This biochar research is interesting.
Soil scientist Jeff Novak at the ARS Coastal Plains Soil, Water and Plant Research Center in Florence, S.C. is the lead researcher to evaluate the effects of biochar on soil moisture and fertility. There are multiple locations across the US involved in this.
Several different kinds of organic matter – ranging from switchgrass, hardwood, poultry manure were used to produce 9 different “kinds” of biochar (and here you thought it was just “one” product. 🙂
The difference were in the temperature differences the material was burned to produce the char.
And the biochar was tested on sandy soil and two kinds of silt loam soils at 20 tons per acre. (approximately 2/3 pound per square foot.
After 4 months, the soil was retested and the results showed biochar made from switchgrass and hardwoods increased the soil moisture storage in all three soils. The switchgrass biochar produced with the highest temperature gave a 3-6 percent increase over the others (it was the best) and increased the soil moisture holding ability of the soil by 3.6 days for soybeans (other crops were not reported – but all have different moisture needs so there’s a variation here)
Having said that, the higher temperature biochars increased soil pH. And poultry litter biochar increased the availability of phosphorus and sodium.
The researchers clearly pointed out that one size does not fit all when it comes to biochar (naturally, there’s not going to be a silver bullet here.) :–
And that we may be able to custom design and deliver benefits to individual crops in the future based on soil deficiencies.
For now – it probably isn’t going to hurt to mess about with this in your own garden (other than the rise in pH which troubles me a bit).
But all the bumpf on the Net about using biochar is likely hype or wishful thinking at this point.
Results from this study were published in Annals of Environmental Science and in the Journal of Environmental Quality.