iSDAsoil: soil clay content (USDA system) for Africa predicted at 30 m resolution at 0-20 and 20-50 cm depths

iSDAsoil dataset soil clay content (USDA system) in % 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_clay_tot_psa_m_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil clay content mean value,
• sol_clay_tot_psa_md_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil clay content (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: clay_tot_psa 
R-square: 0.746 
Fitted values sd: 16.5 
RMSE: 9.63 

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

Residuals:
    Min      1Q  Median      3Q     Max 
-75.803  -4.512  -0.178   3.748  82.146 

Coefficients:
               Estimate Std. Error t value Pr(>|t|)    
(Intercept)    4.494652   8.914671   0.504  0.61413    
regr.ranger    1.076957   0.003611 298.210  < 2e-16 ***
regr.xgboost  -0.012617   0.004678  -2.697  0.00699 ** 
regr.cubist    0.030730   0.003930   7.820 5.32e-15 ***
regr.nnet     -0.238376   0.365390  -0.652  0.51415    
regr.cvglmnet -0.044547   0.004379 -10.174  < 2e-16 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 9.629 on 122269 degrees of freedom
Multiple R-squared:  0.7458,	Adjusted R-squared:  0.7458 
F-statistic: 7.175e+04 on 5 and 122269 DF,  p-value: < 2.2e-16

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