Wikipedia about ocean fertilization '''... open-sea experiments [have] confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up t

Wikipedia about ocean fertilization '''... open-sea experiments [have] confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times.''' I.e adding nutrients leads to plankton growth. So I would assume removing nutrients will lead to less phytoplankton growth. Since phytoplankton is also a carbon sink, doing so via kelp might have zero benefit.