diff --git a/Models/FarmMapsCarbonRequest.cs b/Models/FarmMapsCarbonRequest.cs
index dc925ac..7eeabfe 100644
--- a/Models/FarmMapsCarbonRequest.cs
+++ b/Models/FarmMapsCarbonRequest.cs
@@ -13,7 +13,7 @@ namespace FarmMapsAPI.Carbon.Models
 {
     public class FarmMapsCarbonRequest
     {
-        public int? ModelYear { get; set; }
+        public string ModelYear { get; set; }
         public string ScenarioName { get; set; }
         public int PostalCode { get; set; }