Can seaweed reduce fertilizer in horticulture?


For those of you who do not know it yet: seaweed is one of the most used ingredients of biostimulants for plants in horticulture today. They make up about one third of the biostimulant market. Research indicates that seaweed can comply to recently defined EU legislation on biostimulants, which would allow for their continued use as a biostimulant source in the European Union. This may indicate that seaweed can provide a solution to the challenge of reducing traditional fertilizer use, as well as improving the water-use efficiency of crops. That is why the European project Bio4safe has initiated a research program to further investigate the potency of seaweed in horticulture.

Resource depletion demands new solutions

To increase yield and quality of products, horticulture farmers have been using fertilizer for many years. Yet, traditional fertilizers are being criticized due to excessive use resulting in high levels of phosphor and nitrate that decrease soil biodiversity. Additionally, traditional fertilizers do not protect the plant for abiotic stress, such as drought and salinity, whereas these are expected to increase in coming years. Climate change for instance reduces the amount of fresh water available to use in horticulture, making it a main contributor to abiotic stress. That is why more sustainable farming methods need to be explored to cultivate plants in the agri- and horticulture business.

Biostimulants are an example of a more sustainable farming method. They are designed to help farmers meet growing agricultural demand, whilst battling societal pressure and stricter regulations. Recent EU legislation has determined that biostimulants should contain substances and/or micro-organisms that stimulate natural processes and enhance either nutrient use efficiency, abiotic stress tolerance, quality traits and/or nutrient availability in soil or rhizosphere. Research shows that seaweed-based biostimulants can be beneficial to plant growth and crop yield through at least one of these defined pathways (Battacharyya et al., 2015).

Reduce water and fertilizer amounts

The Bio4safe project investigates multiple biostimulants available on the market today, including seaweed products made from local North Sea seaweed, using high-tech measuring tools and methods.  Seaweed biostimulants can be easily applied through foliar spray & soil drenching. The first results of the project, “do not confirm the outstanding results found in available research on seaweed as a biostimulant” says Frederik van Baelen, project employee of Bio4safe working for Noordzeeboerderij Foundation. In the current trials, researchers find varying results. “Potentially, this has to do with the complexity of accurately measuring variable nutrient and humidity values in soil. That makes it difficult to create the appropriate abiotic stress circumstances for biostimulants to shine.” However: “We do see that when plants are given less water and less fertilizer to induce abiotic stress, the plants are still doing quite well and sometimes even show improved yield than control plants. This could mean that we can immediately reduce our inputs regarding water and fertilizer and, provided further testing, employ biostimulants to reduce these inputs further.” Considering the vast input quantities and narrow profit margins experienced by farmers, this can make a huge financial and sustainable impact.

Made in Holland

“What I found remarkable” Marlies Draisma adds, “is that our locally produced Dutch Seaweed Extract showed similar effects to that of biostimulants extracted from overseas seaweeds. Both from a financial and an ecological perspective. This is highly interesting to explore further, given that there might be a business opportunity for locally produced biostimulants.”


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