About

In the Lehmann Lab, we work on soil biogeochemistry, nutrient and carbon cycling in managed and natural ecosystems. Our investigations span a broad range of ecosystems and include nano-scale observations of soil micro-aggregates and pyrogenic carbon particles to the global carbon cycle. Much of our work focuses on improving our basic understanding of forms and dynamics of organic matter in soil and how we can use that knowledge for sustainable soil management. Biochar research includes basic insights into its behavior in soil, effects on plant growth, microbial composition and dynamics, as well as life-cycle assessment of greenhouse gas emissions or water quality and economics. We run a test kiln in the Cornell Pyrolysis program, conducting research on many aspects of pyrolysis systems from bioenergy to new biomaterials, agronomy and soil science, environmental remediation, economics and social sciences.

Research topics

• Ecology
• Environmental science
• Biology
• Computer Science
• Chemistry
• Soil science
• Economics
• Environmental resource management
• Natural resource economics
• Engineering
• Organic chemistry
• Political Science
• Sociology
• Social Science
• Environmental chemistry
• Botany
• Waste management
• Pharmacology
• Environmental planning
• Public relations
• Agronomy
• Geography
• Chemical engineering
• Business

Selected publications

• Du sollst Dir kein Bildnis machen

  Georg Olms Verlag eBooks · 2026-01-01

  book-chapter1st authorCorresponding
  PublisherDOI

• The impact of enhanced rock weathering on soil organic carbon

  2026-03-14

  articleOpen accessSenior author

  Terrestrial enhanced rock weathering (ERW) is a geoengineering technique that amends soils with crushed magnesium (Mg) and calcium (Ca) rich silicate rock to accelerate carbon dioxide removal (CDR) with the production of dissolved and solid carbonates. Although ERW is projected to store large amounts of inorganic carbon, up to 2 Pg carbon (C) per year (Beerling et al., 2020), significant uncertainty surrounds ERW research, with a critical question remaining as to how ERW affects soil organic carbon (SOC), the largest terrestrial C reservoir with 1550 Pg C globally. While increases to SOC after crushed rock additions could increase the carbon removal capacity of ERW, reductions in SOC could negate its benefits. Field-scale ERW studies examining SOC dynamics, remain few. Sokol et al. (2023), found that ERW can destabilize organic carbon, making a seemingly stable pool vulnerable to decomposition. Conversely, Xu et al. (2024) reported SOC increases four to eight times higher than soil inorganic carbon (SIC) growth in oxisols after CaSiO₃ amendments. These studies highlight that the effect of ERW on SOC is influenced by soil properties. I will address this gap in knowledge by gaining a comprehensive understanding of ERW’s impact on SIC and SOC pools across ten agriculturally relevant soils in the US with unique soil properties that have been previously taken from all major US ecosystems and climate zones (Davenport, 2024). My study involves a one year incubation assessment that leverages exploration of outcomes across a broad soil gradient under a controlled environment. My findings will elucidate what conditions (i.e., soil properties, climate) will lead to the greatest mitigation impact for targeting ERW deployments.

  PublisherDOI

• The roles of litter quality and microbial processing in shaping leachate chemodiversity during early decomposition

  SSRN Electronic Journal · 2026-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Deep mutual learning: incentives and trust through collaborative integration of artificial intelligence into sustainability science

  RSC Sustainability · 2025-01-01

  articleOpen access1st authorCorresponding

  Sustainability science increasingly requires computationally intensive predictive and decision-making tasks across varied temporal and spatial scales.

  PublisherOA PDFDOI

• An organic matter database (OMD): consolidating global residue data from agriculture, fisheries, forestry and related industries

  Earth system science data · 2025-02-03 · 26 citations

  articleOpen access

  Abstract. Agricultural, fishery, forestry and agro-processing activities produce large quantities of residues, by-products and waste materials every year. Inappropriate disposal and inefficient use of these resources contribute to greenhouse gas emissions and non-point pollution, placing significant environmental and economic burdens on society. Since many nations do not keep statistics on these materials, it has not been possible to accurately quantify the amounts produced, their competing uses and the quantities potentially available for recycling at a local level. Therefore, the objectives of the present work were to provide (1) definitions, typologies and methods to aid consistent classification, estimation and reporting of the various residues and by-products, (2) a global organic matter database (OMD) of residues and by-products from agriculture, fisheries, forestry and related industries and (3) regional and global estimates of residues and by-products potentially available for use in a circular bio-economy. To the best of our knowledge, the OMD is the first of its kind to consolidate quantities and nutrient concentrations of residues and by-products globally from agriculture, fisheries, forestry and related industries (available at https://doi.org/10.5281/zenodo.10450921; Sileshi et al., 2024). The OMD will be updated continuously as new production data are published in FAOSTAT and country-specific conversion coefficients become available. This information is expected to contribute to evidence-based policies and actions in support of sustainable utilization and the transition towards a circular economy. The database could be used for a variety of purposes, including estimation of residue availability for soil amendment, livestock feed, bioenergy and other industrial applications as well as assessment of the environmental impacts of residue management practices such as soil application and burning. The estimates in the OMD are only available at the national level. Due to the lack of a uniform methodology, conversion coefficients and data on competing uses across countries, it was difficult to accurately estimate the quantities of all agricultural, fishery and forestry residues and by-products. Therefore, we strongly recommend investment in the inventory of agricultural, fishery and forestry residues as well as by-products and wastes at the national and sub-national levels for use in a circular bio-economy.

  PublisherOA PDFDOI

• Biochar shifts balance between hydrophilic and lipophilic molecules in root exudates

  Bioresource Technology · 2025-03-20 · 2 citations

  articleSenior authorCorresponding
  PublisherDOI

• Solid phase molecular diversity enhances soil organic matter persistence

  Research Square · 2025-11-27 · 1 citations

  preprintOpen access
  PublisherOA PDFDOI

• Spatial fibroblast niches define Crohn’s fistulae

  Nature · 2025-11-12 · 6 citations

  articleOpen access

  Abstract Crohn’s disease often presents with fistulae, abnormal tunnels that connect the intestine to the skin or other organs. Despite their profound effect on morbidity, the molecular basis of fistula formation remains unclear, largely owing to the challenge of capturing intact fistula tracts and their inherent heterogeneity 1–3 . Here we construct a subcellular-resolution spatial atlas of 68 intestinal fistulae spanning diverse anatomical locations. We describe fistula-associated epithelial, immune and stromal cell states, revealing abnormal zonation of growth factors and morphogens linked to establishment of tunnelling anatomy. We identify fistula-associated stromal (FAS) fibroblasts, which are assembled in concentric layers: a proliferative, lumen-adjacent zone beneath neutrophil and macrophage-rich granulation tissue, an active lesion core of FAS cells and a quiescent, pro-fibrotic outer zone. We examine the architecture of the extracellular matrix in the fistula tract and demonstrate that FAS populations associate with distinct collagen structures, exhibiting properties ranging from proliferation, migration and extracellular matrix remodelling to dense collagen deposition and fibrosis. We define niches supporting epithelialization of fistula tunnels and a FAS-like population that is detected at the base of ulcers in non-penetrating Crohn’s disease. Our study demonstrates that common molecular pathways and cellular niches underpin fistulae across intestinal locations, revealing the cellular protagonists of fistula establishment and persistence. This resource will inform the development of model systems and interventions to mitigate aberrant fibroblast activity while preserving their regenerative properties in Crohn’s disease.

  PublisherDOI

• Functional molecular diversity of dissolved organic matter explained by predicted genome size of soil microbial communities

  Soil Biology and Biochemistry · 2025-07-29 · 11 citations

  articleSenior authorCorresponding
  PublisherDOI

• Can batch lab-scale studies of slow pyrolysis describe biochar yields and properties upon upscaling to a continuous auger kiln?

  Journal of Cleaner Production · 2025-02-25 · 17 citations

  article
  PublisherDOI

Recent grants

• Biogeochemical Cycling of Organic Carbon in Soil Ecosystems as Affected by Black Carbon (REVISED)

  NSF · $794k · 2004–2008

• Dissertation Research: Mechanisms of soil organic carbon interactions with black carbon

  NSF · $20k · 2014–2017

• Acquisition of a hydropyrolysis unit for pre-treatment of soils for isotopic analysis and black carbon quantification

  NSF · $86k · 2011–2017

• BREAD: Biochar Inoculants for Enabling Smallholder Agriculture

  NSF · $2.7M · 2010–2018

• Nano-scale biogeochemistry of organic carbon across a long-term mineralogical gradient

  NSF · $299k · 2008–2012

Frequent coauthors

• Annette Dathe

  639 shared

• Michaeline Albright

  Los Alamos National Laboratory

  637 shared

• Rachelle LaCroix

  Cornell University

  637 shared

• John Dunbar

  637 shared

• Marie Kroeger

  Los Alamos National Laboratory

  637 shared

• Akio Enders

  Cornell University

  94 shared

• Rattan Lal

  89 shared

• James E. Amonette

  88 shared

Labs

• Lehmann LabPI

Education

• Ph.D., Soil Science

  University of California, Berkeley

  1993

• M.S., Soil Science

  University of California, Berkeley

  1989

• B.S., Soil Science

  University of California, Davis

  1986