Seaweed as fertilizer

15 January 2020 - Published by Dorte Storper
The German SalFar partner Ökowerk has set out to develop an eco-friendly fertilizer especially suitable for saline soils.

Throughout 2019 Ökowerk has made great progress in the development of a natural fertilizer, which allows crops to thrive on saline soils. 70 % of the fertilizer mixture consists of washed-up algae (seaweed), which is mainly dried bladder wrack. After numerous experiments with different vegetable and mineral components, the fertilizer is showing promising results.

The influence of the fertilizer on local grass varieties in case of salinization is being tested by injecting planting pots with different concentrations of salt and then treating them with the special fertilizer. A total of 264 pots have been planted with grass. Preliminary results show an increase in yield of generally more than 100%. Even when the highest salt concentration has been added, the grass in the pots with fertilizer is more vigorously rooted than those without the fertilizer.

Furthermore, the fertilizer’s effect on growth and production of potatoes is being tested. In this experiment there is also special focus on the sensibility to Phytophthora infestans, which can lead to diseases that can cause serious losses of potato crops.
With these experiments Ökowerk hopes to develop the perfect fertilizer “recipe” which means that pasture, potatoes and other plants can continue to grow in coastal areas affected by salinization.

Another parameter that has been measured, is the soil fertility in the pots. In this process Ökowerk has received great support from two other SalFar partners, namely the soil scientists Iain Gould from the University of Lincoln and Åsgeir Almås from the Norwegian University in Life Sciences. They have provided valuable advice based on their experiences and Åsgeir has also offered to help with a more detailed analysis of the soil.

Apart from the washed-up algae, this natural fertilizer mixture also contains other ingredients, which the managing director of the Ökowerk, Detlef Stang, cannot reveal at this point as the trials are still ongoing. However, he explains that the other ingredients that have been tested are characterized by the fact that they grow on saline soils and that they enhance the growth of crops.

In addition to being a natural product, the fertilizer is also a local product as the washed-up algae is collected nearby Ökowerk close to the shore of the river Ems.

The fertilizer is pressed into pellets, suitable for handling with existing machinery on farm level. About 200 Kilos of fertilizer has been produced in 2019. This material is planned to be handed out to hobby gardeners for testing at the season opening this spring.