diff --git a/CarbonCalculation.cs b/CarbonCalculation.cs
index a549e38..89f5e03 100644
--- a/CarbonCalculation.cs
+++ b/CarbonCalculation.cs
@@ -156,7 +156,7 @@ namespace FarmMapsAPI.Carbon
                                     Crop = cropYear.MiterraCropName,
                                     CropRes = cropYear.CropRes,
                                     OrganicManures =
-                                    cropYear.OrganicManures.Where(y=>y.Quantity > 0 && !string.IsNullOrEmpty(y.Type)).Select(x => new OrganicManureType { Type = x.Type, Quantity = x.Quantity }).ToList(),
+                                    cropYear.OrganicManures.Where(y=>y.Quantity > 0 && !string.IsNullOrEmpty(y.Type)).Select(x => new OrganicManureType { Type = x.Type, Quantity = x.Quantity.HasValue? x.Quantity.Value : 0 }).ToList(),
                                     CropYield = cropYear.CropYield,
                                     Irrigation = crops.Irrigations} }
                             });                            
@@ -171,9 +171,9 @@ namespace FarmMapsAPI.Carbon
                                 {
                                     foreach (var manure in cropYear.OrganicManures)
                                     {
-                                        if (!string.IsNullOrEmpty(manure.Type) && manure.Quantity > 0)
+                                        if (!string.IsNullOrEmpty(manure.Type) && manure.Quantity.HasValue && manure.Quantity > 0)
                                         {
-                                            orgManure.Add(new OrganicManureType { Type = manure.Type, Quantity = manure.Quantity });
+                                            orgManure.Add(new OrganicManureType { Type = manure.Type, Quantity = manure.Quantity.HasValue ? manure.Quantity.Value : 0 });
                                         }
                                     }
                                 }
@@ -244,7 +244,7 @@ namespace FarmMapsAPI.Carbon
             {
                 carbon_organicmatter_factor = 1;
             }
-
+            
             //////////////////////////////////////////////
             // precalculations
             //////////////////////////////////////////////
@@ -276,7 +276,9 @@ namespace FarmMapsAPI.Carbon
                 {
                     soilPropertyDepth10 = true;
                 }
-                //FSA todo: different corrections for depth10 (10, 25, 30 cm)
+                // Different corrections for depth (10, 25, 30 cm)
+                // depth of 10cm has same result as previous checkbox (sample taken at 10cm)
+                parameterSet.LayerDepth = item.Value.Depth.HasValue? item.Value.Depth.Value : parameterSet.LayerDepth;
                 if (initialSoil == "Temp_gras" && soilPropertyDepth10)
                 {
                     oM_corr_SoilType.Add((item.Key, soilOfItem), item.Value.OM_Cont * 0.97);
diff --git a/Models/FarmMapsCarbonRequest.cs b/Models/FarmMapsCarbonRequest.cs
index ce19286..fcd2e29 100644
--- a/Models/FarmMapsCarbonRequest.cs
+++ b/Models/FarmMapsCarbonRequest.cs
@@ -70,7 +70,7 @@ namespace FarmMapsAPI.Carbon.Models
         [Required]
         public string Type { get; set; }
         [Required]
-        public double Quantity { get; set; }
+        public double? Quantity { get; set; }
     }
 
     public class SoilPropertyFarmMaps