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femiguez / apsimx

R package for APSIM-X
https://femiguez.github.io/apsimx-docs/
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Converting DSSAT .SOL files to apsim soils #121

Open AnnaBlanke opened 1 year ago

AnnaBlanke commented 1 year ago

Hi! I am wondering if there is a function out there to convert DSSAT .SOL files to apsim soil profiles. I would like to use the soil data provided by Han et al. (https://www.sciencedirect.com/science/article/pii/S1364815218313033), as they seem to be a bit more comprehensive than the data we get from using get_isric_soil_profile. If not I will try to write a function myself, just want to avoid doing things twice ;) Thanks a lot for the great package!

femiguez commented 1 year ago

I do not have that yet. It is a reasonable request. If you think there are any deficiencies in 'get_isric_soil_profile' please let me know as I would be happy to look at that. I can offer a simple function which converts met files to DSSAT WTH objects. apsim_met_2_dssat_wth.R.zip

AnnaBlanke commented 1 year ago

Thanks for the quick reply and the R script for converting .met files. I read in Han et al. that they used data from HarvestChoice27 to derive soil characteristics (albedo, evaporation limit, drainage rate etc.) that are not available in Isric SoilGrids. So, I was wondering how these variables are retrieved with the get_isric_soil_profile function and also which pedo transfer functions are used. Is there somewhere a more detailed description of the get_isric_soil_profile function?

femiguez commented 1 year ago

The best documentation for the 'get_isric_soil_profile' function is in the code https://github.com/femiguez/apsimx/blob/master/R/get_isric_soil_profile.R I use equations from Saxton and Rawls for the pedotransfer functions. There are other assumptions which are hard to generalize. For example, fresh organic matter, FInert, FBiom and others. So some defaults are used. I could add the function you are requesting, but will be a while before I can get to it.

ankanasadhu commented 3 months ago

How are the default values for, FOM, FInert, FBiom, NO3N, and NH4N selected? If I have to change them according to crop or region what methods or reference can I follow?

femiguez commented 3 months ago

@ankanasadhu There is no good general way of selecting those for a region. Probably, the best approach is to run the model for a 'spin-up' or 'warm-up' period that you later discard. This assumes you have a crop rotation and you run it for 5-10 years before the period of interest. The assumption is that C, N and water will reach reasonable initial values. You might be interested in https://www.sciencedirect.com/science/article/pii/S2215016121003563