Biochar from commercially cultivated seaweed for soil amelioration

• Published in: Scientific reports Vol. 5; no. 1; p. 9665
• Main Authors: Roberts, David A, Paul, Nicholas A, Dworjanyn, Symon A, Bird, Michael I, de Nys, Rocky
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 09.04.2015
• Subjects: Algae; Biomass; Cations; Charcoal; Food; pH effects; Raw materials; Seaweed; Seaweeds; Soil - chemistry; Soil amendment; Soil types
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep09665

Seaweed cultivation is a high growth industry that is primarily targeted at human food and hydrocolloid markets. However, seaweed biomass also offers a feedstock for the production of nutrient-rich biochar for soil amelioration. We provide the first data of biochar yield and characteristics from intensively cultivated seaweeds (Saccharina, Undaria and Sargassum--brown seaweeds, and Gracilaria, Kappaphycus and Eucheuma--red seaweeds). While there is some variability in biochar properties as a function of the origin of seaweed, there are several defining and consistent characteristics of seaweed biochar, in particular a relatively low C content and surface area but high yield, essential trace elements (N, P and K) and exchangeable cations (particularly K). The pH of seaweed biochar ranges from neutral (7) to alkaline (11), allowing for broad-spectrum applications in diverse soil types. We find that seaweed biochar is a unique material for soil amelioration that is consistently different to biochar derived from ligno-cellulosic feedstock. Blending of seaweed and ligno-cellulosic biochar could provide a soil ameliorant that combines a high fixed C content with a mineral-rich substrate to enhance crop productivity.