Each time the dust and iron were added to the surface ocean, we found that there was a corresponding pulse of algae growth. (futurity.org)
How will you get nutrients, such as phosphorus and nitrogen, to stimulate algae growth? (scientificamerican.com)
Additionally, it is difficult to find land with suitable characteristics for algae growth and there are technical challenges of scaling up lab / pilot projects and cost effectiveness. (sciencedaily.com)