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defineaproblem February 22, 2015 08:04 PM

Biochar enhances yield and quality of tomato under reduced irriga
Anyone read this report? I would be interested on your take.

Biochar enhances yield and quality of tomato under reduced irrigation

Worth1 February 22, 2015 08:36 PM

Might as well have a video to go with it.
I have been studying this stuff and the peoples of Amazonia for years.
My opinion, it works.


LDiane February 23, 2015 03:22 PM

This presentation shows a kiln for making biochar on a small farm in British Columbia, and various tests comparing growing with compost, biochar, biochar plus compost, biochar plus compost tea. All produced more beets than the control plot, but the plain compost was best.

Cole_Robbie February 23, 2015 04:18 PM

It's just charcoal. My family has always spread our wood stove ashes on the garden, which would usually have bits of charcoal-looking burnt wood in it.
A report published in 2007 presented results on crop yields over four seasons [35]. Researchers at the University of Bayreuth in Germany, and EMBRAPA Amazonia Occidental Manaus in Brazil carried out a field trial near Manaus 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 (see Fig. 2).
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.

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. The charcoal was derived from secondary forest wood bought from a local distributor, and applied at the rate of 11 tonne/ha. This corresponded to the amount of charcoal C that could be produced by a single slash-and-char event in a typical secondary forest on the dry iron-rich soil of central Amazonia.
The highest yields for all treatments were obtained at the first harvest, and except for chicken manure, yields declined rather sharply by the second harvest.
A second fertilization with chemicals was applied after the second harvest to all remaining treatments, but that did not improve the yields.

Plants fertilized with chicken manure had the highest nutrient contents followed by plants that received compost and/or chemical fertilizer. Chicken manure significantly improved the K and P nutrition compared to all other treatments, while charcoal applications did not show a significant effect on nutrient levels. Most importantly, surface soil pH, phosphorus, calcium and magnesium were significantly enhanced by chicken manure. Plots fertilized by chicken manure had pH higher than 5.5 and increased cation exchange capacity.

NathanP February 23, 2015 10:16 PM

The site at the below link is probably worth reading in it's entirety. FAQ#7 applies most directly.


7. How does biochar affect soil properties like pH and CEC? Biochar reduces soil acidity which decreases liming needs, but in most cases does not actually add nutrients in any appreciable amount. Biochar made from manure and bones is the exception; it retains a significant amount of nutrients from its source. Because biochar attracts and holds soil nutrients, it potentially reduces fertilizer requirements. As a result, fertilization costs are minimized and fertilizer (organic or chemical) is retained in the soil for longer. In most agricultural situations worldwide, soil pH (a measure of acidity) is low (a pH below 7 means more acidic soil) and needs to be increased. Biochar retains nutrients in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil, as does organic matter in general.
CEC stands for Cation Exchange Capacity, and is one of many factors involved in soil fertility. “Cations” are positively charged ions, in this case we refer specifically to plant nutrients such as calcium (Ca2+), potassium (K+), magnesium (Mg2+) and others. These simple forms are those in which plants take the nutrients up through their roots. Organic matter and some clays in soil hold on to these positively charged nutrients because they have negatively charged sites on their surfaces, and opposite charges attract. The soil can then “exchange” these nutrients with plant roots. If a soil has a low cation exchange capacity, it is not able to retain such nutrients well, and the nutrients are often washed out with water.
See Chapter 14: Biochar effects on soil nutrient transformations; Chapter 15: Biochar effects on nutrient leaching; and Chapter 16: Biochar and Sorption of Organic Compounds, in Biochar for Environmental Management: Science and Technology, edited by Johannes Lehmann and Stephen Joseph, Earthscan 2009.

Some information on my background, I was into fishkeeping and planted aquaria for many years prior to getting back into the outdoor plant and gardening hobby, and having a substrate (soil) with high CEC is one of the most important factors in growing aquarium plants. It stands to reason that would be true with mostly any soil. Depending on what the soil is like in different locations, biochar might be more or less effective than in other locations.

snugglekitten February 24, 2015 06:19 PM

slash and burn, isn't it the oldest agriculture known to man?

NathanP February 24, 2015 09:52 PM


Originally Posted by snugglekitten (Post 453176)
slash and burn, isn't it the oldest agriculture known to man?

Possibly, but it is not good for all soils or all locations.

lrussillo April 23, 2015 08:57 AM

Wood ash is high in need to keep that balanced with phosphorus. It will also drive up ph quickly.

Biochar is created through a low-heat, airless burn, so not the same as charcoal.

Char needs to be charged with amendments, compost, etc., before being spread around crops.

google biochar activation for more info.

Redbaron April 23, 2015 08:28 PM

In so much as you are from Cincinnati, I doubt you need irrigation if your soil is healthy and you mulch. Biochar can help if your soil is low in carbon. It is a quick "jump start" for depleted soils low in carbon. If your soil is already good, then I doubt it will help much though.

bower April 25, 2015 12:35 PM

In my experience wood ashes are best sifted to remove any charred wood - it didn't benefit and had a negative effect on growth in my garden (worse than unburned wood chips, which take forever to break down in this cold, wet environment and low pH soil - charred wood takes forever, and forever,... and a day).

In the article cited in the OP, it seems likely that benefits to the tomatoes were due to structural reasons - water retention by the coarse particles - which improved yield under reduced irrigation.

Reading further about this, it seems biochar is being promoted more so for turning agricultural soil into a carbon sink (and 'carbon neutral' activity) because of the low rate of breakdown. It may have some benefit as a coarse material that traps moisture in specific soils or situations and very slowly returns nutrients to the soil (eg burnt forest regeneration), but it's hard to imagine any other benefit to crops, which require a high turnover of nutrients for rapid growth. And there is a risk that toxic PAH's in diet may be increased by the practice.

I had concerns after seeing the toxic effect of charred wood on plants in my garden, which agrees with the fact that PAH's - byproducts of incomplete combustion of wood - are toxic to many, if not all plants, as well as animals - some crops do take up and accumulate them.

See this article by Quilliam. Is biochar a source or sink for polycyclic aromatic
hydrocarbon (PAH) compounds in agricultural soils?

A few quotes:

from the CDC:

"The PAH content of plants and animals living on the land or in water can be many times higher than the content of PAHs in soil or water. PAHs can break down to longer-lasting products by reacting with sunlight and other chemicals in the air, generally over a period of days to weeks. Breakdown in soil and water generally takes weeks to months and is caused primarily by the actions of microorganisms."


"In addition to gathering ashes (and keeping them in a dry metal can until you’re ready to use them as a phosphorus-rich soil amendment, applied in light dustings), make a habit of gathering the charred remains of logs. Take them to your garden, give them a good smack with the back of a shovel and you have biochar."

..."This charcoal releases its carbon 10 to 100 times slower than rotting organic matter."

Charring, traditionally used to harden and preserve fence posts:

lentils and wheat are examples of crops that may take up PAH's from soil:

Personally, I'll be keeping charred wood debris away from my garden, and from any watercourse or groundwater catchments.

Tapout May 5, 2015 02:45 AM

I have been watching the bio char debate for a couple years now, and have done my research since it became a hot topic. I see so many mistakes on testing and terminology its hard to take any of these studies seriously.

Bio char isn't just char coal. Not all char coal is Bio char. Using Bio char without activating it "will decrease yields". Just those two things alone will make some studies fall flat on their faces.

Think of Bio char as a reserve gas tank. When the soil becomes lacking it reaches into the reserve tank. Now what is stored in the reserve tank is up to you. If you don't store what is needed by the plants it is your fault not the Bio chars.


If you place inactivated Bio char into your soil it will activate it's self by pulling whats available around it causing a deficit of nutrients until it has reached its saturation point. This is the number one mistake made by gardeners and why they see stunted growth.

Ashes are not Bio char and are not used when amending Bio char to your soil. Bio char does have some ash content in it already and under standing if your Bio char has a high or low ash content affects the PH impact of your soil.

Randomly tossing any old Bio char in your soil can be detrimental to plant growth as well. As I said above not all Bio chars are created equal. Matching the right Bio char to your soil is needed for success.

Worth1 May 5, 2015 10:01 AM

I think a whole heck of a lot of people are missing the point of bio char.
This stuff was discovered in the Amazon basin not Indiana. :lol:

Done correctly I firmly believe it would do wonders in a highly acidic clay soil like they have in the basin.
It isn't a cure all for every situation.

Redbaron May 5, 2015 10:27 AM


Originally Posted by Worth1 (Post 470231)
It isn't a cure all for every situation.

You are right of course, but it is a tool than can be used to restore degraded soils. Considering how much poor soil is out there, potentially a very big tool indeed.;)

bower May 5, 2015 12:26 PM

The Amazon Basin is certainly a unique situation, due to the high rate of conversion of organic matter into living forest biomass.. there's literally no 'extra' organic matter left around in the soil, it gets sucked right up. In order to do agriculture, the organic matter tied up in the canopy had to go back into the soil.

With 'biochar' actually having a slower rate of breakdown cw other forms of organic material, it's a good fit for that situation - ideal really - to keep some organic matter in the soil as long as needed.

Sure, where I live we also have highly acidic clay soil. But with cold, wet, short growing seasons, a vegetable garden needs the stuff that will cycle as fast as possible in the circumstances. This alone would explain the detrimental effects of burnt wood in my garden.

Those of you in warmer climates might well benefit by tying up that organic matter in the soil, and will not mean you have to wait two years for vegetables. :twisted:

In my environment, ashes also don't fix the soil pH for very long. So much rain just washes it out, and a year later the soil amended with ashes is more acidic than ever. Not a practical alternative to lime (no calcium in the soil here either) but a good source of potassium in the compost, afaik.

4season May 5, 2015 05:38 PM

On the web some info is good some is snake oil. My soil is so alkali if vinegar is poured on it, it foams. Washed all ash out of some charcoal from the woodstove and soaked it in vinegar until it was slightly acidic then soaked in fish emulsion and mixed with compost. There seemed to be no change in production from the bed it was used on last year. I still have hope for 2015.

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