[DennisP]

That's how much is happening naturally, with a low percentage of seaweed sinking to the depths. Large-scale farming operations could do a lot more.

[Shoh3pif]

Intensive farming only happens when the material is used in a profitable way. Growing things only to dump them in the oceans is only profitable with subsidies or carbon taxes.

Extensive farming would likely have the natural rate of sequestration.