Some issues within CROPGRO and FORAGE

[BlueWhaleShark]

Hi DSSAT devs,

I just want to share a few things I discovered (which could be totally nonsense):

1. Under Weather/HMET.for, PARHR is calculated for missing PAR values in HPAR, but daily PAR is calculated not by summing them but by using another equation, which can cause some differences with daily PG methods.
2. Under Plant/CROPGRO/DEMAND.for and same for for_DEMAND.for, a line for growth demand gives "GDMSH = GDMSH + ADDSHL" in the loop but out of IF condition, which will keep adding extra ADDSHL even if "IF (PAGE .LE. LNGSH .AND. SHELN(NPP) .GT. 0.0 .AND. GRRAT1 .GT. 0.0) THEN" is not met. This overestimates the GDMSH.
3. Under Plant/CROPGRO/DEMAND.for, in the strawberry night length and temperature section, NPP refers to DAS - NR2 while the comment says "Adjustemnt of XFRUIT for Strawberry based on days after first flower NR1TIM". Meanwhile, "IF (XFPHT .GT. 0.0 .AND. XFINT .GE. 0.0 .AND. NPP .LE. NCOHORTS) THEN" means XFRUIT never goes back to to exact XFRUIT2, but instead it will be a little bit off based on the value in the previous loop.
4. Under Plant/CROPGRO/GROW.for FORAGE, NRUSLF / 0.16 is included for ALFDOT but not in FORAGE.
5. Under Plant/CROPGRO/DEMAND.for, the seasonal initialization for transplant does not contain the VSTAGE consideration as shown in FORAGE, which could be due to the small VSTAGE for annuals.
6. Under Plant/FORAGE/for_phenol.for, the transplant temperature factor was revised as "SJR 5/26/04 moved statement to this location - must appear before calculation of today's FT(2)...", but this was not implemented in CROPGRO.
7. Under Plant/CROPGRO/PHENOL.for, transplant in CROPGRO considers one stage following another one rather than one stage following the the NPRIOR stage, but i think it should follow the reference stage (NPRIOR). This can be different for transplants starting from a late stage.
8. Under Plant/CROPGRO/PODS.for, for "IF (PAGE .GE. LAGSD .AND. PAGE .LT. LAGSD + TDUMX .AND. SDNO(NPP) .LE. 0.0) THEN", I guess pest damage can potentially cause matching with this condition after the first set, but I haven't tested this.
9. Under Plant/FORAGE/for_demand.for, DAS definition is off by 1 day.
10. In FORAGE, the ECONAME reading seems to be wrong, like Aragon FD7 will be read as Aragon for ecotype parameters.
11. In FORAGE, it seems water-stress senescence is not considered as SLNDOT in CROPGRO.

I don't think I am an expert in crop modeling, so please correct me if I am wrong.

Thanks!

Some additional ones:
12. Under SPAM/ETPHOT.for, SALB for hedgerow pg method without zonal energy balance is not defined, so zero albedo is used for radiation interception.

[chporter]

@BlueWhaleShark thanks for these. We will look into them one by one as we have time.

[chporter]

Item 1 can be easily done (see https://github.com/chporter/dssat-csm-os/tree/HPAR_fix). When running all DSSAT experiments and treatments, there are some mostly minor differences in outputs. Big differences (13%) occur for sunflower in the same treatments that also give similar large differences for release vs debug options. Other differences are minor with max diff of 4.2% for one guar treatment, 1.0% for one soybean experiment, 1.4% for a peanut experiment, 2.5% for a lentil experiment.

It makes sense to make this change for a future release.

[BlueWhaleShark]

Item 1 can be easily done (see https://github.com/chporter/dssat-csm-os/tree/HPAR_fix). When running all DSSAT experiments and treatments, there are some mostly minor differences in outputs. Big differences (13%) occur for sunflower in the same treatments that also give similar large differences for release vs debug options. Other differences are minor with max diff of 4.2% for one guar treatment, 1.0% for one soybean experiment, 1.4% for a peanut experiment, 2.5% for a lentil experiment.

It makes sense to make this change for a future release.

Thanks for check on this! Yes, this mainly causes differences when SRAD is low and the PAR fraction deviates from 0.43, which is the standard setting for sunny days.