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Boosting garden soil after flooding

Posted by Miranda Hodgson on 13 Feb 2014 at 02:25 PM

Being a gardener, one of my major concerns is the soil and the life in it. There can’t be a square inch of soil in the UK that hasn’t been waterlogged these last two months and large areas have been, and still are, under water. I look at the sodden gardens and the fields that now resemble lakes and wonder what’s happened to all the creatures that live under ground or who are caught out by flooding – voles, moles, hedgehogs, mice. Some will have made it to higher ground while others, sadly, will have been washed away and drowned.


This is usually grassy meadows


What’s been on my mind as much as birds and mammals are the small species that live in the soil, in particular earthworms. I have a great appreciation for earthworms and all they do to keep our soils healthy - working silently under the ground to mix in organic matter, release nutrients, turn and aerate the soil. How long can they live under water?

To find an informed answer I turned to the Earthworm Society of Britain and asked them about it. Below is their very helpful answer.

‘Earthworms can survive long periods in aerated water but for a number of reasons (such as deoxygenation of water, chemical pollutants, lack of food and swelling of the body) a lot of earthworms do perish.

There have been a number of studies on the impact of flooding events and different earthworm species are affected in different ways. Lumbricus rubellus (a large red worm generally staying closer to the surface) is often the species worst affected, with populations being almost obliterated in some cases. However their populations recover quickly; generally within 1-3 months their populations are back to original levels. This is because their cocoons survive in the water and fecundity is relatively high in this species.'

So that I can do the best for the gardens I work in, I’ve been reading up on how waterlogging and flooding affects soil life. When you search the internet for information about the state of soil after flooding, much of it relates to possibly dangerous bacteria, with many warnings about washing your hands. It is only when you narrow the search down to soil biology and microbiology that real answers are forthcoming and you begin to get a bigger picture of just how many species live in our soils and realise that healthy soil is absolutely swarming with life.

I want to do what I can to help that life down there and ensure that all forms thrive – mega, macro, meso and micro. Once the soil has drained of excess water, it will have a gentle forking to increase depleted oxygen levels. Then, according to the Farmer’s Guardian (writing about grass, but it also relates to garden soils), ‘regular applications of composted manure provide the necessary organic matter input which generally leads to an increase in the biomass of soil biota.’ This along with dressings of compost and blood, fish and bonemeal will I hope start it on the road to returning health. In three months, I hope to see a positive difference.


Wildlife Trust article about wildlife and floods



Phot's-Moll said:

That's reassuring, Miranda. Thank you.

It seems that whatever the problem, we can't go wrong by applying compost or other organic matter to the soil.

on 13 Feb 2014 at 03:53 PM

Miranda Hodgson said:

I found the Earthworm Society's words reassuring too, Phot's.

There was a story I read once where visitors would bring their hosts a gift of worms - you can almost imagine that happening again.

on 13 Feb 2014 at 05:00 PM

richardpeeej said:

Very interesting to read about the effects of the rain on the earthworm population Miranda. Just looking at the met office warnings on  tv at the  storm on its way spreading through the uk tomorrow morning. I just had to look up a new word 'fecundity'.... ;-)

on 13 Feb 2014 at 10:41 PM

Miranda Hodgson said:

'Fecundity' does roll off the tongue nicely doesn't it. It's good to know they are a fecund species :-)

on 14 Feb 2014 at 06:22 PM