Biochar is a partially burned organic matter that can be used as a soil amendment. Its use was identified in the Amazon jungles where the terra preta (black earth) was first identified in areas where humans had incorporated the charcoal and improved plant growth was noted. There is a growing industry world-wide to take organic matter and create biochar because of potential environmental benefits, such as reduced greenhouse gas emissions, improved soil fertility, reduced leaching of nutrients and chemicals from plant root zones, and water retention. Biochar could potentially last for hundreds of years once incorporated in the soil. There have been many claims for biochar, but so far there is not a lot of scientific basis for these claims. One of the results recently has been the standardization and testing methods for biochar, so the material can be better characterized and studies can be standardized. The guidelines can be found at this link: http://www.biochar-international.org/sites/default/files/Guidelines_for_Biochar_That_Is_Used_in_Soil_Final.pdf
Biochar has been most notable in soils that are of poor quality which are characteristic of highly leached soils found in the Amazon. The question is can biochar perform in the relatively young soils of California where irrigation and nutrients are better controlled. We are doing a quick and dirty little trial on avocado and citrus to evaluate plant performance in rocky soils, calcareous soils and with trees that are doing “poorly”. If we see some indication that there is something working, we will expand the study with more rigor and more situations.
Photo of Terra Preta from Cornell University's College of Agriculture and Life Sciences
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