diff --git a/src/crop/almass.jl b/src/crop/almass.jl
index 68d60eb4759a4b54aa8aab6593a7e54e89453323..4c7dff6d4ce2b19b292679f49c3b6e4812e24ef2 100644
--- a/src/crop/almass.jl
+++ b/src/crop/almass.jl
@@ -91,8 +91,8 @@ end
 croptype(cs::CropState) = cs.croptype
 cropname(cs::CropState) = cropname(croptype(cs))
 cropheight(cs::CropState) = cs.height
-cropcover(cs::CropState) = 0.0
-cropyield(cs::CropState) = 0.0
+cropcover(cs::CropState) = 0.0  # TODO: related to LAItotal, LAIgreen?
+cropyield(cs::CropState) = 0.0  # TODO: units? needs biomass?
 
 """
     Base.tryparse(type, str)
diff --git a/src/crop/simplecrop.jl b/src/crop/simplecrop.jl
index d7b61b21f4f764b24a371074784f0531f93741d2..c653390c49d5ee5c80b2c6f5ca58a0007df2d32f 100644
--- a/src/crop/simplecrop.jl
+++ b/src/crop/simplecrop.jl
@@ -29,7 +29,7 @@ croptype(cs::CropState) = cs.croptype
 cropname(cs::CropState) = cropname(croptype(cs))
 cropheight(cs::CropState) = cs.height
 cropcover(cs::CropState) = 0.0
-cropyield(cs::CropState) = 0.0
+cropyield(cs::CropState) = 0.0  # TODO: units?
 
 
 """