## 2.26.1. Summary of CLM5.0 updates relative to the CLM4.5[¶](#summary-of-clm5-0-updates-relative-to-the-clm4-5 "Permalink to this headline")
-------------------------------------------------------------------------------------------------------------------------------------------

We describe here the complete crop and irrigation parameterizations that appear in CLM5.0. Corresponding information for CLM4.5 appeared in the CLM4.5 Technical Note ([Oleson et al. 2013](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#olesonetal2013)).

CLM5.0 includes the following new updates to the CROP option, where CROP refers to the interactive crop management model and is included as an option with the BGC configuration:

*   New crop functional types
    
*   All crop areas are actively managed
    
*   Fertilization rates updated based on crop type and geographic region
    
*   New Irrigation triggers
    
*   Phenological triggers vary by latitude for some crop types
    
*   Ability to simulate transient crop management
    
*   Adjustments to allocation and phenological parameters
    
*   Crops reaching their maximum LAI triggers the grain fill phase
    
*   Grain C and N pools are included in a 1-year product pool
    
*   C for annual crop seeding comes from the grain C pool
    
*   Initial seed C for planting is increased from 1 to 3 g C/m^2
    

These updates appear in detail in the sections below. Many also appear in [Levis et al. (2016)](https://escomp.github.io/ctsm-docs/versions/master/html/tech_note/References/CLM50_Tech_Note_References.html#levisetal2016).

