Excellent Sargassum-based liquid biofertilizer

Sargassum-based liquid biofertilizer means the use of Sargassum as a raw material for biofertilizer production, it represents a particularly promising avenue, especially for low-income coastal agricultural systems seeking sustainable alternatives to chemical fertilizers.

Organic banana production is of significant importance to the Dominican Republic, positioning the country as one of the world’s leading exporters of organic bananas. This industry contributes substantially to the national economy and promotes sustainable agricultural practices that safeguard both environmental and human health. Despite its success, organic banana farming faces challenges related to nutrient management and pest control without synthetic inputs, highlighting the need for innovative solutions to enhance productivity and sustainability. A key alternative for modern and sustainable agriculture is the development of organic liquid fertilizers through anaerobic digestion, also known as liquid biofertilizers. These can be produced through fermentation processes of various organic materials, undergoing decomposition by microorganisms such as bacteria and fungi. Liquid biofertilizers offer a cost-effective and eco-friendly solution to these challenges, especially when derived from abundant and underutilized biomass such as Sargassum. Moreover, their use can contribute to the reduction of environmental pollution and the protection of human health.

Considering the numerous beneficial substances in the composition of sargassum, some research has explored its potential as a raw material for producing liquid biofertilizers. The chemical composition of sargassum includes elements such as carbon, sodium, iron, nitrogen, phosphorus, potassium, magnesium, and calcium. These elements combine to form both organic and inorganic compounds, including water, carbohydrates (mainly polysaccharides such as alginates, cellulose, mannitol, fucoidan and laminarin), lipids (including fatty acids), proteins, vitamins and secondary metabolites, such as flavonoids, phenols, terpenes, saponins, carotenoids, and fucoxanthin.

Microbiological analysis of the sargassum-based liquid biofertilizer

The microbiological composition of biofertilizers is a critical factor influencing their effectiveness and safety in agricultural applications. The high density of yeast populations in the biofertilizer indicated a robust fermentation process, indicating that yeast played an important role in the decomposition of organic matter and the stabilization of the biofertilizer during the 30-day fermentation period. Yeast produces various metabolites, including vitamins and enzymes, which can enhance plant growth and soil health.

Cultivation of the liquid biofertilizer on potato dextrose agar (PDA) medium led to the identification of several fungal species: Colletotrichum sp., Sepedonium sp., Cladosporium sp., and Geotrichum sp. It is noteworthy that these fungi are not considered pathogenic to plants or humans under normal environmental conditions. Instead, some of these genera have been associated with beneficial effects in soil ecosystems. For example:

-Cladosporium sp.: Commonly found in soil and decaying organic matter, species of this genus can contribute to the decomposition process and nutrient cycling.

-Geotrichum sp.: Known for their ability to decompose pectin and other polysaccharides, they can enhance the breakdown of organic materials in the soil.

The presence of these non-pathogenic fungi suggests that the biofertilizer could positively influence soil microbial diversity and activity, potentially leading to improved soil structure and fertility.

Additionally, the bacterial counts were significantly high, which is beneficial since many bacteria in biofertilizers are known to promote plant growth through nitrogen fixation, phosphorus solubilization, and the production of growth hormones. The actinomycetes presence is advantageous, as they are involved in the complex organic compounds decomposition and have antagonistic effects against soil-borne pathogens. The rich microbial diversity can enhance soil health and plant growth. The high yeast and bacterial populations suggest that the biofertilizer can introduce beneficial microorganisms into the soil, promoting nutrient availability and suppressing pathogenic microbes through competitive exclusion.

Moreover, the absence of pathogenic fungi is critical for guaranteeing the safe application of biofertilizers in agriculture. The identified fungal species are generally saprophytic and contribute to organic matter decomposition, further supporting soil fertility. While the microbiological profile is promising, it is essential to ensure that the biofertilizer does not harbor any harmful microorganisms that could pose risks to crops, soil health, or human safety. Regular microbiological assessments should be conducted to monitor the presence of any potential pathogens, especially if the fermentation conditions or raw materials change.

Furthermore, the high microbial activity in the biofertilizer may lead to rapid nutrient mineralization when applied to the soil, making nutrients readily available for plant uptake. However, this also necessitates careful management to prevent nutrient leaching and to align application rates with crop nutrient requirements.

Evaluation of liquid biofertilizer application in organic banana crops

Researchers in the Dominican Republic evaluated the performance of a Sargassum-based liquid biofertilizer compared with a conventionally produced liquid biofertilizer on local family farms. Figure 1 depicts the trends in foliar emissions after eight weeks on three farms. The results for SBLB application are presented alongside those for BLB application. In plot A, the foliar emission index did not reach statistical significance between the two treatments, meaning that both formulations contributed equally to foliar emissions. However, significant differences were observed in plots B and C, favoring the use of the Sargassum liquid biofertilizer. The superior results achieved with the Sargassum biofertilizer on two of the three farms may be attributed to the nutrients provided by the Sargassum and the biostimulant molecules provided by the seaweed.

Regarding nutrient contribution, the sargassum contains many carbohydrates, primarily polysaccharides. The most prominent polysaccharides in these brown algae are fucoidans, alginates, and laminarins, which are recognized for their antimicrobial and antioxidant effects. Its protein content is also considered high and of good quality, as it typically includes all essential amino acids. Additionally, sargassum provides essential nutrients such as potassium, calcium, sodium, magnesium, and phosphorus, along with several trace elements like iron, zinc, copper, and manganese.

On the other hand, the biostimulant effect can be considered because sargassum has a vast metabolite profile that includes various groups such as terpenes, polyphenols, sterols, phlorotannins, phytosterols, and glycolipids. Among these metabolites are phytohormones such as cytokinins, auxins, gibberellins, and ethylene. These substances play critical roles in coordinating plant growth and development and in responding to biotic and abiotic stressors. This rich metabolite composition makes sargassum an ideal substrate for fermentation and enhances its potential as an agricultural bioinput.

The presence of Black Sigatoka serves as an indicator of the presence of the fungus Mycosphaerella fijiensis, or its evolutionary state. Biologically, plants with adequate nutrition or the presence of microorganisms in the soil or at the vascular level (endogenous) result in reduced attack or increased plant adaptation. Fig. 2 illustrates the evolutionary state of Black Sigatoka after eight weeks of study, expressed in the quantity of Sigatoka spots per banana plant leaf. Statistical analysis reveals no significant difference in disease state progression between the use of Sargassum-Based Liquid Biofertilizer or Traditional Biofertilizer. It is noteworthy that, throughout the study period, the disease state remained below the threshold for chemical treatment intervention (below 300 spots per leaf).

The results obtained during the 8 weeks confirm that Sargassum-Based Liquid Biofertilizer meets the expectations of a liquid biofertilizer, delivering outcomes comparable to traditional liquid biofertilizer in terms of its positive effects on leaf emission and the control of Black Sigatoka’s evolutionary state. Although the differences between the two biofertilizers studied were not statistically significant in controlling Black Sigatoka, the fact that both were able to keep the pest under control at levels that do not lead to disease development is important and confirms the biological control value of both biofertilizer formulations in banana cultivation.

Conclusions

This study demonstrates that Sargassum spp.,can be effectively valorized to produce a safe, nutrient-rich liquid biofertilizer. The resulting product showed acceptable levels of essential macronutrients and significantly reduced concentrations of heavy metals, including arsenic, while maintaining a diverse and beneficial microbial community. Its application on small-scale organic banana farms showed agronomic performance comparable to support healthy plant development and disease control without adverse effects.

These findings suggest that sargassum-based liquid biofertilizer represents a sustainable alternative for organic farming systems, offering both environmental and agricultural benefits.

The sargassum-based liquid biofertilizer made through the bio – enzyme extraction process can promote the rapid growth and differentiation of crops, making the roots and stems thick and the plants lush. It enhances photosynthesis and improves the stress resistance and immunity of crops, helping them better withstand diseases, pests, drought, and other adverse conditions.

See more details of Dora Sargassum-based liquid biofertilizer products: Dora KelpReal Liquid (OMRI), Dora KelpReal Powder(OMRI)

Dora KelpReal is a 100% pure concentrated seaweed extract rich in minerals, amino acids, trace elements, and other active substances. Dora Agri’s unique low-temperature enzymatic technology and its cold-processed extraction methods can preserve the activity and integrity of natural ingredients and nutrients, and ensure plants can be absorbed faster. This product is OMRI Listed under the USDA’s National Organic Standards