Annals of Environmental Science


Annals of Environmental Science
Volume 3, December 2009, Pages 217-225, ISSN 1939-2621

Biomass Derived, Carbon Sequestering, Designed Fertilizers

Kimberly A. Magrini-Bair, Stefan Czernik, Heidi M. Pilath, Robert J. Evans, Pin Ching Maness and Joel Leventhal, National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401, USA

Received August 24, 2009; in final form December 04, 2009; accepted December 11, 2009.

This work explores the hypothesis that functionalized biomass-derived chars (charcoal) can act as fertilizer-delivering, carbon-sequestering soil amendments. A naturally occurring precedent for this approach is based on recent results that clearly link increased soil productivity with charcoal-like Terra Preta deposits, which are characterized by enhanced microbial and fungal activity and are found in both temperate and tropical climates. In this work, peanut shell pellets were pyrolyzed under mild conditions (400oC). The resulting char retained nitrogen from the feedstock's high protein content. This char also provided the baseline material for further nutrient addition by reaction of pyrolysis oil with urea to add more bioavailable nitrogen. Replicated plant growth tests with corn conducted in a controlled greenhouse environment showed that these biomass-derived chars, as produced (raw) and chemically reacted (functionalized) with urea and pyrolysis oil, enhanced above and below ground plant growth similar to the periodic addition of an aqueous NPK fertilizer to the potting soil used for all experiments. We also found that char (raw and functionalized) addition to soil significantly enhanced root growth and that char could support the growth and subsequent release of nitrogen-fixing bacteria (Azotobacter vinelandii) into soils. These promising results provide the basis to design renewable time-release fertilizers for promoting above and below ground plant growth that also sequester carbon in the soil. Sustainable benefits of using these materials as targeted agricultural fertilizers include producing fertilizers from renewable biomass, eliminating conventional fertilizer nitrate runoff into watersheds (a severe and growing water quality problem), increasing soil organic matter accumulation from enhanced root growth, and sequestering carbon in soils.

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