diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd1475e9..15510bc1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Added `FiboaDuckDBBaseConverter` for SQL-based conversion of large Parquet sources.
 - Added `PerFileBaseConverter` to process multi-file sources incrementally.
 - Added support for supplementary HCAT/crop mappings via `hcat_mapping_supplements`.
+- Added `get_hcat_mapping()` and `hcat_lookup()` to `AddHCATMixin` to load the HCAT mapping once and look up codes or names in it.
 - Added support for Esri JSON output and server-side filters in REST converters.
 - Added `WFSConverterMixin` for paged downloads from WFS layers.
 - Added a test guard that rejects fixture files larger than 5 MB.
@@ -94,6 +95,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - `metrics:area` measured from the geometry is now correct in CRSs that are in metres but not equal-area, such as Web Mercator: they are reprojected to an equal-area CRS first. Source areas in hectares are converted to m² also where missing values are filled in, and empty values are filled in, not only 0. Invalid geometries are repaired before they are measured, as they are for the output, so that e.g. a self-intersecting polygon no longer gets an area of 0.
 - Converters no longer publish duplicate `id`s (#282): row-numbered ids count over all source files instead of restarting per file, and ids the source repeats get a `~<n>` suffix.
 - Rows missing `crop:code` are now dropped with a warning (and an error threshold), instead of failing whole conversions.
+- The HCAT mapping, the German IACS crop names and `metrics:area` now use the columns returned by an overridden `get_columns()` instead of the declared `columns`.
+- BR-CONAB: `metrics:area` falls back to the `Hectares` column where `area_ha` is empty.
 - DE-BB:
   - Excluded NBF ineligible patches with empty crop code.
   - Fixed source encoding and FLIK handling.
diff --git a/fiboa_cli/conversion/fiboa_converter.py b/fiboa_cli/conversion/fiboa_converter.py
index ed5b5572..67a28e9a 100644
--- a/fiboa_cli/conversion/fiboa_converter.py
+++ b/fiboa_cli/conversion/fiboa_converter.py
@@ -48,14 +48,15 @@ def _source_column(self, target, columns=None):
                 return source
         return None
 
+    # Also called after the migrations (post_migrate, add_hcat): overrides must be side-effect free
     def get_columns(self, gdf):
         columns = super().get_columns(gdf)
-        self._area_column = self._source_column(AREA_KEY, columns)
-        self._area_in_ha = self.area_is_in_ha
-        if self._area_column is None and self.area_calculate_missing:
+        self._area_added = (
+            self._source_column(AREA_KEY, columns) is None and self.area_calculate_missing
+        )
+        if self._area_added:
             # post_migrate() measures it; the mapping keeps the column in the output
-            columns[AREA_KEY] = self._area_column = AREA_KEY
-            self._area_in_ha = False
+            columns[AREA_KEY] = AREA_KEY
         return columns
 
     def _variants_are_years(self):
@@ -159,9 +160,9 @@ def post_migrate(self, gdf):
         gdf = super().post_migrate(gdf)
         gdf = self._traditional_axis_order(gdf)
 
-        # get_columns() runs first and resolves both; the fallback is for direct callers
-        area_key = getattr(self, "_area_column", None) or self._source_column(AREA_KEY)
-        in_ha = getattr(self, "_area_in_ha", self.area_is_in_ha)
+        # the final mapping, with what an override changes after this class's get_columns()
+        area_key = self._source_column(AREA_KEY, self.get_columns(gdf))
+        in_ha = self.area_is_in_ha and not self._area_added
         if area_key is None:
             return gdf
 
diff --git a/fiboa_cli/datasets/br_conab.py b/fiboa_cli/datasets/br_conab.py
index 2298946a..c03a86ed 100644
--- a/fiboa_cli/datasets/br_conab.py
+++ b/fiboa_cli/datasets/br_conab.py
@@ -1,7 +1,6 @@
 import math
 from pathlib import Path
 
-import numpy as np
 from vecorel_cli.conversion.admin import AdminConverterMixin
 
 from ..conversion.fiboa_converter import FiboaBaseConverter
@@ -89,8 +88,7 @@ def file_migration(self, gdf, path, uri, layer=None):
 
     def migrate(self, gdf):
         gdf = gdf.reset_index(drop=True)
-        gdf["area_ha"].combine_first(gdf["Hectares"]).replace(np.nan, None, inplace=True)
-        gdf.loc[gdf["area_ha"] == 0, "area_ha"] = None
+        gdf["area_ha"] = gdf["area_ha"].combine_first(gdf["Hectares"])
         gdf["cd_mun"] = gdf["cd_mun"].combine_first(gdf["CD_MUN"]).apply(fformat)
         gdf["nm_mun"] = gdf["nm_mun"].combine_first(gdf["NM_MUN"]).combine_first(gdf["NM_MUNIC"])
         return super().migrate(gdf)
diff --git a/fiboa_cli/datasets/commons/de_iacs.py b/fiboa_cli/datasets/commons/de_iacs.py
index 1f768853..992bd820 100644
--- a/fiboa_cli/datasets/commons/de_iacs.py
+++ b/fiboa_cli/datasets/commons/de_iacs.py
@@ -32,9 +32,10 @@ def __init__(self, *args, **kwargs):
 
     def post_migrate(self, gdf):
         gdf = super().post_migrate(gdf)
-        # Look up the source attribute that the converter mapped to crop:code, the same way
-        # AddHCATMixin.get_code_column does. Columns are still source-named at this point.
-        attribute = next(k for k, v in self.columns.items() if v == "crop:code")
+        # Columns are still source-named at this point
+        attribute = self._source_column("crop:code", self.get_columns(gdf))
+        if attribute is None:
+            return gdf
         rows = read_data_csv(CODE_LIST_FILE)
         codes = gdf[attribute]
         gdf["crop:name"] = codes.map({r["original_code"]: r["original_name"] for r in rows})
diff --git a/fiboa_cli/datasets/commons/hcat.py b/fiboa_cli/datasets/commons/hcat.py
index cfe9328f..fb89b17c 100644
--- a/fiboa_cli/datasets/commons/hcat.py
+++ b/fiboa_cli/datasets/commons/hcat.py
@@ -70,10 +70,24 @@ def convert(self, *args, **kwargs):
             )
         return super().convert(*args, **kwargs)
 
-    def get_code_column(self, gdf, code="crop:code"):
-        try:
-            attribute = next(k for k, v in self.columns.items() if v == code)
-        except StopIteration:
+    def get_hcat_mapping(self) -> list[dict]:
+        if self.hcat_mapping is None:
+            self.hcat_mapping = load_hcat_mapping(self.hcat_mapping_csv, url=self.mapping_file)
+            for supplement in self.hcat_mapping_supplements:
+                self.hcat_mapping = self.hcat_mapping + load_hcat_mapping(supplement)
+        return self.hcat_mapping
+
+    def hcat_lookup(self, key: str, value: str, strip: bool = False) -> dict:
+        """Maps one column of the HCAT mapping to another, e.g. original_code to original_name"""
+        return {
+            (row[key].strip() if strip else row[key]): row[value] for row in self.get_hcat_mapping()
+        }
+
+    def get_code_column(self, gdf, code="crop:code", columns=None):
+        if columns is None:
+            columns = self.get_columns(gdf)
+        attribute = self._source_column(code, columns)
+        if attribute is None:
             raise Exception(f"Misssing {code} column in converter {self.__class__.__name__}")
         col = gdf[attribute]
         # Should be corrected in original parser
@@ -89,25 +103,22 @@ def add_hcat(self, gdf):
             # Add HCAT columns based on crop-columns
             # Map to HCAT categories by using the mapping from the csv file
 
-            if self.hcat_mapping is None:
-                self.hcat_mapping = load_hcat_mapping(self.hcat_mapping_csv, url=self.mapping_file)
-                for supplement in self.hcat_mapping_supplements:
-                    self.hcat_mapping = self.hcat_mapping + load_hcat_mapping(supplement)
-
+            columns = self.get_columns(gdf)
+            self.get_hcat_mapping()
             from_code = "original_code"
             if from_code not in self.hcat_mapping[0]:
                 # Some code lists have no code, only a crop_name
                 from_code = "original_name"
-                crop_code_col = self.get_code_column(gdf, "crop:name")
+                crop_code_col = self.get_code_column(gdf, "crop:name", columns)
             else:
-                crop_code_col = self.get_code_column(gdf)
+                crop_code_col = self.get_code_column(gdf, columns=columns)
 
             def map_to(attribute):
                 return {e[from_code]: e[attribute] or None for e in self.hcat_mapping}
 
             name_col = None
             if self.hcat_mapping_name_fallback and from_code == "original_code":
-                name_col = self.get_code_column(gdf, "crop:name")
+                name_col = self.get_code_column(gdf, "crop:name", columns)
 
             def map_by_name(attribute):
                 # Three Walloon crops carry a trailing space in the table.
@@ -130,7 +141,9 @@ def map_by_name(attribute):
 
             if col is not None and col.isna().any():
                 index = [
-                    k for k, v in self.columns.items() if v.startswith("crop:") and k in gdf.columns
+                    k
+                    for k, v in columns.items()
+                    if k in gdf.columns and any(t.startswith("crop:") for t in np.atleast_1d(v))
                 ]
                 missing = gdf[col.isna()][index].drop_duplicates()
                 missing.reset_index(drop=True, inplace=True)
diff --git a/fiboa_cli/datasets/de_by.py b/fiboa_cli/datasets/de_by.py
index ed68f31a..bffe025a 100644
--- a/fiboa_cli/datasets/de_by.py
+++ b/fiboa_cli/datasets/de_by.py
@@ -2,7 +2,7 @@
 from vecorel_cli.conversion.admin import AdminConverterMixin
 
 from ..conversion.fiboa_converter import FiboaBaseConverter
-from .commons.hcat import AddHCATMixin, load_hcat_mapping
+from .commons.hcat import AddHCATMixin
 
 
 class Converter(AdminConverterMixin, AddHCATMixin, FiboaBaseConverter):
@@ -33,9 +33,7 @@ def layer_filter(self, layer: str, uri: str) -> bool:
 
     def migrate(self, gdf: gpd.GeoDataFrame):
         gdf = super().migrate(gdf)
-        self.hcat_mapping = load_hcat_mapping(self.hcat_mapping_csv, url=self.mapping_file)
-        gdf = gdf[gdf["bewirtschaftung"].isin([row["original_code"] for row in self.hcat_mapping])]
-
-        mapping_crop = {row["original_code"]: row["original_name"] for row in self.hcat_mapping}
-        gdf["crop:name"] = gdf["bewirtschaftung"].map(mapping_crop)
+        names = self.hcat_lookup("original_code", "original_name")
+        gdf = gdf[gdf["bewirtschaftung"].isin(names)]
+        gdf["crop:name"] = gdf["bewirtschaftung"].map(names)
         return gdf
diff --git a/fiboa_cli/datasets/de_by_block.py b/fiboa_cli/datasets/de_by_block.py
index 7d3b8ee6..31060779 100644
--- a/fiboa_cli/datasets/de_by_block.py
+++ b/fiboa_cli/datasets/de_by_block.py
@@ -44,10 +44,14 @@ class DEBYBlockConverter(AdminConverterMixin, DEIACSMixin, WFSConverterMixin, Fi
     columns = {
         "geometry": "geometry",
         "flik": ("flik", "id"),  # derived in migrate(); unique, unlike in Baden-Württemberg
-        "agricultural_area_type": "crop:code",  # added in file_migration(), trimmed in migrate()
+        "agricultural_area_type": "crop:code",  # added in file_migration()
         "validFrom": "determination:datetime",
     }
-    column_migrations = {"validFrom": lambda col: pd.to_datetime(col)}
+    column_migrations = {
+        "validFrom": lambda col: pd.to_datetime(col),
+        # …/codelist/de.iacs/AgriculturalAreaTypeValue/AL -> AL
+        "agricultural_area_type": lambda col: col.str.rsplit("/", n=1).str[-1],
+    }
 
     def file_migration(self, gdf, path, uri, layer=None):
         # The land cover class is carried as an xlink attribute, which the GML driver does not
@@ -70,6 +74,4 @@ def migrate(self, gdf):
         # The FLIK is the last dot-separated segment of the identifier URI, e.g.
         # https://registry.gdi-de.org/id/de.by.inspire.invekos.lpis.aa.DEBYLI9412000570
         gdf["flik"] = gdf["id"].str.rsplit(".", n=1).str[-1]
-        # …/codelist/de.iacs/AgriculturalAreaTypeValue/AL -> AL
-        gdf["agricultural_area_type"] = gdf["agricultural_area_type"].str.rsplit("/", n=1).str[-1]
         return super().migrate(gdf)
diff --git a/fiboa_cli/datasets/de_nds.py b/fiboa_cli/datasets/de_nds.py
index cedce6a3..dd21068d 100644
--- a/fiboa_cli/datasets/de_nds.py
+++ b/fiboa_cli/datasets/de_nds.py
@@ -52,14 +52,12 @@ class Converter(AdminConverterMixin, AddHCATMixin, FiboaBaseConverter):
     }
     column_migrations = {"ANTRAGSJAH": lambda col: pd.to_datetime(col, format="%Y")}
 
-    def migrate(self, gdf):
+    def get_columns(self, gdf):
+        columns = super().get_columns(gdf)
+        # older editions name the crop code and the area differently
         if "NC_FESTG" not in gdf.columns:
-            code = {"KULTURARTF", "KULTURCODE", "KC_FESTG"} & set(gdf.columns)
-            del self.columns["NC_FESTG"]
-            self.columns[code.pop()] = "crop:code"
-
+            code = next(c for c in ("KULTURARTF", "KULTURCODE", "KC_FESTG") if c in gdf.columns)
+            columns[code] = columns.pop("NC_FESTG")
         if "AKTUELLEFL" not in gdf.columns:
-            del self.columns["AKTUELLEFL"]
-            self.columns["AKT_FL"] = "metrics:area"
-
-        return super().migrate(gdf)
+            columns["AKT_FL"] = columns.pop("AKTUELLEFL")
+        return columns
diff --git a/fiboa_cli/datasets/de_sh.py b/fiboa_cli/datasets/de_sh.py
index 8a1191cd..ad497bf6 100644
--- a/fiboa_cli/datasets/de_sh.py
+++ b/fiboa_cli/datasets/de_sh.py
@@ -57,10 +57,7 @@ class Converter(AdminConverterMixin, FiboaBaseConverter):
     }
 
     def migrate(self, gdf):
-        renames = {old: new for old, new in self.COLUMN_RENAMES.items() if old in gdf.columns}
-        if renames:
-            gdf = gdf.rename(columns=renames)
-        return super().migrate(gdf)
+        return super().migrate(gdf.rename(columns=self.COLUMN_RENAMES))
 
     columns = {
         "geometry": "geometry",
diff --git a/fiboa_cli/datasets/de_sl_block.py b/fiboa_cli/datasets/de_sl_block.py
index 923fa948..135bc41a 100644
--- a/fiboa_cli/datasets/de_sl_block.py
+++ b/fiboa_cli/datasets/de_sl_block.py
@@ -53,9 +53,13 @@ class DESLBlockConverter(AdminConverterMixin, DEIACSMixin, WFSConverterMixin, Fi
         "geometry": "geometry",
         "flik": "flik",  # derived in migrate(); the block reference
         "id": "id",  # the flik, plus a part number where a block is several polygons
-        "area_type": "crop:code",  # added in file_migration(), trimmed in migrate()
+        "area_type": "crop:code",  # added in file_migration()
         "area": "metrics:area",  # derived in migrate(); in hectares
     }
+    column_migrations = {
+        # …/codelist/de.iacs/AgriculturalAreaTypeValue/GL -> GL
+        "area_type": lambda col: col.str.rsplit("/", n=1).str[-1],
+    }
 
     def file_migration(self, gdf, path, uri, layer=None):
         # The land cover class is a nested xlink attribute, which the GML driver does not guess
@@ -77,8 +81,6 @@ def migrate(self, gdf):
         # "Size in ha: 0.11206, flik: DESLLI0000248744"
         gdf["flik"] = gdf["description"].apply(parse_flik)
         gdf["area"] = gdf["description"].apply(parse_size)
-        # …/codelist/de.iacs/AgriculturalAreaTypeValue/GL -> GL
-        gdf["area_type"] = gdf["area_type"].str.rsplit("/", n=1).str[-1]
 
         # the source publishes several land cover records for one block, each with its own
         # polygon, so the flik alone does not identify a row; the base numbers the repeats
diff --git a/fiboa_cli/datasets/de_th.py b/fiboa_cli/datasets/de_th.py
index 7848ee8a..60e8bc6e 100644
--- a/fiboa_cli/datasets/de_th.py
+++ b/fiboa_cli/datasets/de_th.py
@@ -62,13 +62,9 @@ class Converter(AdminConverterMixin, FiboaBaseConverter):
             {"Geaendert": True, "Unveraendert": False, "Neu": None}
         ),
         "FBI_VJ": lambda column: column.str.split(Converter.delim, regex=True),
+        "GEO_UPDAT": lambda column: pd.to_datetime(column, format="%d.%m.%Y", utc=True),
     }
 
-    def migrate(self, gdf):
-        col = "GEO_UPDAT"
-        gdf[col] = pd.to_datetime(gdf[col], format="%d.%m.%Y", utc=True)
-        return super().migrate(gdf)
-
     column_filters = {"LF": lambda col: col == "LF"}
 
     # Schemas for the fields that are not defined in fiboa
diff --git a/fiboa_cli/datasets/ec_fr.py b/fiboa_cli/datasets/ec_fr.py
index 6e4b01c3..beb42937 100644
--- a/fiboa_cli/datasets/ec_fr.py
+++ b/fiboa_cli/datasets/ec_fr.py
@@ -31,11 +31,5 @@ class Converter(EuroCropsConverterMixin, FiboaBaseConverter):
     column_migrations = {
         "CODE_GROUP": lambda col: col.astype("string").str.strip(),
     }
-
-    def migrate(self, gdf):
-        # SURF_PARC is rounded to 0.01 ha, so a parcel under 50 m2 reads as zero
-        zero = gdf["SURF_PARC"] <= 0
-        if zero.any():
-            self.info(f"Computing the area of {zero.sum():,} parcel(s) rounded down to zero")
-            gdf.loc[zero, "SURF_PARC"] = gdf.loc[zero, "geometry"].area / 10_000
-        return super().migrate(gdf)
+    # SURF_PARC is rounded to 0.01 ha, so a parcel under 50 m2 reads as zero and is
+    # measured from the geometry (area_calculate_missing)
diff --git a/fiboa_cli/datasets/ee.py b/fiboa_cli/datasets/ee.py
index 924bbef6..3735cf24 100644
--- a/fiboa_cli/datasets/ee.py
+++ b/fiboa_cli/datasets/ee.py
@@ -1,7 +1,7 @@
 import pandas as pd
 
 from ..conversion.fiboa_converter import FiboaBaseConverter
-from .commons.hcat import AddHCATMixin, load_hcat_mapping
+from .commons.hcat import AddHCATMixin
 
 COLUMNS = {
     "geometry": "geometry",
@@ -48,9 +48,7 @@ class Convert(AddHCATMixin, FiboaBaseConverter):
 
     def migrate(self, gdf):
         # do a reverse mapping (from name to crop:code)
-        if self.hcat_mapping is None:
-            self.hcat_mapping = load_hcat_mapping(self.hcat_mapping_csv, url=self.mapping_file)
-        codes = {row["original_name"].strip(): row["original_code"] for row in self.hcat_mapping}
+        codes = self.hcat_lookup("original_name", "original_code", strip=True)
         gdf["crop:code"] = gdf["taotletud_kultuur"].str.strip().map(codes)
         return super().migrate(gdf)
 
diff --git a/fiboa_cli/datasets/es.py b/fiboa_cli/datasets/es.py
index 680fdff8..742c803e 100644
--- a/fiboa_cli/datasets/es.py
+++ b/fiboa_cli/datasets/es.py
@@ -31,7 +31,6 @@ class Converter(AddHCATMixin, FiboaBaseConverter):
 
     columns = {
         "geometry": "geometry",
-        "id": "id",
         "provincia": "admin_province_code",
         "municipio": "admin_municipality_code",
         "dn_surface": "metrics:area",
@@ -40,6 +39,19 @@ class Converter(AddHCATMixin, FiboaBaseConverter):
         "parc_supcult": "cultivation_surface",
     }
 
+    # The source has no globally unique row identifier: the SIGPAC cadastral key
+    # plus the declaration-line index is unique per record
+    id_columns = (
+        "provincia",
+        "municipio",
+        "agregado",
+        "zona",
+        "poligono",
+        "parcela",
+        "recinto",
+        "ld_recinto",
+    )
+
     area_is_in_ha = False
 
     extensions = {
@@ -72,31 +84,6 @@ def layer_filter(self, layer: str, uri: str) -> bool:
         # GPKG contains the data layer plus several codelist tables (cod_*) — only read the data.
         return layer == "cultivo_declarado"
 
-    def migrate(self, gdf):
-        # The source has no globally unique row identifier. Build one from the SIGPAC cadastral key
-        # plus the declaration-line index, which is unique per record.
-        def part(col):
-            return gdf[col].astype("Int64").astype(str)
-
-        gdf["id"] = (
-            part("provincia").str.zfill(2)
-            + "-"
-            + part("municipio")
-            + "-"
-            + part("agregado")
-            + "-"
-            + part("zona")
-            + "-"
-            + part("poligono")
-            + "-"
-            + part("parcela")
-            + "-"
-            + part("recinto")
-            + "-"
-            + part("ld_recinto")
-        )
-        return super().migrate(gdf)
-
     def get_urls(self):
         if self.variant not in self.variants:
             opts = ", ".join(self.variants.keys())
diff --git a/fiboa_cli/datasets/jecam.py b/fiboa_cli/datasets/jecam.py
index 45693ae1..5e27b77c 100644
--- a/fiboa_cli/datasets/jecam.py
+++ b/fiboa_cli/datasets/jecam.py
@@ -48,6 +48,7 @@ class JecamConvert(FiboaBaseConverter):
     column_additions = {
         "crop:code_list": CODE_LIST,
     }
+    column_migrations = {"Irrigated": lambda col: col.astype(bool)}
     extensions = {ADMIN_DIVISION, CROP_EXTENSION}
     missing_schemas = {
         "properties": {
@@ -71,7 +72,4 @@ def migrate(self, gdf) -> gpd.GeoDataFrame:
         # but it should be reconsidered in the future
         # (i.e. the removal of .fillna("").astype(str) )
         gdf["crop:code"] = gdf["CropType1"].map(mapping).fillna("").astype(str)
-
-        gdf.loc[gdf["Area_ha"] == 0, "Area_ha"] = None
-        gdf["Irrigated"] = gdf["Irrigated"].astype(bool)
         return gdf
diff --git a/fiboa_cli/datasets/lv.py b/fiboa_cli/datasets/lv.py
index 8da1a692..325a9f64 100644
--- a/fiboa_cli/datasets/lv.py
+++ b/fiboa_cli/datasets/lv.py
@@ -110,7 +110,7 @@ def get_urls(self):
     def post_migrate(self, gdf):
         gdf = super().post_migrate(gdf)
         # The files carry the code without a name; the code list has it.
-        names = {row["original_code"].strip(): row["original_name"] for row in self.hcat_mapping}
+        names = self.hcat_lookup("original_code", "original_name", strip=True)
         gdf["crop:name"] = self.get_code_column(gdf).str.strip().map(names)
         return gdf
 
diff --git a/fiboa_cli/datasets/nz.py b/fiboa_cli/datasets/nz.py
index 254e903a..8076da0c 100644
--- a/fiboa_cli/datasets/nz.py
+++ b/fiboa_cli/datasets/nz.py
@@ -30,7 +30,10 @@ class NZCropConverter(FiboaBaseConverter):
         "yearmapped": "determination:datetime",
         "Region": "admin:subdivision_code",
     }
-    column_migrations = {"yearmapped": lambda col: pd.to_datetime(col, format="%Y")}
+    column_migrations = {
+        "yearmapped": lambda col: pd.to_datetime(col, format="%Y"),
+        "Region": lambda col: col.map(region_codes()),
+    }
     column_additions = {
         "admin:country_code": "NZ",
     }
@@ -42,9 +45,8 @@ class NZCropConverter(FiboaBaseConverter):
         }
     }
 
-    def migrate(self, gdf):
-        # MAP back; https://www.iso.org/obp/ui/#iso:code:3166:NZ
-        rows = read_data_csv("nz_region_codes.csv")
-        mapping = {row["Subdivision name"]: row["3166-2 code"][len("NZ-") :] for row in rows}
-        gdf["Region"] = gdf["Region"].map(mapping)
-        return super().migrate(gdf)
+
+def region_codes():
+    # MAP back; https://www.iso.org/obp/ui/#iso:code:3166:NZ
+    rows = read_data_csv("nz_region_codes.csv")
+    return {row["Subdivision name"]: row["3166-2 code"][len("NZ-") :] for row in rows}
diff --git a/fiboa_cli/datasets/pl.py b/fiboa_cli/datasets/pl.py
index c32a2cc7..5e522fb9 100644
--- a/fiboa_cli/datasets/pl.py
+++ b/fiboa_cli/datasets/pl.py
@@ -36,8 +36,7 @@ class Converter(AdminConverterMixin, AddHCATMixin, WFSConverterMixin, FiboaBaseC
     columns = {
         "geometry": "geometry",
         "id": "id",  # derived in file_migration()
-        "roslina": "crop:name",
-        "crop:code": "crop:code",  # the name, copied in migrate()
+        "roslina": ["crop:name", "crop:code"],
         "grupa_rosl": "crop_group",
         "gr_upraw": "support_schemes",
         "pow": "metrics:area",
@@ -83,7 +82,3 @@ def file_migration(self, gdf, path, uri, layer=None):
         start = int(match.group(1)) if match else 0
         gdf["id"] = [f"{self.variant}-{start + i + 1}" for i in range(len(gdf))]
         return gdf
-
-    def migrate(self, gdf):
-        gdf["crop:code"] = gdf["roslina"]
-        return super().migrate(gdf)
diff --git a/fiboa_cli/datasets/us_usda_cropland.py b/fiboa_cli/datasets/us_usda_cropland.py
index 79059307..3fd6e58d 100644
--- a/fiboa_cli/datasets/us_usda_cropland.py
+++ b/fiboa_cli/datasets/us_usda_cropland.py
@@ -3,7 +3,7 @@
 from vecorel_cli.conversion.admin import AdminConverterMixin
 
 from ..conversion.fiboa_converter import FiboaBaseConverter
-from .commons.hcat import AddHCATMixin, load_hcat_mapping
+from .commons.hcat import AddHCATMixin
 
 
 class Converter(AdminConverterMixin, AddHCATMixin, FiboaBaseConverter):
@@ -37,7 +37,7 @@ class Converter(AdminConverterMixin, AddHCATMixin, FiboaBaseConverter):
     # so it does hold for every field the group produces.
     columns = {
         "geometry": "geometry",
-        # "CDL2023": "crop:code", will be added in migrate
+        # "CDL<variant>": "crop:code", added in get_columns()
         "crop:name": "crop:name",
         "CNTY": "administrative_area_level_2",
         "CNTYFIPS": "administrative_area_level_2_code",
@@ -59,10 +59,7 @@ def migrate(self, gdf):
         geodataframe.Dissolve(method="unary") is **slow** for large datasets
         So we're handling this huge dataset in blocks, states are a natural grouping-method
         """
-        assert self.variant, "Variant must be set"
-        crop_key = f"CDL{self.variant}"
-        self.columns[crop_key] = "crop:code"
-
+        crop_key = self.crop_key()
         gdf = super().migrate(gdf)
         states = list(gdf["STATEFIPS"].unique())
         gdfs = []
@@ -76,12 +73,15 @@ def migrate(self, gdf):
             gdfs.append(df)
         gdf = pd.concat(gdfs)
         del gdfs
-        if self.hcat_mapping is None:
-            self.hcat_mapping = load_hcat_mapping(self.hcat_mapping_csv, url=self.mapping_file)
-        original_name_mapping = {
-            int(e["original_code"]): e["original_name"] for e in self.hcat_mapping
-        }
-        gdf["crop:name"] = gdf[crop_key].map(original_name_mapping)
+        names = self.hcat_lookup("original_code", "original_name")
+        gdf["crop:name"] = gdf[crop_key].map({int(k): v for k, v in names.items()})
 
         # nothing from the source identifies the dissolved fields; the base numbers them
         return gdf
+
+    def crop_key(self):
+        assert self.variant, "Variant must be set"
+        return f"CDL{self.variant}"
+
+    def get_columns(self, gdf):
+        return super().get_columns(gdf) | {self.crop_key(): "crop:code"}
diff --git a/tests/test_area.py b/tests/test_area.py
index 2fb23430..cf4dcffb 100644
--- a/tests/test_area.py
+++ b/tests/test_area.py
@@ -118,6 +118,24 @@ def test_the_area_of_an_invalid_geometry_is_that_of_the_published_one(tmp_parque
     assert result["metrics:area"].tolist() == pytest.approx(published.tolist(), rel=5e-3)
 
 
+def test_an_area_column_chosen_in_get_columns_is_taken_for_hectares(tmp_parquet_file):
+    def get_columns(self, gdf):
+        columns = FiboaBaseConverter.get_columns(self, gdf)
+        if "AKTUELLEFL" not in gdf.columns:
+            columns["AKT_FL"] = columns.pop("AKTUELLEFL")
+        return columns
+
+    result = _convert(
+        tmp_parquet_file,
+        "EPSG:25832",
+        data={"AKT_FL": [1.5, 2.5]},
+        columns={"AKTUELLEFL": "metrics:area"},
+        get_columns=get_columns,
+    )
+
+    assert result["metrics:area"].tolist() == [15_000, 25_000]
+
+
 def test_opting_out_publishes_no_area(tmp_parquet_file):
     result = _convert(tmp_parquet_file, area_calculate_missing=False)
 
diff --git a/tests/test_converters.py b/tests/test_converters.py
index 094040b3..dabf60ad 100644
--- a/tests/test_converters.py
+++ b/tests/test_converters.py
@@ -225,6 +225,49 @@ class Converter(FiboaBaseConverter):
     assert result["metrics:perimeter"].tolist() == [120.0, 60.0]
 
 
+def test_a_crop_column_chosen_in_get_columns_is_mapped_to_hcat(tmp_folder, tmp_parquet_file):
+    from shapely.geometry import box
+
+    from fiboa_cli.conversion.fiboa_converter import FiboaBaseConverter
+    from fiboa_cli.datasets.commons.hcat import AddHCATMixin
+
+    mapping = tmp_folder / "mapping.csv"
+    mapping.write_text(
+        "original_code,translated_name,HCAT3_name,HCAT3_code\n"
+        "W,Wheat,common_soft_winter_wheat,3301011101\n",
+        encoding="utf-8",
+    )
+
+    class Converter(AddHCATMixin, FiboaBaseConverter):
+        id = "hcat"
+        short_name = "HCAT"
+        title = "HCAT"
+        description = "HCAT"
+        license = "CC0-1.0"
+        columns = {"geometry": "geometry", "id": "id", "CROP": ["crop:code", "crop:name"]}
+
+        def get_columns(self, gdf):
+            columns = super().get_columns(gdf)
+            if "CROP" not in gdf.columns:
+                columns["CROP_OLD"] = columns.pop("CROP")
+            return columns
+
+    gdf = gpd.GeoDataFrame(
+        {"id": ["a"], "CROP_OLD": ["W"]}, geometry=[box(0, 0, 100, 100)], crs="EPSG:25832"
+    )
+    src = tmp_parquet_file.parent / "source.parquet"
+    gdf.to_parquet(src)
+
+    Converter().convert(
+        tmp_parquet_file, input_files={str(src): "source.parquet"}, mapping_file=str(mapping)
+    )
+
+    result = gpd.read_parquet(tmp_parquet_file)
+    assert result["crop:code"].tolist() == ["W"]
+    assert result["crop:name"].tolist() == ["W"]
+    assert result["hcat:code"].tolist() == [3301011101]
+
+
 def _determination_converter(**attrs):
     from fiboa_cli.conversion.fiboa_converter import FiboaBaseConverter