Monday, February 17, 2014

Teaming with Microbes - book review

I am coming to realize that the science I learnt at university is no longer current, even though I graduated less than 10 years ago. The study, and more importantly, the application, of microbiology in soil is one area that seems to have advanced significantly and it is difficult to keep up with each new discovery. Fortunately, Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web is a good summary of both the current scientific research and the practical applications in our gardens and farms.

The first half of the book is a summary of different types of microbes and larger soil life, including bacteria, archaea, fungi, protozoa, worms and invertebrates, as well as a chapter each on soil chemistry and the physical nature of soil. Each chapter gives an explanation of the role that each type of microbe pays in the overall “soil web”. I summarized some of this information previously after I attended a course on sustainable agriculture, however there was far more detail in the book, which helped me to understand the importance of balance in the soil food web. The final quote “nobody fertilized the old-growth forest” sums up the potential and the importance of the soil food web. If we recognize and encourage a balanced soil food web, then we will no longer rely on chemicals to grow our food (pesticides and herbicides become obsolete, as well as fertilizers).



The most important concept that I took from this section is that plants actually produce “exudates” that feed and encourage microbes. I was vaguely aware of this, and when I mentioned to my neighbor that I would rather have weeds in my paddock than nothing at all because they are at least feeding the microbes in the soil, he thought I was mad. The common thinking about plants and soil fertility is that the weeds are “sucking all the fertility out of the soil” (I can’t tell you how many farmers have said this to me). The fact that all plants are making exudates that are helping the microbes to create fertility is a huge change in thinking for most gardeners and farmers (obviously if you then harvest the plants you are taking something from the soil, but if you mulch them as per Peter Andrews, you are increasing fertility by recycling the nutrients).

The rest of the book describes the application of the science to gardens and lawns. In particular, there is a chapter each on making compost, using mulch and making aerated compost tea. While you will find information on compost and mulch in many other references, aerated compost tea is a relatively new concept and this is a very good explanation of how to make and use it. Aerated compost tea is not to be confused with weed tea or manure tea, the key is that a small pump is used to bubble air through the brew, so that plenty of oxygen is provided to all the beneficial microbes. Previously I have made teas by just leaving weeds and manure to soak in a bucket of water. While this adds some nutrients, it does not stimulate the soil food web in the same way as aerated compost tea, and may even damage it by encouraging pathogens that prefer to grow in the absence of oxygen. I am pretty excited about trying aerated compost tea.

There are also chapters specifically describing how to best use these three tools to improved lawns, vegetable gardens and trees. The only thing missing is farms, but much of what is written about lawns is applicable to pastures. It is mentioned several times that we should not “rototill” our gardens because of the damage to the soil food web, and logically, we should then also not plough our fields, but what is the alternative when we want to grow grains to feed ourselves and animals? I don’t disagree with the advice, I’m just not sure how best to use it yet.

I thoroughly enjoyed the book, the only concept that I want to discuss further is the suggestion that we shouldn’t use manure on the garden due to the risk of E. coli. I do understand the reasons, and possibly if you don’t have a source of manure on your property and don’t know exactly where it was coming from, this may be good advice, but if you have manure, you should use it! I make the best compost ever from piles of manure. I also spread it around the garden as mulch as it absorbs water wonderfully. Obviously I wash my hands after handling the manure (and I usually wear work gloves). There is a theory that the pathogenic strains of E. coli are produced from cattle that are fed mostly grain due to the unnatural changes in the stomachs of a grain-fed beast. Our cattle are fed a little grain and mostly pasture and hay, so if this theory is correct, they are unlikely to produce pathogenic E. coli (i.e. E. coli that can survive in the acid conditions of the human stomach), this is another reason why I believe it is safe to drink raw milk from our cows, but not necessary from all cows. The recommendation also ignores the possibilities of other manures that may be available on a property, surely sheep, pig and chicken manures carry their own risks, but can be used with some common sense. However, it does make me wonder about the safety of feed-lot manure, which is commonly available to farmers and home gardeners, these cattle are fed exclusively on grain and very likely to produce pathogenic E. coli. It is a good warning to think about where the manure is coming from and take appropriate precautions.

Overall, this is a great reference for gardeners and farmers to learn how to harness the potential of the soil food web to replace the chemicals in our food system. Even if you don’t have a science background, this book has plenty of basic detail to get you started. I think once you know a little about the microbes in your soil and everything they can do to help you, you’re going to want to know more!

How do you encourage the soil food web at your place?  Did you realise how important it is?

click on image to go to Amazon

3 comments:

  1. I sometimes look at the soil in the garden and it is surprising what things are visible to the eye, well with my reading glasses on anyway. I leave certain weeds in the garden as they attract some of the insects to them rather than my green beans. It is nice to know that their roots are feeding microbes. The garden is covered with a layer of snow now but I suspect that it is warm down below the surface with all kinds of things eating away and doing their thing.

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  2. I have wanted to read that book for ages, thanks for the breakdown on it. I have also wondered about aerated compost and hope you will do a post on it when you do try it. My little in ground worm bins seem to be doing great, and I am sure the soil around it is benefitting.

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  3. Great review! And a brilliant book. Recommended to me by a Biodynamic gardener on a forum, I borrowed it first from the Library then bought it but not from Amazon. It is a tad detailed - but the second section is very readable.
    I bought a small airstone and electric pump to make compost tea with; I use it for weed tea as well.
    I have found that using a cover crop gives better soil moisture-retention than just mulching. Working on the theory the microbes need food and housing, a cover crop can provide that better than just mulch. Inevitably though, the cover crop is felled (I don't dig mine in) but a new crop is planted soon after. Still a gap, though.
    In the early days of Brisbane Organic Growers, much emphasis was placed on 'feeding the soil not the plant' but no one was able to explain why. This book does that in spades. There are other simpler explanations in several organic-growing books. None go to the detail and it is that very detail with fabulous micrographs, that make 'feeding the soil' make complete sense.
    Thank you for reviewing it, this book needs to be on more shelves and read by many more gardeners and farmers.

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