ESCOMP · samsrabin · Feb 6, 2026 · Nov 25, 2025 · Nov 2, 2025 · Nov 25, 2025
diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
@@ -76,3 +76,4 @@ cdf40d265cc82775607a1bf25f5f527bacc97405
 ac03492012837799b7111607188acff9f739044a
 d858665d799690d73b56bcb961684382551193f4
 c0c6da391ee359f2765439426f3a2a4593a95343
+598de2f05638286b3d99ac0ed120977cbc554c3d
diff --git a/bld/namelist_files/namelist_defaults_ctsm.xml b/bld/namelist_files/namelist_defaults_ctsm.xml
@@ -703,6 +703,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 
 <generate_crop_gdds                                        >.false.</generate_crop_gdds>
 <use_mxmat                                                 >.true.</use_mxmat>
+<suppress_gddmaturity_warning                              >.false.</suppress_gddmaturity_warning>
 
 <!-- use additional stress deciduous onset trigger    -->
 <constrain_stress_deciduous_onset               >.true.</constrain_stress_deciduous_onset>

diff --git a/bld/namelist_files/namelist_definition_ctsm.xml b/bld/namelist_files/namelist_definition_ctsm.xml
@@ -1484,6 +1484,11 @@ Set to .true. in order to override crop harvesting logic and to instead harvest
 Set to .false. in order to ignore crop PFT parameter for maximum growing season length (mxmat). Must be set to .false. when generate_crop_gdds is .true.
 </entry>
 
+<entry id="suppress_gddmaturity_warning" type="logical" category="physics"
+        group="cnphenology" valid_values="" value=".false.">
+If set to .true., suppress the warning message when a prescribed cultivar GDD requirement is below the minimum allowed value and is replaced with min_gddmaturity. Useful when using prescribed crop calendars with intentionally low GDD requirements.
+</entry>
+
 <entry id="min_critical_dayl_method" type="char*25" category="physics"
        group="cnphenology" valid_values="Constant,DependsOnLat,DependsOnVeg,DependsOnLatAndVeg">
 Method for determining what the minimum critical day length for seasonal decidious leaf offset depends on

diff --git a/cime_config/SystemTests/rxcropmaturity.py b/cime_config/SystemTests/rxcropmaturity.py
@@ -448,6 +448,7 @@ def _run_generate_gdds(self, case_gddgen):
                 f"--hdates-file {hdates_file}",
                 f"--output-dir generate_gdds_out",
                 f"--skip-crops miscanthus,irrigated_miscanthus,switchgrass,irrigated_switchgrass",
+                "--max-season-length-from-hdates-file",
             ]
         )
         stu.run_python_script(

diff --git a/cime_config/testdefs/ExpectedTestFails.xml b/cime_config/testdefs/ExpectedTestFails.xml
@@ -36,6 +36,27 @@
     </phase>
   </test>
 
+  <test name="RXCROPMATURITY_Lm61.f10_f10_mg37.IHistClm60BgcCrop.derecho_intel.clm-cropMonthOutput">
+    <phase name="RUN">
+      <status>FAIL</status>
+      <issue>#3740</issue>
+    </phase>
+  </test>
+
+  <test name="RXCROPMATURITY_Lm61.f09_t232.IHistClm60BgcCrop.derecho_intel.clm-cropMonthOutput">
+    <phase name="RUN">
+      <status>FAIL</status>
+      <issue>#3740</issue>
+    </phase>
+  </test>
+
+  <test name="RXCROPMATURITY_Lm61.f09_g17.IHistClm60BgcCrop.derecho_intel.clm-cropMonthOutput">
+    <phase name="RUN">
+      <status>FAIL</status>
+      <issue>#3740</issue>
+    </phase>
+  </test>
+
   <test name="SMS_Ld5.f09_g17.IHistClm50Sp.derecho_intel.clm-nofire">
     <phase name="SHAREDLIB_BUILD">
       <status>FAIL</status>

diff --git a/cime_config/testdefs/testmods_dirs/clm/crop/user_nl_clm b/cime_config/testdefs/testmods_dirs/clm/crop/user_nl_clm
@@ -13,7 +13,12 @@ hist_fincl2  += 'DYN_COL_SOIL_ADJUSTMENTS_C'
 ! Note that, under normal circumstances, these should only be saved annually.
 ! That's needed for the mxsowings and mxharvests axes to make sense.
 ! However, for testing purposes, it makes sense to save more frequently.
-hist_fincl3 = 'SDATES', 'SDATES_PERHARV', 'SYEARS_PERHARV', 'HDATES', 'GRAINC_TO_FOOD_PERHARV', 'GRAINC_TO_FOOD_ANN', 'GRAINN_TO_FOOD_PERHARV', 'GRAINN_TO_FOOD_ANN', 'GRAINC_TO_SEED_PERHARV', 'GRAINC_TO_SEED_ANN', 'GRAINN_TO_SEED_PERHARV', 'GRAINN_TO_SEED_ANN', 'HDATES', 'GDDHARV_PERHARV', 'GDDACCUM_PERHARV', 'HUI_PERHARV', 'SOWING_REASON_PERHARV', 'HARVEST_REASON_PERHARV', 'SWINDOW_STARTS', 'SWINDOW_ENDS', 'GDD20_BASELINE', 'GDD20_SEASON_START', 'GDD20_SEASON_END'
+hist_fincl3 = 'SDATES', 'SDATES_PERHARV', 'SYEARS_PERHARV', 'HDATES', 'GRAINC_TO_FOOD_PERHARV', 'GRAINC_TO_FOOD_ANN', 'GRAINN_TO_FOOD_PERHARV', 'GRAINN_TO_FOOD_ANN', 'GRAINC_TO_SEED_PERHARV', 'GRAINC_TO_SEED_ANN', 'GRAINN_TO_SEED_PERHARV', 'GRAINN_TO_SEED_ANN', 'HDATES', 'GDDHARV_PERHARV', 'GDDACCUM_PERHARV', 'HUI_PERHARV', 'SOWING_REASON_PERHARV', 'HARVEST_REASON_PERHARV', 'SWINDOW_STARTS', 'SWINDOW_ENDS', 'GDD20_BASELINE', 'GDD20_SEASON_START', 'GDD20_SEASON_END', 'MAX_TLAI_PERHARV'
+hist_fincl3 += 'FROOTC_AT_EMERGENCE_PERHARV', 'FROOTC_AT_ANTHESIS_PERHARV', 'FROOTC_AT_MATURITY_PERHARV', 'FROOTC_AT_HARVEST_PERHARV'
+hist_fincl3 += 'LIVECROOTC_AT_EMERGENCE_PERHARV', 'LIVECROOTC_AT_ANTHESIS_PERHARV', 'LIVECROOTC_AT_MATURITY_PERHARV', 'LIVECROOTC_AT_HARVEST_PERHARV'
+hist_fincl3 += 'LIVESTEMC_AT_EMERGENCE_PERHARV', 'LIVESTEMC_AT_ANTHESIS_PERHARV', 'LIVESTEMC_AT_MATURITY_PERHARV', 'LIVESTEMC_AT_HARVEST_PERHARV'
+hist_fincl3 += 'LEAFC_AT_EMERGENCE_PERHARV', 'LEAFC_AT_ANTHESIS_PERHARV', 'LEAFC_AT_MATURITY_PERHARV', 'LEAFC_AT_HARVEST_PERHARV'
+hist_fincl3 += 'REPRC_AT_EMERGENCE_PERHARV', 'REPRC_AT_ANTHESIS_PERHARV', 'REPRC_AT_MATURITY_PERHARV', 'REPRC_AT_HARVEST_PERHARV'
 hist_nhtfrq = -24,-8,-24
 hist_mfilt  = 1,1,1
 hist_type1d_pertape(3) = 'PFTS'

diff --git a/doc/ChangeLog b/doc/ChangeLog
@@ -1,4 +1,80 @@
 ===============================================================
+Tag name: ctsm5.4.016
+Originator(s): samrabin (Sam Rabin, UCAR/TSS)
+Date: Fri Feb  6 09:09:56 MST 2026
+One-line Summary: Merge b4b-dev to master
+
+Purpose and description of changes
+----------------------------------
+
+Merge b4b-dev to master
+
+Significant changes to scientifically-supported configurations
+--------------------------------------------------------------
+
+Does this tag change answers significantly for any of the following physics configurations?
+(Details of any changes will be given in the "Answer changes" section below.)
+
+[ ] clm6_0
+
+[ ] clm5_0
+
+[ ] ctsm5_0-nwp
+
+[ ] clm4_5
+
+
+Bugs fixed
+----------
+
+List of CTSM issues fixed (include CTSM Issue # and description):
+- [ESCOMP/CTSM Issue #3696: CropPhenology: Rename leafout to gddtsoi](https://github.com/ESCOMP/CTSM/issues/3696)
+- [ESCOMP/CTSM Issue #3057: error in errsol computation in BalanceCheckMod reports the wrong albedo values](https://github.com/ESCOMP/CTSM/issues/3057)
+
+
+Notes of particular relevance for users
+---------------------------------------
+
+Changes to CTSM's user interface (e.g., new/renamed XML or namelist variables):
+- New `suppress_gddmaturity_warning` namelist flag, default false.
+
+
+Notes of particular relevance for developers:
+---------------------------------------------
+
+Changes to tests or testing:
+- New Python unit and system tests.
+- New Fortran unit tests.
+- RXCROPMATURITY_ tests added to expected failure list. Will be resolved soon.
+
+
+Testing summary:
+----------------
+
+  python testing (if python code has changed; see instructions in python/README.md; document testing done):
+
+    derecho - OK
+
+  regular tests (aux_clm: https://github.com/ESCOMP/CTSM/wiki/System-Testing-Guide#pre-merge-system-testing):
+
+    derecho ----- OK
+    izumi ------- OK
+
+
+Other details
+-------------
+
+Pull Requests that document the changes (include PR ids):
+- [ESCOMP/CTSM Pull Request #3713: Factor out new subroutine CropPhase_OnePatch](https://github.com/ESCOMP/CTSM/pull/3713)
+- [ESCOMP/CTSM Pull Request #3633: Add history outputs: Crop biomass and LAI per harvest](https://github.com/ESCOMP/CTSM/pull/3633)
+- [ESCOMP/CTSM Pull Request #3727: Minor improvements to generate_gdd20_baseline.py](https://github.com/ESCOMP/CTSM/pull/3727) 
+- [ESCOMP/CTSM Pull Request #3710: Improve radiation balance check](https://github.com/ESCOMP/CTSM/pull/3710)
+- [ESCOMP/CTSM Pull Request #3729: generate_gdds: Work on arguments](https://github.com/ESCOMP/CTSM/pull/3729)
+- [ESCOMP/CTSM Pull Request #3738: generate_gdds: Get file lists earlier](https://github.com/ESCOMP/CTSM/pull/3738)
+- [ESCOMP/CTSM Pull Request #3741: ctsm5.4.016: b4b-dev merge 2026-02-05](https://github.com/ESCOMP/CTSM/pull/3741)
+
+===============================================================
+===============================================================
 Tag name: ctsm5.4.015
 Originator(s): erik (Erik Kluzek,UCAR/TSS,303-497-1326)
 Date: Tue Feb  3 12:29:48 AM MST 2026

diff --git a/doc/ChangeSum b/doc/ChangeSum
@@ -1,5 +1,6 @@
 Tag                   Who      Date  Summary
 ============================================================================================================================
+       ctsm5.4.016 samrabin 02/06/2026 Merge b4b-dev to master
        ctsm5.4.015     erik 02/03/2026 Update CISM to latest version with answer changes
        ctsm5.4.014 mvdebols 01/29/2026 Fix for xm2 and revise logic for excess ice melt
        ctsm5.4.013     erik 01/28/2026 Patch the Greenland snow hole with initial conditions for ne30 and tweak the C14 isotope latitudes