I
love off the cuff marketing statements such as “the turf management practice
that does most damage to soil microbes, is
synthetic
fertilisation”. Not fungicides or any of the wide range of chemicals and
wetting agents that are used in the turf industry but synthetic fertilisers.
When
it’s taken into account that this statement is made by a company that is
promoting its own range of biologically enhanced fertilisers in direct
competition to these “bad boys” one does tend to be a touch cynical. This same
company also conveniently fails to mention the impact of fungicides that they
supply on soil microbial populations. But why let that get in the way of a good
story!
The
turf industry is unique for a whole host of reasons but one of the key ones is
that quite often turf managers are trying to grow grass in a completely
unnatural environment . A USGA spec golf green for example, is not a natural
environment and in reality it can be best described as a hydroponic medium
which supports turfgrass roots. The key aim, of growing grass whilst
maintaining a freely draining rooting medium and a firm surface, hardly mimics
the requirements of for example a cereal farmer.
As a
result of this, it’s makes sense to conclude that the demands on this surface
differ significantly. The requirements for pesticides and other inputs can vary
dramatically compared to a production system. For example, whilst a farmer
might use manure on a paddock this approach isn’t generally recommended on a
golf green and how many farmers spray weekly as part of a management program?
If
you are intending to go down the pathway of reducing synthetic inputs it can
only be an all or nothing approach. You can’t simply stop using synthetic
fertilisers and switch to biological inputs and expect the same results if you
carry on with your usual practices such as fungicide applications.
There’s
a good chance that any fungicide applied will kill the microbial “goodies” you
are trying to encourage. Sort of defeats the purpose really. As an aside It’s
worth noting that biostimulants tend not to suffer from this issue!
As a
general guide if your applying what are living organisms such as VAM or
trichoderma sp to your turf as a substitute for synthetic fertilisers or as a
soil amendment, your going to have to seriously look at the impact of
fungicides on these.
There
appears to have been very little work done on using biological products in
intensively managed turf situations. The majority of trial work tends to have
been carried out in isolation of other inputs which is hardly a realistic
scenario. Factors such as irrigation regime, pesticide inputs and even wear are
seldom taken into consideration, when in reality we all know these can play a
dramatic role on how a surface performs.
With
the drive to reduce inputs many golf course superintendents are using annual N
levels of less than 1kg/100m2 already which hardly constitutes massive amounts
of fertiliser in anyones book.
In
the case of pesticide use, fungicides dominate. Triazole fungicides including
propiconazole, tebuconazole, tetraconazole, triadimenol, triadimefon, and
triticonazole show toxicity to a wide range of non target organisms. High doses
of triazole fungicides strongly affects the structure of the microbial
communities in soil and usually decrease the soil microbial population and the
activities of enzymes found in soil. (Roman etc Al, 2021).
In
conclusion the statement “our microbes aren’t effected by other inputs such as
fungicides” should set alarm bells ringing and until the appropriate trial work
is carried out. I personally wouldn’t be putting my job on the line in order to
get that warm fuzzy feeling of “doing the right thing”.
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