iSDAsoil: soil fine-earth bulk density for Africa predicted at 30 m resolution at 0-20 and 20-50 cm depths

iSDAsoil dataset soil fine-earth bulk density in 10×kg/m3 predicted at 30 m resolution for 0–20 and 20–50 cm depth intervals. Data has been projected in WGS84 coordinate system and compiled as COG. Predictions have been generated using multi-scale Ensemble Machine Learning with 250 m (MODIS, PROBA-V, climatic variables and similar) and 30 m (DTM derivatives, Landsat, Sentinel-2 and similar) resolution covariates. For model training we use a pan-African compilations of soil samples and profiles (iSDA points, AfSPDB, LandPKS, and other national and regional soil datasets). Cite as:

Hengl, T., Miller, M.A.E., Križan, J. et al. African soil properties and nutrients mapped at 30 m spatial resolution using two-scale ensemble machine learning. Sci Rep 11, 6130 (2021). https://doi.org/10.1038/s41598-021-85639-y

To open the maps in QGIS and/or directly compute with them, please use the Cloud-Optimized GeoTIFF version.

Layer description:

sol_db_od_m_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil bulk density mean value,

sol_db_od_md_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil bulk density model (prediction) errors,

Model errors were derived using bootstrapping: md is derived as standard deviation of individual learners from 5-fold cross-validation (using spatial blocking). The model 5-fold cross-validation (mlr::makeStackedLearner) for this variable indicates:

Variable: db_od
R-square: 0.819
Fitted values sd: 0.269
RMSE: 0.126

Random forest model:
Call:
stats::lm(formula = f, data = d)

Residuals:
Min 1Q Median 3Q Max
-1.06778 -0.06450 0.00215 0.06585 0.90016

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -0.05538 0.04860 -1.140 0.25451
regr.ranger 0.86305 0.01577 54.733 < 2e-16 ***
regr.xgboost 0.15383 0.01651 9.315 < 2e-16 ***
regr.cubist 0.02039 0.01113 1.832 0.06695 .
regr.nnet 0.03465 0.03710 0.934 0.35036
regr.cvglmnet -0.03021 0.01032 -2.927 0.00343 **
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.1263 on 13565 degrees of freedom
Multiple R-squared: 0.8194, Adjusted R-squared: 0.8193
F-statistic: 1.231e+04 on 5 and 13565 DF, p-value: < 2.2e-16

To back-transform values (y) to kg/m-cubic use:

kg/m3 = y * 10

To submit an issue or request support please visit https://isda-africa.com/isdasoil