Tuesday, November 26, 2013

Low-Maintenance Temperate Staple Crops

During my last two years in Portland, I began focusing on calorie crops, those which can actually provide substantial daily energy. I wanted to create a perennial polyculture analog to the annual-based system described in Carol Deppe's The Resilient Gardener. My criteria for a crop included being regenerative for the earth, healthy for humans to eat, low maintenance, able to be consumed in fairly large quantities, and providing decent yields. I didn't get far enough in my research and experiments to say anything conclusive, but I can share a few findings. For the purposes of my harvest logs and for my Self Sufficient Diet drafts (temperate and tropical), I organized foods into categories, presented here from most to least valuable for these purposes.

Animal Products

Ideally, we can convince chickens, bees, and other livestock to spend their copious free time eating food of low value to humans, then eat them and their eggs, meat, milk, and honey. In a well designed system, our critters self-harvest, according to their preferences: small seeds, bugs, grass & other leaves, and pollen & nectar. This maximizes our efficiency, and provides us with some of the healthiest human food possible.

Calories per pound: Eggs - 650, Meat - 525, Milk - 300, Honey - 1400
Black walnut


Nut trees can provide easy, reliable oil-rich seeds year after yaer. The fact that it takes a decade to start getting big yields just means we need to plant them *now*. And of course we can underplant developing nut trees with faster growing crops to use the space in the early years. Besides the usual nuts, oaks for acorns should get some attention. Oikos Tree Crops has some interesting naturally dwarfish seedlings which could fit much more easily into urban & suburban yards.

Possible nuts include walnut (black & english), butternut, filbert, chestnut, ginkgo, acorn, almond, pistachio, pecan, hickory, and pine. Many of these can be foraged easily.

Note that paleodiet circles warn against excess consumption of polyunsaturated fatty acids (PUFA); most oil-rich nuts have high levels of PUFAs. I'm still trying to sort through this issue for myself.

Calories per pound: About 900 for chestnuts, 1800 for ginkgo, and 2700-3300 for the more oily nuts.
Good King Henry seed heads

Small Seeds

Though most of these work best as self-harvested livestock fodder, some may yield abundantly enough and process easily enough to be worth harvesting ourselves. Possible species include good king henry, fennel, Amaranthus sp, Chenepodium sp, perennial grains, dock, perennial flax, sunflower seeds, squash seeds, and various legumes including peas, favas, runner beans, and Carol Deppe's breeds adapted to the Willamette Valley. Not all will be palatable in large enough quantities to truly serve as staple crops: for example, fennel. But we should definitely explore those that do meet all three criteria of good yields, efficient harvest & process, and non-overwhelming flavor.

Calories per pound: around 1600
Mulberries & Serviceberries

Fruits & Berries

Everyone loves nature's candy, and the existing permaculture literature does a great job giving species options and describing how to grow them -- perhaps to an excessive extent, to the detriment of other important calorie crops. I found that I could eat about one pound of fruit per day, and half a pound of berries. Though I could probably push myself to eat more, Sébastien Noël of Paleodiet Lifestyle suggests limiting fructose intake to 50g/day, meaning no more than about 1 1/2 pounds of fruit and berries per day assuming no other sugars (including honey.)

Calories per pound: About 300 for fruits, 200 for berries


Perennial, low maintenance root crops provide a moderately dense calorie crop. I found that I could eat about one pound per day, so they only provided a supplement to daily total calorie intake. Greatly increasing this intake may result in too many carbs for a healthy diet.

Root crops, of course, have the inherent ecological and labor drawback of requiring digging, but appropriate polycultures can mitigate some of the disadvantages.

My notes on perennial roots: part 1 and part 2

Calories per pound: around 300

Winter Squash

Though annuals, these don't require much soil disturbance considering how much space they take up at maturity, and can self-seed themselves (though we may have undesirable results from uncontrolled crossing.) while summer squash have the calorie density and uses of other vegetables, winter squash occupies a gray zone between calorie crop and vegetable. I can eat a lot of it in one sitting, but it has fewer calories than roots or fruits (but more than most other vegetables). It has more nutrients than many staple crops. It yields abundantly when happy, and stores well into the winter without processing. Unfortunately, its season of availability coincides with the primary availability of the super easy perennial roots, somewhat diminishing its staple crop value. Still, it adds diversity to the winter meal options, and can definitely provide a substantial number of calories.

Calories per pound: around 200

Bonus Seed Kernels

We can eat the seeds from many fruits, giving us a small calorie-dense bonus. Species include all Prunus species (cherry, plum, peach, etc), Elaeagnus sp (goumi, autumn olive, silverberry), Cephalotaxus sp, and grapes. With the exception of almonds, a Prunus, no one grows any of these specifically for the seed kernels, but they're worth utilizing if we have them anyway! I used to eat some myself, and fed some to our chickens.

Calories per pound: guessing 1500-2500

Greens & Other Vegetables

Though not calorie crops, these add important nutrients to the diet. I found it very easy to meet our needs of 4 oz/day/person from perennial greens, shoots, stalks, and flowers.

Calories per pound: about 100


Anonymous said...

I'm confused. You talk about soil disturbance. What is the difference between digging up annual root vegetables and digging up Jerusalem artichokes or skirret? Is the soil not equally disturbed in both cases. If perennial root crops are low maintenance, aren't annual root crops equally low maintenance. It seems to me that continuously harvesting, regardless of whether a plant is annual or perennial, is an extractive process that will deplete the soil if thought is not given to feeding the soil as well. If yields are to be maintained, it is important to feed the soil and build soil structure. If one looks at how nature does it, you need biomass that starts out as mulch and then decays into compost. Perhaps fast growing perennial grasses, preferably sterile to avoid a seed problem, are part of the model.

I thought that your essay on Carol Deppe's book was brilliant. Permies tend to think only perennial vegetables because that is what the teaching says. Your first hand experience with yields and calories suggests that serious thought needs to be given to designing a cold climate permaculture model that incorporates annual vegetables in non-traditional ways.

Focusing on nutrition is important. I'm only aware of one other permie besides you who does so - Kay Baxter of New Zealand's Koanga Institute. Permaculture needs to design for nutrition.

I look forward to further posts from you on these subjects.

Norris said...

Thanks for your comment! I agree that perennial roots have many of the same soil disturbance drawbacks as do annual roots. Returning nutrients and mulch is pretty much the same for both.

But I think a few factors allow for less digging and soil disturbance with the perennials, and thus less work:

1) Some plants such as skirret work well dug every 2-3 years instead of annually.
2) You can often replant perennials at the same time you harvest them, or leave bits behind accidentally or purposefully.
3) It's easier to maintain soil protection with perennials, since you can replant large pieces that can come up through mulch or living ground cover.
4) You can stick your large perennial propagation piece into a single hole, instead of needing to prepare a fine seed bed over a large contiguous area each year as with most annual roots.
5) I suspect it's easier to design polycultures with the perennials than with the annuals, to keep the soil covered with living plants through more of the year.

Thanks for the pointer to Kay Baxter; it sounds like she's been doing good, important work for quite a while!

Anonymous said...

If you only harvest skirret every 2-3 years, you will to make up the nutrition from another source. If you want to have skirret each year, you'll be planting 2-3x as much.

Soil protection is very important. If you are mulching and growing green manure crops in rotation, you can achieve the same or possibly more with annual vegetables than with perennials. Green manure crops don't work with perennial vegetables except possibly Dutch white clover but that requires cutting in order to release the nitrogen.

If you are growing intensively, your root vegetables will not require a large contiguous area. Intensive growing is very low maintenance although it does require continuous soil improvement through green manure crop rotation and mulching. You have to grow food for the soil.

It might be interesting to keep track of the time spent (our experience has been that the time is minimal) in maintaining a 4'x8' raised bed of root vegetables - carrots, beets, parsnips from seeding through harvesting one year and growing manure crops in succession the next year. Using the USDA's National Nutrient Database, it would be possible to measure the yield in terms of calories harvested for the time spent.

As for designing polycultures with annuals that's an interesting challenge but doable, I think. Hmmmm. A young tomato plant could be transplanted into a patch of Dutch white clover that acts to keep the roots cool and suppress weeds. Cutting the white clover would release nitrogen. Add marigolds and garlic to repel insect pests. Adding borage would attract pollinators. Although tomatoes don't need pollinators, the borage would attract pollinators to the other plants in the polyculture.. Adding pigweed which is a great accumulator of calcium (blossom end rot is due to calcium deficiency) would be good although regular watering would be required to allow for regular uptake. Adding Lambsquarter would be a good source on potassium, phosphorus, and calcium if it was chopped and spread around the tomato plant. Mycorrhizal inoculation of the tomato plant roots at the time the seedling is transplanted into a larger pot for growing under lights would allow the soil to be inoculated with mycorrhizal fungi when the tomato is planted out.

Norris said...

Our experience with skirret was that it grew larger roots with (we thought) less woody cores the longer we left them in the ground. So you could have a large patch and only have to dig 1/3 of it each year, yielding the same (or more) as if you dug all of it each year for annual roots. Meanwhile, the flowers feed multitudes of insects each year and the plants produce a lot of biomass, with no care required beyond harvesting and replanting.

With perennials, we never needed to sow deliberate cover crops, and we hardly ever had bare soil. I haven't seen, in person, an annual system that can match that. IIRC, Fukuoka's system kept the soil covered while growing annual grains, but took many years to develop, and relied on the ability to flood fields to knock back the white clover perennial ground cover. It's probably possible to create other annual-based systems that do protect the soil, but I'm skeptical that they'll provide as good soil coverage and animal habitat with the same minimal labor input.

Even in our first year of bringing in topsoil for annual beds, when our carrots and beets and turnips grew really well, they required a lot more babying & time than equivalent yields of the perennial roots we grew in later years. A 4x8 bed won't even come close to providing serious calories, so although the time and labor for a single such bed may not seem like much, by the time you scale it up you're looking at a fairly serious investment. I would love to see some real world measurements of time spent and calories harvested for such annual beds!

Not to discourage folks from experimenting with and developing annual polycultures...there are many popular crops for which perennials can't substitute straight-up. So by all means, see what you can develop with tomatoes and clover and borage and all the rest!

Mike said...

I confess to being a bit surprised you don't list Beans. There are good reasons why they're pretty much a staple crop in many places, providing a good bulk of complex carbs while being one of the easiest crops I've ever grown.

Around here (southern, warm-temperate part of South Africa) I just poke the seed into the soil with my finger. If I have plentiful water I might water them once or twice to get them going, otherwise I just leave them to do their thing. Three or four months later, harvesting is simply a case of pulling dried bushed out of the ground and threshing. Could hardly be less work, and they'll keep you alive with not much else to eat.

Anyhow, very leased I've found your blog - not sure what took me so long.