Richard Hackett: Is poor soil quality to blame for the decline in insect numbers?


A succession of reports have identified an alarming decline in pollinator and insect numbers
A succession of reports have identified an alarming decline in pollinator and insect numbers

Richard Hackett

There was a recent report published on the worldwide decline in insect numbers and the primary cause was identified as the use of pesticides.

This conclusion appears to have been accepted without any comment or questioning.

At an Irish, and indeed European level, such commentary and acceptance of these conclusions as fact have to be questioned.

In an Irish context, less than 8pc of the Utilisable Agricultural Area (UAA) is in tillage, which means that 92pc of the land area is in grass.

So for all intents and purposes, 92pc of the land area receives no pesticide whatsoever, except maybe for an occasional herbicide. Of the 8pc that is in tillage, the vast bulk of land receives at most one and generally no insecticide in a season.

Also within these tillage areas, the Irish field structure ensures that there are plenty of 'refuge areas' in the shape of hedgerows/ ditches/ grassy banks etc that also receive no insecticide or any pesticide. So before we even look at the pesticides applied, the fact is that only a small percentage of the country's UAA receives any insecticide, or indeed any pesticide, annually. This takes us to the products we use.

EU pesticides' regulations are among the most stringent in the world.

These tight regulations have resulted in a large number of pesticides being withdrawn from the market place, very few chemicals being released and a general disinterest from chemical companies in developing new products for the European market.

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This tight regulation has created an agricultural environment and production system that is extremely safe for consumers, producers, bystanders and also the bugs, insects and animals that we share our space with.

Before any pesticide can be released for sale, it has to pass many regulatory hurdles, under many different headings. These include:

the impact of the chemical on consumers, operators and bystanders (toxicology)

the impact on birds, insects, non-target organisms micro-organisms (eco toxicology)

how the chemical breaks down in the environment and what it breaks down to (environmental fate)

what the chemical is made up of, what it breaks down to and how long it takes to break down (chemistry)

does the chemical do what it's supposed to do (efficacy).

If at any point of assessment a chemical fails very strict criteria under any of the above headings, no matter how good it is under other headings, it is rejected.

In order to create the rooms full of data necessary for such evaluation, chemical companies employ armies of scientists with a vast range of disciplines and specialities.

At the same time, the EU through the European Food Safety Authority and each member state, Ireland included, employ equally their own armies of scientists to evaluate the data that is produced.

The net result of all this effort, all this regulation and all this cost, is that products that we have available to us are safe. Safe for us, safe for the environment, safe for bugs, insects, birds and mammals.

It is disingenuous that all this research and regulation can be dismissed by sweeping statements that agricultural chemicals are are killing the environment.

Then what is causing the reduction in insects and what can we as food producers do to increase the population of bugs and insects on our land?

I believe that too many years of taking off more from than the land than is being put in, continuous cereals' growing on inorganic fertilisers and too much weight from machinery is taking a heavy tool on soil quality

A colleague of mine, John Geraghty, points towards the soil food web produced by Elaine Ingham as a potential solution.

The soil food web dictates that a biologically active soil allows for the development of an environment suitable for micro-organisms, protozoa and fungi to proliferate, which in turn provides food for nematodes, and arthropods to proliferate.

This in turn provides food for birds and mammals to proliferate.

These are then broken down as they die via the same micro-organisms and bacteria to continue the cycle and keep feeding the web.

How do we go about increasing the biological activity of sour soils?

We have to encourage rotations, we have to balance our soils in terms of pH and soil nutrients.

We have to encourage the use of organic manures on tillage land, especially biologically active manures like farmyard manure. We have to encourage livestock grazing on our tillage soils. We really have to look at the weight of machinery we are using on our soils.

It's not rocket science, but the payback can be great - for us and the bugs and insects we depend on.

Richard Hackett is an agronomist based in North County Dublin and is a member of the ITCA and ACA.

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