Biochar: The Secret to Sustainable Soil Fertility
Why Biochar is Important for Soil Health and Fertility
The people of the Amazon rainforest created the Terra Preta soils, which were rich and fertile soils. This was counter to what we should expect of the tropical soils in the Amazon. Usually these soils are extremely weathered and lacking key nutrients because of the high heat and rainfall. The Terra Preta, which means Black Earth, was created from low-heat wood charcoal. The Amazon people would bury the charcoal along with pottery shards, animal feces, and other amendments to create a highly fertile soil to grow food-producing crops. The most amazing thing about the Terra Preta is the high carbon content. Average carbon content in the Terra Preta soils are 150 g C/kg. The surrounding soils that didn’t get amended average around 20-30 g C/kg. The extraordinary part is that these soils have been abandoned for hundreds if not thousands of years after the Europeans drove out the Amazonian people. The recalcitrant carbon stays put in the soil. Biochar also acts like a magnet for other nutrients, keeping them in the soil profile for plant use.
Biochar can be utilized to hold water, nutrients and to build soil carbon over time. When you use it in the garden, you want to make sure it is pre-charged. Raw biochar can rob the soil of nutrients as it starts pulling it into its matrix. You can pre-charge biochar by soaking it in urine, compost tea or by putting it into a compost pile. Alternatively, you can buy biochar that has already been charged.