3 minute read
Biology Boost: The Benefits of Biochar
BY SIMON HART
There is renewed interest in soil health these days as more gardeners aim for crop quality rather than achieving the highest yield possible. The term ‘super soil’ is thrown around a lot but can be quite misleading. All soil is valuable; we have even discovered ways to improve soilless mixes such as peat and coco-based products vastly! Most of the enhancements are built around biology, which can have a huge effect on both crop yield and, above all else, quality.
With the focus on biology, the soil isn’t just for growing roots anymore (hint: it never was). But how do we modify it to help biology thrive so we, and our gardens, can reap the benefits?
Organic matter is one of the most important things to consider when building soil quality. Carbon-based, it comes in many different forms, including biochar, which is still being studied extensively. Soil research in tropical rainforest regions has shown humans were modifying the soil thousands of years ago in a way that has had a lasting impact on soil health and quality. A fraction of this persistent soil carbon was charcoal-based, and we are now trying to find ways to replicate or at least take lessons from these anthropogenic soil profiles.
Biochar is engineered charcoal. It was not created through slash and burn agriculture, and to this day, is not something that can be reproduced in a backyard bonfire either. Charcoal is not at all the same, and biochar stands out for several reasons.
Biochar is created in a low oxygen environment without the use of a flame after ignition. The two methods primarily used to make it include pyrolysis or gasification. Both ways use the gases found within the wood (or other feedstock) to fuel the process that hardens the fiber into a persistent carbon known as graphite. By removing all the volatile compounds, a hard-walled sponge is produced. This material can last for hundreds of years in the soil and is incredibly beneficial. Not only does biochar amplify the earth and help your gardens grow, but it also sucks up and stores carbon, making it a valuable tool in the fight against climate change.
You can make biochar out of various materials including straw, hardwood, and even manure, but studies are still being done to determine which ones are better than the others. A finding that has remained consistent through all of the research efforts is that biochar provides a range of beneficial impacts on the soil it touches.
Biology likes interacting with biochar. Its infinite pores provide habitat and stimulate biology to communicate more effectively with surrounding soils and plant roots. The substance provides internal air porosity and water holding capacity, and can even mimic activated charcoal and remove heavy metals from the land, saving hungry roots from toxins.
Extra air and more available water can have a tremendous impact on biology working with your plants. Biochar can also have a mild liming effect on soils, which is especially helpful to combat the acidity in many peat-based potting soils. While higher pH is usually more beneficial to bacteria, fungi have a strange affinity for biochar due to its high carbon/nitrogen ratio.
Biochar is an excellent supplement in a compost pile at home or mixed with worm castings. It can also just be combined with soils, or even spread on the surface to leech into the ground over time. A favorite technique of mine is to brew an actively aerated compost tea, and then run the liquid through biochar before adding it to the soil. This gives a more uniform microbial count through the earth. It also helps retain more microorganisms closer to the soil surface, ensuring more root contact than if it continued into the subsoil or out the bottom drain holes of containers.
Like all things we are only just beginning to understand, biochar is not a panacea. There are questions about the ethical sourcing of feedstock material and whether some sources help at all. My personal experience with biochar both outdoors and indoors has shown that it can encourage plant growth in all the right ways. Gardeners of all kinds are now experimenting with biochar to not only achieve maximum yield but crops of superior quality as well.
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Simon Hart has been gardening for over 40 years, including work in the 1980s with nutrient film technique and tissue culture. As a garden experimenter, Simon has taken various skills over the years and applied them to his plants, focusing on observation and soil health both indoors and out. Practical hands-on experience has been combined with post-secondary science-based agricultural programs, and in addition to sharing his knowledge with Garden Culture Magazine, Simon continues to guest lecture at local universities and other establishments on a variety of garden topics.
Follow Simon @BentleyGrove
