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September 2018
36
Focus
Integrated pest control
The effects of herbicides on soil life
T
he internet has opened doors of knowledge for everyone
to enjoy. Research findings are readily available, which al
lows the reader to draw his or her own conclusions on any
topic one can think of. When approached to write a series of
articles on the effects of herbicides, such as glyphostae, on soil
health, we aimed to provide an objective view of international
publications as well as equip the reader to navigate between the
‘potholes’ of publications available online.
These days, anyone can publish online. A popular publication, al
though based on scientific findings, does not carry the same weight
as a scientific paper, however. When compiling a popular publica
tion, the author often presents what he or she perceives to be rele
vant. Additional information can thereby (un)knowingly be excluded,
which could have provided the reader with a better understanding of
the impact of the research findings.
One should, therefore, not jump to conclusions when dealing with a
popular publication, but rather obtain more information on the topic
presented. Contact details of authors are readily available on popular
publications so that readers can request the sources used to write a
specific article.
When producing scientific publications on the other hand, the re
search reported on in such a publication must adhere to certain
requirements. This does not necessarily mean that all research
findings can be seen as equal, however.
The most important criteria of a scientific journal is that it must
be peer-reviewed (i.e. the publication is subject to evaluation by a
panel of reviewers). The second criteria is its impact factor. The im
pact factor of a journal indicates to a reader how much information
published in this journal is referenced in other studies. The higher
the impact factor, the more the information is used.
When in doubt as to whether a scientific publication was based on
sound scientific principles, researchers at the ARC or tertiary institu
tions can be contacted for insight into this matter. Lastly, one cannot
extrapolate research findings to all situations because the results
can easily be misinterpreted, especially by someone that is not a
specialist in the relevant field. Our recommendation is rather to con
tact an expert in the field discussed in the publication to confirm the
interpretation thereof.
The series of articles that will be presented by us on this topic might
accordingly not be in the usual format that
SA Graan/Grain
readers
are used to. It was specifically done in such a way that the reader is
able to access the sources used by us. Regardless, the information
presented in these articles only represent a fraction of what has al
ready been published on the effect of herbicides and their impact on
soil life. Our hope is that this series of articles might inspire further
discussion that would add value to this topic.
Let’s talk herbicide impact
Based on the figures of a report presented on the sale and usage of
the pesticides industry in the United States (USA) for the 2008 to
2012 period, herbicides are the most widely applied pesticide
1
. Since
the development of the first herbicide, the primary aim of research
ers was to understand and predict how herbicides affect soil fertil
ity through their effects on the micro-organisms responsible for the
maintenance of soil fertility and on the populations of invertebrates
responsible for the recycling and translocation of nutrients.
Charles Benbrook
2
states in his research article published during
2016 that no other pesticide is as intensive and widely used in the
USA as glyphosate. In 2014, producers sprayed enough glyphosate
to apply ~1 kg/ha on every hectare of USA cultivated cropland and
nearly 0,53 kg/ha on all cropland worldwide. Because glyphosate will
likely remain the most widely applied pesticide worldwide for years
to come, he further stated that there will be a growing interest in
quantifying the actual ecological and human health impacts.
In the first topic of our series of articles, we will discuss the outcome
of numerous research studies with regards to the effect of glypho
sate on soil health facilitating fungi, bacteria and earthworms – the
innocent bystanders in the war on weeds. In this article we will main
ly focus on microbial biomass and respiration.
Part 1: Microbial biomass and respiration
Dr Maryke Craven, Charné Myburgh, Owen Rhode
and
Dr Jeanetta Saayman-du Toit,
ARC-Grain Crops, Potchefstroom
Grain SA/Sasol photo competition
– Lizette Nel 2014