Fire creates pyrogenic organic matter that accumulates in soil and is transported to streams, lakes and oceans. It is increasingly recognized that global soils contain a large amount of pyrogenic carbon that not only play an important role in the global carbon cycles but also change the biogeochemistry of soils in many different ways. In particular, pyrogenic carbon changes the cycles of biological carbon cycles, on the long term typically decreasing the mineralization of non-pyrogenic carbon, also referred to as ‘negative priming’. But pyrogenic organic matter also contains nitrogen, phosphorus and sulfur, and affects microbial community composition and ecology. Our research focused on the fundamental properties of pyrogenic carbon in soil, its mineralization and movement by leaching and erosion, its change through oxidation, its resultant effects on nutrient retention and on the cycles of other organic matter in soil.

 

Recent insights include:

Nitrogen plays an important role in pyrogenic organic matter formation and affects the persistence of pyrogenic organic carbon.

Adsorption is the most important process decreasing the mineralization of native organic carbon, causing negative priming.

Pyrogenic carbon is not more erodable than non-pyrogenic carbon.

Featured recent publication: Torres-Rojas D, Hestrin R, Solomon D, Gillespie AW, Dynes JJ, Regier TZ and Lehmann J 2020 Nitrogen speciation and transformations in fire-derived organic matter. Geochimica et Cosmochimica Acta 276, 179-185.

 

In the next few years, we will mainly focus on the following questions:

How much pyrogenic carbon is mineralized in situ from soil in comparison to its movement into the aquatic ecosystems and its long-term sequestration in oceans?