POTENTIAL FOR PYROLYSIS CHAR TO AFFECT SOIL MOISTURE AND NUTRIENT STATUS OF A LOAMY SAND SOIL
J.W. Gaskin, Adam Speir, L.M. Morris, Lee Ogden, Keith Harris, D. Lee, and K.C Das, Proceedings of the 2007 Georgia Water Resources Conference, held March 27–29, 2007, at the University of Georgiai.

Abstract.

Pyrolysis of biomass for hydrogen fuel and bio-oil produces a char byproduct. There is evidence that land application of char may increase soil water holding capacity and the ability of the soil to retain nu-trients. Increases in these soil characteristics could be beneficial to plant growth as well as improving water quality. Chars produced under different conditions and from different feedstocks have different characteristics. Of the common feedstocks tested, peanut hull char con-tained higher nutrients and had a higher cation ex-change capacity than pine chip, pine bark, or hardwood chip chars. Preliminary moisture release curve data from a Tifton loamy sand indicated moisture holding capacity may be increased at very high rates of char addition. Soil moisture was periodically measured dur-ing the growing season in a field study of microplots amended with peanut hull and pine chip pellet char. Although the average soil water content of the plots amended at 22 Mg ha-1 was higher than the control, dif-ferences in volumetric water content were only signifi-cant on one date.

Standard Test Method for Chemical Analysis of Wood Charcoal ASTM D1762-84

Attached is the ASTM D1762-84. This test method covers the determination of moisture, volatile matter, and ash in charcoal made from wood. The test method is applicable to lumps and briquets and is designed for the evaluation of charcoal quality. The test method employs apparatus that is found in most laboratories and is adapted to routine analyses of a large number of samples.

Dear friends: terra preta is fascinating in part because it involves so many disciplines. My viewpoint is that of a fuel scientist/chemical engineer.

My laboratory produces well-characterized charcoals for a wide variety of research endeavors, including carbon fuel cell studies, metallurgical charcoal applications, activated carbon production, and terra preta research (with my colleagues Dr. Goro Uehara, Dr. Jonathan Deenik, and Tai McClellan in the University of Hawaii’s College of Tropical Agriculture and Human Resources). With this message I wish to call your attention to the elementary properties of charcoal that I think about when I am producing a charcoal for one of our research endeavors.

Both the feedstock and the process (i.e. pyrolysis) conditions influence the properties of the charcoal product. For example, oak wood has little ash; consequently its charcoal also has little ash. On the other hand, rice hulls have much ash (nearly pure silica), and so does its charcoal.