I have used a number of Green Manure strategies this Winter as part of my soil fertility building program. In fact I think that I have shifted from growing food to growing soil as my primary activity. Using a Green Manure provides a number of benefits for me, which I’ll describe below. Please note that this is an explanation of some of the things that I have done this Winter, and not an attempt to teach people how a green manure should be used.
In 2014 I’m goint to try growing rice in the UK, and the following post describes why, and how I’m going to do it. I’m sure that it has been tried by somebody, somewhere, but I have no idea if anybody has made it work yet. It’s not something that I’ve ever come across before, and my only thoughts up until recently has been the possibility of growing wild rice. That changed when I read The Resilient Farm and Homestead, by Ben Falk, who is one of a number of people growing rice in Vermont, USA. Using rice from Hokkaido, the northernmost Island in Japan, growers in vermont are harvesting marketable quantities of rice. I immediately decided that I wanted to give I a try. So another project has been germinated, or hatched.
I have spent a bit of time exploring paper chromatography as a means of testing the quality of soil and compost, thanks to the help of my friend Nigel. Now I’m not planning to explain what it is all about. Those of you who have stuck with my blog are quite able to find that out for yourselves, and the following links should help you do that. Chromatography 1. Chromatography 2. Instead I wanted to record some of the thoughts and ideas that this new technique has generated, and where I may take it in the future. Continue reading
My small scale grain growing experiment has reached the end of year two, having grown and harvested, rye, spelt, and wheat. I’m almost ready to start sowing the grains for year three, and thought that I would record my results and observations here.
This is the rye and spelt before harvesting. The rye was even more impressive than last year with most of the grain over six feet in height, and some reaching 8 feet tall. I started harvesting a little before I thought that the grain was ripe as I was experiencing a lot of bird predation. I had pigeons eating the spelt, and smaller birds eating the rye.
The picture above shows some of the evidence. The pigeons land on top of a bundle of grain, forcing it towards the ground where they can get to it more easily. Once down it then becomes easier for rats and mice to get at it too.
I was a bit concerned that with harvesting it a bit early germination may be reduced, but I was preparing the beds for sowing today, and there was grain sprouting where some had been missed by the birds.
This is my High Tech measuring system to get a rough idea of yields. I simply stuff the grain into the rubbish bin until I cannot get any more in, and then tie it up into a bundle. Not that scientific, as it only measures the straw, but ti gives me a rough comparison between different crops and systems. That’s not too much of an issue for me, as the straw is as important to me as the grain is. it will be used as poultry bedding, and then returned to the growing area to help build fertility. Were I more concerned with money, the rye straw is perfect for making skeps, for which beekeepers pay a lot of money. The picture also gives you an idea of just how tall these grains are compared to the modern ‘vertically challenged’ grains grown conventionally.
Small Scale Grain Growing yields
It’s difficult to describe or assess what your yields will be when you are growing grains on a small scale, so I thought that |I’d show you my yields in pictures.
The picture above shows a bed of 100 sq feet (4 ft x 25 ft). (In theory this bed would be 5 ft wide, but the high nature of the bed won’t allow planting all the way across). This is the standard size bed for the Grow Bio-intensive system. it’s also the right size to allow comparisons between fertilizer applications (grams per 100 sq ft bed is roughly equivalent to lbs per acre). The picture below shows the yield of spelt taken from it.
The 100sq ft bed produced four ‘stuffed bin’ sized bundles, which is pretty cool. Once these have been threshed and winnowed, I’ll start to get an idea of how much grain i get from each bundle, which will be much more useful.
The overall yield from this year’s grain growing was 30 of these bundles, with roughly equal amounts of each of the three grains.
The only direct comparison that I did was two roughly equal sized beds of wheat. In one the wheat was was spaced at 12 inches apart, and in the other the rows remained 12 inches apart, but the grain was only six inches apart within the rows. of the two, the smaller spacing yielded fractionally more than the wider spacing. 3 1/4 bundles as opposed to 3 for the 12 inch spaced grains.This used twice as much seed, and was harder to weed, but seemed to resist lodging better. The recommended spacing for the System of Wheat Intensification method is 8 inches, and perhaps the results of this comparison bear that out. The difference in yield for such a small plot is not significant, but it will be interesting to repeat this a few times to see if the difference remains over a number of years.
One of the benefits of small scale grain growing is the ability to observe closely what is going in with each grain. On a huge scale you can only look at little patches of the whole picture, whereas I get to see everything in great detail.
Ergot is a problem in chemical free rye, but I only found one infected grain. Earlier in the season when the weather was damp it looked as if more were infected, but the grain seems to have fought it off on it’s own. There were tiny patches of black on the very ends of a couple of grains, but the grains themselves were healthy. The weather may have helped, but it’s reassuring to see a strong, healthy rye plant.
There was very little weed amongst the grains themselves. The picture below shows one of the rye beds after harvest, and you can see for yourself how clean it is.
The next picture shows a bed of spelt after harvest. can you spot the difference?
Well I hope that you can see a lot more green in the second picture. Both of these crops were module sown, and I added some wild white clover to the modules. On planting out, both crops had a small amount of white clover around the base of each plant. As you can see from the pictures. This clover has grown reasonably well with the spelt, but very little has survived with the rye. Some of this may be due to the extra shade cast by the rye, which was taller. Another possibility is that the rye is a bit allelopathic, chemically suppressing it’s rivals. If that’s true it could be really useful to help combat spring germinating weeds, possibly in an organic vegetable system. That’s in addition to the yield of grain, masses of straw for fertility building, a massive root system, and a late sown crop to help mop up Nitrogen after the harvest of an earlier crop. Not a bad set of reasons to incorporate small scale grain growing into your own system. To test the allelopathy I’m going to swap the crops grown on these two beds this year.
Growing Grains in 2013/2014
The next year’s small scale grain growing experiments are similar. The single wheat variety will be replaced by a mixture of six winter wheats, grown as part of the Permaculture Association’s ‘Sustainable Grain’ project. This is a research project to develop a sustainable, small scale grain growing system. Now that I have a good supply of grain and seed, I will grow less of the rye and spelt this year. Sowing just enough to maintain a fresh supply of seed. I want to grow out some Rivet Wheat that I was given, mainly to see what it looks like, but also to keep the seed fresh. I have to read up in chemical free methods to clean the seed from Bunt. I was told that coating in mustard powder, or dried milk works, but I’d like to look into that over the next few days before deciding whether to risk using this seed or not. I also have two different varieties of oats to grow next spring. One variety is Naked Oats, and the other Black Oats. The Black Oats may also have some allelopathy so could be potentially useful. Although oats are normally a spring sown crop here, the Black oats are supposed to be really tough, so I might broadcast sow a small bed soon to see how much survives. Even if none does, it will suppress weeds first, mop up nitrogen, and then winter kill. acting as a non hardy green manure crop. There is a lot that you can do with this small scale grain growing, and I intend to try as much as I can.
All of the best
I first came across references to The Ethylene Cycle in ‘The Earth Care Manual’ by Patrick Whitefield. It was my first ever Permaculture book, and one that I still refer to. The last Permaculture book that I bought was ‘The Permaculture Handbook’, by Peter Bane. It too describes the Ethylene Cycle. Strangely enough I do not recall reading about it anywhere else. In my last post (Balancing Soil Minerals Pt 2) I was reminded of the Ethylene Cycle by a comment from Darius, a fellow Permaculture Practitioner, and decided to look at it more closely.
What is the Ethylene Cycle?
The diagram below gives a quick overview of what the Ethylene Cycle in soil is claimed to be, and what it is supposed to do. It is taken from a Permaculture Site, and we’ll be looking at the accompanying text shortly.
A highly simplified explanation is that Ethylene helps to suppress microbial conversion of organic matter, and helps make available some nutrients to plants.
The Ethylene Cycle and Me
When I first read about the Ethylene Cycle I recognised it, as it was described, as a justification for not digging or ploughing. As I was already convinced that ‘No Dig’ gardening was the right approach, I didn’t bother to investigate it further. When my approach to digging changed, I overlooked the Ethylene Cycle until Darius reminded me of it. A quick bit of internet research, and some help with accessing the original research paper (Thanks Jan), allowed me to dig a bit deeper into this frequently taught piece of Permaculture folk lore.
Permaculture and The Ethylene Cycle
I couldn’t help thinking that there must be an underlying reason for the tight focus on this one piece of soil science by Permaculture Practitioners, and I found it with my first internet search. If you type ‘ethylene cycle in soil’ into your browser and search, you will find the Permaculture College of Australia article fairly close to the top of your list. If you read it it gives you a more detailed explanation of the Ethylene Cycle, and adds a layer of how it justifies or proves the need for no dig/ no plough techniques. The article also hints at why it may be far less appropriate for the UK climate and conditions, but I will save that for later. In the meantime, why not read the article. You can access it directly from the link below.
The article is a highly edited version of a 1976 Australian paper, and the article states that it was published in issue 7 of the International permaculture Journal in 1981. It was then published again in issue 39 in 1992. My initial thought were that this was a 37 year old paper, published twice in Permaculture Literature, and then spread by other Permaculturalists, with little critical thinking or analysis. The concept seems to have been completely ignored by other scientists, which implies to me that it was either proven to be inaccurate, or that it was perhaps irrelevant in some way. Again it was strange how little was written about this process that didn’t originate from this single paper.
Critique of the Permaculture Article
Relevance for Cool Temperate Climates
In the Introductory passage to this Ethylene Cycle article, the editor writes about soil aeration, and the perceived problems that it brings, principally the loss of soil organic matter through decomposition by microbes. She then writes ‘ The ‘Aeration Theory’ really developed in the northern hemisphere where the extended cold winters prevent microbial decomposition of organic residues in soil. In spring it is advantageous to stimulate the decomposition rate so that plants can obtain nutrients during a relatively short growing season’. This is then contrasted with Australian conditions, concluding that they are very different. So the editor is actually outlining why aeration is advantageous in temperate climates, and I wholeheartedly agree. Sadly, this part of the article seems to have been completely overlooked by the Permaculture network, operating in those cool winter climates. Instead it takes the opposite view, using the Ethylene Cycle as its justification
The rest of the article is written by the author of the research paper, and in it he claims that:
- ‘Ethylene is a critical regulator of the activity of soil micro-organisms and, as such, affects the rate of turnover of organic matter, the recycling of plant nutrients and the incidence of soil-borne plant diseases‘.
- ‘Ethylene does not act by killing soil micro-organisms, but simply by temporarily inactivating them‘
- He also discusses the role of anaerobic conditions and ethylene in the release of unavailable soil minerals
There was not enough of the underlying research and data in the article to justify the claims made in it. So I decided to read the original Research Paper.
ETHYLENE IN SOIL BIOLOGY. A. M. Smith
The research that the permaculture article was based on was titled Ethylene in Soil Biology, by A. M Smith. The paper was published in 1976. Sadly I cannot publish the paper for you to read, so I’ve had to quote directly (in italics) the bits that I feel are relevant. If you have access to academic paper through a University, please look at the original paper, and compare my analysis with the original work
With only a cursory initial reading on this Ethylene Cycle paper, a couple of things really leapt out at me.
The Effects of Ethylene on Plant Growth
The first concern came in the Introduction where the author states that only Cursory attention is paid to the significance of ethylene on plant growth and seed germination. That seemed strange when the whole point seemed to be to show it’s importance to plant growth. The paper then quotes other research papers which ‘showed that it may adversely affect plant growth‘. I was taken back a bit by this as it didn’t seem like a good reason to want to encouarge ethylene production. There was no research undertaken into which plants would be harmed by ethylene, but the paper mentioned that lowland rice was unaffected by quite high concentrations, whereas tomato, tobacco, and barley were ‘sensitive to trace amounts‘. It puzzled me why this would be seen as a good thing.
The author of the paper mentions reports that ethylene inhibits the nodulation of leguminous plants. This is really important, as many of the potential solutions to providing a sustainable agriculture involve nitrogen fixing plants. If ethylene inhibits the fixation of Nitrogen by them, this would be an argument to prevent its formation, not to encourage it. In fairness the author does quote from another, older, paper that Nitrification is enhanced near legumes and that this would restrict ethylene production ‘and may permit unimpaired nodulation under most field conditions‘. My emphasis.
The Effects of Ethylene on Soil Microbes
The permaculture article included references to Ethylene stating that ‘it is a critical regulator of the activity of soil micro-organisms and, as such, affects the rate of turnover of organic matter, the recycling of plant nutrients and the incidence of soil-borne plant diseases. ………… Ethylene does not act by killing soil micro-organisms, but simply by temporarily inactivating them‘. This is directly contradicted within the research paper in a number of areas. The first reported on the premature lysing of fungal hyphae by ethylene. This link on LYSIS explains that it is the breaking down of a cell compromising its integrity. Whilst not strictly killing fungi, it certainly doesn’t appear to be good for it either. With fungi having such a key role in the decomposition of organic matter, and in their mycorrhizal associations with plants, I fail to see how this is a good thing, or something to be encouraged. The paper also reaches the conclusion ‘that bacteria are not directly inhibited by ethylene at concentrations likely to occur in soil‘. Later it states that ‘soil respiration may remain relatively high in the presence of Ethylene because soil bacteria do not appear to be directly inhibited by ethylene‘. Taken together it seems difficult to justify the claims that Ethylene controls soil microbes harmlessly. The two principle components are either damaged (fungi), or unaffected (bacteria). In fact my more detailed reading suggested to me that many of the claims that were made on behalf of Ethylene could be attributed to purely to anaerobic conditions, however they were created.
The Effects of Temperature
The permaculture article touched on the differences between cold winter areas, and those with warmer conditions. This is directly referred to in the research paper, which links a twentyfold reduction in ethylene production from 11 C down to 4 C. A reflection of the reduced microbial activity as temperature falls. Stating that by restricting microbial activity, cold winter temperatures reduce the need for additional regulators such as ethylene. To put that in simple terms, in areas with cold winters, little organic matter is decomposed by microbes, making aerating the soil by ploughing or digging significantly less of a problem that in warmer climates, and allowing for the retention and build up of more organic matter in the soil than under warmer (Australian) conditions.
The Effect of Organic Material on Soil Microbes
The paper notes that the addition of organic matter overrides any suppressing effect that ethylene might have on soil microbes. This is attributed to an excess of nutrients, and is portrayed as a good thing, allowing the rapid processing of surplus nutrients. However this describes the situation in many no dig/mulched gardens. The layer of organic material would seem to override any potential benefits that might have been gained by the production of ethylene in reducing microbial activity. In plain language, even if ethylene did inhibit microbial activity, and that wasn’t the conclusion that I came to in the preceeding paragraph, it wouldn’t work in gardens/soils with high levels of organic matter.
The Mobilisation of Essential Plant Nutrients
One of the cornerstones of the perceived benefits of the ethylene cycle to plants is the claim that it has a role in making some minerals available to plants. To examine this claim takes an understanding of how ethylene is produced and some complicated soil science. Rather than try to explain how that works in a relatively simple way, there are a few things that I can highlight from within the paper and article that make the same point. Firstly, there is no direct evidence linking ethylene to the availability of these nutrients. The author of the paper is making an assumption that as these minerals are released in waterlogged soils, and that when ethylene is produced similar chemical conditions occur, the ‘availability of cations and anions should alter as markedly in these microsites as in flooded soils‘. Note the word ‘should’ which I have highlighted. No evidence is produced to support this, and the sequence that is described after this is a prediction based on what happens in submerged soils. To quote directly from the paper ‘Extrapolating from the chemistry of submerged soil, it is possible to predict the sequential seris of reactions in the anaerobic microsite that will lead ultimately to an increase in avaialability of inorganic nutrients‘. I don’t find this convincing. In fact there are some clear indications that the release of nutrients is not linked to ethylene, but rather to the conditions that produce the ethylene in the first case. This suggests to me that the ethylene is a passenger or bystander in another process, rather than the driver. The first is the diagram at the beginning of this post. To save you from having to scroll up to the top of the page, I’ll put it below.
If you look at the bottom left segment you’ll see that both the release of ethylene, and that of soil nutrients, are the result of a change in thechemical form of iron, which in turn is the result of anaerobic conditions. The second is contained in the permaculture article, where the following is written about the release of nutrients. ‘The soil conditions necessary for this mechanism to operate are identical with those required for ethylene production‘.
In actual fact it is anaerobic conditions which create the chemical conditions that release these nutrients, not the ethylene. Those conditions include waterlogging of the soil spaces, compacted soil, and the CO2 given off by the rapid decomposition of organic material by aerobic microbes.
Many of the positive benefits atributed to the ethylene cycle don’t seem to hold up when looked at critically. Inhibition of soil microbes by ethylene seems to be restricted to the damaging of fungal hyphae, with no direct effect on bacteria. Not that I think that it’s a good idea to inhibit them in the first place, but it’s promoted as a benefit to retain organic matter in the soil. Even were ethylene able to do so, not only is it far less important in temperate climtes, but that effect would be inhibited by the addition of large amounts of organic matter, like those used in mulched gardens.
The negative effects of ethylene on plant growth, the germination of some seeds, and nodulation of leguminous plant roots, would seem to be sufficient reason to discourage its production, and not to encourage it.
The release of insoluble nutrients by ethylene is an unproven prediction, with the anaerobic conditions created by water or microbial respiration likely to be the real agents for this process.
The thirty year love affair of permaculture with the ethylene cycle seems to be based on very shaky foundations.
Comments and Feedback
I’d welcome comments and feedback on this post, but especially from those with access to the research paper, who can compare the post with what is contained in the original.