Total dry matter accumulated by crops

[knreddy]

It looks like you can get at this from the sum of the following:

• GRAINC (total grain C); divide by 0.45 to get dry matter mass
• AGLB (Aboveground leaf biomass)
• AGSB (Aboveground stem biomass)

Make sure not to divide AGLB and AGSB by 0.45, because they're already in kg dry matter.

That said, I'm still familiarizing myself with a lot of CLM. Danica, could you check that I'm not missing anything? @dll@ucar_edu

What does the history field TOTALVEGC refer to? Can that be used to get the total amount of dry matter, like how GRAINC_TO_FOOD lets you get the yield?
@samrabin, @dll@ucar_edu

 

[samrabin]

Ah, good find. According to the list of output variables on the CTSM History Fields page, TOTVEGC is "total vegetation carbon, excluding cpool (gC/m2)." CPOOL is the "temporary photosynthate C pool (gC/m2)." So it seems like you can get what you want with TOTVEGC/0.45 + CPOOL.

There is also TOTPFTC ("total patch-level carbon, including cpool") and TOTPFTN ("total patch-level nitrogen"), but from the descriptions it's unclear whether those also include soil. From looking at the code, it seems like no for TOTPFTC, but it does include some accounting variables I'm not familiar enough with to say for sure. Perhaps you could try comparing TOTVEGC+CPOOL vs. TOTPFTC.

 

[knreddy]

Thats interesting. I thought considering only the TOTVEGC would give the total dry matter. I have history fields on a daily time scale. How much difference would the addition of temporary photosynthate carbon to TOTVEGC make?

And I would compare TOTVEGC+CPOOL vs. TOTPFTC and get back with the results.

 

[samrabin]

Re: how much CPOOL would add: Not sure! I can't imagine it's very much, but one never knows.

 

[knreddy]

Here are the results. The plots show the difference between TOTVEGC+CPOOL vs. TOTPFTC for spring wheat and rice for a single growing year.