Composting of seaweed waste: Evaluation on the growth of Sarcocornia perennis.

Composting represents a suitable and cheap method for handling and processing seaweeds accumulated on the coast. Within this framework, two seaweed composts were prepared, one with Undaria pinnatifida accumulated in spring-summer and other with a mixture of seaweeds accumulated in autumn-winter, both from Central Patagonian beaches. The effect of these two composts was evaluated experimentally as an amendment for the growth of Sarcocornia perennis (chickenclaws), a plant species dominating Patagonian salt marshes. Both composts were applied at 75, 50, and 25% doses with perlite. The analysis of the compost properties (phytotoxicity test, C/N, electrical conductivity, pH, and metal content) allowed characterizing both composts as matures and stables. The growth results showed that both composts allow the growth of S. perennis in all doses tested; however, Undaria compost was better in the stimulation of vegetative growth when applied in dose 50%, followed by 75% of both composts. For these reasons, both composts from seaweed waste accumulated on Patagonian coasts could be used in the growth of S. perennis and potentially other plant species, giving value to the seaweeds that currently are considered a waste that disturb these coasts and are discarded without use.