TEST‐FARMING OF THE GIANT KELP, Macrocystis , AS A MARINE BIOMASS PRODUCER

Marine macroalgae grow and produce biomass at a rapid rate. Large‐scale oceanic farms planted with these plants could provide a renewable source of energy and copious amounts of organic feedstocks for the chemical industry, without interfering with food and fiber production on land. Past projections of the potential of large‐scale macroalgal mariculture have been based on estimates of yield rather than actual cultivation trials. In the last year, we planted one acre with 722 plants arranged in three different planting densities. This was done in order to test our cultivation methods and determine what the yield is from plants grown on a farm. We have studied the effects of transplanting, handling, cultivation, density, fertilization and harvesting on a population of farmed giant kelp plants. Furthermore, we have been able to gain an appreciation of plant‐to‐plant variability in growth rate. The results of our work to date indicate that kelp plants grown in the sea are amenable to cultivation. They respond to fertilizer applications and show the effects of competition for light when grown at high planting densities. Under optimum growing conditions, some plants are able to produce nearly a kilo of wet biomass per day. In our view, the very encouraging results of this kelp farming effort show that the giant kelp is nearly as productive as some of the most highly productive land plant crops like sugar cane. It should be possible to further increase the yield from this prototype marine farm through improved marine agronomic practices.