Friday, July 12, 2013

Phosphate and Nitrate Algal Bloom in the Yellow Sea... Again

Once again a massive algae bloom has occurred off the shores of Qingdao (青岛). You may recall that the last time this occurred in 2008 Qingdao was just months away from hosting the Olympic sailing competitions. A massive clean up effort cleared the waters in time for the events but the underlying problem of fertilizer runoff is still very present. Phosphate and nitrate runoff from excessive fertilizer use in Shandong Province empty out into the waters around Qingdao. Combine this heavy nutrient load with the right weather and a massive algae bloom (410 square km according to The Telegraph) is the result.

Zhang qiao pier

Recognize that pier now?

I'll admit that much of the world's population depends on synthetic nitrogen fertilizer and mined phosphorus to provide them with food. However, the excess amounts being applied to Chinese cropland is ridiculous. In a great National Geographic article about nitrogen fertilizer, Dan Charles describes how one rice farmer is using 530 lbs. of nitrogen per acre, while some vegetable growers are using 800 or even 1600 lbs. per acre!

We can see how the majority of nitrogen fertilizer used for crops comes from synthetic sources.  We  can also see that we are applying more than is taken up by crops.

Using the great Roots Tubers & Bananas Maps from CGIAR we can really get a sense for just how excessive fertilizer use in China is compared with the rest of the world.  

Phosphorus use
Nitrogen use

There are dramatic well documented health and environmental problems this type of fertilizer use causes.  What I think is even more concerning though is that these fertilizers come from non-renewable sources.  Phosphorus is currently mined in a few countries - there is not an endless supply in these mines.  The way that synthetic nitrogen fertilizer is produced requires enormous amounts of natural gas- although cheap now this will eventually become more expensive as reserves dwindle.  

As the sources of these fertilizers become scarcer prices will increase.  Poorer nations will be the first to be priced out of the market. Indeed, fertilizer is already difficult to procure for farmers in developing countries.  If we are concerned about the stability of world food production, and the political stability of countries who will be first affected when production falters, we need to take a closer look at fertilizer use.

Alternative sources of fertility are readily available and often times cheaper than chemical fertilizer when the appropriate infrastructures are set up.  In addition to switching to renewable fertility sources, regulation needs to be set up to manage fertilizer runoff.  Most people would agree that dumping toxic pollutants from a factory should not be allowed, so why should applying fertilizer in quantities that will obviously lead to nitrate run off be treated any differently?