Biochar & Soil Texture


As I may have mentioned, biochar’s impact will vary depending on many factors, one of which is soil texture. There are other reasons to use biochar apart from improving soil texture, such as the need for more soil organic material (SOM) and improving microbial activity, but soil texture is pretty darn important in the grand scheme of the world underneath your feet. Soil texture is determined by the amount of sand, silt in clay in a given soil profile. Think of sand as the big boy of the bunch and clay as the tiniest with silt holding down the middle range for particle size.

The soil texture triangle is a great way to understand what kind of soil you’re dealing with. The center of the triangle is generally the sweet spot for most growing situations. When you get closer to the pointy parts of the soil texture triangle, the different soil separates each have different strengths and weaknesses when it comes to different soil properties or behaviors.

The table above (found in one my soils book so this was created by someone who knows a lot more than I ever will about soils!) ranks various soil properties for the three different soil particles. I’ve attempted to highlight, with my magic eHighlighter, where biochar can do the most good. Not surprisingly green is used for where it is likely to have the biggest impact and yellow is used where it will likely have some, but not as much impact.

So now that you understand all of this, you need to find out what kind of soils you have. Doing that just got a whole lot easier for the App-inclined. You can download SoilWeb to your cell phone and it will get your location and tell you what the general soil profile is for that location. Careful though, this is not always true to type. [In my little yard I have a pretty wide range of soil textures!] To find out everything you ever wanted to know and more about your soils, you can send off a soil sample to a lab which isn’t very expensive (e.g. $15 in my neck of the woods). Next you need to understand what the ideal soil texture is for whatever you are planting. Then if you need to change the soil properties, you can use this little chart to see if biochar will help your soils get to where they need to be!