012

The food we eat contains nitrogen and phosphorus, important elements for everything living. It ends up as toilet waste. After treatment in sewage works most of the phosphorus and some of the nitrogen end up in sewage sludge. This contains also some heavy metals, bacteria, hormones, medicins and various chemicals.  Sludge (biosolids) is a kind of fertilizer containing especially phosphorus but some nitrogen and above-mentioned impurities. To apply it on food-producing soils , is that right?

There are processes where the sludge is burnt, pure phosphorus compounds are extracted and a clean phosphorus fertilizer is produced. Then we miss the nitrogen. Is that right?

Systems can be developed where the toilet waste is collected, hygienized and used more directly as fertilizer. Then we take care of both phosphorus , nitrogen as well as potassium and other nutrients. Unfortunately hormones , drugs and chemicals are included.  Physically it is a thin sludge to transport and distribute. Is that right?

We need some guidelines to choose.

Phosphorus is special for two reasons:

1. It is a limited resource. We know about mineral deposits for 10-20 generations, but then ?

2. All we take out from mineral deposits ends up in our environment, in fields, gardens, waste dumps, waters.  It is active and causes eutrophication. And we never get rid of it. It might move, but is still active.

These are two, as I see it, overriding reasons to give phosphorus priority, to keep down extraction from mineral deposits by recycling as much as possible.

Nitrogen is different.

1. We have unlimited resources,  80% of the air is nitrogen. But we need energy to make it active, and all kinds of energy can be used. The present oil and gas can be replaced by hydro- or solar energy or even bioenergy.

2. An important process, denitrification, removes active nitrogen from the biosphere and gives it back to the air. There is no unavoidable  accumulation.

3. Active nitrogen (ammonia, nitrate, nitrogen oxides) are environmenal pollutants. Research has suggested that we already exceed the limits of the globe in this respect.

The main priority for nitrogen is to avoid losses of active nitrogen. To handle the farm nutrients as efficiently as possible. (Organic nitrogen in for instance sludge is in fact a disadvantage in this respect). Environmental analysis should guide the development

Conclusion: Extract pure phosphorus when possible. The loss of nitrogen is no great disadvantage (provided there is no nitrogen pollution from that process)

There are local needs for more smallscale processes.

On nitrogen recycling.

November 29, 2009

 To reduce input of reactive nitrogen to the biosphere improved use of the nitrogen in our waste flows could be important. What do we know?

 Sewage sludge: contains only a small fraction of the total sewage nitrogen flow.

Waste water irrigation. Discussed as a necessity/possibility in some parts of the world. But considering our discussion about impurities and risks with sewage sludge a largescale development does not seem likely.

Re-capture of the nitrogen in sewage works. Norsk Hydro had a practical process in one of the sewage works of Oslo. Driving off ammonia and capturing it in acid to ammonium nitrate solution. Worked commercially in limited scale. Another possibility which has been proposed is precipitation of magnesiumammonium phosphate (struvite). It captures phosphate and some nitrogen. In a new situation such processes can be further developed.

Separation of urine and faeces, use of urine as fertilizer. Takes care of most of the nitrogen. But there is a storage- and transport problem, especially for large cities. But definitely a possible part of a future system.

Composting. Compost has a good reputation but is a process wasting nitrogen.

For developing countries there are developments like Pee-Poo bag.

However, there is another principle, not unlike our present system: we transform the reactive waste nitrogen to unreactive gas and fetch it back in an ammonia factory. Then the nitrogen issue is transformed to an energy issue.

Planetary boundaries. A presentation also in farm journals.

November 13, 2009

 A report by internationally renowned scientists give tentative figures for ecological boundaries. One of those is inflow of active nitrogen to the global ecosystems. The current figure is 121 million tons (fertilizers plus biological fixation). The tentative threshold value is 35, less than a third. The fertilizer nitrogen is currently a little below 100 million tons and the demand is projected to increase by 3 million tons every year. Increasing population  gives increasing demands.

Maybe some shake up is needed.

The figure 35 says nothing about how to manage food production, it is just an estimate of  a safe value for the global ecosystems.

However, we get another reminder of tough challenges ahead:

Efficient nitrogen use in agriculture. There are improvements, but not enough.

The animal production. The most inefficient production in ecological terms is the most fast-growing. There will be questions about this. But cheese and beef and bacon are valued.

The nitrogen in waste. The main aim of agriculture is food to man. The annual nitrogen turnover is about 10 kg per person. The 9 million Swedes release 90 thousand tons of N, to be compared to 160 as mineral fertilizer and in total about 120 released from farm animals, of which 40 is directly wasted as ammonia. There are efforts to reduce losses, but so far very little nitrogen except manure is recycled.

Maybe, for waste nitrogen, an alternative is to denitrify it to nitrogen gas and get fresh active nitrogen by industrial or biological fixation.  It depends on energy relations and emissions. Which is best?

Exchange diesel tax for nitrogen tax – it only gets worse.

March 13, 2009

Daily papers as well as agricultural press is full of arguments. The agriculture is hit by fuel taxes. At least “centerpartiet” seems to advocate scrapping the nitrogen tax as compensation. But – according to farmers organizations the fuel tax means SEK 1 billion for agriculture while the nitrogen tax is about 300 millions.

And there is another calculation to perform. Nitrogen is also an actor in the climate drama. If the tax i abolished the fertilizer use will increase and so the dinitrogen oxide emissions. Let us talk about GreenHouse Gas equivalents, GHG.


Consider cereal production. Removing the N tax means that the economic rate is increased by about 10 kg N per hectare. The yield increases by about 100 kg, According to guidelines from the climate panel IPCC we get increased emissions of dinitrogen oxide by about 90 GHG in the whole chain, provided nitrogen fertilizer from the best factories is used. For an average fertilizer it would be 130. To compensate the 90 we need to save 30 l diesel, almost half the present use. Not easy.

Exchanging nitrogen tax for diesel tax means an increase in climate gas emissions.


If nitrogen is that sensitive maybe we should change to organic production without fertilizers? For crop production that is no solution. The considerably lower yields and the N input from legumes means that organic production is not better concerning climate. A concrete figure from the 3rd rotation of the agricultural systems experiments in south Sweden:  per kg cereal the GHG emission is 0.27 for conventional production (according to the Swedish model with N tax etc) and 0.37 for organic.


If the N tax is removed the N leaching will increase by 2000-5000 tons. It is the N “at the top” which counts.

There must be better ways to compensate the Swedish agriculture.

Competitiveness – soil carbon – cover crops – zero plots – precision farming – Agrotain.

February 12, 2009


Some topics which have been on the agenda the last few days.

The farmers´ organizations stress competitiveness, thinking of Swedish taxes and environmental rules. They are right, we have a problem. Only – one could wish for a wider view.

A well functioning soil also gives competitiveness. But a yield of 8 tons of wheat must imply a good soil? Maybe so, but it could have yielded 8.5.  Soil carbon helps, more organic material from for instance cover crops is positive for soil carbon and biological activity and also soil structure. There are important advantages to harvest.


Nitrogen is a strong agent – it has to be held in tight reins. With zero plots to characterize the soil and precision farming to adapt to the actual crop you are doing just that. But in for instance England there are other ways of development. Much urea is used which means risks for considerable ammonia losses. These can be reduced by means of chemical substance, an urease inhibitor. Market name: Agrotain. This improves the situation somewhat, but you could ask: is this the best way to go? Wouldn´t it be better to use available knowledge and technology to control the use of reliable N sources as well as possible?


The whole and the details.

January 8, 2009


The Swedish Environmental Protection Agency is arranging a workshop next week in order to squeeze out ideas for further reduction of emissions to The Baltic. That is needed, for large commitments have been made in Baltic Sea Action Plan.


It is about N and P. But I hope that the topic can be widened to include the integrated function of the soil. And that is almost necessary, since we have gone very far in correcting malpractices and errors. Few simple solutions remain. But there are possibilities to improve the functioning of the soil. Better structure, better stability and surface protection will help reducing P outflow. The very work in this direction will also reduce N outflow and greenhouse gases. Biodiversity and yield capacity will increase. Cover crops are more than just N catch crops.

Have a look at my post of 30 Dec.


In general, segmentation and specialization is a problem, both concerning authorities and research. Different units have there own segments. Integration is difficult. The economists should perhaps integrate, but also they have got specialized tasks.


A flower to Greppa Näringen (Focus on Nutrients) who has dared to integrate many aspects in “The soil fertility module”.

A report: Nitrogen for sustainable crop production

December 25, 2008

Christmas Day.

A Christmas gift arrived yesterday: a number of copies of  Report 5871 from Swedish Environmental Protection Agency: Nitrogen for a sustainable crop production, with me as the author. It has been a long journey, that is why I see it as a fine Chrismas gift.


Very short: Nitrogen fertilizer can be combined with a sustainable future provided it is used in an ecologically correct manner. The economic definition of  “correct” is not good or safe enough. We cannot rely on market economy alone to guide this ecologically critical procedure. This is a troublesome fact in the world of today, where the Market is seen as the solution to most problems.


Concerning environment I discuss a new concept or at least an expression: “The law of increasing impact.”  For the relation fertilizer – yield the “Law of diminishing returns” is well known. But for environmental impact the relation is reverse. Therefore, it is of utmost importance that the fertilizer use is well adapted to the ecological needs of the crop. This is well known but needs to be stressed.


There are methods and technology for further improvements. Swedish agriculture has been very successful in these respects, but still it is important to continue improving.

Report : important to reduce nitrogen to the seas along the Swedish West Coast.

November 21, 2008

Agriculture is the largest source,  point sources and deposition from the atmosphere are also important.


How could agriculture improve? Already Swedish agriculture is among the best in nutrient efficiency and low losses. Is that not enough?  Apparently not, according to this report about the state of the sea.


And agriculture can do more, and often economic sacrifices are not necessary.


Improved adaptation of nitrogen fertilizer. Use the technology available: precision farming. and sensor guidance. In most cases this is economical. It is a much better line of action than chasing cheap urea. It is a step backward to change to a nitrogen form with larger losses and less predictable effect.


More catch crops and less autumn tillage. That reduces nitrogen leaching. Experimental results also show that these measures increase soil carbon and are positive for the longterm soil fertility development.


Manure: improve distribution, avoid nutrient surplus. Not easy but important.


As said – these measures do not necessarily increase the net costs. There are also gains to consider in the total balance.


But needed is an active interest, what I call Focus Foresight.