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Rainfed corn yield underestimation after 2000 and activation of potato crop in CLM.

uzairrahil

Mohammad Uzair Rahil
New Member
What version of the code are you using?
  • CTSM Version: alpha-ctsm5.2.mksrf.23_ctsm5.1.dev171
  • Resolution: 0.05° over Lower Michigan
  • Compset: IHISTCLM50_BGC_Crop
  • Meterological Forcing: CONUS404
Dear Scientists,

I am running CLM5 to simulate rainfed corn, soybean, and potato. I have encountered a few issues that I would appreciate your guidance on:

  1. Rainfed Corn Yield Underestimation
    The simulated rainfed corn yield tends to be underestimated after the year 2000. I have examined some key variables—such as BTRAN2, which suggests that water stress is not the cause (more than 0.7 in many random location in the growing period)—and also reviewed the phenology, which appears consistent with satellite-derived LAI (i.e., no phenology mismatch). I have attached examples for several representative locations. Could you please suggest additional diagnostics or possible reasons for this post-2000 underestimation?
  2. Potato Crop Activation
    I noticed that potato is listed as inactive in CLM5. Could you please provide guidance or documentation on how to activate or parameterize this crop type for simulation?

Any advice or references would be greatly appreciated.
1761077838096.png 1761077947227.png1761077881077.png
 

slevis

Moderator
Staff member
That's interesting about rainfed corn. Keep in mind that the model does not represent technological advances over time. Another consideration could be changing nitrogen availability.

In the CLM there's no potato parameterization to activate, so you would need to introduce such parameterization yourself.
 

samrabin

Sam Rabin
Member
Yes, technological advancement is always a possible issue in cases like this. That's discussed in Lombardozzi et al. (2020) as a reason for why our global trends aren't as steep as the observed. In this specific instance the adoption of Bt corn might be contributing.

Of course, it's also possible that something we do simulate isn't working well—perhaps something to do with total growing-season NPP and/or translocation of carbohydrates to the harvestable organ. Something is definitely odd with the stair-stepping behavior of CLM LAI in your timeseries graph.
 
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