diff --git a/backend/apps/fertilizer/migrations/0004_fertilizationplan_calc_settings.py b/backend/apps/fertilizer/migrations/0004_fertilizationplan_calc_settings.py
new file mode 100644
index 0000000..ba475e4
--- /dev/null
+++ b/backend/apps/fertilizer/migrations/0004_fertilizationplan_calc_settings.py
@@ -0,0 +1,16 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('fertilizer', '0003_distributionplan_distributiongroup_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='fertilizationplan',
+            name='calc_settings',
+            field=models.JSONField(blank=True, default=list, verbose_name='計算設定'),
+        ),
+    ]
diff --git a/backend/apps/fertilizer/models.py b/backend/apps/fertilizer/models.py
index b50da4c..e758521 100644
--- a/backend/apps/fertilizer/models.py
+++ b/backend/apps/fertilizer/models.py
@@ -34,6 +34,7 @@ class FertilizationPlan(models.Model):
         'plans.Variety', on_delete=models.PROTECT,
         related_name='fertilization_plans', verbose_name='品種'
     )
+    calc_settings = models.JSONField(default=list, blank=True, verbose_name='計算設定')
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)
 
diff --git a/backend/apps/fertilizer/serializers.py b/backend/apps/fertilizer/serializers.py
index 7308b07..02e4191 100644
--- a/backend/apps/fertilizer/serializers.py
+++ b/backend/apps/fertilizer/serializers.py
@@ -31,7 +31,7 @@ class FertilizationPlanSerializer(serializers.ModelSerializer):
         model = FertilizationPlan
         fields = [
             'id', 'name', 'year', 'variety', 'variety_name', 'crop_name',
-            'entries', 'field_count', 'fertilizer_count', 'created_at', 'updated_at'
+            'calc_settings', 'entries', 'field_count', 'fertilizer_count', 'created_at', 'updated_at'
         ]
 
     def get_variety_name(self, obj):
@@ -53,7 +53,7 @@ class FertilizationPlanWriteSerializer(serializers.ModelSerializer):
 
     class Meta:
         model = FertilizationPlan
-        fields = ['id', 'name', 'year', 'variety', 'entries']
+        fields = ['id', 'name', 'year', 'variety', 'calc_settings', 'entries']
 
     def create(self, validated_data):
         entries_data = validated_data.pop('entries', [])
diff --git a/frontend/src/app/fertilizer/_components/FertilizerEditPage.tsx b/frontend/src/app/fertilizer/_components/FertilizerEditPage.tsx
index 1701ef9..0b2d029 100644
--- a/frontend/src/app/fertilizer/_components/FertilizerEditPage.tsx
+++ b/frontend/src/app/fertilizer/_components/FertilizerEditPage.tsx
@@ -91,7 +91,13 @@ export default function FertilizerEditPage({ planId }: { planId?: number }) {
           const fertIds = Array.from(new Set(plan.entries.map((e) => e.fertilizer)));
           const ferts = fertsRes.data.filter((f: Fertilizer) => fertIds.includes(f.id));
           setPlanFertilizers(ferts);
-          setCalcSettings(ferts.map((f: Fertilizer) => ({ fertilizer_id: f.id, method: 'per_tan' as CalcMethod, param: '' })));
+          // 保存済み計算設定を復元、なければデフォルト値
+          setCalcSettings(ferts.map((f: Fertilizer) => {
+            const saved = plan.calc_settings?.find((s) => s.fertilizer_id === f.id);
+            return saved
+              ? { fertilizer_id: f.id, method: saved.method as CalcMethod, param: saved.param }
+              : { fertilizer_id: f.id, method: 'per_tan' as CalcMethod, param: '' };
+          }));
 
           const fieldIds = Array.from(new Set(plan.entries.map((e) => e.field)));
           const fields = fieldsRes.data.filter((f: Field) => fieldIds.includes(f.id));
@@ -172,17 +178,29 @@ export default function FertilizerEditPage({ planId }: { planId?: number }) {
     setAdjusted((prev) => { const next = { ...prev }; delete next[id]; return next; });
   };
 
+  const [calcNewOnly, setCalcNewOnly] = useState(true);
+
   // ─── 自動計算
   const runCalc = async (setting: CalcSetting) => {
     if (!setting.param) return alert('パラメータを入力してください');
     if (selectedFields.length === 0) return alert('対象圃場を選択してください');
 
+    const targetFields = calcNewOnly
+      ? selectedFields.filter((f) => {
+          const hasAdjusted = adjusted[f.id]?.[setting.fertilizer_id] !== undefined;
+          const hasCalc = calcMatrix[f.id]?.[setting.fertilizer_id] !== undefined;
+          return !hasAdjusted && !hasCalc;
+        })
+      : selectedFields;
+
+    if (targetFields.length === 0) return alert('未入力の圃場がありません。「全圃場」で実行してください。');
+
     try {
       const res = await api.post('/fertilizer/calculate/', {
         method: setting.method,
         param: parseFloat(setting.param),
         fertilizer_id: setting.fertilizer_id,
-        field_ids: selectedFields.map((f) => f.id),
+        field_ids: targetFields.map((f) => f.id),
       });
       const results: { field_id: number; bags: number }[] = res.data;
 
@@ -311,7 +329,7 @@ export default function FertilizerEditPage({ planId }: { planId?: number }) {
 
     setSaving(true);
     try {
-      const payload = { name, year, variety: varietyId, entries };
+      const payload = { name, year, variety: varietyId, calc_settings: calcSettings, entries };
       if (isNew) {
         await api.post('/fertilizer/plans/', payload);
       } else {
@@ -481,12 +499,23 @@ export default function FertilizerEditPage({ planId }: { planId?: number }) {
         <div className="bg-white rounded-lg shadow p-4 mb-4">
           <div className="flex items-center justify-between mb-3">
             <h2 className="text-sm font-semibold text-gray-700">自動計算設定</h2>
-            <button
-              onClick={() => setShowFertPicker(true)}
-              className="flex items-center gap-1 text-xs text-green-600 hover:text-green-800 border border-green-300 rounded px-2 py-1"
-            >
-              <Plus className="h-3 w-3" />肥料を追加
-            </button>
+            <div className="flex items-center gap-3">
+              <label className="flex items-center gap-1.5 text-xs text-gray-600 cursor-pointer select-none">
+                <input
+                  type="checkbox"
+                  checked={calcNewOnly}
+                  onChange={(e) => setCalcNewOnly(e.target.checked)}
+                  className="rounded border-gray-300 text-blue-600 focus:ring-blue-500"
+                />
+                未入力圃場のみ
+              </label>
+              <button
+                onClick={() => setShowFertPicker(true)}
+                className="flex items-center gap-1 text-xs text-green-600 hover:text-green-800 border border-green-300 rounded px-2 py-1"
+              >
+                <Plus className="h-3 w-3" />肥料を追加
+              </button>
+            </div>
           </div>
           {planFertilizers.length === 0 ? (
             <p className="text-sm text-gray-400">肥料を追加してください</p>
diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
index b722e9f..82229ba 100644
--- a/frontend/src/types/index.ts
+++ b/frontend/src/types/index.ts
@@ -84,6 +84,7 @@ export interface FertilizationPlan {
   variety: number;
   variety_name: string;
   crop_name: string;
+  calc_settings: { fertilizer_id: number; method: string; param: string }[];
   entries: FertilizationEntry[];
   field_count: number;
   fertilizer_count: number;