The database contains 4 tables described below: articles, data, metadata, and validation.

articles

The table `articles` contains an inventory of scientific articles reporting biochar incubation experiments.

name longName type description
ID_art Identifier of the article integer The unique identifier (integer) given to an article containing biochar incubation observations. The identifer is also used in the tables data & metadata.
AuthorDate First author and publication year string A short text identifier of the article with last name of first author and publication year.
FullCitation Full citation of the article string The full citation of the article, in text format.
DOI Digital Object Identifier url The DOI of the article, for easy online access.
ContactAuthor Contact author email address email Email address of the contact author of the manuscript, as available in published article, or as in mail correspondance with author.
RawData_status Status of the raw data boolean Describes whether the raw data (incubation data & meta data) are available in the database. Values can be: yes, no.
RawData_remark Remark on the status of the raw data string How was the data collected (from author, digitized, supporting information, from other person than authors) or why it was not possible to collect the data (author contacted but no reply received).
RawData_copyright Copyright regarding the raw data boolean Describes to what extent the data can be shared in a public database. By default, the value is `NotPublic`. It can be labelled `Public` if the data was obtained from authors with their approval for sharing, if it was digitized manually, or if the article was published open-source. TO_DO: discuss that.
NbObs Number of observations int The number of observations reported in this article (replicates of a given experimental setup count as a single observation).
Spokas2010 Article included in Spokas 2010 boolean Whether the article was included in the earlier biochar stability estimates by Spokas (2010).
Singh2012 Article included in Sing 2012 boolean Whether the article was included in the earlier biochar stability estimates by Singh (2012).
Budai2013 Article included in Budai 2013 boolean Whether the article was included in the earlier biochar stability estimates by Budai (2013), non-peer reviewed work performed for the International Biochar Institute.
Wang2016 Article included in Wang 2016 boolean Whether the article was included in the earlier biochar stability estimates by Wang (2016).
Lehmann2019 Article included in Lehmann 2019 boolean Whether the article was included in the earlier biochar stability estimates by Lehmann (2019), referring to the appendix of the 2019 revision of the IPCC greenhouse gas inventory guidelines.
Woolf2021 Article included in Woolf 2021 boolean Whether the article was included in the earlier biochar stability estimates by Woolf (2021).

name	longName	type	description
ID_art	Identifier of the article	integer	The unique identifier (integer) given to an article containing biochar incubation observations. The identifer is also used in the tables data & metadata.
AuthorDate	First author and publication year	string	A short text identifier of the article with last name of first author and publication year.
FullCitation	Full citation of the article	string	The full citation of the article, in text format.
DOI	Digital Object Identifier	url	The DOI of the article, for easy online access.
ContactAuthor	Contact author email address	email	Email address of the contact author of the manuscript, as available in published article, or as in mail correspondance with author.
RawData_status	Status of the raw data	boolean	Describes whether the raw data (incubation data & meta data) are available in the database. Values can be: yes, no.
RawData_remark	Remark on the status of the raw data	string	How was the data collected (from author, digitized, supporting information, from other person than authors) or why it was not possible to collect the data (author contacted but no reply received).
RawData_copyright	Copyright regarding the raw data	boolean	Describes to what extent the data can be shared in a public database. By default, the value is `NotPublic`. It can be labelled `Public` if the data was obtained from authors with their approval for sharing, if it was digitized manually, or if the article was published open-source. TO_DO: discuss that.
NbObs	Number of observations	int	The number of observations reported in this article (replicates of a given experimental setup count as a single observation).
Spokas2010	Article included in Spokas 2010	boolean	Whether the article was included in the earlier biochar stability estimates by Spokas (2010).
Singh2012	Article included in Sing 2012	boolean	Whether the article was included in the earlier biochar stability estimates by Singh (2012).
Budai2013	Article included in Budai 2013	boolean	Whether the article was included in the earlier biochar stability estimates by Budai (2013), non-peer reviewed work performed for the International Biochar Institute.
Wang2016	Article included in Wang 2016	boolean	Whether the article was included in the earlier biochar stability estimates by Wang (2016).
Lehmann2019	Article included in Lehmann 2019	boolean	Whether the article was included in the earlier biochar stability estimates by Lehmann (2019), referring to the appendix of the 2019 revision of the IPCC greenhouse gas inventory guidelines.
Woolf2021	Article included in Woolf 2021	boolean	Whether the article was included in the earlier biochar stability estimates by Woolf (2021).

data

The table `data` contains the decomposition time series for each individual observation (statistical average of the replicates). Depending on how the incubation data is reported, the 3 variables (biochar remaining, biochar decomposed, biochar decay rate) can be re-calculated knowing at least one of them.

name longName type unit description
ID_obs Identifier of the observation integer none The unique identifier (integer) given to a biochar incubation observation, i.e. any single experiment leading to a decay curve for a given biochar in a given environment, including replicates. Same field as in the tables article & metadata.
ID_art Identifier of the article integer none The unique identifier (integer) given to a peer-reviewed article reporting biochar incubation data. Same field as in the tables article & metadata.
time Time, in days, relative float days Time of incubation starting at t=0 when incubation starts. Usually, at t=0, the biochar decomposed is equal to 0 and the amount remaining is equal to 100. Time values, in days, can be of type float (decimals) when data were retrieved by digitizing figures.
date Time, in days, relative float days Time of incubation starting at t=0 when incubation starts. Usually, at t=0, the biochar decomposed is equal to 0 and the amount remaining is equal to 100. Time values, in days, can be of type float (decimals) when data were retrieved by digitizing figures.
biochar remaining Date, in YYYY-MM-DD, absolute float YYYY-MM-DD Real date at which incubation took place.
F_tot_abs gC tot / kg soil Total flux of carbon dioxide (expressed in C) mineralised between two measuring times, in absolute terms.
d_bc % Share of biochar carbon in the mineralised flux of carbon, determined by isotopic technique
d_soc % Share of soil organic carbon in the mineralised flux of carbon, determined by isotopic technique
F_bc_abs gC bc / kg soil Flux of biochar carbon (expressed in C) mineralised between two measuring times, in absolute terms.
F_soc_abs gC soc / kg soil Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in absolute terms.
F_bc_rel gC bc/ gC bc ini Flux of biochar carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of biochar carbon).
F_soc_rel gC soc/ gC soc ini Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of soil organic carbon).
Fn_soc_abs gC soc / kg soil Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in absolute terms, in the control experiment.
Fn_soc_rel gC soc / gC soc ini Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of soil organic carbon), in the control experiment
k_tot_abs gC tot / kg soil / day Decay rate of total soil carbon (biochar and soil), average between two measuring times, in absolute terms.
k_bc_abs gC bc / kg soil / day Decay rate of biochar carbon, average between two measuring times, in absolute terms.
k_soc_abs gC soc / kg soil / day Decay rate of soil organic carbon, average between two measuring times, in absolute terms.
k_bc_rel0 gC bc / gC bc ini / day Decay rate of biochar carbon, average between two measuring times, in relative terms (divided by initial amount of biochar carbon).
k_bc_reld gC bc / gC bc t-1 / day Decay rate of biochar carbon, average between two measuring times, in relative terms, dynamic (divided by biochar carbon remaining at the previous time step).
C_bc_loss_abs gC bc / kg soil Cumulative biochar carbon loss since start of incubation, absolute
C_bc_loss_rel gC bc / gC bc ini Cumulative biochar carbon loss since start of incubation, relative to initial amount of biochar carbon
C_bc_rem_abs gC bc / kg soil Cumulative biochar carbon remaining since start of incubation, absolute
C_bc_rem_rel gC bc / gC bc ini Cumulative biochar carbon remaining since start of incubation, relative to initial amount of biochar carbon
C_tot_loss_abs gC tot/ kg soil Cumulative carbon loss since start of incubation, absolute
C_tot_loss_rel gC tot / gC ini Cumulative carbon loss since start of incubation, relative to initial amount of biochar and soil organic carbon
P_soc_abs gC soc - gC n soc Priming flux of soil organic carbon, absolute (flux of SOC in biochar incubation minus flux of SOC in control incubation)
P_soc_rel gC soc / gC soc ini Priming flux of soil organic carbon, relative (flux of SOC in biochar incubation minus flux of SOC in control incubation, divided by initial amount of SOC)

name	longName	type	unit	description
ID_obs	Identifier of the observation	integer	none	The unique identifier (integer) given to a biochar incubation observation, i.e. any single experiment leading to a decay curve for a given biochar in a given environment, including replicates. Same field as in the tables article & metadata.
ID_art	Identifier of the article	integer	none	The unique identifier (integer) given to a peer-reviewed article reporting biochar incubation data. Same field as in the tables article & metadata.
time	Time, in days, relative	float	days	Time of incubation starting at t=0 when incubation starts. Usually, at t=0, the biochar decomposed is equal to 0 and the amount remaining is equal to 100. Time values, in days, can be of type float (decimals) when data were retrieved by digitizing figures.
date	Time, in days, relative	float	days	Time of incubation starting at t=0 when incubation starts. Usually, at t=0, the biochar decomposed is equal to 0 and the amount remaining is equal to 100. Time values, in days, can be of type float (decimals) when data were retrieved by digitizing figures.
biochar remaining	Date, in YYYY-MM-DD, absolute	float	YYYY-MM-DD	Real date at which incubation took place.
F_tot_abs			gC tot / kg soil	Total flux of carbon dioxide (expressed in C) mineralised between two measuring times, in absolute terms.
d_bc			%	Share of biochar carbon in the mineralised flux of carbon, determined by isotopic technique
d_soc			%	Share of soil organic carbon in the mineralised flux of carbon, determined by isotopic technique
F_bc_abs			gC bc / kg soil	Flux of biochar carbon (expressed in C) mineralised between two measuring times, in absolute terms.
F_soc_abs			gC soc / kg soil	Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in absolute terms.
F_bc_rel			gC bc/ gC bc ini	Flux of biochar carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of biochar carbon).
F_soc_rel			gC soc/ gC soc ini	Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of soil organic carbon).
Fn_soc_abs			gC soc / kg soil	Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in absolute terms, in the control experiment.
Fn_soc_rel			gC soc / gC soc ini	Flux of soil organic carbon (expressed in C) mineralised between two measuring times, in relative unit (divided by initial amount of soil organic carbon), in the control experiment
k_tot_abs			gC tot / kg soil / day	Decay rate of total soil carbon (biochar and soil), average between two measuring times, in absolute terms.
k_bc_abs			gC bc / kg soil / day	Decay rate of biochar carbon, average between two measuring times, in absolute terms.
k_soc_abs			gC soc / kg soil / day	Decay rate of soil organic carbon, average between two measuring times, in absolute terms.
k_bc_rel0			gC bc / gC bc ini / day	Decay rate of biochar carbon, average between two measuring times, in relative terms (divided by initial amount of biochar carbon).
k_bc_reld			gC bc / gC bc t-1 / day	Decay rate of biochar carbon, average between two measuring times, in relative terms, dynamic (divided by biochar carbon remaining at the previous time step).
C_bc_loss_abs			gC bc / kg soil	Cumulative biochar carbon loss since start of incubation, absolute
C_bc_loss_rel			gC bc / gC bc ini	Cumulative biochar carbon loss since start of incubation, relative to initial amount of biochar carbon
C_bc_rem_abs			gC bc / kg soil	Cumulative biochar carbon remaining since start of incubation, absolute
C_bc_rem_rel			gC bc / gC bc ini	Cumulative biochar carbon remaining since start of incubation, relative to initial amount of biochar carbon
C_tot_loss_abs			gC tot/ kg soil	Cumulative carbon loss since start of incubation, absolute
C_tot_loss_rel			gC tot / gC ini	Cumulative carbon loss since start of incubation, relative to initial amount of biochar and soil organic carbon
P_soc_abs			gC soc - gC n soc	Priming flux of soil organic carbon, absolute (flux of SOC in biochar incubation minus flux of SOC in control incubation)
P_soc_rel			gC soc / gC soc ini	Priming flux of soil organic carbon, relative (flux of SOC in biochar incubation minus flux of SOC in control incubation, divided by initial amount of SOC)

metadata

The table `metadata` contains a set of metadata describing the experimental conditions of each biochar incubation. The fields in this table relate to the type of biomass, the pyrolysis conditions, the biochar properties, and the incubation conditions.

name longName type unit group method description
ID_obs Identifier of the observation integer none identification na The unique identifier (integer) given to a biochar incubation observation, i.e. any single experiment leading to a decay curve for a given biochar in a given environment, including replicates. Same field as in the tables article & metadata.
ID_art Identifier of the article integer none identification na The unique identifier (integer) given to a peer-reviewed article reporting biochar incubation data. Same field as in the tables article & data.
AuthorDate First author and publication year string none identification na A short text identifier of the article with last name of first author and publication year.
NameObs Name or identifier of the observation in the original research article string none identification na The name or identifier of the observation as in the original article from which it is taken. This field allows to easily cross-check the information collected from the original article.
Replicates Number of replicates integer none identification na The number of replicates performed for this specific observation.
Biomass Name of the biomass string none biomass na The name the biomass used to produce biochar. Text can be as detailed as necessary (e.g. type, species, cultivation details).
BiomassClass Name of the biomass class string none biomass na Classification of the biomass feedstocks in a few number of categories: wood, grass, crop-residue, manure, biosolids. TO_DO: agree on a list of classes.
BiomassLignin Lignin content of the biomass float % biomass na The average lignin content of the biomass feedstock, either reported from the authors or taken from database on biomass properties.
Pyrolysis Pyrolysis process description string none pyrolysis na Brief description of the pyrolysis process (e.g. reactor type, brand, scale, process conditions).
PyrolysisClass Name of the pyrolysis class string none pyrolysis na Classification of the pyrolysis processes into a few number of categories: pyro-slow, gas, htc, pyr-flash, no-treat, torr. Note: no-treat can be used to describe raw biomass incubation.
HHT Pyrolysis Highest Treatment Temperature float °C pyrolysis na The Highest Treatment Temperature reached during the pyrolysis, as reported in the article. Note: there is an uncertainty related to determination of pyrolysis temperature.
RT Pyrolysis Residence time at the Highest Treatment Temperature float min pyrolysis na The residence time at the Highest Treatment Temperature during the pyrolysis. Note: often difficult to distinguish the total residence time in the reactor from the residence time at the highest treatment temperature, in the information available in articles.
HR Pyrolysis Heating Rate float °C per min pyrolysis na The pyrolysis heating rate, i.e. the average speed at which the biomass feedstock is heated during the pyrolysis, until it reaches the highest treatment temperature, as reported in the article.
Soil type Soil type string none incubation na Brief description of the soil type used for the incubation, e.g. using soil classification standards.
Soil clay content Clay content of the soil float % incubation na Clay content of the soil, as reported by authors.
Soil sand content Sand content of the soil float % incubation na Sand content of the soil, as reported by authors.
Soil silt content Silt content of the soil float % incubation na Silt content of the soil, as reported by authors.
Soil organic matter content Organic matter content of the soil float % incubation na Organic matter content of the soil, as reported by authors (neglecting inorganic carbon content). TO_DO: decide if total carbon content rather than organic matter content is preferable?.
SoilMoisture_Absolute Absolute moisture content of the soil float % incubation na Absolute moisture content of the soil, as reported by authors. It can be maintained constant in laboratory incubations, while it may vary with climate in field experiments. In that case, a climatic average can be reported.
SoilMoisture_WHC Moisture content of the soil relative to WHC float % WHC incubation na Moisture content of the soil relative to the soil's water holding capacity, as reported by authors. It can be maintained constant in laboratory incubations, while it may vary with climate in field experiments. In that case, a climatic average can be reported.
pH_soil Soil pH float none incubation na pH of the soil before mixing addition of biochar
pH_bc-soil Soil-biochar blend pH float none incubation na pH of the soil after addition of biochar
SoilOrigin Geographic origin of the soil sample string none incubation na Geographic origin of the soil sample used for incubation, reported as a text value.
SoilGeolocation Geographical coordinates of the soil sample tuple none incubation na Geographical coordinates of the site of extraction of the soil sample, given as a tuple (latitude, longitude) in decimal format. If only a region is given, the approximative center of the region is used.
LabField Lab or field experiment boolean none incubation na Whether the incubation is carried out in a lab environment (`lab`) or in the field (`field`).
Cultivated Lab or field experiment boolean none incubation na Whether the plants are cultivated in the incubation experiment, `yes` or `no`.
IncubationTemperature Temperature of the incubation float °C incubation na For lab experiments, average incubation temperature as reported by authors. For field experiments, climatic average temperature at the field where the experiment is located.
IncubationDuration Duration of the incubation float days incubation na During of the incubation experiment, expressed in days.
ApplicationRate Biochar application rate to the soil float %, dry weight / dry weight incubation na Biochar application rate to the soil.
TotalFluxMeasurement Total Flux Measurement method string none incubation na How the total flux of decomposed carbon dioxide was measured in the incubation. This field can be e.g. titration
BiocharFluxDetermination Biochar Flux Determination method string none incubation na How the fraction of the total flux of decomposed carbon dioxide attributed to biochar was determined. This field can take one of the following values: `13C natural abundance`, `13C depleted`, `14C labeled`, `13C labeled`, `13C isotopic signature`, `Headspace CO2, coulometer, no other source of C in soil`. TO_DO: some namings may be equivalent, to check.
OtherIncubationDescription Other Incubation Description string none incubation na Other information on the incubation experimental setup not covered in other fields. In particular: aged biochar process if any; microbial activity measures or community stucture.
AssociatedControl AssociatedControl boolean none incubation na Whether the biochar incubation was performed alongside a control incubation without biochar: `yes`, `no`
Ash550 Biochar ash content at 550°C float %, dry weight / dry weight biochar na Biochar ash content at 550°C as determined in lab analysis. TO_DO: add references to appropriate laboratory methods (DIN, ASTM).
Ash700 Biochar ash content at 700°C float %, dry weight / dry weight biochar na Biochar ash content at 700°C as determined in lab analysis. TO_DO: add references to appropriate laboratory methods (DIN, ASTM).
Carbon Biochar carbon content float %, dry weight / dry weight biochar na Biochar (total) carbon content, as determined in lab analysis.
Carbon, organic Biochar organic carbon content float %, dry weight / dry weight biochar na Biochar organic carbon content, as determined in lab analysis.
Hydrogen Biochar hydrogen content float %, dry weight / dry weight biochar na Biochar hydrogen content, as determined in lab analysis.
Nitrogen Biochar nitrogen content float %, dry weight / dry weight biochar na Biochar nitrogen content, as determined in lab analysis.
Sulphur Biochar sulphur content float %, dry weight / dry weight biochar na Biochar sulphur content, as determined in lab analysis.
Oxygen Biochar oxygen content float %, dry weight / dry weight biochar na Biochar oxygen content, as determined in lab analysis or more commonly calculated as 100-C-H-N-S.
Magnesium Biochar magnesium content float %, dry weight / dry weight biochar na Biochar magnesium content, as determined in lab analysis.
Potassium Biochar potassium content float %, dry weight / dry weight biochar na Biochar potassium content, as determined in lab analysis.
H/C_org Hydrogen to organic carbon molar ratio float %, dry weight / dry weight biochar na Hydrogen to organic carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition. TO_DO: discuss what to do if C_org or H is not reported; if we know about ash composition or not, re-estimate C_org or H from the rest?
H/C_tot Hydrogen to carbon molar ratio float %, dry weight / dry weight biochar na Hydrogen to total carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition.
O/C_org Oxygen to organic carbon molar ratio float %, dry weight / dry weight biochar na Oxygen to organic carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition. TO_DO: discuss whether to include it at all, whether it should be O/C or O_org/C_org or O/C_org, knowing O_org is never/impractical to measure. Argument to include O/C: reproduce earlier Spokas 2010 results.
C/N Carbon to nitrogen molar ratio float %, dry weight / dry weight biochar na Carbon to nitrogen molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition.
pH_H2O Biochar pH in H2O float none biochar na pH of the biochar sample in water, at 1:5 ratio.
pH_CaCl2 Biochar pH in CaCl2 float none biochar na pH of the biochar sample in calcium chloride, at 1:5 ratio.
CEC Cation Exchange Capacity float cmol / kg biochar na Cation Exchange Capacity of biochar sample
SA_N2 Surface area with N2 float m2 / g biochar na Surface area of biochar sample measured with dinitrogen gas.
SA_CO2 Surface area with CO2 float m2 / g biochar na Surface area of biochar sample measured with carbon dioxide gas.
FixedCarbon Fixed carbon float %, dry weight / dry weight biochar na Fixed carbon of biochar sample as determined in proximate analysis.
VolatileMatter Volatile Matter float %, dry weight / dry weight biochar na Volatile matter of biochar sample as determined in proximate analysis.
ParticleSize Particle Size string ? biochar na Average biochar particle size at the time of incubation.
BulkDensity Bulk density float kg / m3, dry weight biochar na Bulk density of incubated biochar, measured at its particle size (not grinded), untapped. TO_DO: discuss whether needed (rarely available)
TrueDensity Bulk density float g / cm3, dry weight biochar na True density of incubated biochar, as measured in laboratory analysis (finely grinded).
OxidationH2O2 Chemical oxidation with H2O2 float g / cm3, dry weight biochar Cross, A.; Sohi, S.P. A method for screening the relative long-term stability of biochar. GCB Bioenergy 2013, 5, 215-220 Chemical oxidation with hydrogen peroxide, according to Edinburgh stability test.
BiocharYield Yield from biomass to biochar float %, dry weight / dry weight biochar na The pyrolysis yield as biochar dry mass over biomass dry mass
δ ¹³C biochar Biochar isotopic signature biochar na Ratio of isotopes 13C / 12C in the biochar studied, before incubation
δ ¹³C soil Soil isotopic signature biochar na Ratio of isotopes 13C / 12C in the soil studied, before incubation
ID_Lehmann2019 Identifier of this observation in Lehmann 2019 str na identification na Identifier of this observation in Lehmann 2019 (see Excel files in folder former-assessments)
ID_Woolf2021 Identifier of this observation in Woolf 2021 str na identification na Identifier of this observation in Woolf 2021 (see Excel files in folder former-assessments)
ID_Lehmann2021 Identifier of this observation in Lehmann 2021 str na identification na Identifier of this observation in Lehmann 2021 (see Excel files in folder former-assessments)

name	longName	type	unit	group	method	description
ID_obs	Identifier of the observation	integer	none	identification	na	The unique identifier (integer) given to a biochar incubation observation, i.e. any single experiment leading to a decay curve for a given biochar in a given environment, including replicates. Same field as in the tables article & metadata.
ID_art	Identifier of the article	integer	none	identification	na	The unique identifier (integer) given to a peer-reviewed article reporting biochar incubation data. Same field as in the tables article & data.
AuthorDate	First author and publication year	string	none	identification	na	A short text identifier of the article with last name of first author and publication year.
NameObs	Name or identifier of the observation in the original research article	string	none	identification	na	The name or identifier of the observation as in the original article from which it is taken. This field allows to easily cross-check the information collected from the original article.
Replicates	Number of replicates	integer	none	identification	na	The number of replicates performed for this specific observation.
Biomass	Name of the biomass	string	none	biomass	na	The name the biomass used to produce biochar. Text can be as detailed as necessary (e.g. type, species, cultivation details).
BiomassClass	Name of the biomass class	string	none	biomass	na	Classification of the biomass feedstocks in a few number of categories: wood, grass, crop-residue, manure, biosolids. TO_DO: agree on a list of classes.
BiomassLignin	Lignin content of the biomass	float	%	biomass	na	The average lignin content of the biomass feedstock, either reported from the authors or taken from database on biomass properties.
Pyrolysis	Pyrolysis process description	string	none	pyrolysis	na	Brief description of the pyrolysis process (e.g. reactor type, brand, scale, process conditions).
PyrolysisClass	Name of the pyrolysis class	string	none	pyrolysis	na	Classification of the pyrolysis processes into a few number of categories: pyro-slow, gas, htc, pyr-flash, no-treat, torr. Note: no-treat can be used to describe raw biomass incubation.
HHT	Pyrolysis Highest Treatment Temperature	float	°C	pyrolysis	na	The Highest Treatment Temperature reached during the pyrolysis, as reported in the article. Note: there is an uncertainty related to determination of pyrolysis temperature.
RT	Pyrolysis Residence time at the Highest Treatment Temperature	float	min	pyrolysis	na	The residence time at the Highest Treatment Temperature during the pyrolysis. Note: often difficult to distinguish the total residence time in the reactor from the residence time at the highest treatment temperature, in the information available in articles.
HR	Pyrolysis Heating Rate	float	°C per min	pyrolysis	na	The pyrolysis heating rate, i.e. the average speed at which the biomass feedstock is heated during the pyrolysis, until it reaches the highest treatment temperature, as reported in the article.
Soil type	Soil type	string	none	incubation	na	Brief description of the soil type used for the incubation, e.g. using soil classification standards.
Soil clay content	Clay content of the soil	float	%	incubation	na	Clay content of the soil, as reported by authors.
Soil sand content	Sand content of the soil	float	%	incubation	na	Sand content of the soil, as reported by authors.
Soil silt content	Silt content of the soil	float	%	incubation	na	Silt content of the soil, as reported by authors.
Soil organic matter content	Organic matter content of the soil	float	%	incubation	na	Organic matter content of the soil, as reported by authors (neglecting inorganic carbon content). TO_DO: decide if total carbon content rather than organic matter content is preferable?.
SoilMoisture_Absolute	Absolute moisture content of the soil	float	%	incubation	na	Absolute moisture content of the soil, as reported by authors. It can be maintained constant in laboratory incubations, while it may vary with climate in field experiments. In that case, a climatic average can be reported.
SoilMoisture_WHC	Moisture content of the soil relative to WHC	float	% WHC	incubation	na	Moisture content of the soil relative to the soil's water holding capacity, as reported by authors. It can be maintained constant in laboratory incubations, while it may vary with climate in field experiments. In that case, a climatic average can be reported.
pH_soil	Soil pH	float	none	incubation	na	pH of the soil before mixing addition of biochar
pH_bc-soil	Soil-biochar blend pH	float	none	incubation	na	pH of the soil after addition of biochar
SoilOrigin	Geographic origin of the soil sample	string	none	incubation	na	Geographic origin of the soil sample used for incubation, reported as a text value.
SoilGeolocation	Geographical coordinates of the soil sample	tuple	none	incubation	na	Geographical coordinates of the site of extraction of the soil sample, given as a tuple (latitude, longitude) in decimal format. If only a region is given, the approximative center of the region is used.
LabField	Lab or field experiment	boolean	none	incubation	na	Whether the incubation is carried out in a lab environment (`lab`) or in the field (`field`).
Cultivated	Lab or field experiment	boolean	none	incubation	na	Whether the plants are cultivated in the incubation experiment, `yes` or `no`.
IncubationTemperature	Temperature of the incubation	float	°C	incubation	na	For lab experiments, average incubation temperature as reported by authors. For field experiments, climatic average temperature at the field where the experiment is located.
IncubationDuration	Duration of the incubation	float	days	incubation	na	During of the incubation experiment, expressed in days.
ApplicationRate	Biochar application rate to the soil	float	%, dry weight / dry weight	incubation	na	Biochar application rate to the soil.
TotalFluxMeasurement	Total Flux Measurement method	string	none	incubation	na	How the total flux of decomposed carbon dioxide was measured in the incubation. This field can be e.g. titration
BiocharFluxDetermination	Biochar Flux Determination method	string	none	incubation	na	How the fraction of the total flux of decomposed carbon dioxide attributed to biochar was determined. This field can take one of the following values: `13C natural abundance`, `13C depleted`, `14C labeled`, `13C labeled`, `13C isotopic signature`, `Headspace CO2, coulometer, no other source of C in soil`. TO_DO: some namings may be equivalent, to check.
OtherIncubationDescription	Other Incubation Description	string	none	incubation	na	Other information on the incubation experimental setup not covered in other fields. In particular: aged biochar process if any; microbial activity measures or community stucture.
AssociatedControl	AssociatedControl	boolean	none	incubation	na	Whether the biochar incubation was performed alongside a control incubation without biochar: `yes`, `no`
Ash550	Biochar ash content at 550°C	float	%, dry weight / dry weight	biochar	na	Biochar ash content at 550°C as determined in lab analysis. TO_DO: add references to appropriate laboratory methods (DIN, ASTM).
Ash700	Biochar ash content at 700°C	float	%, dry weight / dry weight	biochar	na	Biochar ash content at 700°C as determined in lab analysis. TO_DO: add references to appropriate laboratory methods (DIN, ASTM).
Carbon	Biochar carbon content	float	%, dry weight / dry weight	biochar	na	Biochar (total) carbon content, as determined in lab analysis.
Carbon, organic	Biochar organic carbon content	float	%, dry weight / dry weight	biochar	na	Biochar organic carbon content, as determined in lab analysis.
Hydrogen	Biochar hydrogen content	float	%, dry weight / dry weight	biochar	na	Biochar hydrogen content, as determined in lab analysis.
Nitrogen	Biochar nitrogen content	float	%, dry weight / dry weight	biochar	na	Biochar nitrogen content, as determined in lab analysis.
Sulphur	Biochar sulphur content	float	%, dry weight / dry weight	biochar	na	Biochar sulphur content, as determined in lab analysis.
Oxygen	Biochar oxygen content	float	%, dry weight / dry weight	biochar	na	Biochar oxygen content, as determined in lab analysis or more commonly calculated as 100-C-H-N-S.
Magnesium	Biochar magnesium content	float	%, dry weight / dry weight	biochar	na	Biochar magnesium content, as determined in lab analysis.
Potassium	Biochar potassium content	float	%, dry weight / dry weight	biochar	na	Biochar potassium content, as determined in lab analysis.
H/C_org	Hydrogen to organic carbon molar ratio	float	%, dry weight / dry weight	biochar	na	Hydrogen to organic carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition. TO_DO: discuss what to do if C_org or H is not reported; if we know about ash composition or not, re-estimate C_org or H from the rest?
H/C_tot	Hydrogen to carbon molar ratio	float	%, dry weight / dry weight	biochar	na	Hydrogen to total carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition.
O/C_org	Oxygen to organic carbon molar ratio	float	%, dry weight / dry weight	biochar	na	Oxygen to organic carbon molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition. TO_DO: discuss whether to include it at all, whether it should be O/C or O_org/C_org or O/C_org, knowing O_org is never/impractical to measure. Argument to include O/C: reproduce earlier Spokas 2010 results.
C/N	Carbon to nitrogen molar ratio	float	%, dry weight / dry weight	biochar	na	Carbon to nitrogen molar ratio of the biochar sample, either as reported by authors or recaculated from elemental composition.
pH_H2O	Biochar pH in H2O	float	none	biochar	na	pH of the biochar sample in water, at 1:5 ratio.
pH_CaCl2	Biochar pH in CaCl2	float	none	biochar	na	pH of the biochar sample in calcium chloride, at 1:5 ratio.
CEC	Cation Exchange Capacity	float	cmol / kg	biochar	na	Cation Exchange Capacity of biochar sample
SA_N2	Surface area with N2	float	m2 / g	biochar	na	Surface area of biochar sample measured with dinitrogen gas.
SA_CO2	Surface area with CO2	float	m2 / g	biochar	na	Surface area of biochar sample measured with carbon dioxide gas.
FixedCarbon	Fixed carbon	float	%, dry weight / dry weight	biochar	na	Fixed carbon of biochar sample as determined in proximate analysis.
VolatileMatter	Volatile Matter	float	%, dry weight / dry weight	biochar	na	Volatile matter of biochar sample as determined in proximate analysis.
ParticleSize	Particle Size	string	?	biochar	na	Average biochar particle size at the time of incubation.
BulkDensity	Bulk density	float	kg / m3, dry weight	biochar	na	Bulk density of incubated biochar, measured at its particle size (not grinded), untapped. TO_DO: discuss whether needed (rarely available)
TrueDensity	Bulk density	float	g / cm3, dry weight	biochar	na	True density of incubated biochar, as measured in laboratory analysis (finely grinded).
OxidationH2O2	Chemical oxidation with H2O2	float	g / cm3, dry weight	biochar	Cross, A.; Sohi, S.P. A method for screening the relative long-term stability of biochar. GCB Bioenergy 2013, 5, 215-220	Chemical oxidation with hydrogen peroxide, according to Edinburgh stability test.
BiocharYield	Yield from biomass to biochar	float	%, dry weight / dry weight	biochar	na	The pyrolysis yield as biochar dry mass over biomass dry mass
δ ¹³C biochar	Biochar isotopic signature			biochar	na	Ratio of isotopes 13C / 12C in the biochar studied, before incubation
δ ¹³C soil	Soil isotopic signature			biochar	na	Ratio of isotopes 13C / 12C in the soil studied, before incubation
ID_Lehmann2019	Identifier of this observation in Lehmann 2019	str	na	identification	na	Identifier of this observation in Lehmann 2019 (see Excel files in folder former-assessments)
ID_Woolf2021	Identifier of this observation in Woolf 2021	str	na	identification	na	Identifier of this observation in Woolf 2021 (see Excel files in folder former-assessments)
ID_Lehmann2021	Identifier of this observation in Lehmann 2021	str	na	identification	na	Identifier of this observation in Lehmann 2021 (see Excel files in folder former-assessments)

metadata_validation

The table `metadata_validation` contains two additional fields for each field in the `metadata` tables. The table `metadata_validation` is used for data validation, tracability and transparency. The two fields are `fieldName_comment` and `fieldName_loci`. The field `fieldName_comment` describes how the metadata was retrieved and if any assumptions/calculations were made by the person compiling the data. The field `fieldName_loci` explains where the metadata was found, e.g. Article, Table 3; Article, Section 2.3, p230; SupportingMaterial, Table S3; SupportingMaterial, Excel; DocumentFromAuthors; ReferenceInArticle, Table 2. If needed.

name type
Biomass_comment string
Biomass_loci string
BiomassClass_comment string
BiomassClass_loci string
BiomassLignin_comment string
BiomassLignin_loci string
Pyrolysis_comment string
Pyrolysis_loci string
PyrolysisClass_comment string
PyrolysisClass_loci string
HHT_comment string
HHT_loci string
RT_comment string
RT_loci string
HR_comment string
HR_loci string
Soil type_comment string
Soil type_loci string
Soil clay content_comment string
Soil clay content_loci string
Soil sand content_comment string
Soil sand content_loci string
Soil silt content_comment string
Soil silt content_loci string
Soil organic matter content_comment string
Soil organic matter content_loci string
SoilMoisture_Absolute_comment string
SoilMoisture_Absolute_loci string
SoilMoisture_WHC_comment string
SoilMoisture_WHC_loci string
pH_soil_comment string
pH_soil_loci string
pH_bc-soil_comment string
pH_bc-soil_loci string
SoilOrigin_comment string
SoilOrigin_loci string
SoilGeolocation_comment string
SoilGeolocation_loci string
LabField_comment string
LabField_loci string
Cultivated_comment string
Cultivated_loci string
IncubationTemperature_comment string
IncubationTemperature_loci string
IncubationDuration_comment string
IncubationDuration_loci string
ApplicationRate_comment string
ApplicationRate_loci string
TotalFluxMeasurement_comment string
TotalFluxMeasurement_loci string
BiocharFluxDetermination_comment string
BiocharFluxDetermination_loci string
OtherIncubationDescription_comment string
OtherIncubationDescription_loci string
AssociatedControl_comment string
AssociatedControl_loci string
Ash550_comment string
Ash550_loci string
Ash700_comment string
Ash700_loci string
Carbon_comment string
Carbon_loci string
Carbon, organic_comment string
Carbon, organic_loci string
Hydrogen_comment string
Hydrogen_loci string
Nitrogen_comment string
Nitrogen_loci string
Sulphur_comment string
Sulphur_loci string
Oxygen_comment string
Oxygen_loci string
Magnesium_comment string
Magnesium_loci string
Potassium_comment string
Potassium_loci string
H/C_org_comment string
H/C_org_loci string
H/C_tot_comment string
H/C_tot_loci string
O/C_org_comment string
O/C_org_loci string
C/N_comment string
C/N_loci string
pH_H2O_comment string
pH_H2O_loci string
pH_CaCl2_comment string
pH_CaCl2_loci string
CEC_comment string
CEC_loci string
SA_N2_comment string
SA_N2_loci string
SA_CO2_comment string
SA_CO2_loci string
FixedCarbon_comment string
FixedCarbon_loci string
VolatileMatter_comment string
VolatileMatter_loci string
ParticleSize_comment string
ParticleSize_loci string
BulkDensity_comment string
BulkDensity_loci string
TrueDensity_comment string
TrueDensity_loci string
OxidationH2O2_comment string
OxidationH2O2_loci string
BiocharYield_comment string
BiocharYield_loci string
δ ¹³C biochar_comment string
δ ¹³C biochar_loci string
δ ¹³C soil_comment string
δ ¹³C soil_loci string

name	type
Biomass_comment	string
Biomass_loci	string
BiomassClass_comment	string
BiomassClass_loci	string
BiomassLignin_comment	string
BiomassLignin_loci	string
Pyrolysis_comment	string
Pyrolysis_loci	string
PyrolysisClass_comment	string
PyrolysisClass_loci	string
HHT_comment	string
HHT_loci	string
RT_comment	string
RT_loci	string
HR_comment	string
HR_loci	string
Soil type_comment	string
Soil type_loci	string
Soil clay content_comment	string
Soil clay content_loci	string
Soil sand content_comment	string
Soil sand content_loci	string
Soil silt content_comment	string
Soil silt content_loci	string
Soil organic matter content_comment	string
Soil organic matter content_loci	string
SoilMoisture_Absolute_comment	string
SoilMoisture_Absolute_loci	string
SoilMoisture_WHC_comment	string
SoilMoisture_WHC_loci	string
pH_soil_comment	string
pH_soil_loci	string
pH_bc-soil_comment	string
pH_bc-soil_loci	string
SoilOrigin_comment	string
SoilOrigin_loci	string
SoilGeolocation_comment	string
SoilGeolocation_loci	string
LabField_comment	string
LabField_loci	string
Cultivated_comment	string
Cultivated_loci	string
IncubationTemperature_comment	string
IncubationTemperature_loci	string
IncubationDuration_comment	string
IncubationDuration_loci	string
ApplicationRate_comment	string
ApplicationRate_loci	string
TotalFluxMeasurement_comment	string
TotalFluxMeasurement_loci	string
BiocharFluxDetermination_comment	string
BiocharFluxDetermination_loci	string
OtherIncubationDescription_comment	string
OtherIncubationDescription_loci	string
AssociatedControl_comment	string
AssociatedControl_loci	string
Ash550_comment	string
Ash550_loci	string
Ash700_comment	string
Ash700_loci	string
Carbon_comment	string
Carbon_loci	string
Carbon, organic_comment	string
Carbon, organic_loci	string
Hydrogen_comment	string
Hydrogen_loci	string
Nitrogen_comment	string
Nitrogen_loci	string
Sulphur_comment	string
Sulphur_loci	string
Oxygen_comment	string
Oxygen_loci	string
Magnesium_comment	string
Magnesium_loci	string
Potassium_comment	string
Potassium_loci	string
H/C_org_comment	string
H/C_org_loci	string
H/C_tot_comment	string
H/C_tot_loci	string
O/C_org_comment	string
O/C_org_loci	string
C/N_comment	string
C/N_loci	string
pH_H2O_comment	string
pH_H2O_loci	string
pH_CaCl2_comment	string
pH_CaCl2_loci	string
CEC_comment	string
CEC_loci	string
SA_N2_comment	string
SA_N2_loci	string
SA_CO2_comment	string
SA_CO2_loci	string
FixedCarbon_comment	string
FixedCarbon_loci	string
VolatileMatter_comment	string
VolatileMatter_loci	string
ParticleSize_comment	string
ParticleSize_loci	string
BulkDensity_comment	string
BulkDensity_loci	string
TrueDensity_comment	string
TrueDensity_loci	string
OxidationH2O2_comment	string
OxidationH2O2_loci	string
BiocharYield_comment	string
BiocharYield_loci	string
δ ¹³C biochar_comment	string
δ ¹³C biochar_loci	string
δ ¹³C soil_comment	string
δ ¹³C soil_loci	string

Biochar Stability Database Schema

articles

data

metadata

metadata_validation