Monday, July 9, 2012

The greatest single experiment in global geoengineering

Without knowing it, if you are a European, you might bear costs of over €500 per year for farmers’ use of Nitrogen fertilizers. According to the European Nitrogen Assessment, synthetic N fertilizer has been estimated to sustain nearly 50% of the world’s population, but its use comes with a very big prize tag. The report states that the increased level of reactive Nitrogen in the biosphere might represent the greatest single experiment in global geoengineering ever made. Similar concerns were already expressed by the Millenium Ecosystems Assessment and later echoed by the by now famous article about Planetary Boundaries.

And while this Nitrogen drives yields, a lot of the nitrogen ends up where it isn’t supposed to.The nitrogen recovery (kg N taken up by a crop per kg applied N) for cereals varies between 30% and 0% across Europe, indicating that 40%–70% of the fertilizer N applied is lost to the atmosphere or the hydrosphere.

From the perspective of the individual farmer the use of Nitrogen fertilizer is profitable. The return of one euro invested in nitrogen fertilizer is estimated to between two and five euro. But someone else pays a bigger bill. “Environmental damage related to Nitrogen effects from agriculture in the EU-27 was estimated at €20–€150 billion per year. This can be compared with a benefit of N-fertilizer for farmers of €10–€100 billion per year, with considerable uncertainty about long-term N-benefits for crop yield”  says the report.

This is no European speciality, it is likely the same or worse in many places. In the US the Mississippi, the Columbia, and the Susquehanna rivers together discharge approximately 1 million tons of nitrogen in the form of nitrate per year to coastal waters according to a report from H. John Heinz III Center. In Rwanda, erosion causes loss of almost 1 million tons of organic matter, some 40,000 tons of nitrogen, 280 tons of phosphorus and 3000 tons of potassium—more than the total use of chemical fertilizers according to the Ministry of Agriculture.

The International Assessment of Agricultural Knowledge, Science and Technology for Development assesses that the fertilizer uptake efficiency is less than 30 percent for rice production in South and South East Asia. Globally the nitrogen efficiency in grain production has deteriorated drastically and rapidly. Around 1960, each ton of chemical fertilizer resulted in an increase of grain yield of 75 ton, while in the end of 1990 resulted in just 25 ton, a glaring example of decreasing marginal utility, as nitrogen fertilizer use increased tremendously in the same period.

What comes in - will go out....
In the end there is nothing really surprising in the report. It has always been clear that not only 40%-70% of the nitrogen is lost to the atmosphere or the hydrosphere. It is rather 100% that is lost, as also what is captured in the grain or the grass, ultimately also will leak away, as long as nitrogen is not accumulating in soils. But it isn’t doing that, on the contrary.

Read more:
Overloaded with Nitrogen and approaching peak phosphorus
Scarcity starts to bite
Nitrogen in the biosphere - a cliffhanger
Nitrogen fertilizers destroy soil organic carbon
Plows into Swords and Swords into Plows

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