Organic fertilizer

The sea has always been an source of fertilizers. In earlier times, shore-driven algae was used in Swedish coastal farming but this has come out of fashion after the use of chemical fertilizers. But locally marine substrate are still used - on the island Orust farmers use waste products from blue-mussel industry as valuable fertilizer.

The anaerobic fermentation removes the carbon of the biomass but leaves the nutrients and makes them more accessible to plants.

Ascidians are rich in the nutrient nitrogen (5 % of dry weight) and phosphorus.Fertilizer tests has been conducted by an independent farming organization in 2012. The results was positive and fermented ascidians was comparable to commercial nitrogen fertilizers.During summer and autumn 2013, a second year of tests is ongoing on the same localities.