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Questions on rainfed and irrigated crop

KeerZ

Member
Hi All,

I am reading the CLM5 crop model tech note and the IrrigationMod.F90, trying to figure out how rainfed and irrigated crops (especially rice) impact the soil moisture. I have a few questions about the crop model, and it is very appreciated if anyone can help!

1. According to the description on irrigation model 2.26. Crops and Irrigation — ctsm release-clm5.0 documentation, the irrigation flux is calculated based on a set of parameters like 'irrig_target_smp', 'irrig_threshold_fraction'. These irrigation-related parameters seem to be universal values as specified in Table 2.26.4. Is it correct to say if the irrigated rice and irrigated cotton in one grid cell have exactly the same soil moisture (and other physical states), their irrigation amounts should be the same?

2. I think the IrrigationMod does not consider 'flooding irrigation', is that right? For rainfed/irrigated rice, they should be flooded during their growing season, but it seems that this process is not incorporated in the IrrigationMod. If the irrigationMod does consider flooding irrigation, how does it impact the soil moisture (and other physical states of the rice patch)?

3. Is it correct to say: The major difference between the rainfed and irrigated crop is whether there is qflx_irrig_patch into soil.
The major difference between the rainfed crop and natural vegetation is that they have different values for stomatal conductance parameters, optical parameters, leaf N parameters and so on.

Any insights are appreciated! Thanks!

Keer
 

swensosc

New Member
1. I think that is correct; given the same soil moisture states, the irrigation amounts should be the same.
2. Currently flooding is not considered explicitly.
3. yes, rainfed crops do not receive an irrigation flux. Another key difference between crops and natural vegetation would be the phenology.
 

dll@ucar_edu

Danica Lombardozzi
New Member
To add to this conversation:
1. I agree that this is correct. Note that since each crop is on its own soil column, the I would expect crops in a single grid cell to have different soil moisture and other physical states.

3. In addition to phenology and parameter values, another major difference between rain-fed crops and natural vegetation is the application of fertilizer and the fact that each crop type exists on its own soil column and therefore do not share water or nutrient resources.
 

KeerZ

Member
To add to this conversation:
1. I agree that this is correct. Note that since each crop is on its own soil column, the I would expect crops in a single grid cell to have different soil moisture and other physical states.

3. In addition to phenology and parameter values, another major difference between rain-fed crops and natural vegetation is the application of fertilizer and the fact that each crop type exists on its own soil column and therefore do not share water or nutrient resources.
Oh yes, I ignored that the CFTs are on their own soil column. Thank you all for the quick replies!
 
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