World Soils Harmonized World Soil Database - Chemistry

Retirement Notice: This item is in mature support as of April 2024 and will be retired in December 2026. Please use the following layers as replacements: World Soils 250m pH, World Soils 250m Cation Exchange Capacity, World Soils 250m Nitrogen, World Soils 250m Organic Carbon Density, World Soils 250m Organic Carbon Stocks, World Soils 250m Soil Organic Carbon. Esri recommends updating your maps and apps to use the new version. Soil is a key natural resource that provides the foundation of basic ecosystem services. Soil determines the types of farms and forests that can grow on a landscape. Soil filters water. Soil helps regulate the Earth's climate by storing large amounts of carbon. Activities that degrade soils reduce the value of the ecosystem services that soil provides. For example, since 1850 35% of human caused green house gas emissions are linked to land use change. The Soil Science Society of America is a good source of additional information. The mineral composition of underlying rock, the amount and type of organic material from plants and climatic and other environmental factors affect the chemistry of the soil. Chemical composition and processes determine how and what type of soil forms at a given location and what type of agriculture the areas wil support. Dataset Summary This layer provides access to a 30 arc-second (roughly 1 km) cell-sized raster with attributes related to the chemistry of soil derived from the Harmonized World Soil Database v 1.2. The values in this layer are for the dominant soil in each mapping unit (sequence field = 1). Fields for topsoil (0-30 cm) and subsoil (30-100 cm) are available for each of these soil chemistry attributes: Organic Carbon - % weight Calcium Carbonate - % weight Gypsum - % weight Salinity - Electrical Conductivity - dS/m pH Additionally, 4 class description fields were added by Esri based on the document Harmonized World Soil Database Version 1.2 for use in web map pop-ups: pH Class Description Calcium Carbonate Class Description Gypsum Class Description Salinity - Electrical Conductivity - Class Description The layer is symbolized with the Topsoil pH field. The document Harmonized World Soil Database Version 1.2 provides more detail on the soil chemistry attributes contained in this layer. Other attributes contained in this layer include: Soil Mapping Unit Name - the name of the spatially dominant major soil group Soil Mapping Unit Symbol - a two letter code for labeling the spatially dominant major soil group in thematic maps Data Source - the HWSD is an aggregation of datasets. The data sources are the European Soil Database (ESDB), the 1:1 million soil map of China (CHINA), the Soil and Terrain Database Program (SOTWIS), and the Digital Soil Map of the World (DSMW). Percentage of Mapping Unit covered by dominant component

停用通知：本数据集自2024年4月起进入成熟支持阶段，将于2026年12月正式停用。请使用以下图层作为替代：250米分辨率世界土壤pH值、250米分辨率世界土壤阳离子交换量、250米分辨率世界土壤氮含量、250米分辨率世界土壤有机碳密度、250米分辨率世界土壤有机碳储量、250米分辨率世界土壤有机碳。Esri建议您更新相关地图与应用程序以使用新版本。
土壤是关键的自然资源，为基础生态系统服务提供核心支撑。土壤决定了某一区域可发展的农业与林业类型，能够过滤水体，并通过储存大量碳元素助力调节地球气候。土壤退化活动会削弱其提供的生态系统服务价值。例如，自1850年以来，35%的人为温室气体排放与土地利用变化相关。美国土壤科学学会（Soil Science Society of America）是获取更多相关信息的优质渠道。
下伏岩石的矿物组成、植物源有机物质的数量与类型、气候及其他环境因素，均会影响土壤的化学性质。土壤的化学组成与过程，决定了特定区域的土壤形成类型，以及该区域可支撑的农业类型。
数据集摘要：本图层提供了分辨率为30弧秒（约1公里）的栅格数据，其属性源自《统一世界土壤数据库v1.2》（Harmonized World Soil Database v1.2），涵盖土壤化学相关特征。本图层中的数值对应每个制图单元中的优势土壤（序列字段=1）。针对以下土壤化学属性，均提供了表层土壤（0-30厘米）与亚表层土壤（30-100厘米）的对应字段：
- 有机碳：重量百分比
- 碳酸钙：重量百分比
- 石膏：重量百分比
- 盐度：电导率，单位为分西门子每米（dS/m）
- pH值
此外，Esri基于《Harmonized World Soil Database Version 1.2》文档新增了4个分类描述字段，用于网络地图弹窗展示：
- pH值分类描述
- 碳酸钙分类描述
- 石膏分类描述
- 盐度（电导率）分类描述
本图层以表层土壤pH值字段进行符号化渲染。《Harmonized World Soil Database Version 1.2》文档对本图层包含的土壤化学属性有更详细的说明。
本图层包含的其他属性如下：
- 土壤制图单元名称：空间占比最高的主要土壤群名称
- 土壤制图单元符号：用于专题地图中标注空间占比最高的主要土壤群的双字母代码
- 数据源：统一世界土壤数据库（Harmonized World Soil Database，以下简称HWSD）为多数据集聚合产物，其数据源包括欧洲土壤数据库（ESDB）、中国1:100万土壤图（CHINA）、土壤与地形数据库计划（SOTWIS）以及世界数字土壤图（DSMW）
- 优势组分覆盖制图单元的百分比