aw3831: fix yield with decimal

Models/FarmMapsCarbonRequest.cs

@@ -54,11 +54,13 @@ namespace FarmMapsAPI.Carbon.Models
 
     public class CropData
     {
+        double? yield;
+
         [Required]
         public string CropCode { get; set; }
         public string MiterraCropName { get; set; }
         public List<OrganicManureFarmMaps> OrganicManures { get; set; }
-        public int? CropYield { get; set; }
+        public double? CropYield { get { return (int?)yield; } set { yield = value; } }
         public bool CropRes { get; set; }
     }