Sustainable agriculture requires the sustainable production
of high yields and the minimisation of environmental pollution. Researchers are required to identify the
means by which farmers can best manipulate the complex agro-ecosystem. For the sustainable intensification of
agriculture to be achieved, the behaviour of farmers will have to alter from
the current, unsustainable course. For
arable farmers, this might mean the adoption of novel crop varieties and
agrochemicals, an increased reliance upon and contribution to big data, changes
to crop rotations and changes to tillage, all against and increasingly
changeable climate. Behind those
advances will be crop geneticists, crop protection chemists, computer
scientists, engineers, soil scientists and many more researchers which farmers
will never meet. This blog is a
reflection on doing soil science via field trials, specifically the situation
where a PhD students sets up and manages a field trial only used for their research.
My soil science and agriculture PhD was partly field
based. That meant that I had field
plots, hosted and managed by a farmer, in which experiments were established
and sampled over the course of the three-year PhD. Three years is not a long time in
agricultural field experiments. Every
year is exception in some sense: a dry autumn, an early frost, a lack of frost,
a wet and mild spring, the list goes on and data from every year ends up
couched in a weather-related caveat. The
research was carried out on one farm, with one soil type which differs greatly
from much of the UK, with soil properties also varying across the field and
across plots. I was hoping to observe
changes to soil properties which might take over 3 years to accumulate. All of this raises the question “why use a
field trial?”. It comes back to two pieces
of the sustainable intensification puzzle: 1) soils are complex which means
that it is not always possible to make predictions based on studies of
simplified systems; and 2), sustainable intensification will require the
changing of the behaviour of farmers and farmers trust field trials more than
laboratory or glasshouse studies (see point 1).
My PhD left me with an appreciation of both the value and the difficulty
of conducting soil science via field trials.
This difficulty only increases when you consider publishing scientific
research in academic journals. Because of
the variability inherent in field trials, multi-year studies at multiple sites
are the gold standard. If you’re
investigating changes that are going to take multiple years to develop (i.e.
changes to soil structure following the cessation of tillage) then this will
only lengthen the project (unless you can find field sites differing only in
the treatment you are interested in).
The end result is that the time taken between beginning a field trial
and collecting your last set of data will be at least three years, preferably
five or more. This is slow soil science.
At the other end of the scale, it’s possible to conduct
rapid soil science, independently of field trials. Soil can be sieved and mixed to reduce the
variability that plagues field studies when investigating soil physics, or
sterilised and re-inoculated with pre-determined taxa when investigating soil
biological communities. Basic questions
can be investigated with techniques including x-ray computed tomography (to
investigate soil physics), next generation sequencing (to investigate soil
biology) and isotope tracing methodologies (to investigate nutrient cycling) to
name a few. Important and interesting
questions can be investigated via experiments lasting a period of hours to
weeks, presenting opportunities for the publication of research articles at a
much faster rate than is possible where a researcher establishes and samples
from a field trial. This is the
high-speed science. The trade-off, of
course, is that this science in isolation is unlikely to sway the actions of
farmers, a bridge is required, bringing us back to field trials.
Many PhD projects are based around field trials which are
set up specifically for that piece of research and will last for a maximum of three
years. Carrying out such a PhD gives a
young scientist a great insight into how agriculture actually works, what
problems are faced by farmers and the tools farmers have to tackle these
problems. There is a high chance that
the research will have an effect in the real world. But they are challenging, placing the
researcher at the mercy of the weather, the in-field variability and the rate
of change of soil processes in the field.
One solution is to combine both fast and slow science within a PhD. To investigate the same question in a
simplified system in a laboratory and also in the field. It is certainly appealing but obviously requires
more work which brings me on the issue of supporting research.
Governments
fund research because the outcomes benefit everyone. Better crop varieties mean high yields
benefitting farmers and the public (who pay less for food) whilst field buffers
can provide a public good by improving water quality and any reduction in net
greenhouse gas emissions benefits everyone.
A field trial cannot only be used to investigate the generation of
public goods, it is a public good for the scientific community (a source of
experimental material) in itself. Field
trials don’t just benefit farmers by demonstrating what does and does not work,
they are also a hugely valuable resource for other scientists (who were not
necessarily involved in their planning or running) which utilise them in
previously unplanned ways. Where an
experiment in a simplified system shows an interesting result, one of the next
steps is to investigate this in a more complex system i.e. in the field. The value of a well designed, long-term field
experiment which provides suitable treatments and is ready for use is
obvious. The UK government recognises
this value, i.e. funding Rothamsted Research’s field trials, from the short to
the very, very long (175 years), via the BBSRC.
As a field trial is an extremely valuable resource, I think
it is worth asking if the one-PhD, one-field trial model is an efficient
one? Indulging ourselves for a moment, I’d
suggest, a six-year field trial is far more valuable than two three-year field
trials, that two PhDs sharing two field trials is both more efficient and less vulnerable
to a problem at a single field site, and that a well-designed field study could
support more than one PhD (with the costs associated with running a field trial
shared across projects), especially where both fast and slow research were
carried out. Obviously, the funding is
the sticking point. Getting funding for
a single PhD is hard enough, securing funding for two at the same time is
almost never an option. However, whilst
three years for a PhD sounds like a long time, it’s not when it comes to field
trials.
For the record, I really enjoyed the field-based parts of my
PhD. They gave me a great introduction
into arable agriculture and produced some interesting results. This is just a note that when it comes to a
field-trial based PhD, it pays to be cautious.
The error bars will be big your control of experiments will be low.
P.S. After writing this I came across a scientific
article titled “The importance of long‐term experiments in agriculture: their
management to ensure continued crop production and soil fertility; the Rothamsted
experience” (Johnston and Poulton, 2018) which can be found here
(the article is open access meaning anyone can read it for free, a true public
good). I’d recommend it if you are
interested in a detailed discussion of the value of long-term experiments
including specific examples, rather than the ramblings of a postdoc.
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