Friday, December 19, 2008

Better Permaculture Through Garden Disasters

Sometimes my theoretical knowledge of gardening and permaculture exceeds my practical knowledge and experience. Indeed, I have been known to use my academic credentials to add weight to my gardening suggestions: “look Babcia (grandmother in Polish), I have a Ph.D. in biology and I'm telling you don't have to dig the garden...” A case in point was my first large (20 by 20 ft.) garden in 10 or so years. I had had a garden plot in the same community garden 10 years previously. Unfortunately, at that time, the 10 km distance between the garden and my apartment door meant few trips to the garden resulting in a 20 by 20 ft. island of weeds in a sea of well-tended crops. This time it would be different.

Although we were much closer to the garden (5 km), I swore that I would not be weeding (or using fertiliser, pesticides, or herbicides for that matter). Indeed it would not be necessary as my close plantings of beans, lettuce, etc., would quickly shade them out. In one bed I planted the well-known three sisters guild of corn, climbing beans, and squash. This guild has an ecological foundation. Climbing beans are planted around clusters of corn stalks. The beans and corn have a symbiotic relationship, with the beans fixing nitrogen for the corn, and the corn providing sugars for the beans at their roots. The squash plants that are planted between the corn groupings shade the soil, thus reducing weed growth and soil evaporation. I planted the guild in a state of great excitement and expectation; after all, I was planting a vegetable community that was not only ecologically sound, but that was the basis for much of native North American agriculture for thousands of years. I was reliving history.

My garden did not live up to my expectations. The end result is best described by the broken English of a Korean woman who had wandered over to see my cute and irresistible two year old son. She looked at my plot with a mixed expression of horror and wonder and repeated, “so much weeds, so much weeds”. I was even too embarrassed to put up the rustic “Pureland Garden” sign that I had woodburned onto a split plank. The only worthwhile harvest I had was of tomatoes. The tomato plants had been heavily mulched with straw and grew practically weed free. They also required very little watering, as the straw greatly reduced soil evaporation.

What happened? How could something that appeared so ecologically sound on paper turn so wrong in the ground? This is where my experience as an ecologist comes in handy. A clue to the problem can be found in the histories of the weeds that were overtaking my garden. Most, if not all, of the weeds were not species native to North America, but instead aliens that came over with the European settlers. This means that the Native Americans did not have to contend with many of the weeds that are currently plaguing our conventional agricultural system. From what I have read, their gardens were created by girdling trees in and around natural forest clearings and then burning the undergrowth the following spring. After 10-20 years they allowed the garden to regrow as forest and moved to a different spot. They were, in effect, starting their gardens from scratch and thus had no real weeds to deal with.

A second clue came from the biological attributes of the weed species. Weeds (well all plants) can be classified as being either annual or perennial in nature. Annuals, germinate, grow flowers, and die in a single year. In contrast, perennials live year after year and can typically propagate by both seed and by root division. Annuals produce large numbers of seeds in order to ensure their continued existence. For example, individual plants of Lambsquarters and Red Pigweed can produce close to 100 000 seeds. Chickweed can produce 3 generations a year thus tripling its seed production. Seeds can also remain viable for long periods of time: Red pigweed is viable for at least 40 years while 1 700 year old Lambsquarters seeds have demonstrated the ability to sprout. These species are often considered to be indicators of fertile land. However, they had no problem growing in my garden despite garden plants that showed signs of nitrogen and possibly phosphorus deficiencies. My garden’s soil deficiencies were particularly evident by bean plants that were stunted and yellow-green in colour. Bean plants that were given 20-20-20 fertilizer in a controlled “experiment” turned healthy and green. I think the soil was heavily depleted by the previous tenant who had planted potatoes in it for years. More likely the presence of the weeds is indicative of the gardens disturbance regime. Species are typically adapted to a particular sequenced of environmental disturbances. A dramatic example would be such trees species as Ponderosa pine, Jack pine, and black spruce, which possess cones that open when there is a forest fire in order to regenerate the forest. Similarly, the weeds in our garden are adapted to disturbance. Weed books and manuals indicate that my garden’s annual weeds are either found in cultivated soils or at open, disturbed sites. Part of this community garden’s policy is that the soil is turned over with a tractor every spring. While it is called cultivation or plowing, it could also be labelled as an annual disturbance event. Annual weeds, which only live one year and produce massive numbers of seeds, are perfectly adapted to plowing and will only increase in numbers if they are not eradicated. Even if they are totally removed, a huge number of seeds will still exist in the soil seed bank and will continue to germinate and grow each spring. Indeed, some seeds need the soil to be disturbed to start growing.

Field bindweed, which is listed as one of the world’s most undesirable weeds, was the only perennial I found growing in my garden. This plant can develop 20-30 foot lateral roots with vertical roots having been found 30 feet deep in some cases. New shoots can develop from buds along the roots and these buds can develop into new plants if separated. Thus, while this weed is a perennial and is not necessarily adapted to tilling, its deep root system and ability to expand laterally likely ensures its existence at the garden plot.

The reasons behind my garden’s weed problem are simple enough to explain, but what is the solution to this problem? The weed free and healthy state of my tomatoes provided the answer: sheet mulch. Sheet mulch is basically a horizontal compost pile that is spread over your garden. While sheet mulch instructions vary, they typically call for the following steps:

1. cut or trample weeds and plants on the site;
2. add any required soil amendments (manure, bonemeal, rock dust, etc);
3. apply a biodegradable weed barrier of cardboard or layered newspaper;
4. spread 6 inches or more of compost, leaves, grass clippings, vegetable scraps, etc. on the barrier; and
5. cover with 3 inches or so of weed free hay, wood chips, or ground leaves for a “finished” look.

This method provides a physical barrier to weeds growing at the site as well as dormant seeds in the seed bank. It also releases nutrients as it breaks down which allows for very healthy plants. In the first year plants are placed into the soil underneath the mulch by first tunnelling through the mulch and cutting through the weed barrier. In subsequent years they can be planted directly in the mulch. The web has all kinds of information on this technique as do any of Ruth Stout’s no-dig gardening books or Toby Hemenway Gaia's Garden: A Guide to Home-Scale Permaculture.

If the answer is so simple, why do I not do it? Again, I have no control over the plowing policy of the garden plot and the powers that be do not want to change it. I could sheet mulch every year, however that would not only be labour intensive, but I would also lose much of the organic material that I add as the gardens are raked with the plowing. As such, I have decided that next year I will move my garden to a community garden where I can control the “disturbance regime” and construct permanent raised mulch beds.

While I did harvest some vegetable from the garden, I am sure that my gardening neighbours would say that it was a complete disaster. However, I would argue that I received a hands-on education in gardening ecology and weed dynamics. In terms of permaculture design, one way to learn is by observing nature. Observing the life histories of plants can provide us with clues to understanding the landscape and conceiving a better design. In my garden I learned through my three sisters guild planting that while the idea appears to be ecologically sound, it may not work in all circumstances. This might be because of weeds that were not around when it was historically planted. Does that mean that the technique is worthless? No, but like all techniques it must be modified to fit the circumstances. Perhaps, a fourth guild member is necessary. Would a ground cover of white clover smother the weeds? That would be a good experiment. I also learned that the practice of tilling was actually creating optimum conditions for weed development. The solution would be to stop tilling and create permanent sheet mulched gardens.

My garden was based on the principle that I did not want to weed it or use artificial fertilizers, pesticides, or herbicides. I remember that Masanobu Fukuoka in “The One-Straw Revolution” describes how he pruned and killed some 400 tangerine trees while endeavouring to find the natural growth form of the trees. When we look at the end results of his “research”, it is hard to imagine his early disastrous results. His natural way of farming that uses no cultivation, no fertilizer, no weeding, and no pesticides is a model for us all. In the same vein, Yoshikazu Kawaguchi, a disciple of Fukuoka, applied Fukuoka’s method of growing rice and lost two seasons of rice before realizing that the natural farming methods must be adapted to the circumstances. With this in mind, I believe the final lesson of my garden experiment is to let our principles guide us, learn from our mistakes, and keep working towards our goals. If we do this, then a disastrous garden is really a step in the right direction.

NOTE: I wrote this a couple of years ago, thus the reference to moving to a community garden. I did do that and had a pretty good garden and met lots of interesting people. I have since given up my plot there to work on my own yard.


DJEB said...

Thanks for another great article!

I find plants grow great and gardens flourish with what can best be described as ridiculous amounts of mulch. Under the three inches of mulch you mention, I like to put 8 to 10 inches of mulch broken by a 1 to 2 inch layer of compost then with a good 4 to 6 inches on top of that. The top layer is then seeded with white clover to retain moisture, block weeds and fix nitrogen. My plants and I are not happy unless people look at me like I am crazy while I'm applying huge quantities of mulch.

Pureland Permaculture said...

Yes lots of mulch is good. Often I don't have enough when I need it. This fall I went collecting leaves that the people on the street were kind enough to rake up and bag for me. It will come in handy next year. To me mulching is a bit like cooking, I rarely follow the same recipe twice (if I follow the recipe at all) and it still usually turns out OK. I recommend that people use whatever they have at hand. The crazy looks I get are usually from my wife, that's how I know if I am on the right path or not. lol.