I finally got the process right for making the biochar in a barrel with the woodshavings. This is the second barrel's worth of char. It basically takes 8-10 hours to get over 90% of the wood to char. There is still some wood shavings in tact even after that long, but too much longer and too much of the char starts to turn into ash I think. But I think there is not too much uncharred wood to use as an amendment, especially since it is so fine and has so much surface area that it will probably break down quickly. We will give the citrus a good dose of nitrogen anyway.