SOTER-based soil parameter estimates (SOTWIS) for Senegal and The Gambia

This harmonized set of soil parameter estimates for Senegal and The Gambia. It was derived from the Soil and Terrain Database for Senegal and The Gambia (SENSOTER ver. 1.0) and the ISRIC-WISE soil profile database, using standardized taxonomy-based pedotransfer (taxotransfer) procedures. The land surface of the study area, covering some 200 800 km2, has been characterized using 149 unique SOTER units. Each SOTER unit consists of up to four different soil components. In so far as possible, each soil component has been characterized by a regionally representative profile, selected and classified by national soil experts. Conversely, in the absence of any measured legacy data, soil components were characterized using synthetic profiles for which only the FAO-Unesco (1988) classification is known. Soil components in SENSOTER have been characterized using 90 profiles of which 34 are synthetic. The latter represent some 37 per cent of the territory. Comprehensive sets of measured attribute data are not available for most of the measured profiles (56) collated in SENSOTER. Consequently, to permit modelling, gaps in the soil analytical data have been filled using consistent taxotransfer procedures. Modal soil parameter estimates necessary to populate the taxotransfer procedure were derived from statistical analyses of soil profiles held in the ISRIC-WISE database. The current procedure only considers profiles in WISE that have FAO soil unit names identical to those mapped for SOTER-Senegal (41) and that originate from the Tropics (n= 4510). Parameter estimates are presented for 18 soil variables by soil unit for fixed depth intervals of 0.2 m to 1 m depth. Thes include: organic carbon, total nitrogen, pH(H2O), CECsoil, CECclay, base saturation, effective CEC, aluminium saturation, CaCO3 content, gypsum content, exchangeable sodium percentage (ESP), electrical conductivity (ECE), bulk density, content of sand, silt and clay, content of coarse fragments (less than 2 mm), and available water capacity (-33 kPa to -1.5 MPa). These attributes have been identified as being useful for agro-ecological zoning, land evaluation, crop growth simulation, modelling of soil carbon stocks and change, and analyses of global environmental change. The current parameter estimates should be seen as best estimates based on the current selection of soil profiles and data clustering procedure. Taxotransfer rules have been flagged to provide an indication of the confidence in the derived data. Soil parameter estimates are presented as summary files (in MS-Access format) which can be linked to the SENSOTER map using GIS, through the unique SOTER-unit code (NEWSUID). The derived (secondary) soil data for Senegal and The Gambia are considered appropriate for exploratory studies at national scale (1:1 million); these should consider the full map unit composition.

本数据集为塞内加尔和冈比亚的一套标准化土壤参数估算值，基于塞内加尔和冈比亚土壤与地形数据库（SENSOTER 版本1.0）及ISRIC-WISE土壤剖面数据库，通过标准化的分类学导向土壤转换（taxotransfer）方法生成。研究区域陆地面积约200800平方公里，通过149个独特的SOTER单元进行表征；每个SOTER单元包含至多四个不同的土壤组分。在条件允许的情况下，每个土壤组分均由国家土壤专家筛选并分类的区域代表性剖面进行表征；若缺乏实测历史数据，则使用仅已知FAO-联合国教科文组织（1988）分类的合成剖面表征土壤组分。SENSOTER中的土壤组分通过90个剖面表征，其中34个为合成剖面，后者约占研究区域面积的37%。

SENSOTER中整理的大部分实测剖面（56个）缺乏完整的属性测量数据集，因此为支持建模，土壤分析数据中的空缺通过一致的taxotransfer方法填补。填充taxotransfer方法所需的模态土壤参数估算值，来自于对ISRIC-WISE数据库中土壤剖面的统计分析；当前方法仅考虑WISE中FAO土壤单元名称与塞内加尔SOTER映射单元一致（共41个）且来源于热带地区（样本量n=4510）的剖面。

本数据集按土壤单元提供18个土壤变量在0.2米至1米固定深度区间的参数估算值，包括：有机碳、全氮、pH（H₂O）、土壤阳离子交换量（CECsoil）、黏土阳离子交换量（CECclay）、盐基饱和度、有效阳离子交换量、铝饱和度、碳酸钙含量、石膏含量、交换性钠百分比（ESP）、电导率（ECE）、容重、砂粒/粉粒/黏粒含量、粗碎屑含量（小于2毫米）及有效水容量（-33 kPa至-1.5 MPa）。这些属性已被证实可用于农业生态区划、土地评价、作物生长模拟、土壤碳库及变化建模，以及全球环境变化分析。

当前参数估算值为基于现有土壤剖面选择及数据聚类方法的最优估算结果；taxotransfer规则已添加标记，以指示派生数据的置信度。土壤参数估算值以汇总文件（MS-Access格式）呈现，可通过唯一的SOTER单元编码（NEWSUID），利用地理信息系统（GIS）与SENSOTER地图关联。针对塞内加尔和冈比亚的派生（次级）土壤数据适用于国家级（1:100万比例尺）探索性研究，但需考虑完整的地图单元构成。