Return yield in harvest!

src/crop/almass.jl

@@ -132,10 +132,6 @@ part of a `FarmPlot`.
     events::Vector{Management} = Management[]
     mature::Bool = false  #TODO how do we determine this?
 
-    # biomass::Float64 #XXX I need to figure out how to calculate this
-    # height::Length{Float64}
-    # growingdegreedays::Float64
-
     phase::GrowthPhase
     vegddegs::Float64 = 0   # Vegetation growing degree days since sowing
     ddegs::Float64 = 0      # Growing degree days in current phase
@@ -840,7 +836,7 @@ function harvest!(cs::CropState, model::SimulationModel)
     setphase!(cs, phase, model)
     cs.mature = false
     # height & LAI will be automatically adjusted by the growth function
-    #TODO calculate and return yield
+    return cs.veg_biomass  # TODO: units ok of cs.veg_biomass ?
 end
 
 #TODO fertilise!()