diff --git a/.changeset/free-onions-rest.md b/.changeset/free-onions-rest.md
new file mode 100644
index 000000000..fd0228b6d
--- /dev/null
+++ b/.changeset/free-onions-rest.md
@@ -0,0 +1,5 @@
+---
+"@svenvw/fdm-app": minor
+---
+
+Users can now edit previously created fertilizer applications, both for individual fields or a given cultivation type.
diff --git a/fdm-app/app/components/blocks/fertilizer-applications/card.tsx b/fdm-app/app/components/blocks/fertilizer-applications/card.tsx
index f6316fba5..e3f6c25e7 100644
--- a/fdm-app/app/components/blocks/fertilizer-applications/card.tsx
+++ b/fdm-app/app/components/blocks/fertilizer-applications/card.tsx
@@ -155,6 +155,8 @@ export function FertilizerApplicationCard({
     const params = useParams()
     const navigation = useNavigation()
     const [isDialogOpen, setIsDialogOpen] = useState(false)
+    const [editedFertilizerApplication, setEditedFertilizerApplication] =
+        useState<FertilizerApplication>()
     const previousNavigationState = useRef(navigation.state)
 
     const b_id_or_b_lu_catalogue = params.b_lu_catalogue || params.b_id
@@ -165,12 +167,18 @@ export function FertilizerApplicationCard({
         fetcher.submit({ p_app_id }, { method: "DELETE" })
     }
 
+    const handleEdit = (fertilizerApplication: FertilizerApplication) => () => {
+        setEditedFertilizerApplication(fertilizerApplication)
+        setIsDialogOpen(true)
+    }
+
     useEffect(() => {
         const wasNotIdle = previousNavigationState.current !== "idle"
         const isIdle = navigation.state === "idle"
 
         if (wasNotIdle && isIdle) {
             setIsDialogOpen(false)
+            setEditedFertilizerApplication(undefined)
         }
 
         previousNavigationState.current = navigation.state
@@ -178,14 +186,51 @@ export function FertilizerApplicationCard({
 
     const fieldFertilizerFormStore = useFieldFertilizerFormStore()
     const savedFormValues =
-        params.b_id_farm &&
-        b_id_or_b_lu_catalogue &&
-        fieldFertilizerFormStore.load(params.b_id_farm, b_id_or_b_lu_catalogue)
+        params.b_id_farm && b_id_or_b_lu_catalogue
+            ? fieldFertilizerFormStore.load(
+                  params.b_id_farm,
+                  b_id_or_b_lu_catalogue,
+              )
+            : null
+
+    // See if the saved form was for updating an existing application.
+    // If so, verify that the user can still edit the application and update the state.
+    const applicationToEdit = savedFormValues?.p_app_id
+        ? fertilizerApplications.find(
+              (app) => app.p_app_id === savedFormValues.p_app_id,
+          )
+        : null
+    useEffect(() => {
+        if (applicationToEdit && !editedFertilizerApplication) {
+            setEditedFertilizerApplication(applicationToEdit)
+        }
+        if (savedFormValues?.p_app_id && !applicationToEdit) {
+            fieldFertilizerFormStore.delete(
+                params.b_id_farm || "",
+                b_id_or_b_lu_catalogue || "",
+            )
+        }
+    }, [
+        applicationToEdit,
+        params.b_id_farm,
+        b_id_or_b_lu_catalogue,
+        savedFormValues,
+        editedFertilizerApplication,
+        fieldFertilizerFormStore.delete,
+    ])
+
     useEffect(() => {
-        if (!isDialogOpen && savedFormValues) {
-            setIsDialogOpen(true)
+        if (savedFormValues && !isDialogOpen) {
+            if (savedFormValues.p_app_id) {
+                // Do not open the form if there is a risk it will create a new application
+                if (applicationToEdit) {
+                    setIsDialogOpen(true)
+                }
+            } else {
+                setIsDialogOpen(true)
+            }
         }
-    }, [isDialogOpen, savedFormValues])
+    }, [savedFormValues, applicationToEdit, isDialogOpen])
 
     const detailCards = constructCards(dose)
 
@@ -197,6 +242,10 @@ export function FertilizerApplicationCard({
             )
         }
 
+        if (!state) {
+            setEditedFertilizerApplication(undefined)
+        }
+
         setIsDialogOpen(state)
     }
 
@@ -206,8 +255,8 @@ export function FertilizerApplicationCard({
                 <CardTitle>
                     <p className="text-lg font-medium">Bemesting</p>
                     <p className="text-sm font-medium text-muted-foreground">
-                        Voeg bemestingen toe, verwijder ze en bekijk de totale
-                        gift per hectare voor verschillende nutriënten
+                        Voeg bemestingen toe, wijzig of verwijder ze en bekijk
+                        de totale gift per hectare voor verschillende nutriënten
                     </p>
                 </CardTitle>
                 <Dialog
@@ -220,11 +269,14 @@ export function FertilizerApplicationCard({
                     <DialogContent className="sm:max-w-[800px]">
                         <DialogHeader>
                             <DialogTitle className="flex flex-row items-center justify-between mr-4">
-                                Bemesting toevoegen
+                                {editedFertilizerApplication
+                                    ? "Bemesting wijzigen"
+                                    : "Bemesting toevoegen"}
                             </DialogTitle>
                             <DialogDescription>
-                                Voeg een nieuwe bemestingstoepassing toe aan het
-                                perceel.
+                                {editedFertilizerApplication
+                                    ? "Wijzig een bemestingtoepassing aan het percel."
+                                    : "Voeg een nieuwe bemestingstoepassing toe aan het perceel."}
                             </DialogDescription>
                         </DialogHeader>
                         <FertilizerApplicationForm
@@ -235,6 +287,7 @@ export function FertilizerApplicationCard({
                             b_id_or_b_lu_catalogue={
                                 b_id_or_b_lu_catalogue || ""
                             }
+                            fertilizerApplication={editedFertilizerApplication}
                         />
                     </DialogContent>
                 </Dialog>
@@ -244,7 +297,7 @@ export function FertilizerApplicationCard({
                     {fertilizerApplications.length > 0 ? (
                         fertilizerApplications.map((application) => (
                             <div
-                                className="grid grid-cols-5 gap-x-3 items-center"
+                                className="grid grid-cols-6 gap-x-3 items-center"
                                 key={application.p_app_id}
                             >
                                 <div className="col-span-2">
@@ -274,6 +327,17 @@ export function FertilizerApplicationCard({
                                         )}
                                     </p>
                                 </div>
+                                <div className="justify-self-end">
+                                    <Button
+                                        variant="secondary"
+                                        disabled={
+                                            fetcher.state === "submitting"
+                                        }
+                                        onClick={handleEdit(application)}
+                                    >
+                                        Wijzig
+                                    </Button>
+                                </div>
                                 <div className="justify-self-end">
                                     <Button
                                         variant="destructive"
diff --git a/fdm-app/app/components/blocks/fertilizer-applications/form.tsx b/fdm-app/app/components/blocks/fertilizer-applications/form.tsx
index 31e3660e8..2f4e939f8 100644
--- a/fdm-app/app/components/blocks/fertilizer-applications/form.tsx
+++ b/fdm-app/app/components/blocks/fertilizer-applications/form.tsx
@@ -1,11 +1,11 @@
 import { zodResolver } from "@hookform/resolvers/zod"
+import type { FertilizerApplication } from "@svenvw/fdm-core"
 import { Plus } from "lucide-react"
 import type { MouseEvent } from "react"
-import { useEffect } from "react"
+import { useEffect, useId } from "react"
 import type { Navigation } from "react-router"
 import { Form, useNavigate, useSearchParams } from "react-router"
 import { RemixFormProvider, useRemixForm } from "remix-hook-form"
-import type { z } from "zod"
 import { useFieldFertilizerFormStore } from "@/app/store/field-fertilizer-form"
 import { Combobox } from "~/components/custom/combobox"
 import { DatePicker } from "~/components/custom/date-picker"
@@ -32,7 +32,11 @@ import {
     TooltipContent,
     TooltipTrigger,
 } from "~/components/ui/tooltip"
-import { FormSchema } from "./formschema"
+import {
+    type FieldFertilizerFormValues,
+    FormSchema,
+    FormSchemaModify,
+} from "./formschema"
 import type { FertilizerOption } from "./types.d"
 
 export function FertilizerApplicationForm({
@@ -41,24 +45,34 @@ export function FertilizerApplicationForm({
     navigation,
     b_id_farm,
     b_id_or_b_lu_catalogue,
+    fertilizerApplication,
 }: {
     options: FertilizerOption[]
     action: string
     navigation: Navigation
     b_id_farm: string
     b_id_or_b_lu_catalogue: string
+    fertilizerApplication: FertilizerApplication
 }) {
     const navigate = useNavigate()
     const [searchParams] = useSearchParams()
-
-    const form = useRemixForm<z.infer<typeof FormSchema>>({
+    const formId = useId()
+    const form = useRemixForm<FieldFertilizerFormValues>({
         mode: "onTouched",
-        resolver: zodResolver(FormSchema),
+        resolver: zodResolver(
+            fertilizerApplication ? FormSchemaModify : FormSchema,
+        ),
         defaultValues: {
-            p_id: undefined,
-            p_app_method: undefined,
-            p_app_amount: undefined,
-            p_app_date: new Date(),
+            p_app_id: fertilizerApplication?.p_app_ids
+                ? fertilizerApplication.p_app_ids.join(",")
+                : fertilizerApplication?.p_app_id,
+            p_id: fertilizerApplication?.p_id,
+            p_app_method: fertilizerApplication?.p_app_method,
+            p_app_amount: undefined, // Handled through an effect due to blank behavior
+            p_app_date: fertilizerApplication?.p_app_date ?? new Date(),
+        },
+        submitConfig: {
+            method: fertilizerApplication ? "PUT" : "POST",
         },
     })
     const p_id = form.watch("p_id")
@@ -66,10 +80,13 @@ export function FertilizerApplicationForm({
     const isSubmitting = navigation.state === "submitting"
 
     useEffect(() => {
-        if (p_id) {
+        if (
+            p_id &&
+            (!fertilizerApplication || fertilizerApplication.p_id !== p_id)
+        ) {
             form.setValue("p_app_method", "")
         }
-    }, [p_id, form.setValue])
+    }, [p_id, fertilizerApplication, form.setValue])
 
     const fieldFertilizerFormStore = useFieldFertilizerFormStore()
 
@@ -97,6 +114,12 @@ export function FertilizerApplicationForm({
         fieldFertilizerFormStore.load,
     ])
 
+    useEffect(() => {
+        if (fertilizerApplication) {
+            form.setValue("p_app_amount", fertilizerApplication.p_app_amount)
+        }
+    }, [fertilizerApplication, form.setValue])
+
     // Change fertilizer selection if the user has added a new fertilizer
     const new_p_id = searchParams.get("p_id")
     useEffect(() => {
@@ -134,7 +157,7 @@ export function FertilizerApplicationForm({
     return (
         <RemixFormProvider {...form}>
             <Form
-                id="formAddFertilizerApplication"
+                id={formId}
                 action={action}
                 onSubmit={form.handleSubmit}
                 method="post"
@@ -270,6 +293,8 @@ export function FertilizerApplicationForm({
                                         <LoadingSpinner />
                                         <span>Opslaan...</span>
                                     </div>
+                                ) : fertilizerApplication ? (
+                                    "Opslaan"
                                 ) : (
                                     "Voeg toe"
                                 )}
diff --git a/fdm-app/app/components/blocks/fertilizer-applications/formschema.tsx b/fdm-app/app/components/blocks/fertilizer-applications/formschema.tsx
index b75e939d9..5aa24ced7 100644
--- a/fdm-app/app/components/blocks/fertilizer-applications/formschema.tsx
+++ b/fdm-app/app/components/blocks/fertilizer-applications/formschema.tsx
@@ -23,3 +23,15 @@ export const FormSchema = z.object({
         invalid_type_error: "Meststof is ongeldig",
     }),
 })
+
+export const FormSchemaModify = FormSchema.extend({
+    p_app_id: z.string({
+        // TODO: Validate against the options that are available
+        required_error: "Bemesting id is verplicht",
+        invalid_type_error: "Bemesting id is ongeldig",
+    }),
+})
+
+export type FieldFertilizerFormValues = z.infer<typeof FormSchema> & {
+    p_app_id?: string | undefined
+}
diff --git a/fdm-app/app/routes/farm.$b_id_farm.$calendar.field.$b_id.fertilizer._index.tsx b/fdm-app/app/routes/farm.$b_id_farm.$calendar.field.$b_id.fertilizer._index.tsx
index f97d614da..c33282a1e 100644
--- a/fdm-app/app/routes/farm.$b_id_farm.$calendar.field.$b_id.fertilizer._index.tsx
+++ b/fdm-app/app/routes/farm.$b_id_farm.$calendar.field.$b_id.fertilizer._index.tsx
@@ -6,6 +6,7 @@ import {
     getFertilizers,
     getField,
     removeFertilizerApplication,
+    updateFertilizerApplication,
 } from "@svenvw/fdm-core"
 import {
     type ActionFunctionArgs,
@@ -16,7 +17,10 @@ import {
 } from "react-router"
 import { dataWithError, dataWithSuccess } from "remix-toast"
 import { FertilizerApplicationCard } from "~/components/blocks/fertilizer-applications/card"
-import { FormSchema } from "~/components/blocks/fertilizer-applications/formschema"
+import {
+    FormSchema,
+    FormSchemaModify,
+} from "~/components/blocks/fertilizer-applications/formschema"
 import { getSession } from "~/lib/auth.server"
 import { getTimeframe } from "~/lib/calendar"
 import { clientConfig } from "~/lib/config"
@@ -209,6 +213,37 @@ export async function action({ request, params }: ActionFunctionArgs) {
             )
         }
 
+        if (request.method === "PUT") {
+            // Collect form entry
+            const formValues = await extractFormValuesFromRequest(
+                request,
+                FormSchemaModify,
+            )
+            const { p_app_id, p_id, p_app_amount, p_app_date, p_app_method } =
+                formValues
+
+            if (!p_app_id || typeof p_app_id !== "string") {
+                return dataWithError(
+                    "Invalid or missing p_app_id value",
+                    "Helaas, er is wat misgegaan. Probeer het later opnieuw of neem contact op met ondersteuning.",
+                )
+            }
+
+            await updateFertilizerApplication(
+                fdm,
+                session.principal_id,
+                p_app_id,
+                p_id,
+                p_app_amount,
+                p_app_method,
+                p_app_date,
+            )
+
+            return dataWithSuccess("Date edited successfully", {
+                message: "Bemesting is gewijzigd",
+            })
+        }
+
         if (request.method === "DELETE") {
             const formData = await request.formData()
             const p_app_id = formData.get("p_app_id")
@@ -216,7 +251,7 @@ export async function action({ request, params }: ActionFunctionArgs) {
             if (!p_app_id || typeof p_app_id !== "string") {
                 return dataWithError(
                     "Invalid or missing p_app_id value",
-                    "Oops! Something went wrong. Please try again later.",
+                    "Helaas, er is wat misgegaan. Probeer het later opnieuw of neem contact op met ondersteuning.",
                 )
             }
 
diff --git a/fdm-app/app/routes/farm.create.$b_id_farm.$calendar.fertilizers.$b_lu_catalogue._index.tsx b/fdm-app/app/routes/farm.create.$b_id_farm.$calendar.fertilizers.$b_lu_catalogue._index.tsx
index 99817a2c7..cc1417153 100644
--- a/fdm-app/app/routes/farm.create.$b_id_farm.$calendar.fertilizers.$b_lu_catalogue._index.tsx
+++ b/fdm-app/app/routes/farm.create.$b_id_farm.$calendar.fertilizers.$b_lu_catalogue._index.tsx
@@ -5,6 +5,7 @@ import {
     getFertilizerParametersDescription,
     getFertilizers,
     removeFertilizerApplication,
+    updateFertilizerApplication,
 } from "@svenvw/fdm-core"
 import {
     type ActionFunctionArgs,
@@ -15,7 +16,10 @@ import {
 } from "react-router"
 import { dataWithSuccess } from "remix-toast"
 import { FertilizerApplicationCard } from "~/components/blocks/fertilizer-applications/card"
-import { FormSchema } from "~/components/blocks/fertilizer-applications/formschema"
+import {
+    FormSchema,
+    FormSchemaModify,
+} from "~/components/blocks/fertilizer-applications/formschema"
 import { getSession } from "~/lib/auth.server"
 import { getTimeframe } from "~/lib/calendar"
 import { clientConfig } from "~/lib/config"
@@ -67,6 +71,15 @@ export async function loader({ request, params }: LoaderFunctionArgs) {
         session.principal_id,
         b_id_farm,
     )
+
+    // Map fertilizer catalogue ids to their farm fertilizer acquiring ids
+    const fertilizerAcquiringIds: Record<string, string> = {}
+    for (const fertilizer of fertilizers) {
+        if (fertilizer.p_id_catalogue) {
+            fertilizerAcquiringIds[fertilizer.p_id_catalogue] = fertilizer.p_id
+        }
+    }
+
     const fertilizerParameterDescription = getFertilizerParametersDescription()
     const applicationMethods = fertilizerParameterDescription.find(
         (x: { parameter: string }) => x.parameter === "p_app_method_options",
@@ -126,7 +139,13 @@ export async function loader({ request, params }: LoaderFunctionArgs) {
                     existingApplication.p_app_ids.push(app.p_app_id)
                 } else {
                     // If it's a new application, add it to the accumulator with a new p_app_ids array.
-                    accumulator.push({ ...app, p_app_ids: [app.p_app_id] })
+                    accumulator.push({
+                        ...app,
+                        p_id:
+                            fertilizerAcquiringIds[app.p_id_catalogue] ??
+                            app.p_id_catalogue,
+                        p_app_ids: [app.p_app_id],
+                    })
                 }
             })
 
@@ -229,6 +248,37 @@ export async function action({ request, params }: ActionFunctionArgs) {
                 { message: "Bemesting is toegevoegd! 🎉" },
             )
         }
+        if (request.method === "PUT") {
+            const formValues = await extractFormValuesFromRequest(
+                request,
+                FormSchemaModify,
+            )
+            const rawAppIds = formValues.p_app_id
+
+            if (!rawAppIds || typeof rawAppIds !== "string") {
+                throw new Error("invalid: p_app_id")
+            }
+
+            const p_app_ids = rawAppIds.split(",")
+
+            const { p_id, p_app_amount, p_app_date, p_app_method } = formValues
+
+            await Promise.all(
+                p_app_ids.map((p_app_id: string) =>
+                    updateFertilizerApplication(
+                        fdm,
+                        session.principal_id,
+                        p_app_id,
+                        p_id,
+                        p_app_amount,
+                        p_app_method,
+                        p_app_date,
+                    ),
+                ),
+            )
+
+            return dataWithSuccess({}, { message: "Bemesting is gewijzigd" })
+        }
         if (request.method === "DELETE") {
             const formData = await request.formData()
             const rawAppIds = formData.get("p_app_id")
diff --git a/fdm-app/app/store/field-fertilizer-form.tsx b/fdm-app/app/store/field-fertilizer-form.tsx
index f716042cc..75dedf5f7 100644
--- a/fdm-app/app/store/field-fertilizer-form.tsx
+++ b/fdm-app/app/store/field-fertilizer-form.tsx
@@ -1,9 +1,7 @@
-import type { z } from "zod"
 import { create } from "zustand"
 import { createJSONStorage, persist } from "zustand/middleware"
-import type { FormSchema } from "~/components/blocks/fertilizer-applications/formschema"
+import type { FieldFertilizerFormValues } from "~/components/blocks/fertilizer-applications/formschema"
 
-type FieldFertilizerFormValues = z.infer<typeof FormSchema>
 interface FieldFertilizerFormStore {
     db: Record<string, Partial<FieldFertilizerFormValues>>
     save(