Why soil matters?

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8 Why soils matters - A european perspective
Stephane le Foll launches the programme
(‘4 pour 1000’), which aims to increase the organic
content of the soil by 4gr per 1000gr of carbon stock
in the soil. If this programme is implemented with an
increase in the organic content of 4 per 1000 every
year, this could result in soils absorbing the totality of
global carbon dioxide emissions, representing 75%
of total man made GHG.
So, soil is an essential, vital asset in combating
climate change and reducing GHG emissions. But at
the moment we are losing this battle as a result of
the quality of the soil.
There is today a debate within the international
community as to how to re-launch agriculture, how
to increase the ability of agriculture to satisfy a
growing demand for agricultural products. We can
summarize 2 approaches to these questions:
- The first approach is the classic, conventional
approach - sometimes still called ‘the green revolution’
approach - which insists on bringing more external
inputs: pesticides, synthetic nitrogen-based fertilizers-
based on the NPK formula (Nitrogen-Phosphorus
and Potassium), to re-inject into the soil the fertility
that it would otherwise be losing. This approach also
invests in mechanisation, large-scale irrigation and
use of improved varieties of plants - so-called high-
yielding varieties, often commercially bred seeds. This
commonly known approach is expanding in Africa after
having been developed in South America in the 1950’s
and in south Asia in the 1960’s and 70’s. It is the model
that has been promoted in Europe since the 1920’s.
- Agroecology is the other approach. It is a different
way of looking at the challenge of agriculture. A way of
looking at agriculture that recognizes the complexity of
nature, the natural interaction between plants, trees
and animals, and tries to replicate at farm-level the
natural interactions between these different elements.
Rather than simplifying nature, it recognises the
complexity of nature and adapts agricultural practices
to this complexity, to play with nature as an ally rather
than reducing nature to a chemical formula.
This implies a range of agronomic techniques:
- Agroforestry: the use of trees to reduce erosion, to
allow soil to better capture moisture from rainfall. For
example, in Africa there is currently a widespread use
of a particular type of acacia, called Acacia Faederbia,
which is a fertilising tree that re-injects nitrogen into the
soils, enabling farmers to plant trees around their fields
to reduce their dependency on chemical fertilisers.
And we see this developing well in countries such as
Zambia and in the Sahel: in Mali, Burkina Faso, Tchad,
Sudan, Niger. It is this method - agroforestry - which
is promoted by the Nobel Peace Laureate
, or in Africa by the
and (UNEP).
- Biological control: using plants rather than pesticides
in order to protect cultures. E.g in Africa, beginning in
Kenya, developed the use of desmodium
intercropped with maize, in order to repel insects which
attack either maize or sorghum, and alongside the field
of maize intercropped with desmodium, you plant a
grass called which attracts the pests and traps
them alongside the field. And this biological control is
again a way to play with nature, rather than trying to
simplify nature thanks to the use of chemicals.
- Use of leguminous plants, such as peas, beans, alfalfa
and clover, in order to fertilise the soil and reduce the
need to rely on chemical fertilisers
We are now at the end of the cycle where the
‘Green Revolution’ approach was seen as desirable
and as the only way forward.
This is for 4 reasons:
- ‘Green Revolution’ approaches lead to a significant
dependency of agricultural production on non-
renewable resources. Gas to produce nitrogen-based
fertilisers, oil for mechanisation, phosphorus which is
mined in different parts of the world and is not infinitely
available either. Even nitrogen - we remove nitrogen
from the atmosphere at a rate 4 times above what
should be allowed. We remove about 120 million tons of
nitrogen per year from the atmosphere, when it would
be sustainable to use no more that 35 million Tons.
Proceedings of the Conference