Biochar Potential or Pitfall? Carbon Storage vs Soil Quality

Biochar is being touted for soil improvement and carbon sequestration. Our New England soil laboratory explores the subject in lab, field and greenhouse trials. We find some surprising pitfalls especially extreme pH that will need to be overcome before Biochar is widely used for soil application.

Category:

Science & Technology

Tags:

• Carbon Sequestration
• Biochar
• soil
• global warming
• charcoal
• Terra Preta
• biokohle
• acid soil

[DDDarray]

Biochar could be used instead of lime to buffer acids formed during composting.

[WoodsEndLaboratory]

@DDDarray Waat is the evidence that biochar is a buffer? The high pH from potash might temporarily neutralize organic acids, but they go away on their own anyhow.

[jeromnimooo1]

Compost and biochar don't have to be seen and used separatly. If you use biochar alone, no effect on crop will be observable (except at long term maybe, because of the enhance of microorganisms activity). It need nutrients. then the compost will bring nutrients and microorganism. The nutrients will be fixed and slowly released, and the microorganisms will reproduce in the pores.

[WoodsEndLaboratory]

Many people report better results when adding compost to biochar,- probably due to composts' very positive influences masking or ameliorating the harsh negative effects of the charcoal, which it is true are short lived- but enough to rule it out for most commercial farm operations. Factorial studies conducted by unbiased parties would have to be performed to determine if there is really any synergistic effect.

[ForestFront]

So, char will improve acid soils, but will have adverse effects on neutral or basic soils. Is this correct?

[WoodsEndLaboratory]

@ForestFront Yes-  we think biochar functions as a strong cationic fertilizer (Ca, Mg, K) which will undoubtedly improve highly depleted soils but may be deleterious in under circumstances where flooding the CEC sites with more cations is obviously not desirable or agronomicaly responsible.-

[pflugelhorn]

No one is proposing to use large quantities of fossil energy to make biochar. It wouldn't be cost-effective.

The scientifically valid commercial biochar devices use small amounts of propane to start the pyrolysis, but the process then heats itself using the biogas emitted from the biomass.

[Pangolinx1]

@fm928 _ The answer is simple. Compost will burn off in a few years while biochar remains in the soil and continues to benefit. Repeated applications of compost with biochar accumulate benefit while repeated applications of compost alone will only reach equilibrium. The biomass to form the compost also has to come from outside your farmed area.

[lock2hart]

The Terra preta sites would back up the use of biochar, but there is another naturally accuring way biochar has been 'used' for centuries. Lightning setting forest on fire. The result is lush acres of grassland to support wildlife, because without natures intervention animals could starve. The trees slowly invade to start the process over again and again. I don't have a science background, but I do believe in these simple facts.

[turborabbit1114]

I have been using bio-char in my garden for years now and other than that it absorbs nutrients the first year you use It, I have seen no harmful effects, and its not like someone would use it as a sole fertilizer you still need to add some N-P-K the biochar just holds the N-P-K where the plants can get it, rather than haveing it runoff with the rain.

[doktorandom]

One reason that I can see and am engaged in developing is the quick conversion of animal wastes into more stable materials for ag. Horse manure for example is hard to store, too 'hot' for immediate use in soil amendments and leaches into groundwater in wet climates. Interested in using pyrolysis in conjunction with other processes , and determining what plants thrive in the resulting product when added to local soils.

[fernpharao]

Dosis facit venenum! In Germany in Max-Planck-institute they found a way to control the biochar processing to a degree, where the output is biochar (as final product) as well as other products like some type of carbon-goo which could be processed to make gasoline and the producing of a kind of topsoil, without producing climate gas as its the case in the natural process of compost (of course good natural topsoil/humus/compost is more than this). On top of that, the processing is exothermic.

[snookmeister6]

In my comparison plantings, biochar led to a significant (100%) improvement in vegetable yields. I encourage gardeners to learn to make it and then apply it. Test it yourself and see if it makes a difference. I'm convinced and plan to continue using it. If you use sterile char alone and and expect to grow anything, you're likely to be disappointed. By all means, use compost, with and without char. See for yourself. Don't smoke your neighbors - learn smokeless methods. Cheers.

[Helioforge]

Just made a video on the properties of materials of charcoal for Terra Preta, a few days ago. If you look at it, please tell me if it misses anything important. It is of great interest to me to create a comprehensive visual teaching tool for Terra Preta.

Otherwise, people could potentially be led away from Terra Preta by not understanding that the material must first soak up tremendous amounts of mineral nutrients, and then allow microorganisms to find their natural balance within the soil.

[chrispecht]

Agricultural fires are everywhere on earth. The remaining ash has a much higher pH than biochar and it is often desired to increase the pH in agricultural soils. That is why lime is used in agriculture. Lime is very effective in increasing the pH.