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Festina lente
-make haste...slowly

Tuesday, January 25, 2011

Carbohydrate Crops - Potatoes and Sweet Potatoes

Chances are, if you are working on improving your self-reliance, you've at least considered growing one or both of these crops. Few species of plants have had a more dramatic influence on the planet. From its home high in the Andes, the potato has migrated around the globe, changed the face of geopolitics, altered population dynamics, and brought an entire country to its knees. Also from South America, the Brazilian native sweet potato has become a staple from Honolulu to Istanbul, and enabled the political expansion of Polynesia after its arrival on their shores. In particular, the sweet potato radically changed highland agriculture in New Guinea. In contrast to taro and older New Guinea root crops, the sweet potato could be grown to higher elevations, and grown more quickly, with higher yields per acre cultivated and per hour of labor. The result was a highland population explosion, setting new records for the population densities they could attain, and elevations they could occupy (Diamond).
But back to potatoes first.

What a beautiful plant the potato is to see growing in your garden! It's an obvious member of the Solanaceae family, the nightshades, with a flower reminiscent of an eggplant's. Some tomatoes, like the Brandywine, are commonly dubbed "potato leaved" varieties, and that makes plenty of sense once you see these babies growing. But where tomatoes and eggplants play their cards out in the open, harvesting potatoes is far more like opening presents on Christmas morning! Like Forrest Gump's box of chocolates, you never know what you're gonna get. There are few joys in the garden like turning up a pile of hidden spuds at the end of the potato season. One pound of seed potatoes yields roughly 10 pounds of calorie-dense, protein-dense tubers that can keep all winter in the root cellar (or in the ground if you prefer!). Matter of fact, potatoes produce more calories per acre than any other crop. And if you've grown them yourself, you'll know why it's worth the effort! And all you have to do to repeat the joy of growing potatoes next year is set aside a bucket of the small ones to plant the following spring. No reason to ever buy that variety again.
But make sure you rotate their location in the garden. Pest pressure can be nightmarish in the potato patch. Leaving them in the same place year after year is a sure recipe for pest build-up and reduced yield. The picture above shows my potato patch, the lush leafy green ring dotted with white and pink flowers, in Washington two years ago. Had I stayed in this garden, the patch would have been moved out to the next ring the following season. Potatoes also tend to revert back to their wild form after staying in the ground for a few years, becoming woody and less palatable. If not, they would easily be the undisputed number one crop on Earth!

One of the best things about potatoes is that they make a great first year crop for new gardens. They help loosen compacted soil, allowing air and water to penetrate down the root channels and tuber cavities. They are a fine crop to use with a new sheet mulch. Simply cut a hole in the weed-suppressing cardboard or newpaper layer just big enough to place a seed spud before covering up the whole business with the other layers of compost and mulch. They will grow under and on top of the suppressive layer as it decomposes, leaving nothing but a cluster of potatoes and deep rich humus by the end of the season.

Another simple method of bed development comes from Scandanavia, where they mow the would-be garden bed down tight, lay the seed potatoes out, and then cover them with about a foot of loose straw. Very little water necessary. Just let them do their thing. And at the end of the season just grab the plant and pull it up, potatoes and all. Once again, what you end up with is a beautiful deep soil bed with lots of organic matter and very few weeds.

From Austria, and particularly adaptable for potato cultivation, comes the "hugelkultur" method, with the pronounced emphasis on the first and last syllables - hoo'-gul-kool-tyur', or something like that. It's been a while since college German. The photo above illustrates this alternative use for woody biomass in the garden. You can chip it and mulch it, you can let the city pick it up (heaven forbid), or you can hugelkultur it! As you can see I'm in the process of pruning back the trees and shrubs around the garden in this picture, but instead of getting rid of the "yard waste" (gasp) I'm stacking it up into a berm and covering it with leaves, grass clippings, hedge trimmings, compost, whatever biomass I can find. After that I cover it with a generous layer of wheat straw to tidy up the look and retain moisture more effectively.

Most hugelkultur is done with large rotting logs. This one was fresh branches with lots of air space between. It needed time to break down to something more useful. In this second picture you see my goat assisting in the breakdown process in a couple of ways. First, physically she is applying pressure, literally breaking the branches down. Second, she is browsing on the fenceline of beggar's ticks, catbrier, and privet, and converting these undesirable species (in this application anyway) into goat pellets that are falling into the hugelkultur. Turning a problem into a solution is what permaculture is all about. Piles of rough biomass, weedy species encroaching on the garden, even poison ivy, all turned into deep rich garden beds. And goat meat.

One thing you'll probably want to do with your potatoes is "earth up". As they develop, rake new soil up around the growing plant. The formerly-aerial nodes now covered with soil will develop new roots, and potatoes, and again you'll be left with wonderful friable mounds of living organic topsoil for the next crop.

Another big permaculture topic is "guilding," where we plant lots of mutually beneficial plants together to create a system that functions like Nature - plants that serve rolls as living mulch, biomass generators, mineral miners, beneficial insect attractors, etc. The most beautiful old growth forests on Earth never required any intervention from human "stewards," yet they are supremely productive. But it doesn't require much more effort to steer a successional ecosystem toward more human uses, and potatoes are a fine living mulch in such a system, where they can help structure and protect soil, and create a humidity interface between the ground and the aerial biomass of the system. Famous permaculturalist Sepp Holzer uses potatoes extensively in his Alpine food forests, grown mounded on contour to retain moisture on his unforgiving slopes and improve soil texture. Used in the right ways, potatoes are not only a tasty and diverse world-class calorie crop, but they are one of the best garden helpers around.

Sweet potatoes:

This is not a particularly robust stand of sweet potatoes pictured here, but then, they weren't the primary crop in this space either. They were an extra crop, in space already filled by tomatoes. And, as you can see from the next picture, we got some hefty sweet potatoes out of the deal! Again, just like with potatoes, finding these jewels underground is exciting - small, medium, large, they all have a perfect use. The hog-leg in the last photo fed all three of us. (Oliver wasn't eating solid food yet.) What these sweet potatoes did do, however, was form a great living mulch under the tomatoes, helping to regulate moisture loss from this bed. You can almost see the ghostly shadows of the tomatoes that had already been taken out outlined in the leaf pattern below. And of course there are the worm towers poking up through the bed as well.

In the U.S. we are quite familiar with the delicious roots of Ipomoea batata - in the vegetable world they are tough to beat - but most of us are wholly unfamiliar with the equally common practice of eating the leaves as cooked greens in other parts of the world. Not all varieties have good leaves, but many do, and the leaves of these improved cultivars help make up the protein the roots lack.

Stacking functions is the name of the game in permaculture, and sweet potatoes are world-class function stackers. Both the roots and greens are tasty and nutritious, they make an attractive soil-shading, water-conserving ground cover, and if you live in the right climate, they can be perennialized! Any time we can perennialize a food crop it is desirable, from an energetics perspective, and if you live at the zone 8/9 interface or warmer, this can be done. And we at Tonic Permaculture in south Georgia just happen to meet that requirement! We grew Beauregard last season at Small Batch in middle Georgia, and the roots were delicious, but we are going to be particular about our sweet potato varieties this season and look for a few with high quality greens too. Eric Toensmeier, author of Perennial Vegetables, recommends Seed Savers Exchange for acquiring sweet potato genetics, but they aren't showing a single selection tonight. Anyone who can point me in the right direction would be my hero!

But whatever you start with, or add to your already substantial collection this season, enjoy growing these amazing carbohydrate crops for nutrition, flavor, diversity, and the sheer weight of self-reliance they convey.

Happy planting this new year.

A few more links to potato and sweet potato related sites:





The go-to resource for perennial vegetables is a wonderful book by the same name, written by Eric Toensmeier, and published by Chelsea Green in 2007. I highly encourage people to get serious about using perennial vegetables to increase their self-reliance.

Another fantastic resource for all things permacultural is "Earth Users Guide to Permaculture," written by Australian permaculture guru Rosemary Morrow, and published by Kangaroo Press in 2006.

And what survey of the sweet potato and potato's use in permaculture systems would be complete without Toby Hemenway's brilliant book "Gaia's Garden: A Guide to Homescale Permaculture," also published by Chelsea Green in 2009.

Thanks also to Dr. Jared Diamond, author of the outstanding and panoramic review of deep human history, "Guns, Germs, and Steel," published by Norton in 1999. This is a must-read for any industrial human who takes him or herself seriously.

1 comment:

  1. you look great in sweet potato/ i missed you, so sorry. went up 1-95 from the beach. Im going to go the the ga natl fair though. see ya then? love the new header