How about Genesis Wave? You can get a lot of cards off of that. I also suggest to take out the fogs for more Arbor Elf, Voyaging Satyr, and Utopia Sprawl. It's better to get more mana so you can kill faster, than to at best stall until the next turn where you'll still die.

Isn't Primal Surge a cheaper, better version of Genesis Wave?

Primal Surge is unreliable in that it WILL run into a sorcery/instant at some point. With 5 other non permanents in your deck, you'll probably only get 10 cards on average. It can get less, it can get more, but it is less reliable than Genesis Wave. Once you have a lot of mana, genesis wave is much better. Genesis wave can also be cast earlier in the game for ramping if needed.

That is true. I'll test the deck with Genesis Wave in place of Primal Surge and see which works better but Primal Surge is working very well as 10 cards is quite a lot.

Just a thought, you may not want to change the balance of this deck that much, but I always liked the idea of using Omnath, Locus of Mana in mono green ramp decks that had cards with (X) in the cost. Having the mana overflow from previous turns of tapping out all your lands is great (though he'll probably be Murder'd pretty quick). He can also be an excellent blocker while you're storing mana to ramp up to something bigger, and forces your opponent to either spend removal to deal with him, or risk you utterly destroying them with a massive mana dump into hydras or an eldrazi titan.

Trenditon, I did have him in there but I was using all my mana up every turn anyway. He was usually only a 2/2 or 1/1. I've found I just need to get 10 mana as quick as possible so I can play Primal Surge and get out my entire deck in one go or play Ulamog or Kosilek.