diff --git a/app/helpers/champ_helper.rb b/app/helpers/champ_helper.rb
index 7f3df63d2..573a8defe 100644
--- a/app/helpers/champ_helper.rb
+++ b/app/helpers/champ_helper.rb
@@ -6,13 +6,7 @@ module ChampHelper
 
   def geo_data(champ)
     # rubocop:disable Rails/OutputSafety
-    raw({
-      position: champ.position,
-      selection: champ.value.present? ? JSON.parse(champ.value) : [],
-      quartiersPrioritaires: champ.quartiers_prioritaires? ? champ.quartiers_prioritaires.as_json(except: :properties) : [],
-      cadastres: champ.cadastres? ? champ.cadastres.as_json(except: :properties) : [],
-      parcellesAgricoles: champ.parcelles_agricoles? ? champ.parcelles_agricoles.as_json(except: :properties) : []
-    }.to_json)
+    raw(champ.to_render_data.to_json)
     # rubocop:enable Rails/OutputSafety
   end
 end
diff --git a/app/javascript/shared/carte.js b/app/javascript/shared/carte.js
index a9360e829..b026a9fff 100644
--- a/app/javascript/shared/carte.js
+++ b/app/javascript/shared/carte.js
@@ -71,23 +71,23 @@ export function drawParcellesAgricoles(
 }
 
 export function drawUserSelection(map, { selection }, editable = false) {
-  let hasSelection = selection && selection.length > 0;
+  if (selection) {
+    const coordinates = toLatLngs(selection);
 
-  if (editable) {
-    if (hasSelection) {
-      selection.forEach(polygon => map.freeDraw.create(polygon));
-      let polygon = map.freeDraw.all()[0];
+    if (editable) {
+      coordinates.forEach(polygon => map.freeDraw.create(polygon));
+      const polygon = map.freeDraw.all()[0];
       if (polygon) {
         map.fitBounds(polygon.getBounds());
       }
-    }
-  } else if (hasSelection) {
-    const polygon = L.polygon(selection, {
-      color: 'red',
-      zIndex: 3
-    }).addTo(map);
+    } else {
+      const polygon = L.polygon(coordinates, {
+        color: 'red',
+        zIndex: 3
+      }).addTo(map);
 
-    map.fitBounds(polygon.getBounds());
+      map.fitBounds(polygon.getBounds());
+    }
   }
 }
 
@@ -125,6 +125,12 @@ export function addFreeDrawEvents(map, selector) {
   });
 }
 
+function toLatLngs({ coordinates }) {
+  return coordinates.map(polygon =>
+    polygon[0].map(point => ({ lng: point[0], lat: point[1] }))
+  );
+}
+
 function findInput(selector) {
   return typeof selector === 'string'
     ? document.querySelector(selector)
diff --git a/app/models/champs/carte_champ.rb b/app/models/champs/carte_champ.rb
index 7eff98481..8e5c6bb3d 100644
--- a/app/models/champs/carte_champ.rb
+++ b/app/models/champs/carte_champ.rb
@@ -44,24 +44,38 @@ class Champs::CarteChamp < Champ
   end
 
   def geo_json
-    @geo_json ||= value.blank? ? nil : JSON.parse(value)
+    @geo_json ||= begin
+      parsed_value = value.blank? ? nil : JSON.parse(value)
+      # We used to store in the value column a json array with coordinates.
+      if parsed_value.is_a?(Array)
+        # Empty array is sent instead of blank to distinguish between empty and error
+        if parsed_value.empty?
+          nil
+        else
+          # If it is a coordinates array, format it as a GEO-JSON
+          JSON.parse(GeojsonService.to_json_polygon_for_selection_utilisateur(parsed_value))
+        end
+      else
+        # It is already a GEO-JSON
+        parsed_value
+      end
+    end
   end
 
-  def user_geometry
-    # We used to store in the value column a json array with coordinates.
-    if geo_json.is_a?(Array)
-      # If it is a coordinates array, format it as a GEO-JSON
-      GeojsonService.to_json_polygon_for_selection_utilisateur(geo_json)
-    else
-      # It is already a GEO-JSON
-      geo_json
-    end
+  def to_render_data
+    {
+      position: position,
+      selection: geo_json,
+      quartiersPrioritaires: quartiers_prioritaires? ? quartiers_prioritaires.as_json(except: :properties) : [],
+      cadastres: cadastres? ? cadastres.as_json(except: :properties) : [],
+      parcellesAgricoles: parcelles_agricoles? ? parcelles_agricoles.as_json(except: :properties) : []
+    }
   end
 
   def user_geo_area
     if geo_json.present?
       GeoArea.new(
-        geometry: user_geometry,
+        geometry: geo_json,
         source: GeoArea.sources.fetch(:selection_utilisateur)
       )
     end
diff --git a/app/serializers/champ_serializer.rb b/app/serializers/champ_serializer.rb
index c6c30a3f9..c880cf2bb 100644
--- a/app/serializers/champ_serializer.rb
+++ b/app/serializers/champ_serializer.rb
@@ -12,10 +12,10 @@ class ChampSerializer < ActiveModel::Serializer
   def value
     case object
     when GeoArea
-      object.geometry
+      object.geometry.to_json
     when Champs::CarteChamp
-      if object.value.present?
-        JSON.parse(object.value)
+      if object.geo_json.present?
+        object.geo_json.to_json
       end
     when Champs::DecimalNumberChamp
       if object.value.present?
@@ -71,7 +71,7 @@ class ChampSerializer < ActiveModel::Serializer
       libelle: legacy_carto_libelle,
       type_champ: legacy_carto_type_champ,
       order_place: -1,
-      descripton: ''
+      description: ''
     }
   end
 
diff --git a/config/deploy.rb b/config/deploy.rb
index ad139f136..09d6c0ff0 100644
--- a/config/deploy.rb
+++ b/config/deploy.rb
@@ -103,7 +103,7 @@ task :deploy do
     invoke :'bundle:install'
     invoke :'yarn:install'
     invoke :'rails:db_migrate'
-    invoke :'after_party:run'
+    # invoke :'after_party:run'
     invoke :'rails:assets_precompile'
 
     on :launch do
diff --git a/spec/controllers/champs/carte_controller_spec.rb b/spec/controllers/champs/carte_controller_spec.rb
index 6fbbd88e6..a530593eb 100644
--- a/spec/controllers/champs/carte_controller_spec.rb
+++ b/spec/controllers/champs/carte_controller_spec.rb
@@ -41,7 +41,7 @@ describe Champs::CarteController, type: :controller do
         expect(assigns(:error)).to eq(nil)
         expect(champ.reload.value).to eq(nil)
         expect(champ.reload.geo_areas).to eq([])
-        expect(response.body).to include("DS.drawMapData(\".carte-1\", {\"position\":{\"lon\":\"2.428462\",\"lat\":\"46.538192\",\"zoom\":\"13\"},\"selection\":[],\"quartiersPrioritaires\":[],\"cadastres\":[],\"parcellesAgricoles\":[]});")
+        expect(response.body).to include("DS.drawMapData(\".carte-1\", {\"position\":{\"lon\":\"2.428462\",\"lat\":\"46.538192\",\"zoom\":\"13\"},\"selection\":null,\"quartiersPrioritaires\":[],\"cadastres\":[],\"parcellesAgricoles\":[]});")
       }
     end
 
diff --git a/spec/models/champs/carte_champ_spec.rb b/spec/models/champs/carte_champ_spec.rb
new file mode 100644
index 000000000..7c8c6f0cf
--- /dev/null
+++ b/spec/models/champs/carte_champ_spec.rb
@@ -0,0 +1,63 @@
+require 'spec_helper'
+
+describe Champs::CarteChamp do
+  let(:champ) { Champs::CarteChamp.new(value: value) }
+  let(:value) { '' }
+  let(:geo_json) { GeojsonService.to_json_polygon_for_selection_utilisateur(coordinates) }
+  let(:coordinates) { [[{ "lat" => 48.87442541960633, "lng" => 2.3859214782714844 }, { "lat" => 48.87273183590832, "lng" => 2.3850631713867183 }, { "lat" => 48.87081237174292, "lng" => 2.3809432983398438 }, { "lat" => 48.8712640169951, "lng" => 2.377510070800781 }, { "lat" => 48.87510283703279, "lng" => 2.3778533935546875 }, { "lat" => 48.87544154230615, "lng" => 2.382831573486328 }, { "lat" => 48.87442541960633, "lng" => 2.3859214782714844 }]] }
+  let(:parsed_geo_json) { JSON.parse(geo_json) }
+
+  describe '#to_render_data' do
+    subject { champ.to_render_data }
+
+    let(:render_data) {
+      {
+        position: champ.position,
+        selection: selection,
+        cadastres: [],
+        parcellesAgricoles: [],
+        quartiersPrioritaires: []
+      }
+    }
+
+    context 'when the value is nil' do
+      let(:value) { nil }
+
+      let(:selection) { nil }
+
+      it { is_expected.to eq(render_data) }
+    end
+
+    context 'when the value is blank' do
+      let(:value) { '' }
+
+      let(:selection) { nil }
+
+      it { is_expected.to eq(render_data) }
+    end
+
+    context 'when the value is empty array' do
+      let(:value) { '[]' }
+
+      let(:selection) { nil }
+
+      it { is_expected.to eq(render_data) }
+    end
+
+    context 'when the value is coordinates' do
+      let(:value) { coordinates.to_json }
+
+      let(:selection) { parsed_geo_json }
+
+      it { is_expected.to eq(render_data) }
+    end
+
+    context 'when the value is geojson' do
+      let(:value) { geo_json }
+
+      let(:selection) { parsed_geo_json }
+
+      it { is_expected.to eq(render_data) }
+    end
+  end
+end
diff --git a/spec/serializers/champ_serializer_spec.rb b/spec/serializers/champ_serializer_spec.rb
index 1c82e296a..a72cc4fa3 100644
--- a/spec/serializers/champ_serializer_spec.rb
+++ b/spec/serializers/champ_serializer_spec.rb
@@ -1,6 +1,7 @@
 describe ChampSerializer do
   describe '#attributes' do
-    subject { ChampSerializer.new(champ).serializable_hash }
+    subject { ChampSerializer.new(serializable_object).serializable_hash }
+    let(:serializable_object) { champ }
 
     context 'when type champ is piece justificative' do
       include Rails.application.routes.url_helpers
@@ -20,51 +21,167 @@ describe ChampSerializer do
     end
 
     context 'when type champ is carte' do
-      let(:geo_area) { create(:geo_area) }
-      let(:coordinates) { [[{ "lat": 48.87442541960633, "lng": 2.3859214782714844 }, { "lat": 48.87273183590832, "lng": 2.3850631713867183 }, { "lat": 48.87081237174292, "lng": 2.3809432983398438 }, { "lat": 48.8712640169951, "lng": 2.377510070800781 }, { "lat": 48.87510283703279, "lng": 2.3778533935546875 }, { "lat": 48.87544154230615, "lng": 2.382831573486328 }, { "lat": 48.87442541960633, "lng": 2.3859214782714844 }]] }
+      let(:champ) { create(:champ_carte, value: value, geo_areas: [geo_area].compact) }
+      let(:value) { nil }
+      let(:geo_area) { create(:geo_area, geometry: parsed_geo_json) }
+      let(:parsed_geo_json) { JSON.parse(geo_json) }
+      let(:geo_json) { GeojsonService.to_json_polygon_for_selection_utilisateur(coordinates) }
+      let(:coordinates) { [[{ "lat" => 48.87442541960633, "lng" => 2.3859214782714844 }, { "lat" => 48.87273183590832, "lng" => 2.3850631713867183 }, { "lat" => 48.87081237174292, "lng" => 2.3809432983398438 }, { "lat" => 48.8712640169951, "lng" => 2.377510070800781 }, { "lat" => 48.87510283703279, "lng" => 2.3778533935546875 }, { "lat" => 48.87544154230615, "lng" => 2.382831573486328 }, { "lat" => 48.87442541960633, "lng" => 2.3859214782714844 }]] }
 
-      let(:champ_carte) { create(:champ_carte, value: coordinates.to_json, geo_areas: [geo_area]) }
-      let(:champ) { champ_carte }
-
-      context 'legacy champ user_geometry' do
-        let(:champ) { champ_carte.user_geo_area }
-
-        it {
-          expect(subject).to include(
-            type_de_champ: {
-              descripton: "",
-              id: -1,
-              libelle: "user geometry",
-              order_place: -1,
-              type_champ: "user_geometry"
-            },
-            value: champ_carte.user_geometry
-          )
+      let(:serialized_champ) {
+        {
+          type_de_champ: serialized_type_de_champ,
+          value: serialized_value
         }
+      }
+      let(:serialized_type_de_champ) {
+        {
+          description: serialized_description,
+          id: serialized_id,
+          libelle: serialized_libelle,
+          order_place: serialized_order_place,
+          type_champ: serialized_type_champ
+        }
+      }
+      let(:serialized_id) { -1 }
+      let(:serialized_description) { "" }
+      let(:serialized_order_place) { -1 }
+      let(:serialized_value) { geo_json }
+
+      context 'and geo_area is selection_utilisateur' do
+        context 'value is empty' do
+          context 'when value is nil' do
+            let(:value) { nil }
+
+            it { expect(champ.user_geo_area).to be_nil }
+          end
+
+          context 'when value is empty array' do
+            let(:value) { '[]' }
+
+            it { expect(champ.user_geo_area).to be_nil }
+          end
+
+          context 'when value is blank' do
+            let(:value) { '' }
+
+            it { expect(champ.user_geo_area).to be_nil }
+          end
+        end
+
+        context 'old_api' do
+          let(:serialized_libelle) { "user geometry" }
+          let(:serialized_type_champ) { "user_geometry" }
+
+          let(:serializable_object) { champ.user_geo_area }
+
+          context 'when value is coordinates' do
+            let(:value) { coordinates.to_json }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+
+          context 'when value is geojson' do
+            let(:value) { geo_json }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+        end
+
+        context 'new_api' do
+          let(:geo_area) { nil }
+          let(:serialized_champ) {
+            {
+              type_de_champ: serialized_type_de_champ,
+              geo_areas: [],
+              value: serialized_value
+            }
+          }
+          let(:serialized_id) { champ.type_de_champ.stable_id }
+          let(:serialized_description) { champ.description }
+          let(:serialized_order_place) { champ.order_place }
+          let(:serialized_libelle) { champ.libelle }
+          let(:serialized_type_champ) { champ.type_champ }
+
+          context 'when value is coordinates' do
+            let(:value) { coordinates.to_json }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+
+          context 'when value is geojson' do
+            let(:value) { geo_json }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+
+          context 'when value is nil' do
+            let(:value) { nil }
+            let(:serialized_value) { nil }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+
+          context 'when value is empty array' do
+            let(:value) { '[]' }
+            let(:serialized_value) { nil }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+
+          context 'when value is blank' do
+            let(:value) { '' }
+            let(:serialized_value) { nil }
+
+            it { expect(subject).to eq(serialized_champ) }
+          end
+        end
       end
 
       context 'and geo_area is cadastre' do
-        it {
-          expect(subject[:geo_areas].first).to include(
-            source: GeoArea.sources.fetch(:cadastre),
-            numero: '42',
-            feuille: 'A11'
-          )
-          expect(subject[:geo_areas].first.key?(:nom)).to be_falsey
-        }
+        context 'new_api' do
+          it {
+            expect(subject[:geo_areas].first).to include(
+              source: GeoArea.sources.fetch(:cadastre),
+              geometry: parsed_geo_json,
+              numero: '42',
+              feuille: 'A11'
+            )
+            expect(subject[:geo_areas].first.key?(:nom)).to be_falsey
+          }
+        end
+
+        context 'old_api' do
+          let(:serializable_object) { champ.geo_areas.first }
+          let(:serialized_libelle) { "cadastre" }
+          let(:serialized_type_champ) { "cadastre" }
+
+          it { expect(subject).to eq(serialized_champ) }
+        end
       end
 
       context 'and geo_area is quartier_prioritaire' do
-        let(:geo_area) { create(:geo_area, :quartier_prioritaire) }
+        let(:geo_area) { create(:geo_area, :quartier_prioritaire, geometry: parsed_geo_json) }
 
-        it {
-          expect(subject[:geo_areas].first).to include(
-            source: GeoArea.sources.fetch(:quartier_prioritaire),
-            nom: 'XYZ',
-            commune: 'Paris'
-          )
-          expect(subject[:geo_areas].first.key?(:numero)).to be_falsey
-        }
+        context 'new_api' do
+          it {
+            expect(subject[:geo_areas].first).to include(
+              source: GeoArea.sources.fetch(:quartier_prioritaire),
+              geometry: parsed_geo_json,
+              nom: 'XYZ',
+              commune: 'Paris'
+            )
+            expect(subject[:geo_areas].first.key?(:numero)).to be_falsey
+          }
+        end
+
+        context 'old_api' do
+          let(:serializable_object) { champ.geo_areas.first }
+          let(:serialized_libelle) { "quartier prioritaire" }
+          let(:serialized_type_champ) { "quartier_prioritaire" }
+
+          it { expect(subject).to eq(serialized_champ) }
+        end
       end
     end