Planetary Boundary 2 – Eutrophication – Nitrates and Phosphates

What is a “Planetary Boundary” and why is it important? Link to the introduction article on this topic. The “Planetary Boundaries” is a model of global biophysical systems that support our life on the planet. For each system, quantitative models and indicator metrics have been developed to indicate the health of the system.

The second planetary boundary that our civilization has crossed into the catastrophe zone is Eutrophication, by polluting surface waters with nitrates and phosphates. The nitrates and phosphates come from fertilizers in agriculture, mainly from chemical-industrial agriculture (non-organic practices).


The indicators chosen are:
Nitrates – how much synthetic fertilizer nitrates do we make per year (Haber-Bosch process) from nitrogen in the air – million tons/year.
Phosphates – how much phosphorus is rinsed out into the sea from human activities – million tons/year.

1. Pre-industrial value: Nitrates 0 million tons/year, Phosphates -1 million tons/year
2. Current value: Nitrates 121 million tons/year, Phosphates 15.8 million tons/year
3. Safe zone boundary: Nitrates 69 million tons/year, Phosphates 6.9 million tons/year
4. Catastrophe boundary: Nitrates 91 million tons/year, Phosphates 12.5 million tons/year

We are therefore deep into the catastrophe zone for both nitrates and phosphates. We need to cut these geochemical flows in half on a global scale, as soon as possible.


The effect of fertilizers in surface waters (rivers, lakes, shallow sea bays) is an increase of algae, which die off and fall to the bottom in great volumes. The composting of these algae consumes all the oxygen in the water and the bottom areas die off. The most famous one is along the coast of Louisiana, USA, and the size of the death zone is as big as New Jersey (half of The Netherlands) – 11,000 km2. There are now >400 documented dead zones in the world and the number and intensity is growing every year.


“Dead zones” in the world oceans 2013 ( This is driven by chemical-industrial agriculture.

When the lakes and oceans die, not only fish and whales die off, but also the oxygenation of the air we breathe goes away.

The “dead zone” outside Louisiana. 11,000 km2 of dead ocean.


Algal bloom in Lake Eire, the first step in creating a fully dead zone. (

Who shat in my water?

The largest source of phosphates and nitrates in surface waters is agricultural “run off”, and on the second place is untreated human domestic sewage. (Therefore, I focus today on the agricultural sources, and I will come back to the humanure problem/solution in another post.)

Synthetic fertilizers in chemical-industrial agriculture is driving the nutrient overload wherever grains are grown. Most of the maize/corn and soy beans in the world are fed to pigs, chicken and cattle, who concentrate these nutrients in their manure.

The manure ends up both in the ground water (especially nitrates), which is the leading source of groundwater contamination, but also in our rivers, lakes and oceans. Most of the nutrients in the oceans thus come from factory meat production.

Global use of synthetic fertilizers. We need to come back to below the level of 1980. (Source UN FAO / Our World in Data.)

In Netherlands, where I live, the situation is peculiar. The meat-and-dairy sector imports animal feed containing 100,000 ton phosphates per year, which is twice as much as the agricultural fields can take. Therefore this excess manure is an important local problem, as well as contributing to the global eutrophication.

Where do the nitrates and phosphates come from?

Nitrates are magicked from thin air. Norsk Hydro/Yara is the biggest global player who uses fossil methane gas to drive the chemical process of converting nitrogen (N2) gas from the atmosphere into ammonia (NH3). The process was invented by Fritz Haber 100 years ago and has been used with ever increasing volumes. (Synthetic nitrates are therefore a problem for CO2 emissions, fossil fuel depletion and eutrophication!)

In classic (organic) agriculture, leguminous plants like clover do this job. Every third year or so, the fields were in fallow, planted with clovers, lupines and other nitrogen fixing plants. (really plants in symbiosis with nitrogen fixing bacteria). This reduces the run-off immensely and is really part of the solution. However, the temptation to use synthetic fertilizers in strong – synthetic fertilizers increase the speed of production.

Phosphates comes almost exclusively from mined rock phosphates. Morocco, China and USA are the leading producers of phosphates, with 70% of the world production. The rocks often contains other elements like cadmium, which leads to pollution at the source, and sometimes to poisoning in the field.


Since the largest chunk of nitrates and phosphates come as run-off from chemical-industrial farming, this is where we need to change. First of all we can drastically reduce the area in production by eating less meat.

Secondly, we should as a society stop (or dramatically reduce) using synthetic fertilizers. If we cut it to half, we are back in the safe zone of this planetary boundary.

The third stage is to produce healthy food in a circular way. Agriculture in balance with ecology to strengthen the soils – a.k.a. agro-ecology. There are innovative farmers who build rich soils using animals, trees, bushes and grasses. This has positive effects on other life support systems like biodiversity and the climate system. There is a whole new branch of agriculture called “Carbon Farming”, which produces food and at the same time captures CO2 into the soil and plants. Another advantage of these perennial systems is that they capture nutrient runoff so that it does not end up in the oceans!

 What can I do?

  • Eat less meat. Buy organic meat. If you can from a farmer you know.
  • Join a political party and push for a transition to organic farming.
  • Support local agro-ecology projects. Find an organic nut grower, or join an agro-ecology interest group.
  • Grow a garden or plant a fruit-tree in your yard.
  • Get the book “The Carbon Farming Solution” by Eric Toensmeier
Get your own copy of this excellent book at Chelseagreen,com or your favourite bookstore.



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