Database of Soil Organic Carbon (SOC) stock up to 20 cm depth: A collection of studies from Uruguay

This database comprises 667 soil organic carbon (SOC) stock measurements, collected from various studies conducted across Uruguay, with sampling depths extending up to 20 cm. The database aggregates data from 14 studies, including undergraduate and postgraduate theses and research projects, sampled between 2002 and 2024. It provides comprehensive details on the geographic location of sampling sites (latitude and longitude coordinates), the date of sample collection, the methodology employed for SOC determination, the technique used to estimate SOC stock values at the specified depths, and a description of land use at the moment of sampling.

This data collection is particularly relevant for evaluating SOC stocks modeling exercises, as it contributes to a more comprehensive understanding of carbon dynamics across various soil types, environmental conditions, land use, and land cover types. The database is available in shapefile format and is expected to serve as a valuable resource for researchers and professionals in the field.

Data Table Description

The associated data table from this database contains the following key variables:

ID: Unique identifier for each sampling point.

Latitude & Longitude: Geographic coordinates of the sampling site.

SOC Stock: Soil Organic Carbon (SOC) stock calculated at a fixed depth using the equation SOC stock (MgC/ha) = C × Bd × d, where C represents carbon concentration (%C), Bd is the bulk density of the soil (g/cm³), and d is the depth (cm).

Depth: Depth (cm) used for SOC stock calculation. Data were harmonized to a depth of 20 cm; however, lower values are reported for sites where the sampling scheme was conducted at depths less than 20 cm or where bedrock was encountered before reaching 20 cm.

Land Use: Simplified land use classification with “grassland”, “agriculture”, or “forest” categories

Land Use Extended: If available, the responsible party provides a more detailed explanation of land use.

Month & Year: Month and year of sample collection.

SOC Method: Methodology used for SOC determination, such as Walkley-Black or dry combustion.

Published: Indicates whether the data have been published, with a URL provided if available. If not published, the data are marked as unpublished.

SOC Calc: The approach used for calculating SOC stock at a fixed depth, detailed in two possible methods:

Real: For sampling schemes that include a segment ending at 20 cm depth, SOC stock was calculated directly up to 20 cm. This method was also applied when the maximum soil sampling depth was less than 20 cm.

Spline: When the sampling depth did not include 20 cm but extended beyond it, a spline interpolation was applied. This method employs all available cumulative values and their associated depths to estimate the SOC stock at 20 cm.

Additional Observations

For sites listed in rows 200-216, the GPS position represents the plot´s centroid, as no specific location was reported.

For sites listed in rows 344-633, sampling was conducted at 0-7.5 cm, 7.5-15 cm, and 15-30 cm depth. In sites where the total depth was 15 cm, bulk density was measured only in the first layer (0-7.5 cm), and this value was also applied to the 7.5-15 cm layer. In sites where the total depth was 20 cm, bulk density was measured in all layers and calculated for 20 cm as a weighted average.

For sites listed in rows 102-134, bulk density measurements were not taken directly. Instead, data were retrieved from the "SoilGrids" website (https://soilgrids.org/). Bulk density values for the 0-5 cm and 5-15 cm layers were downloaded, and a weighted average was calculated before determining the SOC stock.

Funding:

Funded were provided by ANII (FSDA_1_2018_1_154817, Procesos Inductivos para generación de buenas prácticas agropecuarias: Compilación y análisis de bases de datos a nivel predial; FSA_1_2022_1_175272, Evaluación multiescalar del desempeño ambiental de sistemas agropecuarios con diferente nivel de intensificación a partir de indicadores derivados de sensores remotos); INIA (FPTA-515, Indicadores de sostenibilidad ambiental para el sector agropecuario de Uruguay basados en información derivada de sensores remotos y modelos biofísicos); and IDB (URUGUAY/UR-T1277, Adopción de prácticas Agroecológicas y Huella de Carbono en la Agricultura Uruguaya).

本数据库包含667份土壤有机碳（Soil Organic Carbon, SOC）储量实测数据，采集自乌拉圭境内多项相关研究，采样深度最大可达20厘米。本数据库整合了14项研究的数据，涵盖2002年至2024年间采集的本科及研究生学位论文及科研项目的采样数据。该数据库提供了采样点的详尽地理信息（经纬度坐标）、样品采集日期、SOC测定方法、特定深度下SOC储量的估算技术，以及采样时的土地利用现状描述。

本数据集对评估SOC储量模拟研究具有重要意义，有助于更全面地理解不同土壤类型、环境条件、土地利用及土地覆被类型下的碳动态过程。该数据库以Shapefile格式提供，预计将成为该领域研究人员与专业人士的宝贵资源。

数据表格说明
本数据库配套的数据表格包含以下核心变量：
ID：每个采样点的唯一标识符。
纬度与经度：采样点的地理坐标。
SOC储量：在固定深度下通过公式SOC储量（MgC/ha）= C × Bd × d计算得到的土壤有机碳储量，其中C为碳浓度（%C），Bd为土壤容重（g/cm³），d为采样深度（cm）。
采样深度：用于计算SOC储量的深度（cm）。所有数据均统一至20 cm深度，但对于采样深度小于20 cm或在达到20 cm前已遇到基岩的采样点，将报告实际的较低深度值。
土地利用类型：简化的土地利用分类，包含“草地”“农用地”或“林地”三类。
扩展土地利用类型：若有相关信息，数据提供方将给出更详细的土地利用说明。
采集月份与年份：样品采集的月份与年份。
SOC测定方法：用于测定SOC的方法，例如沃克利-布莱克法或干式燃烧法。
是否已发表：标识数据是否已发表，若已发表则提供对应的URL；若未发表，则标记为“未发表”。
SOC储量计算方法：用于固定深度下SOC储量计算的方法，包含两种可选方式：
直接计算法：对于采样深度终点为20 cm的采样方案，直接计算至20 cm深度的SOC储量；当最大采样深度小于20 cm时，同样采用该方法。
样条插值法：当采样深度未覆盖20 cm但超过该深度时，采用样条插值法。该方法利用所有可获得的累积值及其对应深度，估算20 cm深度处的SOC储量。

补充说明
对于行号200-216对应的采样点，由于未报告具体位置，其GPS坐标为样地的中心点。
对于行号344-633对应的采样点，采样分别在0-7.5 cm、7.5-15 cm及15-30 cm深度进行。若总采样深度为15 cm，则仅在第一层（0-7.5 cm）测定土壤容重，并将该值同样应用于7.5-15 cm土层；若总采样深度为20 cm，则对所有土层测定容重，并以加权平均法计算20 cm深度的容重。
对于行号102-134对应的采样点，未直接测定土壤容重，而是从"SoilGrids"网站（https://soilgrids.org/）获取数据。下载0-5 cm和5-15 cm土层的容重数据，通过加权平均法计算后，再用于SOC储量的测定。

资助信息
本数据库由以下机构资助：ANII（项目编号FSDA_1_2018_1_154817，项目名称：Procesos Inductivos para generación de buenas prácticas agropecuarias: Compilación y análisis de bases de datos a nivel predial；项目编号FSA_1_2022_1_175272，项目名称：Evaluación multiescalar del desempeño ambiental de sistemas agropecuarios con diferente nivel de intensificación a partir de indicadores derivados de sensores remotos）；INIA（项目编号FPTA-515，项目名称：Indicadores de sostenibilidad ambiental para el sector agropecuario de Uruguay basados en información derivada de sensores remotos y modelos biofísicos）；以及IDB（项目编号URUGUAY/UR-T1277，项目名称：Adopción de prácticas Agroecológicas y Huella de Carbono en la Agricultura Uruguaya）。