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Monday, 6 August 2012

teaming with Microbes - a book review

Currently I'm sitting indoors rather than outside helping our helpers finish the pond as I somehow managed to injure my foot.  Not sure what happened, but it's swollen to the size of a pumpkin and I can't walk any more.  Look away now if you are of a delicate disposition:

As you can see the left foot is much larger than the right one.  The almost funny thing is I know what I can do about it, which is apply a comfrey poultice, only thing the nearest comfrey plant I know of is too far away to hobble to and too difficult to explain to Susan where to find it, as she is a) not the best at plant identification and b) is likely to get lost in the woods trying to find it.  And yes I know, I also have a fungal problem, but I'm already working on a solution for that:  I'm making a salve made from field marigold, curry plant and St. John's Wort, which should help.  More of that in another post soon.

But talking about fungi, this leads us neatly into our next subject: a book review on the above book, 'Teaming with Microbes - The Organic Gardener's Guide to the Soil Food Web' by Jeff Lowenfels and Wayne Lewis, since I don't have anything else much to do at the moment.  I did threaten a post on soil science the last time around and that is what this book is about.

Note the pun in the title, the authors are trying to explain how healthy garden soil is not only full of life, but that we should work in cooperation with that life to create a healthier environment for our garden plants.  The book is divided into 2 parts: 1. The Basic Science and 2. Applying Soil Food Web Science to Yard and Garden Care.

Part one was maybe surprisingly the far more interesting part, because by understanding the underlying science you can come to your own conclusions, which, as in my case, may lead you to different conclusions than to those propagated by the author.  The book begins with an explanation why understanding the soil food web is important. 

In general we tend to think of food chains as a kind of pyramid, where the top predator sits at the top of the food chain, but of course, it is much more complex than that, both above ground or within the soil.  Much smaller parasites eat big predators from within, parasitic fungi eat live nematodes or plants, etc, so it makes much more sense to think of the interrelationships between different life forms as a web, where everything tries to get it's sustenance from wherever it is available.  It's a fungus eat nematode world out there, a constant feeding frenzy.  Apparently one single teaspoon of healthy soil has more than a billion lifeforms present in it.  It's a world we have yet to explore properly, which is as alien to us as outer space or the deep sea.

Yet we depend on this soil life in highly complex ways.  The first part goes on to describe the various forms of soil life, each in their own chapter.  Plants deliberately excrete sugars to attract the smalles forms of life, bacteria and fungi, to their roots.  Plants need these life forms to make what they need to feed on available to them.  The most famous example of course is the way legumes attract nitrogen fixing bacteria, which form nodules around the roots.  Nitrogen is ingested by bacteria directly from the atmosphere, which is also why it is important that a quarter of the soil's composition consists of nothing but air.  As these bacteria get ingested by other life forms, the nitrogen is released into the soil through excretion and becomes thus available to plants.  It is important that all parts of the soil food web stay in tact and in balance, for these processes to happen.

Fungi also play an important role as they can break down more complex organic matter and break it down.  Their rhizomes can also travel for literally miles to get to food sources quite some distance away, unlike bacteria, who rarely travel far.  Dying rhizomes create small channels in the soil full of decomposed organic matter, which also let water and air penetrate the soil.  Other notable members of the soil food web each with their own chapter in the book, include algae and slime molds (I particularly liked the example of the slime mold that gangs up as a colony looking like a puddle of dog vomit and moving across your driveway at the speed of 1cm an hour),


protozoa (incl. amoeba aka jelly babies),

Nematodes (not all nematodes are bad!)

Arthropods, i.e. your more visible bugs and insects and other creepy crawlies, earthworms, your most visible sign of soil health, i.e. the more the better, gastropods, i.e. snails and slugs (yes they do have an iportant role to play, as long as they are part of a balanced system),  and finally the bigger animals, such as birds mammals and reptiles.  as you can see the book boasts some impressive microscopic photos, which may or may not give you bad dreams tonight.

The overall conclusion is that each part of the soil food web plays an important role in supporting plant life and you mess with it at your peril.  Whilst many of us regard fungi as a nuisance as they attack our crops in the form of leaf curl disease on peaches, botrytis on our grapes or other fungal diseases, applying fungicide, even one considered safe by organic farmers such as Bordeaux mixture (copper sulphate and lime, the blue stuff everybody seems to spray on their vines and tomatoes) destroys all fungal life, poisons the soil and breaks an important link in the soil food web.  Also adding liqud nitrogen feed has a long term negative effect.  Whilst initially plants will grow better, it also destroys or at least severely damages the soil food web.  In both cases you create a dependency having to constantly re-apply those substances and in the process making the soil poorer.

The authors also argue that tilling and double digging has a severely negative effect on the soil life, especially on the fungal rhizomes, which act like the communication web of a healthy soil.  Theses mile long rhizomes get disconnected and distroyed, leading eventually to compaction and therefore again, leading to extra work again as the soil needs to be dug over again year after year.  The life that lives in the soil is perfectly capable of doing the job for us if we only let it.

The second part of the book then deals with practical solutions by setting up 19 rules to using the soil food web, using just 3 tools.  I don't agree fully with their conclusions.  The 3 tools to create and work with the soil food web according to the authors are: composting, mulching and applying compost teas.  As for composting, they give you the usual compost recipes.  Whilst I agree that, if you make a compost pile you need to mix 'green', nitrogen rich materials (such as freshly cut grass and kitchen wastes) with 'brown' waste (such as old leaves and woody wastes), I am off building compost heaps as a major tool.  The reasons for me are thus:

  1.  Producing a compost heap at one corner of your yard, then involves transporting the final compost to where you need it, which partyicularly in my case with our steep land, involves considerable effort.  Not to mention the effort of regularly turning your compost.  
  2. While turning the compost and transporting it around, you disturb the soil food web you have created, thus going against the principles the authors advocate.
  3. If I produce a compost I use whatever happens to be at hand rather than following some sort of recipe, which depends on specific materials being available and possibly necessitating importing materials to get the 'correct' balance.
What I do instead most of the time, as I have many gaps in raised beds as it is, I simply fill these raised beds with any organic matter which happens to be available.  The authors also advice against the use of any animal or human manure.  I on the other hand succesfully use donkey manure, which effectively is the same as horse manure, which has a good nitrogen balance and occasionally throw it on top of a pile of other organic materials and plant straight into it.  I have done this on the raised terraced beds for my tomatoes during last winter and now have the most wonderfully rich, mosture attentive soil where those exceptionally healthy tomatoes grow.  If I find myself with spare compost in the future (at the moment I'm busy filling in beds left, right and centre), I shall make myself a wormery, which is one of the most effective and fast ways of producing rich compost.

Mulching on the other hand is nature's way of adding organic matter to the soil.  As you add mulch, it encourages beneficial fungi and bacteria.  Worms will drag down some of the material into the soil and mix it in.  Apart from that it of course suppresses weeds and minimises evaporation, meaning you need to water less.

For the compost teas, this is something I should try in the future.  The authors advocate a method of Actively aerated compost teas (AACT).  This involves some equipment to blow bubbles through some water with some compost added to it, which means extraction of the good bacteria and fungi is very quick and non-smelly.  These teas are not only applied to the soil, but also sprayed onto foliage, strengthening the whole system and making it more resilient against harmful diseases and pests.  Once I get around making one of those I shall write about it in a bit more detail.

Interesting also were the points made about the different preferences of different plants as to the symbiosises.. symbiosae symb... which parts of the soil food web they like to associate with.  There are two basic types: bacterially dominated and fungally dominated.  The bacteria are always the first to join any feeding frenzy, followed by fungi, who take a little longer to establish themselves.  Most annual plants prefer a bacterially dominated soil, whilst perennials prefer a fungally dominated soil.  That makes perfect sense again if you just observe nature.  Pioneer species, such as the legumes, form relationships with nitrogen fixing bacteria, whilst of you look at a mature forest with long-lived trees... where is it that you find mushrooms? 

So this is useful information for my bed building again.  If you remember in my last post I was building a raised bed, where I am planning to plant perennials.  We build it up using mainly brown materials, including whole branches and old leaves.  These encourage a fungally dominated soil.  I even threw in an old tree mushroom, to speed up the process.  For your annuals on the other hand you should add plenty of green manure for them to flourish.  My tomato beds also include some chicken manure which is rich in nitrogen.

On a final note on the book, they dedicate a whole chapeter on lawn maintenance.  That seemed to me a bit of a waste of time.  I don't think a lawn has any place in an ecologically balanced garden, as you constantly try and stop it doing what it wants to do, i.e. evolve into a forest.  But all in all this is a really useful, well written and easily understandable book, which I can heartily recommend.  Anybody out there short on money like myself, I do have the e-version on my hard drive and be happy to share it with anybody who wants it.

Finally, the pond really is taking shape now.  Yesterday, already with an injured foot, we constructed the raised bed below the pond, which will be home to some soft fruit bushes:

It's about 5m long and will be filled up with predominantly brown materials.  The pond itself is almost ready.  It just needs another fott depth and some terracing within to give different levels of depth:

 and from above we diverted the way the water comes down into a little feeder channel, so rain water drains into the pond:

Now I just need my foot to get better...


Unknown said...

Flip your foot looks terrible! It's quite puffed up with excess water isn't it? It really looks like you've dropped something heavy on it.

The book looks interesting but I'm leaning towards your idea of filling in beds directly with organic material. Though I don't think I'll ever give up my compost piles I have also been burying some of my green waste and other bits in the soil over the last couple of years. It seems to work just as well as composting it.

Unknown said...

Looks like a good book. I just did a course on biological agriculture, and want to make some compost tea to spray on our pastures. It doesn't look too hard, I'll be interested to see what you come up with. I agree that compost is not practical on a large scale, but worm farms are good for making compost to start the tea :) I'm still working out how to use mulch and cover crops on a large scale.

Heiko said...

Tanya, the foot has increased considerably in size since yesterday. My feeling is it a broken mid-foot bone, which is going to put me out for several weeks, which going to be a real blow! I think burying your organic waste attracts worms to just where you want them.

Farmer Liz, a wormery definitely is a good idea. It makes some of the best compost there is. With the mulch you work on the same principle with the bacterially or fungally dominated soil. Add green stuff to your annuals and brown stuff to your perennials. As for cover crops, if you have the right combination of plants your cover crops can be edibles too, such as nasturtium. And just plant things closer together than generally recommended.