Biochar: Ancient Soil Amendment

As we continue to learn about gardening, we are often reminded of nature’s essential role in the process, and, by extension, the wisdom demonstrated by historical gardeners as they worked in concert with nature.

We have countless examples of the benefits of “gardening with nature,” and ample evidence of the short-sightedness of technology-based agribusiness.

”Technology” as used here encompasses monocropping, animal feedlots and synthetic fertilizers and pesticides, as well as more constructive activities such as the use of drone aircraft to monitor crops. Should watch out drone jammers, though.

One fascinating historical instance of natural gardening is biochar. The briefest definition of biochar is organic matter that has been heated to high temperatures with limited oxygen to produce charcoal. This process (pyrolysis) also produces gasses that can be burned to produce electricity.

Screen Shot 2016-02-28 at 12.08.40 PM

Biochar is very similar to charcoal, which is made principally from wood, and used in backyard barbecues and a variety of industrial processes. Biochar, by contrast, is made from all kinds of organic waste, particularly garden or agricultural waste, and is used as a soil amendment, adding carbon to the soil.

 

Note: The biochar photo is from a good article by Jeff Cox in Rodale’s Organic Life.

Biochar apparently has been produced and used for thousands of years by early gardeners in Brazil’s Amazon River Basin to improve their rather poor soils. In 1870, an American geologist and explorer discovered and reported areas of dark and highly fertile soil. Researchers puzzled over the origin of this unusual soil, called “terra preta” but recognized that it has strong benefits for agriculture.

During the past twenty years or so, scientists have attributed several valuable properties to biochar, beyond improving crop yields. The additional benefits include increasing water-holding capacity of soil, reducing the need for chemical fertilizers, reducing natural emissions of greenhouse gasses (nitrous oxide and methane) from agricultural soils, increasing soil microbial life, resulting in carbon sequestration, avoiding the natural decomposition of agricultural and forestry waste and thereby decreasing carbon dioxide emissions.

These benefits are stimulating great enthusiasm for uses of biochar in both gardening and agriculture. For example, scientist James Lovelock, author of The Gaia Theory, has written, “There is an outside chance that one procedure could really turn back the clock on Global warming and that is burying carbon. All you have to do is get every farmer everywhere to make a profit by turning all his agricultural waste into char and burying it.”

This success story has only an outside chance because it assumes universal participation by the world’s farmers, but does reflect the genuine value of biochar.

Still, individual gardeners could help to reverse global warming by using biochar. This material is available commercially, but it’s costly. A quick survey of sources on the Internet shows a typical price around $30 per cubic foot, enough to amend a garden bed of twenty-four square feet.

A gardener could produce biochar with little or no expense. Here are brief directions from Barbara Pleasant, Mother Earth News (2009): “Pile up woody debris in a shallow pit in a garden bed; burn the brush until the smoke thins; damp down the fire with a one-inch soil covering; let the brush smolder until it is charred; put the fire out.”

For more on this topic, visit the International Biochar Initiative.

Biochar could increase dramatically the fertility of your soil, and help you to rival the successes of ancient gardeners of the Amazon Basin.

More

A reader’s query and my reply.

Q: I read your article in Friday’s Sentinel about biochar. I am wondering if I can put used, regular, charcoal from the grill in the garden. There is always some left over. Can I break it up and put it in my garden?

It seems like I read somewhere years ago I could, but I can’t remember.

A: By “used charcoal” do you mean ashes?

I have attached a short article that is about Colorado’s soil, but California soil also tends to be alkaline, so the article has relevance in our area as well.

Charcoal is Not a Good Soil Amendment in Colorado

The bottom line is that charcoal ash, which is alkaline, would have some value when added to very acidic soil, i.e., low pH, but doesn’t add any fertility to the soil.

On the other hand, unburned, or partially burned charcoal briquettes (made from wood) could be useful as a soil amendment, although they have less nutrient value than biochar, which is made from a range of vegetative materials.

Charcoal briquettes usually contain cornstarch as a binder, and might include coal, lime and other ingredients, none of which would be harmful in the garden. Soften them in water to break them down, then dry the result to mix into fertilizers or directly into the soil.

I hope this is helpful

Another reader’s comment: 

Dylan Gillis

Fine article, though it sort of glosses over the fact that biochar itself is 99% carbon that stays in the soil for hundreds if not thousands of years. While compost only costs $3 or more per cubic foot (depending on quality, volume you buy and packaging/marketing variables) it needs to be replaced every year, forever, to result in similar levels of carbon sequestration and fertility. Of course the best is to add biochar, once to satisfactory levels, and then amend with compost for the nutrients and energy feeding the soil life, every year. In this approach you would use less compost to get the same or better results and your carbon sequestration would be more or less permanent!

Drama for the Landscape

 

One of the most spectacular plants from South Africa, in exuberant bloom at this time of the year, is Aloe arborescens. It can be seen throughout the Monterey Bay area, occasionally having spread into impressively large clusters of plants.

The specific name means “tree-like,” because the plant can grow to close to ten feet high. Structurally, the plant consists of several branches, each of which ends in a rosette of leaves edged with small spikes. Each rosette can generate several flower stalks that produce cylindrical inflorescences (racemes). The individual flowers, typically a bright orange-red, are tubular and attractive to hummingbirds. The clusters of flowers resemble the flame of a torch, leading to the plant’s common name: Torch Aloe.

DSCF0022 DSCF0023 DSCF0024 DSCF0025

Several years ago, I planted my first specimen of this succulent plant, a single rosette, in a well-drained bed. It grew rapidly and extended runners (stolons) that produced new plants, ready to take over the bed. Not knowing its full growth potential, but realizing that it was too productive for that small bed, I shovel-pruned it, replanted three rosettes in front of a nearby compost bin, and placed most of the rest in the bin.

The replanted rosettes grew readily into a dramatic presence in my garden, and also shielded the compost bin from view.

A. arborescens is related to A. vera, a smaller, more familiar South African native that is popular for its ornamental, cosmetic and medicinal values: its juices reportedly have rejuvenating, healing, or soothing properties.

The Torch Aloe also reportedly has value in promoting good health. Some people advocate a drink made from the pureed whole raw A. arborescens leaf, unheated raw honey and 1% certified organic alcohol. This drink is claimed to support immunity from a range of diseases and provide general cleansing for the whole body. It is reported to be “bitter, but unctuous and savoury as well, thanks to the honey.”

I have plenty of leaves but have not tried the drink. This is not a testimonial.

A. arborescens is one of about 500 species of the genus Aloe, which includes natives of South Africa, tropical Africa, Madagascar, Jordan, the Arabian Peninsula and some islands in the Indian Ocean. Many grow well in the summer-dry climate of the Monterey Bay area. Most species, unlike A. arborescens, are stemless: the rosettes grow directly on the ground.

A smaller, yellow-flowered variant, called Golden Torch Aloe (A. arborescens lutea), can be found in limited numbers.

Another yellow-flowered form, Yellow Aloe, was discovered in a private garden in Santa Barbara. This plant might be a variant of A. arborescens, a hybrid with another species, or an entirely different species: A. mutabilis, which has red flower buds that mature into yellow.

Aloe arborescens can be an attractive and interesting addition to a landscape that has sufficient space.

Pollinator Friendly Gardening

The current period of warm weather surely doesn’t signal the end of El Niño rains, but it does bring to mind the coming of spring. And with that cyclical change comes the inspiration to plan for garden development.

Our gardens can support many different objectives. One timely objective to consider is to support healthy lives for nature’s pollinators, primarily bees and butterflies.

We have frequently touched upon the vital role that bees and butterflies fill in the propagation of plants. The development of fruits and vegetables, which are essentially seed cases, often depends on bees, and butterflies are important pollinators of wild and cultivated flowers.

Our pollinators are threatened by civilization, notably habitat loss and agricultural chemicals. In May of 2015, the U.S. Dept. of Agriculture and the Environmental Protection Agency, in response to a directive by President Obama, established the Pollinator Health Task Force. That multi-agency group has begun reporting on studies and releasing recommendations to help bees and butterflies. We can expect a continuing flow of constructive new directions.

In June of 2015, with endorsement by First Lady Michelle Obama, environmentalists created the National Pollinator Garden Network and launched the Million Pollinator Challenge, with the goal to create one million new pollinator gardens by the end of 2016. Clearly, individual gardeners are invited to join in nationwide efforts to support pollinators.

In this context, we have a new book by Master Gardener Rhonda Fleming Hayes: Pollinator Friendly Gardening, (Voyageur Press, 2015).

Screen Shot 2016-02-16 at 12.51.35 PM

This is a valuable resource for developing a garden that supports healthy lives for bees and butterflies. Fleming, a dedicated advocate of pollinators, provides a readable and complete introduction to the subject and maintains a calm and informative style. (We respect fervent commitment to a cause, but the strident alarms and urgent calls to action we sometimes see can be trying.)

Fleming offers three principals for pollinator-friendly gardening: provide blooming plants all year, allow nesting and overwintering sites, and avoid uses of pesticides.

She also focuses on native plants, which have co-evolved with many insects and developed reciprocal dependencies. These relationships are site-specific so that the plants and insects that are native to California are not the same as the plants and insects of the east coast of the U.S. Many garden books, including this one, address national readerships, so each reader should adapt plant lists to his or her own garden environment.

Also, note that honeybees were imported to the U.S. long ago from Europe and other regions, and do not relate to U.S. native plants in the same way as the thousands of species of U.S. native bees. Imported bees particularly appreciate plants from their native lands that have been introduced in the U.S.

Here are sources for more information on pollinator-friendly gardening:

The Pollinator Partnership

National Pollinator Garden Network

Xerces Society

Monarch Watch

Ladybird Johnson Wildflower Center

A pollinator-friendly garden has direct benefits for the bees and butterflies, and also serves the gardener with the pleasure of beautiful surroundings and the satisfaction of ecologically sound practices. Also, an enjoyable and educational counterpart to bird-watching is the emerging activity of bee-watching. There is much to learn from the bees!

Color in the Winter Garden

A good practice is to walk through your garden occasionally to see what is succeeding, and what might need changing. It’s rewarding to visit your plants in the spring, but the winter months (now) are when we look for dormant season instances of attractive color, form or fragrance.

In the Monterey Bay area, the dormant season brings nothing like the severe conditions experienced in some other parts of the United States, but our gardens still rest at this time, and might present only limited interest.

It doesn’t have to be that way! There are many plants that can enhance our gardens while other sleep, when we plan for all season interest.

A first step is to take note of plants that are already in your garden, and looking good right now. They might be providing attractive blooms or interesting foliage, taking the center of attention while others have dropped their leaves or died to the ground.

You could supplement the tour of your own garden with a walk through your neighborhood to see what looks good in nearby gardens. That approach automatically identifies plants that would thrive in the climate and soil conditions of your garden. It can also be a good excuse to meet new people, to ask them about their gardens.

My garden, while not a true all-season display, still has several plants that are attractive during the winter months. For example, succulent plants, which have done well during our drought period, can maintain their appearance during dormancy.

I recently renovated a small bed of Mexican succulents, and the plants are looking good. They will produce blossoms later in the year, but the forms and colors or their foliage works well year-round. The recent addition of a large Talavera bowl, recently added, serves to mark the bed’s Mexican theme.

Talavera pottery, offered by many garden stores, is a style of glazed ceramic pottery that dates to the Italian Renaissance. Authentic Talavera items are from the Mexican city of Puebla and nearby communities, but imitations (which includes my own piece) are widely available. Imitations from other parts of Mexico are properly identified as Maiolica, which refers to the decorative style.

Other plants that are starring during the winter include a Purple Lilac Vine (Hardenbergia violacea), an Australian native, now covered with small violet flowers; an enormous Candelabra Plant (Aloe Arborescens) from South Africa, blooming later than others in the area, and a favorite, a Variegated Winter Daphne (Daphne odora ‘Aureomarginata’), which offers both colorful evergreen foliage and a sweet fragrance that highlights the season.

Daphne odora 'Aureomarginata'

Daphne odora ‘Aureomarginata’

When provided good drainage and afternoon shade, daphnes are reliable performers for years until they suddenly and without apparent cause, give up. An older specimen recently showed arrested development: flower and leaf buds simply didn’t mature for months. After quizzing three knowledgeable friends, without success, I removed the plant (making space for another fuchsia). By this time, I already had three replacement daphnes growing nearby, so I still could enjoy the wafts of fragrance this year.

Prepare now to bring new interest to your garden for next winter with more seasonal bloomers and evergreen foliage, either adding specimens of existing plants that you like or bringing in good performers that you have seen in nearby gardens. Winter gardens can be very pleasing environments.

More

A quick Internet search or a visit to your local library or bookstore could lead to useful lists of winter-blooming plants. For example, one good source of information is Dan Hinkley’s book,  Winter Ornamentals.