Charcoal-like biochar improves soil hydration and enhances agricultural production while it curtails nutrient leaching, increases nitrogen available to plants and reduces the release of gas pollutants. A new study by researchers at Rice University and North Dakota State University gathers current and potential sources of government support to promote the production and use of biochar. Credit: Ghasideh Pourhashem, from the January 11, 2019, Rice University post. Read more Biochar holds promise for sequestering carbon and cleansing polluted air.
Fans rave about its virtues. Some are skeptical but want to learn more. So, wanting to learn, possibly use, I typed in ‘2018 2019 Biochar pros cons’…carefully read the latest noncommercial posts and their comments threads.
A few years ago a knowledgeable gardener I know raved about biochar. Now, some years later, recently a friend sent an article that turned the tables enough to make me want to check it out. One is how it was compared with natural soil that is replenished with biochar by forest fires. Two is how Biochar has several soil sustainable features, but foremost is how it keeps Carbon in our soil hundreds, maybe even 1000s of years! And that is to say nothing of its water holding capacity! Carbon is the foundation of our soil ecosystem. Three: Also, I recalled how amazingly my winter and summer garden plants grew last year. It started with a collusion of happenstance. I planted quite late, Dec 10, 2018 during the Thomas Fire ash fall. The ground was literally solid white with ash and chunks. But this winter my plants didn’t do nearly as well. Hmm… Granted, the ash is not biochar, but it’s a relative – it came from the high heat of a forest fire.
Right now, planet wide, by many, Biochar is considered crucial to our planet’s sustainability. Using it is a regenerative practice that will help our plants not only weather extreme conditions, but thrive!
BIOCHAR RESEARCH
There are technical discussions, both pro and con, in a language all their own, to simple explanations for the home gardener. The main research is in consideration of farmers with vast tracts of land that could have significant impact on climate change.
CONSIDERATIONS
Nov 29, 2018 From a field day presentation at California State University-Fresno, here are some points from Suduan Gao, a research soil scientist with the USDA San Joaquin Valley Agricultural Sciences Center in Parlier. She talked of the potential of applying a biochar amendment to help in water and nutrient management.
Biochar is charcoal used as a soil amendment. It is made from biomass through thermal decomposition [fire]. Gao said it increases water use efficiency and nitrogen retention, reduces leaching, cuts nitrous oxide emissions and reduces ammonia emissions.
Gao said nitrogen dynamics are influenced by biochar and are highly affected by irrigation levels.
She said ammonia volatilization loss was substantially higher when fertilizer was applied only a few times in a larger amount than when it was applied more frequently in smaller amounts.
“Soil accumulates more nitrogen at lower irrigation levels than at higher irrigation levels,” Gao said. “The accumulated nitrogen, however, can be all leached during the rain system.” [Fertilizing after rains is more better!]
She said there were no significant biochar effects on ammonia, nitrous oxide and soil nitrate concentration, but there was a significant interaction between biochar and irrigation.
PROBLEMS WITH BIOCHAR? Fabulous or Fantasy? Is it too good to be true? There are extensive rebuttals to its use, even warnings that it’s not all the fans say, can even cause harm!
Nov 18, 2010 DR MAE-WAN HO said ‘Turning bioenergy crops into buried charcoal to sequester carbon does not work, and could plunge the earth into an oxygen crisis towards mass extinction.’ She further says: …implementing the biochar initiative could be dangerous, basically because saving the climate turns out to be not just about curbing the rise of CO2 in the atmosphere that can be achieved by burying carbon in the soil, it is also about keeping oxygen (O2) levels up. Keeping O2 levels up is what only green plants on land and phytoplankton at sea can do, by splitting water to regenerate O2 while fixing CO2 to feed the rest of the biosphere.’
- She cites: A ten-year trial in Swedish forests showed that buried charcoal appear to promote the breakdown of humus, the decomposing plant matter on the forest floor, thus completely offsetting the carbon sequestered in the charcoal.
- She discusses examples of the stability of biochar stating that it isn’t always stable. [In a 2012 Mother Earth News post, Editor Dr. Kehres (Journal “Humus and Agriculture“) summed up a symposium: “Biochar appears over-rated — the biochar claim to 1,000 year stability is revised downwards to 10 to 100 years, roughly the same as compost.”]
- She warns that things that happen so fast now that we have the internet and huge commercial organizations, a lot goes on without public awareness or understanding and no testing. Since this one expressly claimed climate change remediation, it was touted to be necessary immediately. Some fads are found to be faulty later.
- She gets into comparisons of interest to gardeners, stating that Biochar effects on soil fertility are not always positive. Field trials were conducted on cleared secondary forest with 15 different amendment combinations of chicken manure (CM), compost (CO), forest litter, chemical fertilizer (F), and charcoal (CC) applied once on rice and sorghum, and followed over four cropping cycles. Chicken manure gave by far the highest yield over the four cycles (12.4 tonne/ha). Compost application came second at about half the yield, but was still four times higher than chemical fertilizer. The control, leaf litter (burnt and fresh), and charcoal treatments gave no grain yields after the second season, and were discontinued. Further, in combination with compost, charcoal amendment decreased yield by about 40 percent compared to compost alone, and only improved yield in combination with chemical fertilizer.
Read the comments on this page for rebuttals and further information. It is suggested Biochar is not THE answer, but part of a complex mix of possibilities.
This 2013 Mother Earth News post Biochar: Not All It’s Ground Up to Be? states the appropriate use of Biochar depends first on soil type. Some soils retain nutrients very well without any amendments like biochar. Tim Crews says: ‘If you’re cropping on soil types other than Ultisols or Oxisols and you manage your organic matter (residues, manure, compost, etc.) well, you don’t need biochar. It won’t do anything for your fertility.’
Second, a ‘situation in which biochar could provide benefits is on very sandy soils in arid climates, because of its ability to improve such soils’ water-holding capacity, reducing drought stress on plants. But making biochar requires large quantities of bulk plant material, and the biochar factory needs to be close to the source of that material; therefore, the product would have to be manufactured in or around highly productive lands or on vast areas of unproductive lands, and then be hauled long distances to the arid environments where it’s to be applied.’ Not only is the available quantity of crop residue per acre too small, but to haul residues off of cropland to a biochar plant would be to further rob the soil of organic matter, while paying a price in energy and other resources as well. After all that, some ‘studies that found yield increases with such heavy application found that after a few years, soil carbon was no higher in biochar-treated plots than in control plots.’
Biochar has been under discussion for years! When you are doing your own questing about it online, look for current posts and research. Note whether the post is on a commercial site, a university, posted by a farmer, if the poster is knowledgeable, what their credentials are or aren’t, if they have experience. Remember that universities make money from research grants on popular topics and sometimes the donation is made by a company. Go to permaculture sites for a look at possible long term possibilities, concerns. Look for pros and cons.
In 2018, the agriculture application segment accounted for 71.1% of the total biochar demand. That makes sense because they have the biggest land holdings. [But it also means 28.9% is used by others, including home gardeners! That’s a big % considering the sizes of their small gardens!] Quoted from a Biochar fan, he says ‘However, a large number of farmers still lack in knowledge about the product and its benefits.’ My question back to him was ‘Do you know what % of farmers use biochar?’
Some say Biochar alone added to poor soil has little benefit to plants, but when used in combination with compost and organic fertilizers, it can dramatically improve plant growth while helping retain nutrients in the soil.
When would you, a home veggie gardener, use biochar?
First, are wood ash and biochar the same thing? Yes and no. Biochar is made at 450 °C/842 degrees F with low oxygen and wood ash is made at 870 °C from the same mixed hardwood. What about BBQ charcoal? Not the same thing as wood ash or biochar! Not recommended for garden use.
How do you even know if you need Biochar? Was there a forest fire ever there and you already have it? They say biochar comes from such fires and lasts 100 to 1000 years, or 10 to 100 depending on where you read… That translates to the question whether Biochar is considered to be stable or not and under what circumstances.
Have you been applying wood ash from your fireplace regularly? Some gardeners say Yes, used it for years, readily absorbed, amazing crops! Great substitute for lime to raise pH. Others say it’s grey death. It has a high pH that throws off the balance of your compost/soil, can kill off the microbes that are producing your compost. Poster Mr Bill says: ‘Charcoal chemically functions like a sponge, absorbing many organic compounds. When placed in nutrient rich soil, it absorbs the excess nutrients and traps them in the soil. As the carbon in the charcoal is annexed by fungal colonies, those nutrients are released over time. By tying these nutrients up in the soil with charcoal, they resist erosion and release at regular intervals, rather than the feast or famine spikes in levels that occur with manual fertilization by humans.
However, ‘…added to poor soil, or soil deficient in even one nutrient (which may not be obvious), the charcoal’s sponge-like absorption can compete with the roots of plants for the nutrients, leading to increased disease susceptibility or irregular growth hazardous to the plant.’ So it’s good with good soil, bad with deficient soil.
Lord knows even a 10X20′ community garden plot has varying soil content within the plot for many reasons. In my case, I trench in kitchen waste given to me by neighbors. One eats lots of bananas, hence peels. One is a super juicer, greens, carrots, etc. + lettuce and avocado. Another is a senior tea drinker, so little bags along with old snacking grapes, a few eggshells, a bit of coffee and citrus peels, etc. I get them when they have enough. They put them in a bucket outside my door. I take them to the garden and trench them in where compost is needed most. Sometimes a certain kind of plant never thrives in one area no matter what I do. It would take a lot of soil testing to sort out these small areas. I do my own remediation by adding store bought fluffy compost, and chicken manure in general. Most of the time it works fine.
FYI! If you are using or opt to use wood ash as an amendment, DO NOT mix the wood ash with nitrogen fertilizer; a reaction can occur releasing ammonia gas.
Be careful with your choice to use biochar. Is your garden flourishing because it is high on temporary soil amendments that will be spent this season? Is one area doing great, another adjacent area not doing so well; great for one plant but not another? Does your summer or winter garden do well and the other season doesn’t? Plus, all Biochar is not created equal. Its pH and ash content vary depending on the temp it was created at and the feedstock (what was burned) used, whether that was contaminated or not. In general Biochar raises soil pH. You need to use the right amounts. In a community garden 10X20′ plot, where the soil pH varies within the plot, you don’t have room to test/experiment. The increase in soil pH with alkaline biochar will be higher in acid soils than in originally alkaline soils. However! If a biochar has less ash content it will decrease soil pH because of the organic matter content.
Clearly, fireplace ash that is added every season or spring, doesn’t function the same as biochar that lasts 100 to 1000 years. It is either used up or leached away by watering, otherwise, your garden would have the highest pH in history! If biochar can’t be removed from your soil, and lasts for 100 to 1000 years, and your soil is unfavorably balanced, you may need to adjust your soil for a long time. Ironically, it works best where you already have a super flourishing garden!
Note, the type of fire makes another difference. There is increased growth after a forest fire, but slash and burn techniques have a long term bad effect in just a few years. Definitely not sustainable. Wildfires get much hotter, average over 1600°F, than farmer-made controlled burn fires kept under 1000°F to clear a field. Wood burns differently at different temps; the coals have a different structure. Forest fires burn hot at the center with low oxygen and you get Biochar. Big difference. All fires are not equal.
Mr Bill made a convenient list for us home gardeners!
• Use on rich soil with no deficiencies
• Use to correct acidic soils, or amend the pH of the char before application
• Never use on acid loving plants like blueberries [strawberries, celery, beans]
• Add to compost after composting has finished, not during composting. The recommendation for application is about ½ cup per cubic foot of finished compost. [That’s not a lot!]
• Use in moderation
• Never use char from pressure-treated or painted wood.
• Don’t use petroleum based fire starters or fluids if you intend to use the ash.
• Fires started with alcohol or non-paraffin wax are acceptable for garden use.
• Be mindful of your nutrient levels and pH when using char, test regularly for best results.
• Not all char is equal, refuse from wood gasifiers or efficient wood stoves is preferable to that from your campfire, fireplace or grill, but all are acceptable for use given the correct use of your discretion.
HOW to MAKE OUR OWN BIOCHAR?!
Though it’s been many years since the Biochar cure has been offered and raved about, using biochar on a mass basis has not been implemented to an extent that is making a planet wide difference. But that doesn’t mean we can’t use it individually. The simplest way to do it is right where you will use it, just like the Amazon Indians did 2000 years ago.
First check your legal situation before you go for it! Per the Santa Barbara County Air Pollution Control District where I live: A burn permit is required for all outdoor burning activity except recreational (campfires) and cooking (BBQ). This includes: Agricultural Burning (see definition) … Residential backyard burning (permitted only in the unincorporated areas of the Santa Ynez Valley)
Highly flammable gases are released during pyrolysis, so make it outside, well away from buildings, animals and people!
Barbara Pleasant, famed author of 5 garden books, throws in her two cents! ‘Last year, I committed one of the great sins of gardening: I let weeds go to seed. Cleaning up in fall, I faced down a ton of seed-bearing foxtail, burdock and crabgrass. Sure, I could compost it hot to steam the weed seeds to death, but instead I decided to try something different. I dug a ditch, added the weeds and lots of woody prunings, and burned it, thus making biochar. It was my new way to improve soil—except the technique is at least 3,000 years old.’
Barbara words the process more simply… What’s biochar? Basically, it’s organic matter that is burned slowly, with a restricted flow of oxygen, and then the fire is stopped when the material reaches the charcoal stage. Unlike tiny tidbits of ash, coarse lumps of charcoal are full of crevices and holes, which help them serve as life rafts to soil microorganisms. The carbon compounds in charcoal form loose chemical bonds with soluble plant nutrients so they are not as readily washed away by rain and irrigation. Biochar alone added to poor soil has little benefit to plants, but when used in combination with compost and organic fertilizers, it can dramatically improve plant growth while helping retain nutrients in the soil.
She speaks of the Amazonian ‘dark earths,’ terra preta, that ‘hold plant nutrients, including nitrogen, phosphorous, calcium and magnesium, much more efficiently than unimproved soil. Even after 500 years of tropical temperatures and rainfall that averages 80 inches a year, the dark earths remain remarkably fertile…’ They were produced this very way, burning. …composts and other soil-enriching forms of organic matter last longer. …increased productivity by making nutrients already present in the soil better available to plants. …organically enriched soil retains nutrients for decades rather than for a couple of seasons. This charcoal releases its carbon 10 to 100 times slower than rotting organic matter. See the details See Twin Oaks Forge for making charcoal in a barrel!
Why buy commercial Biochar?
Jeremy Menefee says, first, because they use more advanced tools and techniques than the home producer can easily acquire, commercially-produced biochar is usually more consistent in composition and charred under ideal temperatures.
Second, they are able to produce inoculant tailored to specific uses. Vermont Biochar, for example, produces (by hand) several versions ideally suited for either leafy annuals, root crops, or shrub or woody perennials. Each uses a different composition of inoculant to tailor it for the specific application.
Experienced permaculturist Jeremy also says to Biocharge your Biochar! Even commercial biochar producers say their products benefit from being biocharged again once it’s on your property, to tailor it to your site conditions. Here are two easy methods he recommends.
1) Compost charging Even if you buy inoculated biochar, rather than producing it on-site, it will be improved by maturing in your compost. You can use as much biochar as you want, up to about an even 1:1 ratio with the compost, so don’t worry too much about overdoing it. The Biochar doesn’t break down in the process. You may have shorter compost times! Some experts recommend adding both manure and bones.
Quick tip: If you have time, a great way to get the most out of your biochar is to spread it an inch thick or less into your farm animal bedding. Then, when the bedding is spent, add it to the compost pile. [LOL Black Sheep?!] The biochar is essentially ‘double-charged’ in this way. Also, in addition to stacking functions of your animal bedding, this can help reduce odors. Anecdotal evidence suggests it can also reduce illness among your animals!
2) Rapid Charging! The other way to inoculate your biochar is a bit more labor-intensive, but you can complete the process in hours or days, not months. First, fill a 55 gallon (210 litre) drum with fresh water and biochar. If you are using municipal treated water, let it sit for a couple days to remove any chlorine. Then add compost tea or worm castings and leachate to the barrel with some soil from the area where you will use the finished biochar. For example, if you are going to apply the biochar to your fruit orchard, add some soil from around a robust and healthy tree in that orchard. This will help charge the biochar with the ideal microbiology for your specific orchard.
Once everything is well mixed, insert a long tube such as a length of PVC pipe into the barrel and direct air from a blower into the tube, or use a pond aerator and air stones. Aeration supercharges the inoculant and gives the beneficial microbes a massive head start, and helps them adhere to the biochar. Continue this for 12-24 hours.
Be careful when applying dry Biochar!
Wear a dust mask such as the 3M™ 8511 Particulate Respirator – N95 to protect your lungs. Moistening biochar can help a lot with dust control. Some Biochar is shipped with about 30% moisture content to help with dust control. Protective eyewear will reduce the chance of getting dust in your eyes. Wear gloves! Wear rubber boots that can be cleaned easily! Apply evenly on a dry, windless day. Mix thoroughly into the soil before planting.
How much do you apply? Doing it right depends on what kind of soil you have and it’s tested content, its pH, how much you want to raise the pH if at all. And, of course, none, if you don’t need it or your situation isn’t right for it!
There are different answers!
- A company says: From everything we have seen in our own use and through the research of others a good “rule of thumb” is 10% of the planting area should be biochar. If your soil is absolutely horrible you should probably start with a 50/50 mix of biochar and compost and apply about 1/4 lb per square foot.
- Typically home gardeners use 5-10% biochar in the top 6 inches of their soil.
- A gardener says: If bought, follow the instructions on the bags, but I would suggest 50/50 with soil and the same for containers, and see your results the first season before you adjust quantities.
- Farmer Jeremy Menefee says: It takes about 10 pounds of biochar to properly cover 100 square feet. For potted plants, use pure biochar at a ratio of about 1:16 with your potting soil – about ½ cup per gallon of soil. This ratio is good for raised beds as well, one gallon of biochar per 16 gallons of soil. If you inoculated your biochar in compost (at ratios up to 1:1), just apply compost as normal – the presence of biochar doesn’t change the amount of compost used.
How to apply? Simple!
- Made your own in place? Just add amendments of your choice, especially compost, and till it in.
- Purchased, preferably inoculated? Lay on about 1/4″, amendments and till it in. If you don’t have much, spread it out and add more each time you amend.
- If you’re not able to till, spread out your inoculated Biochar, cover with mulch to hold it in place, let Nature do the work for you.
Biochar IS big business. There is university research devoted to it for sustainable reasons. They make huge grant monies from it. Yale and Cornell, Ames Iowa, Delaware, Missouri, North Dakota, Rice U in Houston Tx to name just a few schools. Government is in on it too, for example the USDA’s Southern Regional Research Center in New Orleans. There are subsequent conferences, magazines, books, products at your nursery.
USBI Biochar 2019 – is the largest event in North America dedicated to advancing the sustainable production and use of biochar through scientific and engineering research, policy development, field practice, and technology transfer. It will focus on bridging scientific, industrial, practitioner, and policy gaps in biomass utilization for biochar and bioenergy production. June 30 – July 3 at Colorado State University in Fort Collins Colorado.
BIOMASS Magazine – Beyond the Hype
Check out the BioChar Journal …we want our readers to be confident that what is written in the Biochar Journal is based on sound science and practicality.
Local gardeners might see various products at their nursery. A blend in snowy Maine might be quite different than in SW SoCal droughty areas. Before you order up online, take this into consideration. When buying locally, look on the package to see where it was made, then check out those ingredients. The bag shown here is definitely intended as a pH raiser; it has biochar and lime!
For those of us gardening at community gardens, we need to think of what the next gardener’s soil needs might be after you leave. What if they primarily want to plant acid loving plants, those blueberries, strawberries, celery or beans? In keeping with rotating crops, planting in a different place each year, to avoid soil diseases various plants are susceptible to, we may need to stay flexible – amend each season or year with regular or acidic compost per patch as we go.
If you have a good size parcel of land for veg gardening, that you plan to keep for many years, soil test different areas. You might coordinate your Biochar choices with the land’s own natural flow, plant accordingly. Some sites say it takes about a year for the Biochar/soil relationship to be fully established. If you are planting in raised beds/containers, where soil is leached of nutrients due to higher soil temps, drying, in those structures and frequent watering to compensate, replacing spent soil/compost each year, Biochar isn’t going to work for you.
Making your own Biochar is cheap, but a lengthy process you hope you do right. Probably wise to have someone experienced with you when you do your first processes. First there is gathering the right materials, selecting the right place and technique for the kind of results you want, doing the burning. Then there is the biocharging process for it to do its best work. Buying Biochar can be pricey if you get the best, inoculated. If you put it where it can be used to best advantage, that is worth the one-time expense.
Your final decision to use or not use Biochar may be based on your instinct. You may decide not to use it at your current location or in a specific area of your garden. You might move, or be visiting in another gardener’s location and feel it is the right choice for that place. Maybe you will decide to wait and see. Honor your feelings. You might not save the planet today, or maybe you will by using succinct educated choices.
Bless you for being a garden guardian, a caring Earth Steward.
The Green Bean Connection newsletter started as correspondence for the Santa Barbara CA USA, Pilgrim Terrace Community Garden. All three of Santa Barbara city community gardens are very coastal. During late spring/summer we are in a fog belt/marine layer area most years, locally referred to as the May grays, June glooms and August fogusts. Keep that in mind compared to the microclimate niche where your veggie garden is. Bless you for being such a wonderful Earth Steward!
Love your Mother! Plant bird & bee food! Think grey water! Grow organic!