The Use of NDVI in Digital Mapping of the Content of Available Lithium in the Arable Horizon of Soils in Southwestern Siberia

We have determined the informational value of the Normalized Difference Vegetation Index (NDVI) for predictive mapping of the content of available lithium in the arable horizon of soils of different slope positions: the first (280–310 m) and the second (240–280 m) altitudinal levels. The NDVI is not informative for the diagnostics or mapping of the content of available lithium in soils of small drainage valleys, the width of which is smaller than the resolution of the satellite image (30 m). In the regression model, the NDVI explains 28% of the variation in the content of available lithium in soils. Based on this model, a predictive map of the content of available lithium in soils has been compiled. Data on the spatial distribution pattern of the NDVI calculated based on a Landsat 8 satellite image (resolution of 30 m) were used as an indicator and the cartographical basis for digital mapping. The accuracy of the prediction of the content of available lithium in soils is good (MAPE is 16.9%). It has been revealed that the NDVI values and the content of available lithium in soils of the first altitudinal level are higher than in the second. The differences between NDVI in the drainage valley and on the first altitudinal level are not insignificant.