Okay, I have moderator approval to post this (thanks, Burra). I've been asked to do a bit of pruning, but here goes.
There is so much in this book that my section reviews are turning into posts similar to the length of many of my book reviews. In part this is where his book makes excites me intellectually. The other side to this is where I disagree with the author.
About three years ago I did a lot of reading on how we might be able to feed everyone while preventing a massive extinction event that might well take humans down with so much else. I ended up getting myself tied up in intellectual knots that I still haven't been able to untangle: it was clear even then that doing so was not going to be simple and would require massive changes to what we eat and how we grow it. Toensmeier has a single goal – carbon sequestration. I recognise there are more complex issues at stake, of which the
reasons for carbon sequestration (a liveable planet) are among them. Arguably the biggest problem with this section is that the author examines the annual, perennial and livestock systems in isolation, rather than examining them in the context of each other and other planetary (and less so social) needs.
My main interest in terms of permaculture lies in perennial polyculture, which appears to me both to be the epitome of the practice, as well as being the most efficient means of sequestering carbon. Four problems present themselves:
1) Perennial cropping systems take time to mature – five years to decent yields is a reasonable rule of thumb. This means that someone planting a homegarden, whether tropical, subtropical or temperate, requires an interim food supply while the woodland matures.
2) The strong possibility of us hitting some form of tipping point (
https://en.wikipedia.org/wiki/Tipping_point_(climatology)) followed by abrupt climate change may make the retention of annual cropping systems a sensible precaution for food security. Annual species have shorter reproductive cycles, making the plant breeding process considerably shorter than with most perennials, and non-native species may be carefully selected in order to replace those for which the climate may have become unsuitable.
3) The abysmal state of research on yields from temperate and subtropical homegardens (what we usually call forest gardens) means that there are little good data on how many people can be fed on given areas of land. This will, of course, depend on many factors, the most obvious being soil, climate, design and species selection and relative dominance, but there is a critical need for this research to take place: it is my opinion that the ongoing failure to do this amounts to near-criminal negligence. There are a range of factors influencing decisions to use any of the practices outlined in this book, but I think we need to be thinking very carefully about land use, and in particular land use efficiency. There are practices that are clearly inefficient, such as feeding grain to livestock, which Toensmeier talks about and comes down firmly against, but there are too many for which we just don't have enough information.
4) This leads to a massive problem about the simple feasibility of moving from one practice to another: much will depend on local knowledge, local conditions and research that is in the early stages or that just has not been conducted.
Whether
annual systems are going to be a permanent feature of the agricultural landscape or merely a transitional state in the direction of perennial systems remains unclear to me. I am interested in the integration of
hedgerow systems with annual polycultures, both as a means of producing food and as windbreaks and shade from intense sunlight in some (I'm thinking Mediterranean, but the principle is probably generalisable elsewhere) climates. In this case, I'm interested in plants that exhibit reverse leaf phenology (where they leaf out in the dry season – see p. 75), but I'm concerned that these are species likely to become invasive (thus defeating the avoiding extinction criterion).
Can
strip intercropping be modified to provide windbreaks and shade for annual polycultures, thus improving yields while sequestering more carbon, if less than might be expected than with perennial polycultures? It seems to me that the answer should be yes (this is basic agroecology), provided the horticulturalist can work out how to avoid nutrient competition and produce enough protein. It should be possible to calculate the proportion of land required for pulse and grain crops in a system to meet human requirements, but more research may be needed. This is one such study, which invites replication efforts:
http://balkanecologyproject.blogspot.co.uk/2016/05/perennial-polycultures-biomass-belt.html
It also seems relevant to address the
question of yields against primary productivity. Where cattle are grazed, native grass species are replaced with grass species with higher net primary productivity (Toensmeier's “better-quality pastures” (p.86): and we are then often told that this is the same as prairie; an evident fallacy). Carbon sequestration levels remain low. Perennial polyculture systems take time to mature, as we've seen and, while net primary productivity is high, as are rates of carbon sequestration, yields remain a near-unknown quantity, and good design may be key.
It's well known that the highest rates of protein yield per unit area of land are produced by hemp (
Cannabis sativa) (also an excellent fibre crop) and the soya bean (
Glycine max) (which also fixes nitrogen) – there are dozens of varieties which have not had their genomes fiddled with by the agri-pesticide corporations, and which often have better flavour, better regional climate adaptation and greater aesthetic appeal than the mainstream ones. Monoculture soya beans, as with monoculture anything else, present their own problems but they, along with other beans and grains, present opportunities for the development of annual polycultures, either permanently or as part of a transition to perennial polycultures. Trials incorporating this, SRI (pp. 70-71) and regenerative organic (p. 71) seem to be called for, and may close the yield gap between regenerative organic systems and conventional farming (see p. 71).
Yields are the thing that most bothers me about all the systems outlined in this book. We're going to have about ten billion humans to feed by 2050, absent some major disaster that would wipe out hundreds of millions or more. I admit I'm having great difficulty making the numbers add up. Conventional farming typically has higher yields, although some perennials found in the tropics do approach these. That requires massive (and unsustainable) inputs. Most of the systems discussed in this book, including the temperate homegarden, have lower yields and take several years with minimal yields before maturity.
I respect Toensmeier's view (p.86) that there may be a difference between experience and theory as regards
soil formation under grazing regimes. The problem is the nobody appears to be consciously controlling the variables, having followed up Toensmeier's references and others but, given what we do know about carbon sequestration, grazing appears to be
counterproductive in all cases. In those cases where minimal quantities of carbon are sequestered, this seems to be the result of other practices, such as the use of cover cropping, no-till systems, tree planting (all of which appear to sequester more carbon where livestock are absent) or the use of external inputs such as compost (a scarce resource, probably better used elsewhere) or supplementary feed (often imported, with the usual levels of energy conversion efficiency: I mean Savory and Salatin, among others). One study cited did find moderate levels of sequestered carbon, but this required the planting of fodder trees – and it's no secret that trees sequester carbon: that's about trees, not cows: the
carbon sequestration occurs in spite of, not because of, the grazing. Those fodder trees were
Leucaena: a highly invasive species, as likely to make land unusable while having adverse consequences to the ecosystem.
I'd be interested to learn of any exceptions to this rule. Toensmeier calls for research into conditions where grazing sequesters carbon. In the case of homegardens we have some idea about primary productivity (and thus carbon sequestration): in the case of grazing we know about yields, but much less about best practice – if there is such a thing given the alternatives – in terms of carbon sequestration.
Is there a place for any livestock moving forward? I don't want to say maybe, but that's where the evidence leads. If so, however, we're not talking much. There are complex policy decisions to be made where traditional pastoralist communities in much of the Global South are concerned, and I don't want to get involved in a discussion that needs to be taking place between those communities and those policy makers. I'm interested in this from a Global North permaculture farming and by implication diet perspective.
I can work out how to close the gap, and these are not new ideas. Reducing waste in the system is critical; we throw out too much food, and processing is part of that. Paper after paper emphasises a shift down the food chain (this summarises what I think is the most recent one, but they come out quite regularly:
https://theconversation.com/can-we-feed-the-world-and-stop-deforestation-depends-whats-for-dinner-58091). According to the study cited here:
Of all the variables involved, the feasibility of feeding the world with no deforestation is more dependent on what we are eating, than on how well we farm. “The only diet found to work with all future possible scenarios of yield and cropland area, including 100% organic agriculture, was a plant-based one.”
I think it's important to factor in the fact that we are losing arable land at a very frightening rate:
http://www.globalchange.umich.edu/globalchange2/current/lectures/land_deg/land_deg.html, some of it to bad annual cropping practices, some to overgrazing. We need to factor in the extinction rate, and the need to address that. There is the simple fact that a disrupted climate seems likely to result in regional crop failures.
I still can't make the numbers add up, except perhaps in a best-case scenario. I don't see how to head off mass extinction and feed everybody. Just how big the gap between feeding everyone, staving off mass extinction and the related question of halting the climate crisis actually is isn't clear – there isn't enough information – but it's pretty clear there is one.
Toensmeier mentions mulching as an important adaptation strategy (p. 73), but this seems incompatible with feeding crop residues to livestock (see p. 91) (and indeed with the suggestion for using it for biofuels): we may have to make a choice. Given that ruminants can obtain no more than 50% of their diets from crop residues (i.e. mulch) (his figure), and the other half has to come from somewhere (land-inefficient grazing or imported feed) I find it hard to countenance this practice.
The integration of livestock seems to have one major advantage, but this only applies from one perspective. The System of Rice Intensification (see pp. 70-71) is extremely labour intensive. Grazing has higher yields per unit of labour. From a capitalist perspective, this is a good thing: it means more unemployed, which forces labour costs down, which means more profit, especially from broad-scale agriculture. For the rest of us, more labour-intensive systems are a good thing, because it means work. Provided we can avoid some sort of return to serfdom or other forced-labour practices this should be a good thing for most of us.
This goes back to what I said in an earlier thread:
addressing the problem of climate change means changing everything, whether we like it or not. I want to embrace that change – not least because I realise that if we don't do it our way, Nature is likely to do it Her way, and we may like Her way even less. Eating much less meat, if any, is simply going to be one way in which we will all have to make do with less. Eating different, and probably a much wider range, of fruits and, in particular vegetables, pulses and grains, is another. I'm going to have to make do with many fewer potatoes, however much that upsets me.
This brings me back to what I think is one of Toensmeier's biggest problems: he is focused (at least in the global North) on us not needed to substantially modify our diets. I am not the first person to observe that whether or not we can feed ten billion humans while addressing all our other problems depends on what's for dinner (see link above). If, and I'm yet to be persuaded of this, there is a place for livestock in a future of farming centred round agroecology, whether permaculture or otherwise, it seems clear to me that it's going to be a very small place, perhaps as draft animals: meat, and by implication eggs and milk products, are likely to be rare treats. My parents kept chickens, and kept the compost pile in the chicken run, but my compost has always been turned by hand. Little else grew in the rest of the pen: this may have been an overstocking problem, although I do remember discussions on this question, but I do know that chickens scratch.
There are two broader questions, neither of which have clear answers. One relates to
which is the best use of land, as regards sequestering carbon. The other is
whether annuals provide superior food security in a disrupted climate. The loss of one annual crop would be bad enough: the medium-term loss of a perennial one would be worse. The answer to that would depend largely on whether we were talking about a one-year incident or a major change in climate patterns over a longer period.
As Toensmeier points out (p. 89) livestock can be fed on slopes unsuited to tillage – which is a reasonable argument until one considers the use of no-till systems, contour hedgerows, swales (on or off-contour) and terracing. Where I come from these are often soils that have been heavily degraded and with such poor water-infiltration rates (as a direct result of grazing) that they are linked to substantial downstream flooding with the consequent economic losses and human misery (
http://www.monbiot.com/2013/05/30/sheepwrecked/ and also
http://www.monbiot.com/2015/12/08/a-storm-of-ignorance/ - the lessons seem clear: stop grazing and start foresting) that continued grazing seems strongly contraindicated, especially with climate disruption likely to lead to more intensive storms (
http://earthobservatory.nasa.gov/Features/ClimateStorms/page2.php). These are precisely the places I think we should probably be considering either reforesting or finding other means of improving water infiltration.
In short, all three systems have problems that need to be addressed, with some urgency, and there will be tradeoffs between the relative implementation of each one. I don't see how to make livestock systems work, except on a very small scale, possibly, but there are questions about both annual and perennial systems that need to be overcome.
What I found particularly interesting, after that headache, was the
Introduction to Species (Chapter 10). I'm aware that the life involved in smallholding can be pretty repetitive, and I'm keen to find ways to keep my brain active. I've already touched on research opportunities, but opportunities for plant breeding not only could be extremely useful (a perennial bean with the soya bean in its recent parentage, or a perennial buckwheat, would work wonders for both food security and carbon sequestration). Equally, there are undomesticated perennial species that might be open to a breeding programme. A comprehensive investigation of my own regional flora might well turn up neglected species suitable for domestication. I have a short list of suitable plants already, but have no doubt this might be added to.
I find this an incredibly exciting prospect.
We've had endless discussions on this site on the subject of invasive plants. I half agree with Toensmeier on this subject, but there are points where I dispute his position – quite strenuously.
I come to permaculture asking myself several questions, but when you scratch deeply enough it comes down to this:
How do we feed ten billion humans while preventing the worst extinction event in sixty-five million years?
I'm no nativist. I can't even sensibly define the word “native”. I'm all for providing corridors for species to move as a result of climate change, even artificially helping some of them to move. Many of the crops in my garden have no relatives growing in the region. I have nothing against growing non-native species. Toensmeier argues that
“Will it help to reduce emissions, sequester carbon, reduce the amount of tilled cropland? These are the questions we should be asking rather than “Where does it come from?” and “Does it belong here?””
Actually, I agree, but I want to add one, which he skims over but fails to properly address:
Does it cause ecological damage? Is there a tendency for it to become a monoculture, squeezing out other species and those on which those species depend? This is, at root, why around ten per cent of the species listed in the book are also listed in the Global Invasive Species Database (
http://www.iucngisd.org/gisd/).
Toensmeier argues (and it's not the first time I've seen this argument) that
“Even in Hawaii, where 100 flowering plants have gone extinct and 1,000 new plants have escaped cultivation (or otherwise arrived) and joined the flora since human arrival, ecosystem functions continue.”
This is all true, but those 100 species have most probably gone for ever. E. O. Wilson, one of the world's top ecologists, points out (and again I've said this elsewhere):
The Hawaiian archipelago, like the equally far-flung Easter, Pitcairn, and Marquesas archipelagoes, deserves mention in part for what it once was. Its tropical climate, relatively large size, and mountainous terrain with multitudinous habitats promoted the genesis of a large diversity of land-dwelling plants and animals. A high percentage of these originated as products of adaptive radiations. Dramatic examples of such species swarms include the honeycreepers among the smaller birds, tree crickets among the insects, and lobelias among the flowering plants. The beautiful assemblage has been largely wiped out or pushed into the remote uplands of the central mountains by agricultural conversion and semiwild gardens of invasive species. Perversely, the latter have become a poster child for the “novel ecosystems” celebrated by Anthropocene supporters." Half Earth: Our Planet's Fight for Life, 2015 (my emphasis)
This is a far-different characterisation to Toensmeier's.
The thousand are all, as far as I know, thriving elsewhere: actual global biodiversity has declined. This is only one part of a much broader picture of a rate of extinction at least a thousand times greater than the background rate. It is also true that one of the other reasons for such a high rate of extinction is because of the kinds of land use changes we want to avoid: I do not oppose the introduction of non-native species, but I do think it's important to understand the implications for organisms that have evolved relationships with native ones, and I think it's even more important to consider the environmental impact a minority may have if they get through the hedge, or what may happen if the deliberate circumvention of biosecurity measures results in the introduction of a disease (think of sudden oak death in North America (and, increasingly, elsewhere)), ash dieback in Europe and avian malaria in Hawaii. All of these suggest to me that biosecurity measures may need to be more stringent, not less.
For example, the author raves about
Leucaena leucocephala as a crop for intensive silvopasture (p96) (the success of carbon sequestration in silvopasture systems may be contingent on it) and also discusses it as biomass (p248) but, if you were to only be interested in its silvopasture potential you might be unaware that
“This thornless tree can form dense monospecific thickets and is difficult to eradicate once established. It renders extensive areas unusable and inaccessible and threatens native plants.” - GISD: http://www.iucngisd.org/gisd/100_worst.php
That does not mean it should not be used at all but that it, like many similar species, should probably remain where it is.
In conclusion, there is some really good material in this book, but I keep finding key – often related – weaknesses in it.