Agent guidance — Field boundaries for Lower Saxony / Bremen / Hamburg, Germany

Germany, Lower Saxony/Bremen/Hamburg (parcels) field boundaries in the fiboa schema, 1 edition (2026). Every claim below is quoted from the source, the converter, or measured from the published files; each query was run before it was written down, and its output follows it as comments.

Access

• Latest edition, stable path: https://data.source.coop/ftw/harmonized-field-data/de_nds_block/latest/de_nds_block.parquet
• One edition: https://data.source.coop/ftw/harmonized-field-data/de_nds_block/year=<year>/<file>.parquet, e.g. https://data.source.coop/ftw/harmonized-field-data/de_nds_block/year=2026/de_nds_block.parquet
• All editions (hive partitioned): s3://ftw/harmonized-field-data/de_nds_block/year=*/*.parquet — the S3 form of the same prefix through the Source Cooperative proxy, because * needs a listing that plain https does not provide. In DuckDB: CREATE SECRET sc (TYPE s3, PROVIDER config, ENDPOINT 'data.source.coop', URL_STYLE 'path', REGION 'us-west-2'); then read_parquet(glob, hive_partitioning = true) adds the year column. No credentials are needed.
• PMTiles for maps: https://data.source.coop/ftw/harmonized-field-data/de_nds_block/year=2026/de_nds_block.pmtiles, layer de_nds_block; MapLibre styles in styles/.

Quirks that produce silently wrong answers

• CRS is EPSG:25832, not WGS84. ST_Area/ST_Distance return units of that CRS; transform with ST_Transform if you need lon/lat, or use metrics:area.
• metrics:area is in square metres, taken from the source column FLAECHE (hectares × 10 000). Divide by 10 000 for hectares.
• year is the edition, not the observation date. It is the year of the source publication (the converter variant). determination:datetime, where present, is the source's own date for a field.
• id is only guaranteed unique within one edition (fiboa requires uniqueness per file; it is the source column FLIK). Whether an id persists across editions is not verified here; do not join editions on it without checking.
• Some fiboa properties are not columns. Values constant for the whole file are stored once in the GeoParquet collection key-value metadata: ant_jahr = 2026, admin:country_code = DE, admin:subdivision_code = NI (2026 edition). Read them with parquet_kv_metadata() in DuckDB or pyarrow.parquet.ParquetFile(f).schema_arrow.metadata[b'collection']; they differ per edition where the source does.

Tested queries

Fields and hectares per edition, through the partition glob:

Fields around a point, transforming the point into the data's CRS instead of the data into WGS84:

Related collections

Every collection in this catalog shares the fiboa core columns, so the same queries work across countries; s3://ftw/harmonized-field-data/*/latest/*.parquet with union_by_name = true reads the newest edition of all of them (see the catalog AGENTS.md).

Structure

Assets and structural links resolve relative to the object that carries them; there is no self link. Source: this collection is generated by tools/catalogize.py in the catalog repository — fix documentation there.