I studied ecology and conservation as an undergraduate
before taking the opportunities available to me and beginning a PhD
investigating the sustainability of agricultural practices, particularly
tillage (the preparation of soil for the planting of a crop). I’m not from a farming background and had not
studied soil science extensively before my PhD so faced a steep learning curve
(a reason for my lack of blogging).
However, my education as an undergraduate equipped me with ways of
thinking which could be addressed to this new context. I’m writing this blog for two reasons and two
audiences: I want to promote soil
science to those interested in ecology and conservation who may not have an
agricultural or soil science background and I want to share a way of thinking
about soil management which I hope might ring true to the farmers acting as
custodians of our soils.
To me, the essence of conservation science is identifying
situations in which the ability of nature to provide benefits to humans is threatened
or being degraded. Often these
situations exist because of a lack of awareness of either the benefits that
healthy ecosystems deliver or the impact of a practice on the ability of an
ecosystem to continue to deliver these benefits. The hope is that by making the value of a
healthy ecosystem clear individuals or companies are motivated to protected its
health and reap the rewards themselves (e.g. water companies working to restore
upland peat ecosystems to save on water processing costs) or government actions
can be taken to protect ecosystems which provide benefits to many people (e.g.
national parks protected so that the public can benefit from spending time in
these spaces). Where the benefits or
changes to the ecosystem are less visible then degradation is more
likely.
To state the obvious, food is a basic human requirement and
you can’t grow (the vast majority) of it without soil. It’s also valuable for its role in regulating
the quality of water and the flow of water through the environment. And, crucially, not all soil is equal. Just as a dense, wide mangrove forest provides
better flood protection than a narrow, sparse forest the ability of a soil to
support crop growth and regulate water quality will depend on its properties. This is where soil science gets more
complex. The ability of a soil to
deliver these benefits will be determined by a range of chemical, biological
and physical properties of the soil, all of which are interlinked and many of
which are hard to observe by eye. Soil
degradation may go largely unnoticed, obscured by the use of fertilisers to
compensate for a reduction in the soil’s capacity to cycle nutrients or the use
of tillage to restructure soil whilst any changes in yield can be easily
attributed to a year’s weather. In fact,
it might not be until an extreme weather event that the costs of soil
degradation become visible in the form of brown runoff carrying valuable
topsoil (and the associated nutrients) from the field to watercourses where it
contributes to sedimentation and nutrient pollution.
Soil health (the ability of a soil to provide the required
benefits) is affected by farming operations and tillage is the one I am most
interested in. Tillage can involve
flipping the soil over (i.e. ploughing), or chopping and mixing soil, breaking
up the soil structure. The full range of
pros and cons of tillage and synergies between reducing tillage and other
practices such as cover cropping and glyphosate use are a topic for another
day. For now, I want to present tillage
to (non-soil) ecologists and conservationists as a wonderful example of a ‘disturbance
event’. By rearranging the soil
structure and killing many organisms (e.g. earthworms and fungi), tillage is analogous
to hurricane or forest fire and the same questions apply (i.e. how long do biological
communities take to recover? and what is the relationship between the intensity
of the disturbance event and the effect on the biological community?) . Whilst studying forest fires and hurricanes
leaves you largely at the whim of nature, tillage is a disturbance event which
you can have under your own control. It
affects an incredibly biodiverse system which underpins the generation of
vitally important services such as nutrient cycling, soil structuring and
biodegradation of pollutants.
As an undergraduate I preferred ecology to pathology because
I preferred studying organisms and systems which I could see with a naked
eye. To me, conservation science is
about identifying the overlooked, and for most of my life, soil hid in plain
sight. I have to encourage any ecology
and conservation undergraduates to take a good look at soil ecology.
To farmers, this is not meant as an attack on tillage or a
plea for minimum or zero tillage systems, that’s something which I will address
in another blog.
