Charcoal Carbon in U.S. Agricultural Soils

来自 EBSCO

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作者：

JO Skjemstad，DC Reicosky，AR Wilts，JA Mcgowan

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摘要：

High levels of charcoal carbon resulting from repeated historical burning of grasslands, open woodlands and agricultural crop residues have been reported in soils from Australia and Germany. In this study, five U.S. soils were selected from long-term research plots in widely different agricultural areas. The charcoal carbon content was estimated on each soil using a combination of physical separation, high-energy photo-oxidation an solid-state **13C nuclear magnetic resonance spectroscopy. These analyses showed that all five soils contained measurable amounts of charcoal carbon, <53 um in size and ranging from 1.8 to 13.6 g C kg**-1 soil and constituted up to 35% of the soil total organic carbon. Scanning electron microscopy showed that the charcoal material had a plant-like morphology but was blocky and had fractured edges. These particles were similar in morphology to those separated from Australian and German soils. The implications of this charcoal material, which must be highly resistant to microbiological decomposition, to the soil carbon cycle and issues such as greenhouse gas emissions from soil are discussed. The processes of charcoal formation, its biological, physical and chemical properties and distribution in many soils are largely unknown and require further study. Understanding the role of charcoal in nutrient cycling and C sequestration is vital for understanding the role and minimizing the impact of agriculture on climate change.

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关键词：

agricultural soils Alfisols carbon carbon cycle charcoal chemical composition clay loam soils clay soils Mollisols organic carbon