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

iSDAsoil dataset soil silt content 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_silt_tot_psa_mehlich3_m_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil silt content mean value,
• sol_silt_tot_psa_mehlich3_md_30m_*..*cm_2001..2017_v0.13_wgs84.tif = predicted soil silt content 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: silt_tot_psa 
R-square: 0.64 
Fitted values sd: 11.9 
RMSE: 8.92 

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

Residuals:
    Min      1Q  Median      3Q     Max 
-63.746  -3.631  -0.526   2.630  72.486 

Coefficients:
                Estimate Std. Error t value Pr(>|t|)    
(Intercept)   -35.876865  36.887592  -0.973    0.331    
regr.ranger     0.948111   0.003874 244.733  < 2e-16 ***
regr.xgboost    0.062717   0.005506  11.391  < 2e-16 ***
regr.cubist     0.025705   0.004747   5.415 6.14e-08 ***
regr.nnet       1.902142   1.968248   0.966    0.334    
regr.cvglmnet  -0.028579   0.005799  -4.928 8.32e-07 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 8.915 on 122223 degrees of freedom
Multiple R-squared:  0.6399,	Adjusted R-squared:  0.6399 
F-statistic: 4.344e+04 on 5 and 122223 DF,  p-value: < 2.2e-16

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