Utilization of Waste Sugar Kelp Crops as a Soil Amendment for Land Farms and Gardens

The emerging seaweed aquaculture industry in the United States, particularly the cultivation of sugar kelp (Saccharina latissima), faces significant challenges. Kelp farmers in Connecticut, Rhode Island, and other New England states confront issues related to the short harvest season and a lack of commercial processing facilities. These limitations force kelp farmers to sell their seaweed in its raw form, restricting access to market outlets beyond the harvest season. Additionally, the unpredictable cycle of biofouling, driven by changing water temperatures, can quickly render kelp crops unmarketable. While biofouled kelp remains edible, it necessitates labor-intensive cleaning efforts to remove snails, non-kelp algae species, and epiphytes, making it cost-prohibitive for farmers. Currently in southern New England, the only markets available to small and medium farmers is for food.

Each season, sugar kelp farmers are left with substantial quantities of biofouled kelp, which, due to the presence of additional species, cannot be sold in the fresh commodities market. Furthermore, commercial kelp farming permits mandate the complete removal of crops from the water at the end of the growing season, resulting in tons of waste. Sugar kelp grown in Connecticut and Rhode Island is nutrient-dense and cultivated in clean aquaculture-approved waterways. The absence of an alternative sales channel that would not require labor-intensive cleaning poses challenges to stabilizing farmers' income and incentivizing new farm establishments in the region.

Proposed Solution:

This project aims to address the identified challenges by developing an effective post-harvest soil amendment from biofouled kelp, thereby reducing waste for kelp farmers and providing them with an end-of-season revenue stream. Simultaneously, it will create a sustainably sourced and natural soil amendment that can reduce the need for chemical inputs in terrestrial farming and improve water retention. Sugar kelp, known for its richness in nitrogen, phosphorus, and calcium, offers significant potential as a soil amendment.

The U.S. seaweed fertilizer market, valued at $7.28 million in 2020, is expected to grow to $10.38 million by 2027, while the soil amendments market is projected to reach $6.0 billion by 2027. As these markets expand, there is an opportunity for small farmers in the region to contribute to the development of a locally-produced kelp-based soil amendment. Given the established agricultural benefits of brown seaweeds, like Ascophyllum nodosum, as nutrient-rich soil conditioners (Verma et al., 2021), there is strong justification for investigating Saccharina latissima (sugar kelp) as a soil amendment. Brown seaweeds contribute organic matter, enhance soil health, and support sustainable agriculture practices, with current seaweed production reaching 15 million metric tonnes annually (FAO, 2015). Researching sugar kelp could unlock new ways to leverage these resources in soil enrichment while establishing new markets for local farmers of sugar kelp. According to the FAO, over 120 million tons of chemical fertilizer was used in 2014 and approximately 15–30% of it entered the ocean (FAO, 2015). This project aims to present a natural and sustainable alternative. 

In this project, we will explore a dried kelp mulch to be applied directly to the soil and measure the impact it has on commonly grown plants in our region (tomatoes, brassicas, peppers, cucumbers)

Expected Impact:

The proposed solution aligns with sustainable agriculture principles by addressing several key aspects:

• Reduction of Environmental and Health Risks: By utilizing biofouled kelp to create a natural soil amendment, the project aims to reduce waste and minimize the environmental impact of disposing of biofouled kelp. It also reduces the need for chemical inputs in terrestrial farming, contributing to healthier, more sustainable agricultural practices including improved water retention by soil. 

• Improved Productivity and Income: The development of an alternative sales channel for biofouled kelp provides kelp farmers with an additional revenue stream, potentially stabilizing their income. Additionally, the use of a nutrient-rich kelp-based soil amendment can enhance crop productivity for terrestrial farmers, leading to increased net farm income. 

• Conservation of Soil and Natural Resources: The use of a kelp-based soil amendment can improve soil quality, conserve soil, and protect natural resources by reducing the need for chemical fertilizers and promoting healthier soil ecosystems.

This project has the potential to improve the quality of life for farmers, their families, employees, and the farming community at large by addressing the challenges faced by both kelp farmers and terrestrial farmers while contributing to the growth of sustainable agricultural markets.