Nitrogen benefits and environmental costs,

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.

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