A permanent tuber based agriculture

Over at the Home grown goodness forum, I have a thread (see below for the link) about my project to breed perennial root crops for Colorado. Over here, I'd like to focus more on the agroecological system that these plants will grow in.

First, a bit of background.

I've been putting a lot of thought into what a permanent, localized agriculture for the high plains and foothill of Colorado would look like.

Trees and shrubs, though beloved of permaculture designers, seem poorly suited to be staple crops here. Fruit and nut set is dependent on stable weather, and of late our already unpredictable weather seems to be getting wilder. As I type this, a heavy wet snow is falling on flowering crabapple and pear trees outside the window; by tomorrow morning, it will have dropped into the low 20s. And this after a March almost devoid of snow and sub freezing weather. Not only are flowers easily damaged, but trees also put a lot of energy into building aboveground infrastructure. Thus, they do not bounce back well from severe weather events. We get hail, late and early snow storms, drought, high winds, and fluctuating temperatures which play havoc with woody plants. In the end, trees are just not adaptable enough for this climate, either genetically or structurally, at least on short time scales.

Annuals are structurally and genetically adaptable. If an early planting is hailed out or snowed out, they can be replanted. Landraces can quickly adapt to harsh climates. However, they have a reverse problem to the accumulated infrastructure of the trees. They have too little infrastructure and are thus not resilient enough; hail can wipe them out easily. Wet weather in the spring can delay planting; I'd prefer something that came back by itself dependably. On a small scale, for garden vegetables, they work well in this climate with a little extra care; on larger scales, as staple crops, they seem risky.

This "leaves" us with herbaceous perennials. They are more efficient and adaptable then trees, more resilient then annuals. They tend to require less work; many of them spread vigorously, which I consider desirable in a food plant. The ultimate herbaceous perennial is, of course, grass.

Thus, I think a permanent local food system for Colorado would contain the following components: trees and shrubs providing windbreaks, fodder, fuel, building materials, and the occasional fruit/ nut crop when the weather worked out right; animals grazing on extensive dryland silvo-pastoral systems; small scale home gardens with water catchment, microclimate modification, and intensive care growing annual and perennial vegetables; and, on an intermediate position on the scale of intensity of use, small fields growing tuberous perennials and the most adaptable of the seed bearing annuals (buckwheat, ancient wheats, rye, possibly quinoa or amaranth.)

Why the focus on tubers as a calorie crop? They have many advantages. They are resilient to disturbances aboveground; damage to their stems and leaves will lower but not eliminate a crop. (Potatoes became popular in Ireland partially because they could stand up to trampling armies and late summer rain, both of which would devastate annual grain crops.) They have the potential to be perennial, low work, soil holding crops, and to keep well underground with no extra work. They are easier to harvest and prepare by hand then almost all the grain crops. They don't have to bloom to yield, which is an advantage in this era of dying pollinators and changing weather. They are easy to plant, even in wet, muddy weather. There is probably a reason that the Inca empire depended heavily on a range of tuber crops in an area with variable and harsh weather.

Native tribes in the West of what is now the USA tended to depend on tuber crops for a large part of their diet, from camas bulbs to sunchoke tubers. Thus this is a tried and true pattern for the West.

Most of the pieces described above are already in place; we know how to graze cattle; silvo-pasture systems have been worked on; adaptive annual vegetable and grain crops are available. But perennial tuber systems and crop have not been worked on much, so that is what I'm going to focus on.

The Home Grown Goodness thread. http://alanbishop.proboards.com/thread/9054/developing-suite-perennial-tuberous-colorado

I think this is an excellent plan.

So now, let's say I have a perennial, winter hardy, edible, highly productive, drought resistant tuber crop, which can be regenerated from seed if necessary. (Over at Home Grown Goodness I list the various species I'm interested in working with.)

What system of growing this will be best for the land?

I'm really inspired by what Fukuoka did in Japan with rice cultivation; he used just the right amount of disturbance, found the leverage points in his system, and put in the minimal amount of effort necessary to raise an abundant crop, while keeping his land fertile and healthy.  I think similar systems are possible anywhere. One example would be the edible meadows maintained by native peoples here in the West.

So my tuber field is an ecological system; it needs to provide a high yield of tubers for consumption while at the same time keeping the soil covered, accumulating soil carbon, and maintaining a high level of biological diversity at all levels.

I assume the fields would have keyline swales installed.

One of the big problems is that the soil would be bare after harvest. The remaining tubers and roots would not sprout until the spring; in the case of some crops, not till late spring. On this scale, hauling in mulch would not be feasible. Some of these crops, such as Jerusalem artichoke, produce lots of biomass, but many do not, and in any case the biomass will be to some extent broken up by harvesting.

There seems to be a niche for either an annual that sprouts in the cool, open soil after the tuber harvest, survives through the winter, and rapidly goes to seed and dies back in the spring before the tubers sprout back up, or for a disturbance adapted, low growing, cool weather loving perennial that goes dormant underneath the crop canopy in the summer, but that would rapidly bounce back from disturbance in the Fall to cover the open ground.

For the cool season annual, I was thinking about grasses or mustards; for the perennial, I was thinking about clovers.

Of course, there could be many possible combinations of tuber crops and secondary species. It would also be interesting to integrate grazing animals.

The big questions to my mind are; how to harvest effectively; what polycultures will work best; how to keep secondary plants and weeds from hogging too much water; how to minimize the damage of harvesting; what types of mowing/ grazing/ rolling/ burning would maintain the community on its desired trajectory; how how many years a stand could remain productive for and how to integrate it into larger, longer rotations; and how to get secondary yields.

If I'm understanding properly, you've got two breeding or sourcing efforts you need to focus on. One is for the primary tuber crop during the regular growing season. The other is a soil preserving crop (cover crop?) for after harvest. If your main tuber crop has  a short growing cycle, I could see it being much easier to do this.

In my area (which has very little winter weather) we have a wide assortment of winter annuals that go to seed just as it's getting warm enough to plant things like corn, squash, and sweet potatoes. No native perennials come to my mind, though. I do have saffron planted that sprouts and blooms right after the first sign of cold weather, grows all winter, and is went dormant when the winter annuals started flowering. I think it's commonly grown in colder climates than mine. You'd probably have to have skilled laborers who could identify and replant the corms as you harvested the other tubers, but they are completely dormant outside of their growing season.

You aptly express the greatest challenge to permaculture: How to produce a large quantity of (carbohydrate) staple without turning the soil? The only solution I have come up with is a compromise: it can't be uniquely perennial. There are two systems that I think are feasible and can be combined: alley cropping and rotational grazing.

1. If you alley crop fast growing trees that are cut for mulch twice a year, then you have the biomass for the annuals that are grown in between.
2. As you mention, even an annual tuber is no longer annual when you harvest it! (and eating it is kind of the point.) So you need to set up a rotational system where you're only harvesting a portion of the land every year. In this case, your crop need not be perennial at all. You can have a perennial cover crop on the plots not being harvested. They are maintained and improved with rotational grazing. And the production plot is plowed (yep) and planted for production, but heavily mulch with the cuttings of the alley trees.

Casie; some of my desired crops are in the Solanum, Ipomoea, Canna, Helianthus, and Dahlia genuses. They wouldn't come up till the soil was warm, and would die back at the first sign of frost, or earlier. So they would be above ground in this climate between May and September; some potatoes would die back earlier. Any of them could probably be harvested a little earlier without much loss; I'm not sure that these crops would gain much in the second half of September. I'm hoping that a hardy grass or mustard would be able to complete a seed to seed cycle in that time frame; the main problems would be ensuring that the grass or mustard seeds stayed dormant during the summer, and getting a good stand during the fall. Our soil is never very warm; I'm not sure that it would be warm enough to inhibit the germination of cool weather plants once they shattered in the spring.

My dream scenario is something like the following. I have a main tuber crop, ( let's say a hardy sweet potato relative) a cool annual grass, ( maybe some type of wild barley), a cool season annual legume (maybe some type of vetch) and a perennial low growing legume (probably white clover.) After harvest in the fall, the vetch and barley seeds break dormancy and grow vigorously in the disturbed soil; combined with the residue from the proceeding crops, they provide a fairly good cover by the time hard cold sets in. If they get too tall at this stage, they could be grazed or mowed. In the spring, they shoot away and quickly produce several feet of biomass; then they produce seed and die down toward the beginning of May. A mower or slasher of some sort is run through the field, chopping up the biomass and scattering the seeds. (I'd have selected for dormancy; ironic, considering that 10 thousand years of agriculture was mostly about selecting against it!) The tubers break dormancy and grow through the mulch, and the white clover spreads and recovers from the preceding year's disturbance. In the fall, just before the frost came to kill the sweet potato tops and before the soil cooled enough to start the vetch and barley germinating, the field would be mowed again, and the clover and vines would be made into hay or silage. The potatoes would be dug with broadfork like implements; small tubers would be left for next year, either intentionally or inevitably. The vetch and barley would germinate, and we'd be off again.

Of course, each main crop would probably have different companions, and main crops could themselves be mixed. Apios fixes nitrogen itself, for instance.

Some of the grain crop could be harvested, too; it would have to be done inefficiently, much as the Native Americans purposefully let some of the wild rice drop into the water, ensuring another harvest.

I like your idea about the saffron. I don't think that would work here, but I'm sure there is a niche in this system for many edible bulb flowers.

What do you know, it is starting to sound like the food meadows the natives created and maintained!

Nathanael,

I agree. At least in temperate climates, and particularly in dry temperate climates, true perennials are not going to do the trick.

I like the alley cropping idea; my farm would definitely incorporate tree lines along the key-lines. Hazel, popular, Eleagnus, and honey locust would be posibilities for this climate, and some would provide harvests of their own in good years.

I agree with the the concept of only harvesting part of the land in any given year; that could make for a different range of possibilities then the one outline above in response to Casie.

And yes, my tubers won't be true perennials in that sense. However, they would be "sort of" perennial; they would overwinter in the soil. This would have several big advantages.

Harvest and planting would be the same operation.

Our spring is erratic and often hard to work in. The fall is the best time to work here. Tubers would be ready to sprout in the spring, rain or shine.

Tubers give new plants a big boost at a critical point in time. Plant growth is exponential; 2, 4, 8, 16 So if a new plant can get a big boost of energy from a tuber and get hit 4 while a seed crop is at 2, it will have a much higher yield.

Tubers can give plants enough reserves to come back if a freak late snowstorm or hail storm comes through.

Tubers don't need a fine seedbed, which is what leads to soil erosion. They can be planted with just a hoe.

the indians ate cattails roots and seeds , and the first sprouts in spring . i know from experience the sprout cores are very good. the roots are not the easiest to prepare but they are a high energy food. in the kaw river valley there are acres and acres in the local preserve---swamp.

Black Truffles are full of carbs.. they grown under hazelnut and oak trees..underground.  I'm planning of putting these in for an additional cash crop. Plus they taste good!

Tubers don't need a fine seedbed, which is what leads to soil erosion. They can be planted with just a hoe.

That's your best argument right there! Would Apios americana grow in your region? It's a tuber and a nitrogen fixer.

my farm would definitely incorporate tree lines along the key-lines. Hazel, popular, Eleagnus, and honey locust would be posibilities for this climate

Also excellent. Are you thinking of Eleagnus umbellata? The fruit is absolutely delicious. I know a lot of people think it is a terrible invasive species, but that's only because people don't harvest the fruit and so the birds scatter the seed! The nice thing about this species is that it will never get so big as to shade out your crops in an alley system.

Robert; if I was in the Mississippi river valley or on the East coast, I'd be focusing on developing a paddy system raising cattails. Out here in Colorado, there is not as much water available, though they do grow in the irrigation ditches (and block them up!) I think they are a very promising crop for wet areas.

Giselle; very interesting! I've never really thought about truffles. I'm sure mushrooms of various sorts could be stacked into the kind of system I'm trying to build; probably the types that like open meadow land.

Nathanael;

Apios would grow here, and they are on my list of crops to work on. The main problem with them is that 5% of people have a severe allergic reaction, so I've got to be careful. Also the yield can be low and breeding is complicated.

The Russian olive is a wild "invasive" here; I think it is a very pretty tree. I'd probably plant Goumi, E. multiflora, since it is not registered as an invasive here and would bear better edible fruit then the other Eleagnus in good years.

Nathanael has given some great ideas for the direction you seem to be headed in Gilbert.

definitely do the water control works first, that will set up your alley, tree line segments along with some small pooling ponds for water storage.

Look into the different nut trees, that way you have multi cropping going on all year long.

It is ok to till alleys in such a system, what they become are part of your savanna, disruption (disturbance) is part and parcel to natures way of keeping an area at a particular stage of succession, we mimic this with tilling, tree cutting and so on.
What you don't want to do is total disturbance of a huge amount of land all at the same time.

Mark Shepard's book, if you don't have a copy, is almost a bible for what you are describing as wanting to do.

For a tuber cropping in alleys think more sweet potato than white potatoes, they are more resistant to diseases and easy to replant when needed.
As far as covers go, you can use just about any of the N fixers, they only release their stores of N when you chop them down, then the rotting mass becomes the mulch.
For winter, cereal ryes work well or even oats and old world wheat varieties. Clovers are always good, and they won't suck up all the water since the plants you are growing will shade them back once established.

Redhawk