Friday, March 21, 2014

Terra Preta - Links to More Info and Interesting Stuff

There is a bunch of information about Terra Preta online, but here's a short list of a few sites that I think summarize most of the information into an quick and easy to understand form.

You can find The Secret of Eldorado, which is the documentary that I originally watched that first got me interested in biochar and terra preta at:

There isn't much technical information about terra preta besides the fact that it is typically rich in biochar and pottery shards, and seems to be present in multiple areas of the Amazonian basin.  But, watching this documentary will give you enough of a background on the story to bore anyone that will listen with the relationship between conquistadors, charcoal, and that barrel you have been cutting and pounding on.

Living Web Farms has a bunch of different workshops on different subjects including a Biochar Workshop you can watch at:

There are a total of five different videos in the Biochar series, so you might want to watch all of them.  There is a lot of different information, such as a slightly more involved version of a backyard retort to make biochar, a larger commercial version of a retort, how biochar works, etc. 

There's a description of a SARE project dealing with some test plots and different TLUDs at:

One of the interesting details learned from these test plots is that applying as little as 500 lb. of  biochar per acre can start to give desirable results.

Besides all that, I've been applying about half of a wheel barrow full of biochar at a time to an area that's about 100 square feet (I believe that comes out to be about 5 tons/acre).   Over the last 8-10 years, I've covered the entire garden with bio char at a cumulative rate that's somewhere around 50-100 tons/acre. 

When I first started, I made sure to "charge" that biochar with manure, compost, or even fertilizer.    Now that my soil fertility has risen, I think I can get away with just applying the biochar to the garden (or I can start building another garden instead of applying more biochar where it really isn't needed anymore).  

I haven't done any side-by-side comparisons to verify the the biochar is actually doing everything that I'm claiming it does, but the last soil test I had done on the garden showed I had a pH level of just over 7, the nitrogen, phosphorus, and potassium levels were at relatively high levels, calcium levels were high, and the water infiltration rates seem to have gone way up since I started applying biochar.  I don't believe I would have those sort of soil test results from just applying manure, compost, or fertilizer.

Because of my experiences, I'm convinced that applying biochar works.


  1. It's great to hear your experiences. I didn't realize you had been at this for so long.

    I'm convinced the idea has a lot of merit, and since I've got plenty of woody debris that would just otherwise rot or feed a wildfire, I may as well try it. I also like the notion of applying fertilizer indirectly by pre-charging the mix... from what I understand of biochar, it should help a whole lot with leaching, which would help me a lot with figuring out when to apply.

    I had not seen all of those links, so I'll check them out when I get a chance.

    1. When I first started experimenting with biochar about ten years ago I was using some charcoal that was left over from some tornado cleanup on the farm where contractors came in, dug pits, and burned all the fallen trees. They fed those fires continuously for days with debris and when they were done, they buried whatever was left.

      There was one pit that only got covered about a foot or so for some reason and I happened to notice that there was a pile of charcoal just below the surface in one spot. So, I dug out a bunch of it with a shovel to use as biochar. I spread it in a small area of the garden, and when it didn't kill everything that I tried to grow there, I started adding more at a time over a larger area.

      Then, I started making biochar with open fires, trying to duplicate the way the tornado debris charcoal was created, and I started applying even more to the garden.

      Then a year or so ago, I made my first TLUD (thanks to a link on Ron's blog that led me to another link, etc.), and I found that I could make a higher volume of higher quality biochar a whole lot quicker than I had ever made it before.

      The biochar does something more than just help with leaching, in the last soil teat I did on the garden, I had Nitrogen levels of 150 lb./acre with a cation exchange ratio of 16. Typically, you can take your cation exchange ratio and multiply it by 10 to get an idea of how much Nitrogen your soil can hold without leaching, so my soil was holding all the nitrogen it could hold.

      But, I took those soil samples at the end of the summer when some of the nutrients should have been used by the garden crops. And, the only fertility I had added for the previous year was from cleaning out the chicken house (about 8 chickens), ashes from the fireplace, and cover crops. There is no way that I reached those levels of N, P, and K just from the manure from 8 chickens and some cover crops.

      It did take 8-10 years to reach those numbers, but if I had had a TLUD ten years ago, I bet I could have either improved it quicker or covered a larger area.

      If I was you, I would take your soil test, find out your cation exchange ratio, multiply that by ten to figure out how much N your soil can hold (you shouldn't have to worry about any leaching until you start to exceed that holding capacity), then apply something like 10-20-10 at a high enough rate to reach that amount of N per acre with your bio char (you probably can't apply too much) and whatever compost or manure you have. After you apply your fertilizer/bio char/compost mix, plant a grass cover crop so that it can use any excess fertility to grow more organic material which will eventually make your organic matter levels go up.