Black Carbon from Rice Residues as Soil Amendment and for Carbon Sequestration
Stephan M. Haefele 1, J.K. Ladha 1, and Yothin Konboon 2.
(1) International Rice Research Institute, Los Banos, 4031 Laguna, Philippines, (2) Ubon Rice Research Centeri, Ubon Ratchathani, Thailand
18th World Congress of Soil Science, July 9-15, 2006 - Philadelphia, Pennsylvania, USA

On highly weathered soils in tropical and subtropical climates, maintenance of soil organic matter is essential to sustain system productivity and avoid rapid soil degradation. But climatic conditions as well as soil characteristics favor the rapid decomposition of organic matter. However, several recent studies indicated that black carbon, the product of incomplete combustion of organic material, could combine characteristics highly beneficial for soil nutrient dynamics with high stability against chemical and microbial breakdown. Lasting soil amelioration by incorporation of black carbon from wooden plants was proposed based on the beneficial evidence from “Terra Preta” soils in Western Amazonia. Theoretically, charred crop residues in rice-based systems could serve the same purpose but this hypothesis has never been tested. Within this context, our objectives were to 1) assess possible options for the use of charred rice residues, to 2) test the effect of charred rice residues on important soil fertility parameters and rice growth, and 3) to evaluate the effect and stability of charred rice residues in a variety of rice growing environments.