A Chicken Named Dog

Adventures with a Flock Family

Tag: Soil

Hugelkultur In Raised Garden Beds And The Miracle of Harvesting Nitrogen Out of Thin Air

I will admit to using hugelkultur long before it became popular, and it was really a result of finding the purchase of “dirt” prohibitively expensive when building raised beds. I also found that when I bought “dirt,” it just crusted up and formed a sort of caliche crust on everything, making it difficult to dig. Just this past weekend I bought a small bag of dirt for $2.73 at Menards, and it didn’t even form a one-inch layer on my smallest garden beds. I used that dirt, on a smaller scale, to see if it would be more cost effective to set up a garden bed for planting strawberries with purchased ingredients versus using layer bedding (a.k.a. chicken poop straw) in small raised beds. Cost-effective to buy dirt? No, not for me, and I can also make it much more easily than I can carry it, but hugelkultur, or mounding up a pile of logs with compostable and dirt-making materials has been apparently been a garden method used before.

Example of hugelkultur

Turns out that hugelkultur has a long culture of use in Europe, according to Permaculture.org:

Used for centuries in Eastern Europe and Germany,hugelkultur (in German hugelkultur translates roughly as “mound culture”) is a gardening and farming technique whereby woody debris (fallen branches and/or logs) are used as a resource.

Often employed in permaculture systems, hugelkultur allows gardeners and farmers to mimic the nutrient cycling found in a natural woodland to realize several benefits. Woody debris (and other detritus) that falls to the forest floor can readily become sponge like, soaking up rainfall and releasing it slowly into the surrounding soil, thus making this moisture available to nearby plants.

For myself, my general dilemma is that I have a large garden space I want to prepare and no good means or money to buy dirt that I can haul in large quantities. Who has the trucks? The arm power? The patience? It’s much simpler to put cardboard in the base of my garden bed and fill it in with sticks I am trying to clean up, or fallen logs, branches, whatever I want cleared out of the path, then layer poopy straw, wood chips used as chicken bedding and kitchen veggies on top and put more straw or leaves on that.  My garden beds are large compost piles, essentially, with layers of wood at the bottom to hold moisture, layers of compost on top to provide nutrients, and presto-change-o-alakazoo, dirt is formed!

There is a book on this kind of sort of (and I use this term in the loosest way possible) “method,” called Lasagna Gardening,by Patricia Lanza, that I read years ago. The book advocates a specific layering pattern. You can read more about it here. I am not that precise.

I am rather averse to “precise” methods, and I don’t use peat moss as Patricia Lanza recommends in Lasagna Gardening and as is recommended by the other raised bed method of Square Foot Gardening because I have no desire to decimate someone else’s yard/ peat bog and emit a ton of CO2 into the environment in order to build my garden bed. The use of peat is not environmentally sustainable. And besides, I would have to pay for peat moss, which again raises that pesky barrier of getting enough material to fill multiple 4 foot by 12 foot by 2 feet garden beds, multiple, as in 5 and growing, not to mention an acre of other plantable land.

My “method” is born of a layering method that involves using all the organic matter I can to fill a garden bed and then I wait to see if it gets hot, if there is heat coming off the compost inside. If it’s not hot, releasing heat from the composting, then I go by smell. If it smells like rotting veggies, then I add a carbon source, usually straw. If it  smells like mold and is cold, I add a nitrogen source, like veggie scraps from my kitchen sink pile.  When a compost pile is actively breaking down nutrients, the microbes that digest the organic matter release heat, and this creates a sweet earthy smell. This heat is useful for killing off weed seeds and any possible harmful bacteria.  I like to stir up the uppermost layers of compost and then feel for heat in a day or two. Ideally, the raised bed stays warm for a few weeks, as I keep turning and mixing the top layers together. There will be mold in the pile, and some veggies that rot, but a well-balanced compost pile shouldn’t have any kind of bad odor.

As the compost rots, it builds great garden dirt. I tweak the mix depending on what I am growing, after the compost pile has been “hot” for a couple of weeks.  If I am growing a fruiting plant, I add a bit of calcium, in the form of oyster shells, or bone meal, because the calcium is important for setting the sweetest fruit, and I know that my particular mix has a lot of wood chips in it, making it more acidic, and the calcium source also helps balance the acidity from the pine chips. .

I sometimes “prepare” the bed by planting beans or peas in it before other crops to make sure that there is a usable source of nitrogen in the soil. Generally, I plant peas instead of beans because our spring is often cold and the peas are in preparation for tomatoes. Beans and legumes take nitrogen from the air and store it in root structures, which then break down and make nitrogen from the air available in the soil for roots of other plants. Plus, I like to eat peas.

How cool is it that nitrogen can be harvested from the air and deposited in the soil? I think it’s the equivalent of  a miracle, free fertilizer sucked right out of thin air? How does it work?  The Earth’s atmosphere (layers of “air”/gases surrounding the Earth) contains N2, or Nitrogen gas, and legumes (plants in the bean family) have the ability to convert this nitrogen gas into nitrogen for a plant.

Layers of Earth Atmosphere

Sounds like magic, but look at the picture above, the atmosphere level contains nitrogen that is captured by legumes and stored in these little nodules pictured below. This is a root system that has lumpy nitrogen nodules attached.

Nitrogen fixing nodules

New Mexico State University provided the nodule photographs, and this handy explanation of exactly how this process works:

Legume nitrogen fixation starts with the formation of a nodule (Figure 1). The rhizobia bacteria in the soil invade the root and multiply within its cortex cells. The plant supplies all the necessary nutrients and energy for the bacteria. Within a week after infection, small nodules are visible with the naked eye (Figure 1). In the field, small nodules can be seen 2–3 weeks after planting, depending on legume species and germination conditions. When nodules are young and not yet fixing nitrogen, they are usually white or gray inside. As nodules grow in size, they gradually turn pink or reddish in color, indicating nitrogen fixation has started (Figure 2). The pink or red color is caused by leghemoglobin (similar to hemoglobin in blood) that controls oxygen flow to the bacteria (Figure 2).

Healthy nodules have red centers

Ack, I am boring even myself with that description, even with the big pictures. Suffice to say that a type of bacteria on a legume root system helps the plant store nitrogen from the atmosphere in nodules at its roots so that the plant needs no nitrogen fertilizer. Making fertilizer out of thin air with no application needed. I will use that kind every time.

Cowpeas, soybeans, and fava beans, according to research, Walley et al., 1996; Cash et al., 1981, apparently fix the most nitrogen of any bean type, about 250 pounds per acre. Consider how much it costs to apply 250 pounds of fertilizer, at a rate of $10 for a 20 pound bag, and planting peas will net you $125 worth of fertilizer from the air. Combine that with savings “making” your own dirt, and building a raised bed using hugelkultur, compost, and nitrogen-fixing plants, and it really doesn’t get more cost-effective to garden. There is also no better man-made fertilizer around. Nature does these things best, and often most efficiently. If I want added fertilizer, I simply put worms in my compost pile, and I wait for them to make fertilizer. Notice how I let Mother Nature do the work, and that greatly reduces my work load.

Using compost and the hugelkultur method also helps a garden bed retain water. When a garden bed is filled with straight dirt, even finely sifted dirt, it drains water too quickly and compacts rapidly. Drains water quickly as in requiring watering every day. Personally, I have too many gardens to worry about watering every single day in a heat spell. I would lose too many plants if the gardens required watering everyday.

One might say that hugelkultur, composting, lasagna gardening, worms making fertilizer, and nitrogen-harvesting crops are all signs of profound laziness on my part, an apparent character flaw that attests to the fact that I don’t like garden work quite as much as I profess. I will say this: I love garden work, but it’s the simple economics of time management. I can’t manage all my plants and all my animals, and all the purchases, if the process is too fussy or expensive, let alone keep up with the watering in our increasingly variable summers. Usually when it’s 90 degrees F, with lots of humidity, I am worried about keeping my birds cool, setting out ice for our old roo, and I always put the animals first. I can’t water every garden bed and plant everyday, so while some might call it laziness, I call it sheer survival. Happily enough, it works, regardless of the perceived motivation. Hugelkultur, nitrogen-fixing, compost, and gardening–try it– just don’t pay for dirt, because it’s not really cheap at all, no matter the old saying.

Hardy freebies

image

This last spring one of the garden catalogs offered a “free” bulb (we had to pay shipping).  So, I took a chance and sent back the card.

A few weeks later I received by $6, free bulb, which I promptly put in a good spot to get it planted.  Three months later I found the bulb in a box.  A week later it was planted–there were some follow-through issues.

The bulb (it might technically be a tuber) lay dormant to the point I was convinced I was cheated in a marketing scam (ignore the four month delay in planting–I was working myself up into a good, self-righteous state).  Then after a good soaking rain: sprouts.

So, my free elephant-ear something (I have lost the description) is now growing next to the first garden box.  Yay for hardy freebies.

 

 

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