diff --git a/CHANGELOG.md b/CHANGELOG.md
index 111bbcfe..dfa7cd44 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,9 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-
 ## [UNRELEASED]
 
+### Fixed
+- Add datetime: null when an item has start_datetime and end_datetime but no datetime. Fixes (#158)
+
+
 ##[v0.9.9]
 
 ### Changed
diff --git a/src/pgstac/sql/001a_jsonutils.sql b/src/pgstac/sql/001a_jsonutils.sql
index 9fcb2375..2ff94ac6 100644
--- a/src/pgstac/sql/001a_jsonutils.sql
+++ b/src/pgstac/sql/001a_jsonutils.sql
@@ -108,12 +108,7 @@ BEGIN
     THEN
         RETURN j;
     ELSE
-        includes := includes || (
-            CASE WHEN j ? 'collection' THEN
-                '["id","collection"]'
-            ELSE
-                '["id"]'
-            END)::jsonb;
+        includes := includes || '["id","collection"]'::jsonb;
         FOR path IN SELECT explode_dotpaths(includes) LOOP
             outj := jsonb_set_nested(outj, path, j #> path);
         END LOOP;
@@ -151,21 +146,19 @@ CREATE OR REPLACE FUNCTION merge_jsonb(_a jsonb, _b jsonb) RETURNS jsonb AS $$
     SELECT
     CASE
         WHEN _a = '"𒍟※"'::jsonb THEN NULL
-        WHEN _a IS NULL OR jsonb_typeof(_a) = 'null' THEN _b
+        WHEN _a IS NULL THEN _b
         WHEN jsonb_typeof(_a) = 'object' AND jsonb_typeof(_b) = 'object' THEN
             (
-                SELECT
-                    jsonb_strip_nulls(
-                        jsonb_object_agg(
-                            key,
-                            merge_jsonb(a.value, b.value)
-                        )
-                    )
-                FROM
-                    jsonb_each(coalesce(_a,'{}'::jsonb)) as a
-                FULL JOIN
-                    jsonb_each(coalesce(_b,'{}'::jsonb)) as b
-                USING (key)
+                SELECT jsonb_object_agg(key, val)
+                FROM (
+                    SELECT key, merge_jsonb(a.value, b.value) AS val
+                    FROM
+                        jsonb_each(coalesce(_a,'{}'::jsonb)) as a
+                    FULL JOIN
+                        jsonb_each(coalesce(_b,'{}'::jsonb)) as b
+                    USING (key)
+                ) sub
+                WHERE val IS NOT NULL
             )
         WHEN
             jsonb_typeof(_a) = 'array'
@@ -196,18 +189,16 @@ CREATE OR REPLACE FUNCTION strip_jsonb(_a jsonb, _b jsonb) RETURNS jsonb AS $$
         WHEN _a = _b THEN NULL
         WHEN jsonb_typeof(_a) = 'object' AND jsonb_typeof(_b) = 'object' THEN
             (
-                SELECT
-                    jsonb_strip_nulls(
-                        jsonb_object_agg(
-                            key,
-                            strip_jsonb(a.value, b.value)
-                        )
-                    )
-                FROM
-                    jsonb_each(_a) as a
-                FULL JOIN
-                    jsonb_each(_b) as b
-                USING (key)
+                SELECT jsonb_object_agg(key, val)
+                FROM (
+                    SELECT key, strip_jsonb(a.value, b.value) AS val
+                    FROM
+                        jsonb_each(_a) as a
+                    FULL JOIN
+                        jsonb_each(_b) as b
+                    USING (key)
+                ) sub
+                WHERE val IS NOT NULL
             )
         WHEN
             jsonb_typeof(_a) = 'array'
diff --git a/src/pgstac/tests/basic/hydration.sql b/src/pgstac/tests/basic/hydration.sql
new file mode 100644
index 00000000..88508762
--- /dev/null
+++ b/src/pgstac/tests/basic/hydration.sql
@@ -0,0 +1,23 @@
+-- Test that JSON null values survive the dehydrate/hydrate round-trip
+SET ROLE pgstac_ingest;
+
+-- Setup: collection with empty base_item
+INSERT INTO collections (content) VALUES ('{"id":"pgstactest-hydration"}');
+
+-- Create item with explicit datetime:null (STAC-compliant temporal range)
+SELECT create_item('{
+    "id": "temporal-range-item",
+    "collection": "pgstactest-hydration",
+    "geometry": {"type": "Point", "coordinates": [0, 0]},
+    "properties": {
+        "datetime": null,
+        "start_datetime": "2026-01-01T00:00:00Z",
+        "end_datetime": "2026-01-31T23:00:00Z"
+    }
+}');
+
+-- Verify datetime:null is preserved in stored content
+SELECT content->'properties'->'datetime' FROM items WHERE id='temporal-range-item';
+
+-- Verify datetime:null is preserved after hydration
+SELECT get_item('temporal-range-item', 'pgstactest-hydration')->'properties'->'datetime';
diff --git a/src/pgstac/tests/basic/hydration.sql.out b/src/pgstac/tests/basic/hydration.sql.out
new file mode 100644
index 00000000..cbdc12a1
--- /dev/null
+++ b/src/pgstac/tests/basic/hydration.sql.out
@@ -0,0 +1,25 @@
+-- Test that JSON null values survive the dehydrate/hydrate round-trip
+SET ROLE pgstac_ingest;
+SET
+-- Setup: collection with empty base_item
+INSERT INTO collections (content) VALUES ('{"id":"pgstactest-hydration"}');
+INSERT 0 1
+-- Create item with explicit datetime:null (STAC-compliant temporal range)
+SELECT create_item('{
+    "id": "temporal-range-item",
+    "collection": "pgstactest-hydration",
+    "geometry": {"type": "Point", "coordinates": [0, 0]},
+    "properties": {
+        "datetime": null,
+        "start_datetime": "2026-01-01T00:00:00Z",
+        "end_datetime": "2026-01-31T23:00:00Z"
+    }
+}');
+
+-- Verify datetime:null is preserved in stored content
+SELECT content->'properties'->'datetime' FROM items WHERE id='temporal-range-item';
+ null
+
+-- Verify datetime:null is preserved after hydration
+SELECT get_item('temporal-range-item', 'pgstactest-hydration')->'properties'->'datetime';
+ null
diff --git a/src/pgstac/tests/pgtap/003_items.sql b/src/pgstac/tests/pgtap/003_items.sql
index ddebf80a..c4efdcac 100644
--- a/src/pgstac/tests/pgtap/003_items.sql
+++ b/src/pgstac/tests/pgtap/003_items.sql
@@ -52,3 +52,22 @@ SELECT results_eq($$
     $$,
     'Test delete_item function'
 );
+
+-- merge_jsonb and strip_jsonb must preserve JSON null values
+SELECT results_eq(
+    $$ SELECT merge_jsonb(
+        '{"properties": {"datetime": null, "start_datetime": "2026-01-01T00:00:00Z", "end_datetime": "2026-01-31T23:00:00Z"}}'::jsonb,
+        '{"properties": {}}'::jsonb
+    )->'properties'->'datetime' $$,
+    $$ SELECT 'null'::jsonb $$,
+    'merge_jsonb preserves explicit JSON null values'
+);
+
+SELECT results_eq(
+    $$ SELECT strip_jsonb(
+        '{"properties": {"datetime": null, "start_datetime": "2026-01-01T00:00:00Z", "end_datetime": "2026-01-31T23:00:00Z"}}'::jsonb,
+        '{"properties": {}}'::jsonb
+    )->'properties'->'datetime' $$,
+    $$ SELECT 'null'::jsonb $$,
+    'strip_jsonb preserves explicit JSON null values'
+);