Soil parameter initialisation using SLGA and ISRIC databases

[Chloe0317]

Describe the new feature

The current APSIM Next Gen downloads soils from ASRIS (SLGA) and World Modellers (ISRIC) databases. These don't represent the most up-to-date version of SLGA and ISRIC SoilGrids. It is potentially useful, particularly for model initialisation, to use mapped site-specific soil parameters from national and global soil databases such as SLGA and SoilGrids and for in-filling un-measured soil parameters.

This R script SoilTextureExtraction.R is an illustration for batch-extracting soil texture information from SLGA (3 arc seconds/90 m resolution) and ISRIC SoilGrids (250 m spatial resolution, compared to 2.5 km World Modellers Resolution). The script reports these values in the native mapped depth intervals of the GlobalSoilMap project (0-5, 5-15, 15-30, 30-60, 60-100, and 100-200 cm). These values can be converted to your target depth intervals by using the ea_spline() function of the ithir package in R.

These could be used to obtain a more realistic initialisation of soil texture and, consequently, the new Soil Temperature model, which currently assumes a uniform distribution of sand, silt and clay percentages of 5, 65, and 30 % down the depth highlighted in red should the included soil doesn't contain an estimate of particle size distribution.

The code can also be easily adapted to extract any other variables of interest mapped by SLGA and SoilGrids by changing the URLs in the code to the respective DSM products.

This functionality may be incorporated into the APSIM Next Gen one day but remains aspirational.

[femiguez]

@Chloe0317 The apsimx R package has a function 'get_isric_soil_profile' that can build a soil profile for APSIM. It includes texture. Adding SLGA is on my TO-DO list. :)