'fertile' achievement now needs using fertilizer

mods/rp_default/achievements.lua

@@ -76,9 +76,9 @@ achievements.register_achievement(
    "fertile",
    {
       title = S("Fertile"),
-      description = S("Craft a bag of fertilizer."),
+      description = S("Use fertilizer to fertilize a plant."),
       times = 1,
-      craftitem = "rp_default:fertilizer",
+      item_icon = "rp_default:fertilizer",
 })
 
 -- Literature

mods/rp_default/fertilizer.lua

@@ -151,6 +151,11 @@ minetest.register_craftitem(
                           " at " .. minetest.pos_to_string(above_soil_pos, 0) .. " with timeout="..timeout.." set from elapsed="..elapsed..
 			  " to elapsed="..new_elapsed)
 	       end
+               if placer and placer:is_player() then
+                  if minetest.get_item_group(above_soil_node.name, "plant") == 1 then
+                     achievements.trigger_achievement(placer, "fertile")
+                  end
+               end
 	    end
          end