Late summer color provided by sweet coneflowers.
In 2013 I critiqued a concept that has become embedded in discussions about living sustainably: that it is possible to grow all the required calories and nutrients needed to maintain health for a vegan diet for one adult in a space of 1400 square feet or less. David Duhon designed gardens intended to do just that using the medium yields for crops in John Jeavons’ book How to Grow More Vegetables and published his results in the book One Circle. While I find the procedure Duhon used to be valuable in analyzing the nutritional possibilities of a small garden space, a careful reading of that book and subsequent garden design publications from Ecology Action shows that these are thought experiments only. The most recent small garden diet design I’ve seen from a source outside of Ecology Action is also a thought experiment. I wanted to know if a real gardener in a particular place could obtain high enough yields to grow a complete diet for a vegan adult in 1400 square feet or less while also practicing sustainable gardening principles such as crop rotation and soil re-mineralization. I promptly volunteered myself for the role of that real gardener and have spent the last 8 growing seasons seeking to answer the question for my suburban St. Louis, Missouri garden. Now I have learned enough to wrap up the project in this and the next few posts. I’ll begin with my current garden design and ask what percentage of an adult vegan’s diet for a year it can supply.
I garden in a fenced-off area of the backyard with full sun exposure containing twelve 100 square foot beds separated by paths. This post discusses the reasons for my adoption of the gardening techniques and soil re-mineralization methods described by Steve Solomon rather than those promoted by Ecology Action. Each report on the previous year’s garden such as the most recent report includes the spacing and timing for each crop I grew that year and the yield I obtained. I have set up the garden so that the group of three beds of corn rotates as a block through the nine beds planted to grains or vegetables, so that any one bed in the garden is grown to corn one year, then to something other than corn for the next two years. Each of the other beds is rotated so that no bed is grown to crops of the same plant family two years in a row. This feature addresses one of the major flaws in Duhon’s designs, the inability to rotate crops properly. My garden design addresses the climate limitations of my location, such as the inability to overwinter any crops other than potato onions and garlic in an open garden. The very short springs and autumns I experience restrict double-cropping, a feature of Duhon’s designs that does not translate well to this climate.
The beds in the 2021 garden are planted as follows. Each bed is 4 feet by 25 feet, for a total of 100 square feet of growing space in each bed.
· One bed of annual and perennial flowers and herbs, including sorrel, the only crop eaten as a vegetable from this bed
· One bed of strawberries
· One bed of raspberries
· Three beds of popcorn, two of which also include naked-seeded pumpkin vines
· One bed consisting of peppers, tomatoes, eggplants, and basil
· One bed of squash-family plants (summer and winter squash including zucchini, cucumbers, and muskmelons)
· One bed of overwintering potato onions and garlic. After June harvest, this bed was replanted to a mix of zinnia, sunflowers, cucumbers, soybeans (for edamame), and zucchini
· One bed of bean-family plants (green and lima beans and cowpeas)
· One bed of potatoes. After the potato harvest this bed was planted to an autumn crop of greens and roots, mostly from the cabbage family but also to include lettuce
· One bed of spring-planted greens and roots, including lettuce, cabbage, bok choy, carrots, beets, and leeks
The spreadsheet below includes the names of each variety of each crop that I am growing this year; whether or not the crop is a grain (G), dry bean (B) or special root crop (R) according to Ecology Action; a yield I have obtained for that crop, in pounds per 100 square feet; and the number of square feet of garden space I have allotted for that crop in the 2021 garden.
Because I am in the middle of the growing season, I only have a yield for 2021 for the crops I have already removed from the garden. On the spreadsheet, those crops are in bold type. Some of the varieties I’m growing this year are new to me. Those crops are in italic type. For these crops, I have reported the best yield I have obtained for a similar variety that I have grown.
For the rest of the crops, I have reported the best yield I have so far obtained for that crop. Some of the crops may yield better than that this year. Some may not yield as well. Thus the best I can do is approximate the percentage of a complete diet for one vegan adult that I will grow this year. You’ll soon see that this is good enough to answer the question.
In the case of popcorn, some animal – I suspect squirrels – has already eaten every single ear on every plant. In its place, I have substituted the dent corn variety that I have grown in previous years and the best yield I obtained for it, which occurred in 2019. Thus the results given in the spreadsheet are actually an overestimate of the nutrition that the 2021 garden will provide. However, including it gives an upper limit to how much nutrition this garden design is capable of providing when everything goes right.
How To Grow More Vegetables includes the calories, protein (in grams), and calcium (in milligrams) for each crop listed in the Master Charts. Using the total weight of each crop that I have already harvested or that I can reasonably expect to harvest, I multiplied the per-pound values given in HTGMV by the weight of each crop in pounds to obtain the total calories, protein, and calcium provided by that crop. Summing up the columns for each of those provides the total amount of calories, protein, and calcium that I estimate I will harvest from the garden in 2021. Then I divided that number by 365 to obtain the daily amount of each, to compare with the dietary needs chart on pages 69-71 in One Circle.
No, my current garden will not supply me with sufficient
calories, protein, or calcium to sustain me for a full year. In fact, it falls
quite far from that standard in both calories and protein, by a factor of three
to five. In terms of calcium it does somewhat better, supplying me with close
to half of what I need for a year. Since two adults are
eating from this garden, the garden falls even farther short of supplying us
with a complete diet.
Why does Ecology Action highlight grains, dry beans, and certain root crops in their gardening method? A look at the spreadsheet gives the answer. The corn crop provided by far the highest amount of calories compared to any other crop – more than half of the total, in fact. Potatoes, one of the special root crops, were also a significant source of calories, as were soybeans even though they were eaten green rather than dry. If the cowpeas had yielded better they also would have been a significant source of calories. The corn, potatoes, and soybeans were also the most significant sources of protein. Garlic and leeks provided good amounts of calories for the small amount harvested. This is why Ecology Action recommends allotting about 60% of garden space to grain crops (this category also includes dry beans), about 30% to high yielding root crops such as potatoes, garlic, and leeks, and about 10% to everything else. Such a design, however, has the disadvantage of not allowing for crop rotation unless you include grain crops that are not in the grass family, such as sorghum or quinoa, in the grain crop area in sufficient quantity to avoid growing plants in the same crop family in any bed two or more years in a row.
Using the current garden design, then, my garden would need to be four times the size it now is, or 4400 square feet, to provide a just-sufficient amount of calories and protein for my needs. Could a change in design using the same crops that also allows for proper crop rotation reduce the space needed to grow a complete diet? I’ll investigate that possibility in the next post.
This is a rather brilliant exercise - needed doing and many thanks for doing so. Your conclusions seem perhaps surprisingly widely applicable, even as far as our gardening here in the UK.ReplyDelete
There is a program that can calculate all nutrional content using original USDA data. I am not up to date on the status of the 'Walford' program, but it was available many years ago through the CR society. The range of vegetables you grow should provide a high level of vitamins and minerals, except of course for Vitamin B12, although calcium can seem a bit tricky, (veg provide high values per 100 Cal) .
Potato of course needs rotation, and is very techical if you think in terms of self-saved seed, but seems an obvious way to boost sheer calories per sq ft as it can use high N in the soil. There are issues for storage.
Beets are pretty good calories producers and they also have nutritious foliage, but the volume to eat is a bit too much.
Extra beans and potatoes might complement one another and reasonably raise both calories and protein. We are trying that in our garden. Otherwise it is the traditional corn and beans, or whatever high-yielding grain that suits the temperature and growing season.
At >55 degN in Scotland / N England (cool days; long summer photoperiod)the highest yielding grain crop per area is modern winter wheat (sown September/October) which can benefit from higher N input than traditional wheats, and is less dependent on strict rotation, but can alternate with lower yield but nutritionally valuable barley or oats for a while. It is grown round us at very large scale, but we have not tried it in the garden as an organic crop. The farmed grains need crop protection products in some years, and are always grown with chemical weed control. All the grains need careful attention to maintaining soil carbon in rotation.
Am looking forward to your next installment!
You're right, it's one thing to design a garden that can produce all of one's nutritional needs and quite another to have to live on what it produces. The third post in the series will look at that issue, among others, using the winning garden design from the second post.Delete
And thank you for pointing out that the design is potentially more widely applicable than I thought; that's really interesting and not something I would have expected. I'm at about 39 deg N, but I'm also in the interior of the country where there are no oceans to moderate the climate. Your 55 deg N climate is much less severe, because of the Gulf Stream influence, than 55 deg N in the Canadian prairie provinces, which is all I know to compare it to.
Thank you for sharing your backyard gardening experiences. IMHO Real world experiments are far better than thought experiments.
I live in a different climate, so the details of e.g. the variety choice is not so important to me. On the other hand, you describe the thinking and the reasoning, which I think is generalizable to every garden. Thank you very, very much for this!
I have a friend in my village who grows organic grains on a medium scale (5-10 acres per year, with an old combine from the 1960s), which covers a big chunk of our family caloric needs. A small input of diesel gives a lot of grains. It would take quite some skill building to replace this with hand-sown, hand-harvested, hand-threshed grains...
We also get more and more food from nut trees, both walnut and hazel for oils and protein, and chestnuts for carbohydrates. Trees take up a lot of space, so in a back-yard setting it is usually not suitable. Do you have any nut trees nearby that yield well for you?
Please keep writing.
You are very welcome! That's exactly why I include my thinking and reasoning in my posts, so that other people can adapt it to their own conditions.Delete
This year the squirrels ate all the nuts except for one chestnut that I got to before they did. I'll have more to say about squirrels next year, when I sum up the 2021 garden results.
I rediscovered your post from 2019 about your nut trees. Now I remember you wrote about both hazelnuts and chestnuts.
I've heard those claims too and likewise have a great deal of trouble believing them. Excluding the orchards which take up a huge amount of land, I easily have more than 1400 square foot under cultivation, but the winter months are cold and very little goes on in the garden at that time. For your interest, years ago I came across a story of a farming family down under. And excluding grains, they had from memory 800 square metres or 8600 square feet set aside for vegetables and berries, and that met all of their needs.
Soils are more fertile in your part of the world, but I'm tending to lean towards accepting the fact that some of my vegetable beds are just going to need to rest every now and then. At the moment it is easy to grow intensively, but any one loss in mineral supplies for any of us, and then you just have to do as the old timers used to do. And that is a bit of a worry. Dunno.
I just put up the next post, where I worked out a 2100 square foot garden design that provides marginally enough nutrition for one adult. Multiplying that by 4 gives 8400 square feet, or about the same amount of land that the farming family you mentioned cultivated for their own needs. That's quite interesting. Thank you for mentioning it!
Although my garden is still producing well after close to a decade of re-mineralization, I think it would be better to have a larger garden space and rest part of the garden under cover crops on occasion, for the reason you mentioned. And I think you're right that part of the reason that I can still grow on that land is because I started out with a very young and fertile soil. Still, before I began re-mineralization yields were slowly dropping.
Fascinating experiment, Claire! Thanks for sharing this with your readers.ReplyDelete
Thank you! I've just put up the next post in the series.Delete