World Soils 250m Percent Clay

Soil is the foundation of life on earth. More living things by weight live in the soil than upon it. It determines what crops we can grow, what structures we can build, what forests can take root. This layer contains the physical soil variable percent clay (clay). Within the subset of soil that is smaller than 2mm in size, also known as the fine earth portion, clay is defined as particles that are smaller than 0.002mm, making them only visible in an electron microscope. Clay soils contain low amounts of air, and water drains through them very slowly. This layer is a general, medium scale global predictive soil layer suitable for global mapping and decision support. In many places samples of soils do not exist so this map represents a prediction of what is most likely in that location. The predictions are made in six depth ranges by soilgrids.org, funded by ISRIC based in Wageningen, Netherlands. Each 250m pixel contains a value predicted for that area by soilgrids.org from best available data worldwide. Data for percent clay are provided at six depth ranges from the surface to 2 meters below the surface. Each variable and depth range may be accessed in the layer's multidimensional properties. Dataset Summary Phenomenon Mapped: Proportion of clay particles (< 0.002 mm) in the fine earth fraction in g/100g (%) Cell Size: 250 meters Pixel Type: 32 bit float, converted from online data that is 16 Bit Unsigned Integer Coordinate System: Web Mercator Auxiliary Sphere, projected via nearest neighbor from goode's homolosine land (250m) Extent: World land area except Antarctica Visible Scale: All scales are visible Number of Columns and Rows: 160300, 100498 Source: Soilgrids.org Publication Date: May 2020 Analysis: Analysis-Optimized Data from the soilgrids.org mean predictions for clay were used to create this layer. You may access the percent clay in one of six depth ranges. To select one choose the depth variable in the multidimensional selector in your map client. Mean depth (cm) Actual depth range of data -2.5 0-5cm depth range -10 5-15cm depth range -22.5 15-30cm depth range -45 30-60cm depth range -80 60-100cm depth range -150 100-200cm depth range What can you do with this Layer? This layer is suitable for both visualization and analysis across the ArcGIS system. This layer can be combined with your data and other layers from the ArcGIS Living Atlas of the World in ArcGIS Online and ArcGIS Pro to create powerful web maps that can be used alone or in a story map or other application. Read more in our blogs: Dsicoveries and Revelations: Exploring the World Soils 250m Layers Getting Started with Multidimensional Soil Layers in the ArcGIS Living Atlas of the World Because this layer is part of the ArcGIS Living Atlas of the World it is easy to add to your map: In ArcGIS Online, you can add this layer to a map by selecting Add then Browse Living Atlas Layers. A window will open. Type "world soils soilgrids" in the search box and browse to the layer. Select the layer then click Add to Map. In ArcGIS Pro, open a map and select Add Data from the Map Tab. Select Data at the top of the drop down menu. The Add Data dialog box will open on the left side of the box, expand Portal if necessary, then select Living Atlas. Type "world soils soilgrids" in the search box, browse to the layer then click OK. In ArcGIS Pro you can use the built-in raster functions or create your own to create custom extracts of the data. Imagery layers provide fast, powerful inputs to geoprocessing tools, models, or Python scripts in Pro. Online you can filter the layer to show subsets of the data using the filter button and the layer's built-in raster functions. This layer is part of the Living Atlas of the World that provides an easy way to explore the landscape layers and many other beautiful and authoritative maps on hundreds of topics. Analysis In order to leverage the optimization for analysis, the capability must be enabled by your ArcGIS organization administrator. More information on enabling this feature can be found in the ‘Regional data hosting’ section of this help doc. Optimized for analysis means this layer does not have size constraints for analysis and it is recommended for multisource analysis with other layers optimized for analysis. See the ArcGIS Living Atlas: Analysis-Optimized Imagery Layers Group for a complete list of imagery layers optimized for analysis. More information about soilgrids layers Answers to many questions may be found at soilgrids.org (ISRIC) frequently asked questions (faq) page about the data. To make this layer, Esri reprojected the expected value of ISRIC soil grids from soilgrids' source projection (goode's land WKID 54052) to web mercator projection, nearest neighbor, to facilitate online mapping. The resolution in web mercator projection is the same as the original projection, 250m. But keep in mind that the original dataset has been reprojected to make this web mercator version. This multidimensional soil collection serves the mean or expected value for each soil variable as calculated by soilgrids.org. For all other distributions of the soil variable, be sure to download the data directly from soilgrids.org. The data are available in VRT format and may be converted to other image formats within ArcGIS Pro. Accessing this layer's companion uncertainty layer Because data quality varies worldwide, the uncertainty of the predicted value varies worldwide. A companion uncertainty layer exists for this layer which you can use to qualify the values you see in this map for analysis. Choose a variable and depth in the multidimensional settings of your map client to access the companion uncertainty layer.土壤是地球生命的根基。以重量计，栖息于土壤之中的生物总量远超土壤表面之上的生物。它决定了我们可种植的作物、可建造的构筑物，以及可扎根生长的森林。该图层包含物理土壤变量——黏粒百分比（clay）。在粒径小于2mm的土壤子集（即细土组分，fine earth portion）中，黏粒被定义为粒径小于0.002mm的颗粒，仅能通过电子显微镜观测。黏质土壤的空气含量较低，水分下渗速度极为缓慢。 本图层为通用的中尺度全球预测性土壤图层，适用于全球制图与决策支持。在诸多区域尚无实地土壤采样数据，因此本地图通过预测给出该区域最可能的土壤状况。该预测由位于荷兰瓦赫宁根的国际土壤参考与信息中心（International Soil Reference and Information Centre, ISRIC）资助的soilgrids.org生成，共涵盖6个深度层级。每个250米分辨率的像素均包含由soilgrids.org基于全球最优可用数据预测得到的对应区域数值。 黏粒百分比数据按6个深度层级提供，覆盖从地表至地下2米的范围。各变量与深度层级可通过图层的多维属性进行访问。 ### 数据集摘要 **制图现象**：细土组分中黏粒（粒径<0.002mm）的占比，单位为克每百克（即百分比%） **像元尺寸**：250米 **像元类型**：32位浮点型，由原始的16位无符号整型在线数据转换而来 **坐标系**：Web墨卡托（Web Mercator）辅助球面投影，通过最邻近重采样从古德同源陆地投影（Goode's Homolosine Land, 250m分辨率）转换得到 **覆盖范围**：除南极洲外的全球陆地面积 **可视比例尺**：全比例尺可见 **行列数**：160300行，100498列 **数据来源**：Soilgrids.org **发布日期**：2020年5月 **分析适配说明**：本图层基于soilgrids.org的黏粒平均预测值经分析优化后生成。您可选择6个深度层级中的任意一个获取黏粒百分比数据：在地图客户端的多维选择器中选定深度变量即可。各深度对应的平均深度（cm）与实际深度范围如下： - 平均深度-2.5cm：0-5cm深度范围 - 平均深度-10cm：5-15cm深度范围 - 平均深度-22.5cm：15-30cm深度范围 - 平均深度-45cm：30-60cm深度范围 - 平均深度-80cm：60-100cm深度范围 - 平均深度-150cm：100-200cm深度范围 **本图层的应用场景**： 本图层适用于ArcGIS生态系统内的可视化与分析工作。您可将其与自有数据及ArcGIS世界生活地图集（ArcGIS Living Atlas of the World）中的其他图层相结合，在ArcGIS Online与ArcGIS Pro中创建功能强大的网页地图，可独立使用，或用于故事地图及其他应用场景。更多详情可参阅我们的博客： 1. 《探索与发现：解析全球250米分辨率土壤图层》 2. 《ArcGIS世界生活地图集中的多维土壤图层快速上手》 由于本图层属于ArcGIS世界生活地图集的一部分，您可轻松将其添加至地图中： #### 在ArcGIS Online中： 选择「添加」→「浏览生活地图集图层」，将弹出窗口。在搜索框中输入"world soils soilgrids"，浏览至目标图层后选中并点击「添加至地图」。 #### 在ArcGIS Pro中： 打开地图并选择「地图」选项卡下的「添加数据」，在下拉菜单顶部选择「数据」，将在左侧打开「添加数据」对话框。如有需要，展开「门户」选项并选择「生活地图集」，在搜索框中输入"world soils soilgrids"，浏览至目标图层后点击「确定」。 在ArcGIS Pro中，您可使用内置栅格函数或自定义函数对数据进行定制化提取。影像图层可为ArcGIS Pro中的地理处理工具、模型或Python脚本提供高效且强大的输入源。在线环境下，您可通过过滤按钮与图层内置的栅格函数筛选图层以显示数据子集。 本图层是ArcGIS世界生活地图集的组成部分，该地图集为您提供了便捷途径，可探索各类景观图层及数百个主题下的众多优质权威地图。 **分析优化说明**： 若要使用本图层的分析优化功能，需由您所在的ArcGIS组织管理员启用该特性。有关启用此功能的更多信息，请参阅本文档「区域数据托管」部分。分析优化意味着本图层不受分析的尺寸限制，推荐与其他分析优化图层进行多源分析。如需查看所有分析优化的影像图层完整列表，请参阅ArcGIS世界生活地图集：分析优化影像图层群组。 **有关soilgrids图层的更多信息**： 诸多常见问题的解答可访问soilgrids.org（ISRIC）的数据常见问题（Frequently Asked Questions, FAQ）页面获取。 为制作本图层，Esri将ISRIC土壤网格的预期值从其原始投影（古德陆地投影WKID 54052）通过最邻近重采样转换为Web墨卡托投影，以适配在线制图。Web墨卡托投影下的分辨率与原始投影一致，均为250米。但请注意，本Web墨卡托版本是由原始数据集经重投影得到的。 本多维土壤集合提供了由soilgrids.org计算得到的各土壤变量的均值或预期值。若需获取土壤变量的其他分布数据，请直接从soilgrids.org下载原始数据。该数据以虚拟栅格格式（Virtual Raster Format, VRT）提供，可在ArcGIS Pro中转换为其他影像格式。 **访问本图层的配套不确定性图层**： 由于全球各地的数据质量存在差异，预测值的不确定性也存在区域差异。本图层配有配套的不确定性图层，可用于佐证您在本地图中看到的用于分析的数值。在地图客户端的多维设置中选择变量与深度，即可访问该配套不确定性图层。