Lorraine Williamson
Andalucia is turning a long-standing environmental problem into an innovative opportunity for agriculture. The regional government has approved a pilot project using invasive seaweed as fertiliser and biostimulant for crops, offering a new sustainable solution to ongoing challenges in farming.
Since 2015, large amounts of Rugulopteryx okamurae, an invasive Asian brown algae, have washed up along the southern Spanish coastline. Piling up on beaches and in fishing ports, the seaweed has disrupted marine life, burdened fishing communities, and created serious financial strain for coastal towns such as Marbella, Estepona, and Benalmádena. At one point, up to 40,000 tonnes accumulated at the landfill site in Tarifa.
The clean-up costs, combined with a negative impact on tourism and fishing, led local authorities to search for alternative approaches. Now, scientists and policymakers are exploring how this troublesome seaweed might instead contribute to sustainable farming.
Pilot project under strict environmental controls
The Junta de Andalucía, in collaboration with the University of Málaga, IFAPA, and the Institute for Biotechnology, has launched a controlled scientific study. Only naturally detached seaweed, washed up along beaches in Tarifa and Algeciras, is collected for the project. To protect marine life, living algae are left untouched. The collected seaweed is transported in sealed containers to a fermentation centre in Castellar de la Frontera, where it is biologically treated.
Andalucian Minister for Sustainability and Environment, Catalina García, described the project as “a perfect example of circular economy,” highlighting the potential to turn environmental challenges into agricultural innovation.
Potential benefits for agriculture and avocado farming
Researchers are now studying how the composted seaweed can benefit crops such as grains, grapes, and avocados. Many avocado plantations in southern Spain face challenges related to poor soil quality and limited water resources. The organic seaweed fertiliser could improve soil structure, enhance moisture retention, and contribute to more resilient and sustainable farming practices.
In addition to fertiliser, the project is also examining the role of seaweed as a biostimulant. Natural compounds like polyphenols may help stimulate plant growth and improve resistance to certain crop diseases, offering further support to farmers facing increasing climate pressures.
Early success with cork oaks in Tarifa
In Tarifa, a small experimental project has already delivered encouraging results. Researchers Luz Pelayo and Mari Luz Caballero treated six cork oaks suffering from “seca” – a disease linked to drought and fungal infections – with a simple mixture of washed seaweed, sugarcane, and rainwater. Over two years, the health of the trees improved by 15%. Their work earned second place at the Concienciarte environmental innovation awards in 2023.
From waste problem to circular solution
The reuse of invasive seaweed supports Andalucia’s broader sustainability goals. What was once an expensive environmental burden is now being transformed into a valuable resource for agriculture. If current trials continue to show positive results, seaweed fertiliser could soon become a regular feature of farming in southern Spain — benefiting both farmers and the environment.
Source: CanalSur