This is my first time blogging about a conference. To avoid a boring, he said, she said
structure, I’m going to try and pull out some themes which ran through the
talks I attended to today and which I found interesting.
Professor Rattan Lal provided the opening keynote for the
2018 World Congress of Soil Science (WCSS), setting the context for the
research to be presented over the rest of the conference. Listening to this talk was an odd experience
as it took me back to my days as an undergraduate studying conservation
science. The theme of natural resources
being both undervalued and managed based on an oversimplified understanding was
front and centre with the value of soil being described in terms of the
ecosystem goods and services it is capable of generating.
As if this was not motivation enough for improving management
of global soils, Professor Lal finished on a flourish, arguing that improving
soil management would represent a significant step towards world peace. Throughout I was reminded of a phrase from
Charles Godfrey which I came across as an undergraduate: “if we [conservationists]
fail on food, then we fail on everything”.
Professor Lal took a step beyond this to argue that if we fail on soil
then we fail on food (and everything that follows). So, I think that should be motivation enough
to make the most of this conference.
Professor Lal stressed that soil health (both positive and
negative) is multidimensional, cannot be effectively managed via one management
practice (from mineral fertiliser application to liming to tillage), and is
associated with significant co-benefits (human nutrition, environmental quality
and world peace). Themes which ran
through the talks of Professor Claire Chenu and Professor Budiman Minasny who
discussed the 4 per mille initiative- the policy aim of increasing soil organic
carbon levels of the top 30cm of agricultural soil by 0.4% each year.
Whilst I was expecting this series of talks to be structured
around a for-and-against this initiative, I was surprised by a far more open and
interesting set of presentations which forced me to reconsider the value of the
purpose and value of the initiative. The
idea that soil quality or health is context specific is nothing new to soil
scientists and was the subject of my last
blog. These talks argued that for
the 4 per mille initiative, context is key.
Sure, the socio-political context of soil management and the properties
of a particular soil are important, increasing soil carbon is easiest in the
first 10-20 years after adoption of conservation agriculture principles on degraded
soils, whilst the aim for organic soils should be maintaining (not increasing)
soil carbon stocks. What was more
interesting to me is the political context of the 4 per mille initiative
itself. Both speakers argued that the
value of the initiative came from two sources: 1) achieving a relative increase
in soil carbon stocks is a broadly good thing to do (thanks largely to the wide
range of co-benefits associated with soil organic matter) and 2) politicians
and policy makers can get behind the initiative because it is simple and
quantitative- Professor Chenu compared it to the 5-a-day fruit and veg
campaign, whilst Professor Minasny refered to it as a “slogan”.
If you’re trying to define a global initiative to improve
soil quality/health then identifying a single outcome or a set of management
practices to be implemented across the globe is not a simple task. At best you can hope to be broadly right, at
worst, you can be precisely wrong incentivising detrimental actions in some
contexts. Part of the reason that incentivising
increasing soil carbon is robust (with a low risk of incentivising detrimental
actions) is that soil carbon interacts positively with so many dimensions of
soil health from soil structure to nutrient retention and cycling to
hydrological regulation, whilst also contributing to mitigating climate change.
All of this raises the question of exactly which management
practices should be adopted to increase soil carbon levels and what co-benefits
(or dis-benefits) may arise. Talks by Dr
Marcelo Valadares Galdos, Professor Richard Heck and Professor Stephen Anderson
presented their investigations of the effects of tillage, crop rotation and
cover cropping (respectively) on soil structure, which were conducted utilising
X-ray computed tomography. These three
practices represent important tools in the conservation agriculture toolbox
which should be expected to increase soil carbon levels. Together, these presentations highlighted that
if the practices described were adopted with the aim of increasing soil carbon
levels then changes to soil structure would arise with consequences for the
regulation of water flow (amongst other dimensions of soil health). And here I’ll finish with a consideration of
just how complex soil health is, and how challenging it is to develop a robust
soil policy. Whilst the macropore
increases observed by Dr Galdos and Professor Anderson are beneficial when one
is considering the effect of infiltration-excess runoff, under other
circumstances then may result in increases in leaching. That’s not to say that these practices will
be bad for the environment, just that there will also be tradeoffs in such a
complex system as soil.
So, that’s it from my first day. Hopefully this blog was broadly decent and
not precisely wrong in too many ways.
Out to dinner and on to day 2!
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