Biochar FAQs

Biochar Basics

Question: How does biochar benefit my garden?

Answer:

  • Improved Soil Structure: Biochar can improve soil structure by increasing its water-holding capacity and aeration.
  • Nutrient Retention: It can help retain nutrients in the soil, reducing nutrient runoff and fertilizer needs.
  • Enhanced Microbial Activity: Biochar can provide a habitat for beneficial soil microorganisms, which can enhance plant growth.
  • Reduced Soil Acidification: It can help neutralize acidic soils and maintain optimal pH levels.

Question: How can biochar help the environment?

Answer: Carbon Sequestration. By storing carbon in the soil, biochar can help mitigate climate change.

Question: How can I use biochar in my garden?

Answer:

  • Soil Amendment: Mix biochar into your garden soil before planting.
  • Top Dressing: Apply a layer of biochar to the soil surface as a mulch.
  • Potting Mix: Incorporate biochar into your potting mix for container gardening.

Question: Are there any drawbacks to using biochar?

Answer: Biochar can be expensive to buy. Fortunately you can make your own biochar in your backyard while enjoying your biochar fire pit.

Making Biochar

Question: What makes the biochar fire pit different from traditional fire pits?

Answer: The biochar fire pit prevents air from entering from the bottom of the fire pit which allows biochar to form without being completely burned up. Its tapered shape allows enough air to come in from the top to keep the fire burning. 

Question: Is it hard to make biochar?

Answer: With the biochar fire pit making biochar takes similar skills as using any fire pit. There is slightly more skill involved to feed the fire and let it burn down but it is simple enough to successfully make biochar on your first try.

Question: Why does the biochar fire pit have a hose attachment?

Answer: We included a bottom up quenching pipe to make quenching biochar cleaner (virtually no ash dust like when quenching from the top) and to allow the quench water to be easily and cleanly drained through your garden hose. 

Question: How does the Biochar Fire Pit reduce smoke?

Answer: The unique design of the Biochar Fire Pit develops a  vortex that sucks smoke back into the fire causing it to be reburned resulting in a much cleaner burning fire.

Biochar Storage - Application

Question: What time of the year should I make biochar?

Answer: You can make biochar any time of the year. Just check with your local authorities to make sure backyard fire pits are allowed and avoid making biochar when the fire danger is high.

Question: How long can I store biochar after I make it?

Answer: Biochar out of the kiln is not biologically active and assuming it doesn't catch on fire will stick around for more than 1000 years so you can store it as long as you want. Inoculated biochar also does not have a shelf life so it can be stored also as long as you want.

Question: Where can I store biochar before I add it to my garden?

Answer: Store in an area that does not have the risk of introducing contaminants (E.g. motor oil, plastic, chemicals, etc.) You could simply pile biochar in your garden but if strong winds are a possibility it may be required to cover up your biochar.

Charging Biochar With Nutrients (Inoculating)

Question: Should I charge my biochar with nutrients right away or wait to charge it in the spring before planting?

Answer: If you compost I would add biochar directly to your compost as you make it as long as you are not making so much compost that the biochar exceeds 50% of the volume of your compost pile. After a month in your compost the biochar will have been inoculated with nutrients and microbes giving the biochar (and your garden) a head start for your next growing season. You can add the biochar compost mixture to your garden as you fill up your compost bin. Note that for the long term benefits of biochar (and some of the short term benefits) inoculating your biochar is not necessary.

Question: What can I use to inoculate my biochar?

Answer: Composting with about 50% by volume in your compost for a month is an excellent way to inoculate your biochar. This adds nutrients and microbes to the biochar over time and is a free source of nutrients. Other sources of nutrients and microbes include manure, worm castings, worm/compost tea, mushroom soil. Really any source of nutrients and biological activity will help biocharge your garden.

Question: Will the biochar freezing kill off beneficial microbes?

Answer: The microbes in soil that are adapted to freezing and thawing cycles and survive freezing so most likely if you do have inoculated biochar that freezes those well adapted microbes will be just fine - or the populations that survive will be well adapted to your climate. The microbial activity will slow down and the inoculation process will be slower the colder it is. The heat generated in a compost pile will keep the temperature up and therefore microbial activity up which will speed biochar inoculation if you are inoculating your biochar in a compost pile.

Question: Do I have to inoculate my biochar?

Answer: No. Direct mixing without inoculation can also have benefits for your garden right out of the gate. One example of direct mixing without charging with good results was in raised beds in Allan's (a co-owner of Pi Fabricators) greenhouse. The raised beds dried out too fast but had plenty of nutrients since the watering system supplied nutrients regularly. The first year with uncharged biochar the bed with biochar had healthier tomato plants than the bed without biochar. 

  • If nutrient scarcity is your soil's main problem (e.g. nitrogen) you will be much better off the first growing season inoculating your biochar. 

Question: Will biochar that has not been inoculated sponge up, and lock away nutrients and microbes lowering my garden's growth.

Answer: It is possible that if nutrients are  the main thing that is holding your plants back that biochar (that has not been inoculated) could sponge up some of those nutrients in the first year and that could hurt growth. Our personal experience has been that we don’t see negative effects of biochar the first year if it is not inoculated, but you will miss out on what could be a big growth improvement offered by inoculated biochar that first year if you do not inoculate.  

  • Regardless of whether or not your biochar is inoculated after several years your soil will inoculate your biochar and all the benefits of biochar will benefit your garden for generations.

Question: Can I use my own urine to charge biochar with nutrients?

Answer: Yes urine would definitely work to charge biochar and is a free source of nutrients. The only possible problem that could be a concern are PFAS. As of my writing this in 2024 there does not seem to be a solid understanding of PFAS or safe thresholds but pretty much everyone has been exposed to some level of PFAS and according to the CDC “Some PFAS leave the body slowly over time, mostly through urine.”

Environmental Aspects of Biochar

Question: Besides sequestering carbon, can biochar help solve the climate crisis in any other ways?

Answer: Yes, biochar can help in other ways. It can reduce harmful greenhouse gasses being released from the soil like nitrous oxide and methane. These gasses trap heat even more effectively than carbon dioxide. This makes biochar an even more powerful tool in the fight against climate change.

Question: How does biochar reduce fertilizer runoff that pollutes rivers? 

Answer: Nutrients stick to biochar so they stay in your soil rather than being flushed into water tables or streams. This prevents the fertilizer you add to your garden from contributing to this kind of pollution. The added benefit for you is that the fertilizer you paid for stays in your soil to be used by your plants so you won’t need to buy as much fertilizer.

Question: How long will biochar last?

Answer: About ¾ of Biochar made from wood at the temperatures produced in a biochar firepit will last for more than 1000 years. About ¼ will last less than 100 years.

Question: How can we know biochar will last so long?

Answer: Because biochar was made by people in the amazon basin thousands of years ago and it is still around today. There are also natural sources of biochar produced by forest and brushland fires that can be dated to older than 1000 years.