Tier 4 maps of soil pH at 25 m resolution for the Netherlands

This dataset contains maps (GeoTIFFs) of soil pH of six standard depth layers for the Netherlands at 25 m resolution. The six standard depth layers are from 0-5 cm, 5-15 cm, 15-30 cm, 30-60 cm, 60-100cm and 100-200cm. For each of these depth layers, there is a map of mean predictions, the 5th, 50th (median) and 95th quantile, as well as the 90% prediction interval (PI90 = 95th - 5th quantile) and a categorical map of the accuracy thresholds ("none", A, AA and AAA) based on GlobalSoilMap specifications for Tier 4 products. The accuracy thresholds were derived from the PI90, which is a measure of prediction uncertainty. All maps are based on predictions (mean) and estimations (quantiles) using a Quantile Regression Forest model, which was calibrated using 15338 soil pH measurements from the "Bodemkundig Informatie Systeem" (BIS) and 195 covariates (spatially explicit environmental variables of soil forming factors).

本数据集涵盖荷兰地区25米分辨率的6个标准深度层土壤pH值地理栅格（GeoTIFF）数据。六个标准深度层分别为0-5厘米、5-15厘米、15-30厘米、30-60厘米、60-100厘米与100-200厘米。针对每个深度层，数据集均包含平均值预测栅格、5%分位数、50%分位数（中位数）及95%分位数栅格，同时提供90%预测区间（PI90=95th分位数与5th分位数的差值），以及符合全球土壤图（GlobalSoilMap）四级产品规范的精度阈值分类栅格，其分类类别包含“无（对应原文"none"）”、A、AA与AAA。上述精度阈值由PI90推导得出，而PI90是预测不确定性的量化衡量指标。所有栅格数据均基于分位数回归森林（Quantile Regression Forest）模型的预测值（平均值）与分位数估计值生成，该模型以15338条取自荷兰土壤信息系统（Bodemkundig Informatie Systeem，简称BIS）的土壤pH实测数据，以及195项协变量（即表征土壤形成因子的空间显性环境变量）完成校准。