The Effect of Brown Seaweed Waste Streams on Plant Growth

Author: Alex Yang

Editors: Linzi Yeung, Jonathan Chen, Ethan Tai

Artist: Becky Li

Brown seaweed waste, including species Ascophyllum nodosum, Laminaria digitata, and Sargassum, has been found beneficial for product preparation. Recently, these species of algae have received recognition for their ability to stimulate plant growth and improve organic farming. Before the release of new research, brown seaweed waste was discarded after the extraction of useful compounds, including alginates and mannitol–two biochemicals with various applications. However, current reports consistently show high percentages of bioactive nutrients and compounds, both of which can help improve crop yield and reduce chemical fertilizer consumption.

Within brown seaweed are plant growth stimulants and hormones–such as auxins, cytokinins, and gibberellins–which facilitate cell division, root growth, and shoot growth. Furthermore, wastes contain alginates and laminarin polysaccharides, which affect soil structure, water storage, and root environment to facilitate plant growth. Seaweed waste is further rich in primary micronutrients such as potassium, iron, and iodine; therefore, they are good for plant nourishment from the very start. Collectively, these traits make brown seaweed waste streams a highly potential substitute for expensive synthetic fertilizers, which are neither environmentally friendly nor energy efficient to produce.

The beneficial effect of brown seaweed waste streams on plant growth is indicated in various ways, with the most significant being accelerated root growth. The plant's endogenous growth hormones contained in the seaweed extract stimulate better root elongation and branching, two events that enhance water and nutrient uptake. Better root system development increases the establishment of the plant and helps to produce cover for the enhanced plant desiccation tolerance. Aside from that, the polysaccharides produced in the polysaccharides enhance the porosity of the water and soil, providing a balanced root system and bolstering nutrient intake.

Brown seaweed waste streams also enhance photosynthesis by triggering the concentration of chlorophyll, a naturally occurring green pigment, in plant leaves. According to research, plants treated with brown seaweed extract generally express greener and healthier leaves. This allows them to take in more light and produce more energy through photosynthesis. Thus, it is posited that brown seaweed waste can enhance plant growth rates, leaf size, and overall biomass–the total living matter within an organism. Moreover, brown seaweed extract possesses bioactive compounds that act as physiological biostimulants.  These substances help enhance the immune system of plants, allowing them to experience less disease and stress-related damage, such as salinity, heat, and cold.

The positive effects of brown seaweed waste streams on plant development were revalidated by experiments on various crops, including radish, lettuce, tomato, and wheat. Seeds treated with seaweed extracts at diluted strengths germinated earlier and more uniformly, giving the crops a head start in growth. During their vegetative growth stage, the seaweed-treated crops were taller, had more leaves, and had a robust stem compared to their non-treated counterparts. Furthermore, results showed that root crops, such as radish, treated with seaweed extract possessed greater root diameters and weights. These developments helped increase yields–healthier crops have more energy to invest in fruit, seed, and root growth.

It is possible to minimize the quantity of organic waste poured into sea and land ecosystems by transforming industrial wastes into usable materials. The application of brown seaweed waste streams can potentially reduce society’s reliance on chemical fertilizers, a primary source of water pollution and greenhouse gas emissions. Since seaweeds absorb an enormous quantity of carbon dioxide during cultivation, their use in agriculture indirectly complements efforts in carbon sequestration and climate change mitigation. However, there are hindrances to the large-scale application of brown seaweed waste streams.

One major barrier is the variation in nutrient content; such disparities in seaweed type, harvest time, and processing method can obstruct the creation of reproducible results for different crops and regions. Salinity is another issue. Some seaweed waste streams are also salty and, if excessively applied, can be toxic to plants. To combat this, various dilution and testing practices can be implemented before field application. On a commercial basis, the cheap production methods for processing generic products will determine the viability of seaweed-based fertilizers. Nonetheless, brown seaweed waste streams hold great potential to become a sustainable and eco-friendly alternative to chemical fertilizers.

Brown seaweed waste is not only rich in nutrients but also supplemented with growth promoters that enhance germination, trigger vegetative development, increase photosynthesis, and bolster crop yields collectively. As they are capable of optimizing plant feeding and soil health, these extracts are driving more sustainable food production systems and environmental sustainability. Yet, to fully maximize the potential of these extracts, the research process must enhance the formulation, use, and compatibility of such extracts with future agricultural production systems. Brown seaweed waste streams may play a role in the future of sustainable food production; however, it is up to society to properly address the large-scale application-related issues.

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