Caroline Masiello with Rice University and her team of researchers has recently published a paper that studies the effect of the temperature used to create the biochar on field capacity and hydrophobicity.

In the study, they made biochar out of tree leaves, corn stalks and found that wood chips, and found that it was the pyrolisis temperature that had the biggest impact on field capacity and hydrophobicity. Their study recommends a pyrolisis temperature of 400 °C–600 °C.

This is a quick summary of the work:
http://phys.org/news/2012-03-cooking-biochar-recipe-soil-additive.html

The journal article is here:
http://www.sciencedirect.com/science/article/pii/S0961953412000438
(support your local college and/or technical library, or contact the authors for a copy of the article).
latest Nike Sneakers | adidas NMD Human Race