Several years ago, I read an article in one of those science magazines about an expedition into the Amazon jungle that had come upon what the archaeologists named “Colombian Black Earth.” It seems that they noticed that some farmers in the area they were studying had soil that was inexplicably productive. The archeologists noted that the soil was very black and unlike the native soil. They also discovered that it was filled with pottery shards. They asked the local farmers about the soil and were told that it was very ancient, that the ancient people put it there. Intrigued they took samples and discovered that the pottery shards were very old—in some cases several thousands of years. They concluded that the black earth had been deposited there in the pottery deliberately but they couldn’t figure out what was in the soil that gave it its rich black appearance or made it so productive.
Studies since have determined that the rich, dark earth is a form of charcoal. Studies have been on going to determine how it was made and what benefits it has. And, of course, there is now a thriving industry trying to make what came to be called bio char and sell it---yes, to you! For your very own garden.
Research has determined that true Columbia black earth is a mixture of bone, manure and charcoal. The charcoal is believed to be the essential ingredient and it is 70 times more concentrated in the black earth than in the poor native soils around it and was made in an oxygen free or oxygen poor environment at very high temperatures. While a number of producers are now selling “agricultural charcoal”, the jury is still out on how to actually make the desired material. But for the most part, bio char seems to have some really interesting properties that could be beneficial in a number of ways. Among the interesting benefits of bio char is that it seems to regulate water flow. In clays, it makes the soil more porous and encourages drainage. But in sands, it makes the soil hold more water. It appears to raise the pH of highly acidic soils and depending on the material that was used to make it, it can provide phosphorous, zinc and other essential nutrients. The key here is that what nutrients and properties bio char provides seems to depend entirely on what organic material was burned to make it. Bamboo for example gives a different set of properties than oak. Bio char is also creating a lot of excitement in the climate change community as a potentially valuable carbon sink to reduce greenhouse gases.
So far, there has been one serious potential negative side effect of agricultural bio char: In a recent study done in Europe, thale cress and lettuce plants grown in soils treated with bio char grew at a rate 100% faster than without the bio char. But at the same time, the plants were found to be far more susceptible to plant diseases and pests than the non-bio char crops.
Scientists don’t seem to have the answer yet. (Why do we keep hearing that?)
Studies since have determined that the rich, dark earth is a form of charcoal. Studies have been on going to determine how it was made and what benefits it has. And, of course, there is now a thriving industry trying to make what came to be called bio char and sell it---yes, to you! For your very own garden.
Research has determined that true Columbia black earth is a mixture of bone, manure and charcoal. The charcoal is believed to be the essential ingredient and it is 70 times more concentrated in the black earth than in the poor native soils around it and was made in an oxygen free or oxygen poor environment at very high temperatures. While a number of producers are now selling “agricultural charcoal”, the jury is still out on how to actually make the desired material. But for the most part, bio char seems to have some really interesting properties that could be beneficial in a number of ways. Among the interesting benefits of bio char is that it seems to regulate water flow. In clays, it makes the soil more porous and encourages drainage. But in sands, it makes the soil hold more water. It appears to raise the pH of highly acidic soils and depending on the material that was used to make it, it can provide phosphorous, zinc and other essential nutrients. The key here is that what nutrients and properties bio char provides seems to depend entirely on what organic material was burned to make it. Bamboo for example gives a different set of properties than oak. Bio char is also creating a lot of excitement in the climate change community as a potentially valuable carbon sink to reduce greenhouse gases.
So far, there has been one serious potential negative side effect of agricultural bio char: In a recent study done in Europe, thale cress and lettuce plants grown in soils treated with bio char grew at a rate 100% faster than without the bio char. But at the same time, the plants were found to be far more susceptible to plant diseases and pests than the non-bio char crops.
Scientists don’t seem to have the answer yet. (Why do we keep hearing that?)