Code (Text):

1.  
2. on place of haybale:
3.   Set {_loc} to location of block above event-block
4.   add {_loc} to {HayLocs.%player%::*}
5.  
6. on place of dried kelp block:
7.   Set {_loc} to location of block above event-block
8.   add {_loc} to {KelpLocs.%player%::*}
9.  
10. on mine of dried kelp block:
11.   Set {_loc} to location of block above event-block
12.   remove {_loc} from {KelpLocs.%player%::*}
13.  
14. on mine of hay bale block:
15.   Set {_loc} to location of block above event-block
16.   remove {_loc} from {HayLocs.%player%::*}
17.  
18. every 80 ticks:
19.   loop all players:
20.     loop {HayLocs.%loop-player%::*}:
21.       drop 1 wheat at {HayLocs.%loop-player%::%loop-number%}
22.     loop {KelpLocs.%loop-player%::*}:
23.       drop 1 dried kelp block at {KelpLocs.%loop-player%::%loop-number%}
24.  

I think that this will work
Im sorry, but i dont know what to do with any of the commands, as they aren't needed for you described.