Introduction
Why do we talk about phosphorus ?
1 of the 9 planetary limits 1 of the 3 planetary limits exceeded What is phosphorus ? What is its cycle ? In which human activities is it used ? How to return to a "normal" situation ? |  |
During the course, think about the different interactions between humans, nature and systems involving phosphorus.
How was phosphorus discovered ?
According to you, how did humans discovered phosphorus ?
A. By looking for the Philosopher's Stone
B. By doing caving (spéléologie)
C. By observing a carp population in a lake
A - Complete answer :
By looking for the Philosopher's Stone AND analyzing urine. Yes.
Who ? Hennig Brand
When ? 1669
Why ? By looking for the Philosopher's Stone
How ? By analyzing large quantities of urine
Properties :
it is phosphorescent
it ignites spontaneously on contact with air
1769 : Scheele discovery
(Gervy, 1970)
(Joseph Wright, 1771)
What is phosphorus ?
According to you, where can we find phosphorus ?
A. In our DNA
B. In our Smartphones
C. In our clothes
(Compound Interest, 2014)
(Sanderson, 2018)
Where is phosphorus ?
(Cordell, 2009)
(Syers, 2011)
(Baturin, 2003)
Why and how humans use phosphorus ?
According to you, why do we use phosphorus ?
A. To create bombs
B. To create fertilizers
C. To create match scrapers (grattoirs pour allumettes)
(Cordell, 2009)
And HOW ?
Use of phosphates before their discovery :
1. Use of bones
2. Use of guano
According to you, what is guano ?
A. A plant that can be smoked
B. A typical Latin American outfit
C. A pile of excrement
Seabirds and bats dropping are full of
phosphorus !
2 reasons to use guano :
Both live in large colonies
High concentration of phosphorus
Phosphorus cycle
The cycle
According to you, what is not involved in the phosphorus cycle ?
A. Atmosphere
B. Oceans
C. Lacks
Anthropogenic phosphorus input
Why phosphorus became toxic ?
An ever increasing amount of phosphorus in ocean.
(Baturin, 2003)
(Gaujous, 1995)
Eutrophication phenomenon
(Pinay, 2018)
Social consequences :
Crystalization of social tensions
Agricultural world, local elected officials and environemental protection associations
DIfferent environement conceptions of public action, social responsability and scientigic knowledge
Why is it important ?
According to you, is this phenomenon reallyimportant ?
A. I guess, otherwise this course wouldn't exist
B. It is important but there are bigger issues
C. Not important, it is nothing in front of other issues
(Steffen, 2015)
Current phosphorus dependency
Rapid food demand to rapid population growth
Rectification of phosphorus deficiency of soils
Saving people from starvation
« 90% of global demand for phosphorus is for food production, currently around 148 million tonnes of phosphate rock per year (Smil, 2000a, Smil, 2000b, Gunther, 2005) »
(Cordwell, 2009)
Phosphorus peak
(White, s.d.)
Prospective of phosphorus demand
« Following more than half a century of generous application of inorganic high-grade phosphorus and nitrogen fertilizers, agricultural soils in Europe and North America are now said to have surpassed ‘critical’ phosphorus levels »
« Consequently, demand for phosphorus in these regions has stabilized or is decreasing. »
« However in developing and emerging economies the situation is different. Global demand for phosphorus is forecast to increase by around by 3–4% annually until 2010/11 »
=> high demand and an approaching peak...
A new war on phosphorus ?
(Wikipedia, s.d.)
How can we ensure the safety of phosphate supplies?
Phosphorus security goals might therefore include:
"Increase number of people fed per tonne phosphorus input, or, reduce total phosphorus demand while maintaining food/agricultural output;
Reduce dependence on phosphorus imports (to reduce vulnerability to geopolitical dynamics and thereby increasing long-term access to phosphorus);
Ensure healthy soils (no phosphorus-deficiency, no phosphorus accumulation, balanced nutrition and presence of organic matter);
Ensure farmers needs are met (e.g., maintaining or increasing productivity; ensuring access to phosphorus fertilisers);
Reduce losses and wastage where avoidable;
Reduce eutrophication and pollution by preventing phosphorus from the food system from entering waterways."
4/5 phosphorus mined for food production never actually reaches the food on our forks
Existence of a whole toolbox of phosphorus recycling and efficiency
Low tech and high tech phosphorus recovery in the sanitation sector to changing diets
Sustainable management of phosphorus
Possible solutions for the management of phosphate nutrition of tropical crops in the context of ecological intensification :
Making better use of the diversity of the plant world and genetic resources
Greater use of species assemblages in time and space
Make more efficient use of mineral and organic inputs
Assessing the potential of microbial inoculants and bio-effectors
Maintain and promote the activity of the soil's macrofauna
earthworms = ver de terre
(Hinsinger, 2015)