Activate Arbor Elf by tapping it, untapping the enchanted forest.
Activate the Forest by tapping it, adding {U}{G}.
Activate Freed from the Real by paying {U}, untapping Arbor Elf.
Repeat.

Infinite colored mana

Arbor Elf

Fertile Ground

Freed from the Real

Activate the land with Fertile Ground attached, adding at least {1}.
Fertile Ground triggers, adding {U}.
Activate Clever Conjurer by tapping it, untapping the land.
Activate Freed from the Real's second ability by paying {U}, untapping Clever Conjurer.
Repeat.

Infinite mana lands you control can produce

Infinite mana permanents you control can produce

Clever Conjurer

Activate the land with Fertile Ground attached, adding at least {1}.
Fertile Ground triggers, adding {U}.
Activate Clever Conjurer by tapping it, untapping the land.
Activate Pemmin's Aura's first ability by paying {U}, untapping Clever Conjurer.
Repeat.

Pemmin's Aura

Activate the enchanted land by tapping it, adding {1}.
Fertile Ground triggers, adding an additional {1}.
Activate Earthcraft by tapping an untapped creature, untapping the enchanted land.
Activate Marath by paying {1} and removing a +1/+1 counter from it, creating a 1/1 Elemental token.
Repeat until Marath has no more +1/+1 counters.
Marath dies due to having 0 toughness and goes to the command zone.
Cast Marath by paying {R}{G}{W} plus commander tax, leaving zero mana unspent.
Marath enters the battlefield with a number of +1/+1 counters equal to the amount of mana spent.
Repeat any number of times.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite storm count

Infinite tapped creature tokens

Marath, Will of the Wild

Earthcraft

Activate the land with Fertile Ground attached by tapping it, adding {1}.
Fertile Ground triggers, adding {1}.
Activate Silvanus's Invoker by paying {1}, untapping the land and causing it to become an 8/8 Elemental with trample and haste in addition to its other types until end of turn.
Repeat.

Infinite power and toughness for most creatures you control until end of turn

Infinite untap of lands you control

Agatha of the Vile Cauldron

Silvanus's Invoker

Activate the basic land with Fertile Ground attached by tapping it, adding at least {1}.
Fertile Ground triggers, adding {U}.
Activate Earthcraft by tapping Horseshoe Crab, untapping the basic land.
Activate Horseshoe Crab by paying {U}, untapping it.
Repeat.
If the basic land is an Island, you may add mana of any color using Fertile Ground's trigger, and you may infinitely repeat steps 3-4 with any other basic land you control.

Infinite untap of basic lands you control

Horseshoe Crab

Play the land that taps for multiple mana.
That land enters as a creature due to Living Plane, triggering Vigean Graftmage's Graft ability, allowing you to move a +1/+1 counter from Vigean Graftmage to that land.
Cast Fertile Ground by paying {1}{G}, attaching it to that land creature.
Activate that land by tapping it, adding at least two mana.
Fertile Ground triggers, adding at least one additional mana.
Activate Vigean Graftmage by paying {1}{U}, untapping the land creature.
Repeat.

Combos with "Fertile Ground"