Neptune’s Harvest: Organic Fertilizer From Seafood Byproducts

Truly sustainable businesses avoid waste by turning byproducts into high-value products. Yet, waste and high disposal costs plagued the fishing industry in Gloucester, Massachusetts, and beyond. The fillet comprises just 30% to 40% of the fish. But for the fishing industry, the remaining 60% to 70%, called gurry, consists of bones, guts, fins, scales, and organs. Disposing of the gurry from cod, haddock, flounder, and other species can be expensive for fish processing plants and is often harmful to the environment. But what if seafood byproducts could become a useful product?

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Turning Seafood Byproducts Into Fertilizer

The origins of Neptune’s Harvest’s fish-byproducts-based fertilizer start with its parent company, Ocean Crest Seafood, a family-owned wholesale fish and seafood business. To dispose of the gurry, it was paying fishermen to dump it out at sea, yet this approach was clearly wasteful and costly. The company owner had another idea.

Why not turn this organic waste into a high-quality organic garden fertilizer? This notion inspired the creation of Neptune’s Harvest in 1986. Using a process that the company created in conjunction with the State of Massachusetts and its local universities, Neptune’s Harvest started making its natural fertilizer out of fish byproducts.

“We grind up the byproducts, liquify them, and then stabilize and screen the mixture, in a cold process that keeps heat-sensitive nutrients and oils intact,” explains Ann Molloy, co-owner and director of sales and marketing at Neptune’s Harvest. “This innovative approach utilizes 100% of the fish and is the perfect organic fertilizer. It is the consistency of chocolate milk and safe for pets and kids.”

Neptune’s Harvest uses wild-caught, deep-ocean fish from the North Atlantic. “They are caught well offshore, in cold, clean, mineral-rich ocean water, so they are a good source for nutrients,” says Molloy.

Today, Neptune’s Harvest has a full line of organic garden fertilizers, including liquid fish fertilizer, liquid seaweed plant food, and powdered crab and lobster shells. The ingredients are harvested from the North Atlantic and processed by Neptune’s Harvest in their Gloucester facility.

Neptune's Harvest liquid fish fertilizer label
Neptune’s Harvest liquid fish fertilizer label. Image source: Neptune’s Harvest

How To Use Neptune’s Harvest Garden Fertilizers

The company’s products fall into two general categories: liquid fertilizers and powders, each with different uses.

Using Liquid Fertilizers in Home Gardens

Neptune’s Harvest Fish Fertilizer has an NPK ratio of 2-4-1 (2% nitrogen, 4% phosphorus, and 1% potassium). The Seaweed Fertilizer has an NPK ratio of 0-0-1, but seaweed is rich in trace elements. The nutrients in liquid garden fertilizers tend to break down more readily, making them available to the plants more quickly. Therefore, liquid fertilizers are especially beneficial to distressed, sick, or malnourished plants that could use a quick nutrient boost.

Molloy recommends using the fish and seaweed fertilizers throughout the growing season to provide plants with nutrients and trace minerals. Dilute the liquid organic garden fertilizers at 1 oz. per gallon of water before applying them to soil or plant leaves. You can simply add them to a watering can or use a hose attachment for a garden hose or a backpack sprayer. Because Neptune’s Harvest products are filtered, gardeners can use them in sprayers without clogging.

“The more people are learning and getting into organic farming, the more they are realizing the benefits of liquid fertilizers,” says Molloy. “Our fertilizers feed the biological life in the soil, draw nitrogen from the atmosphere, and sequester carbon.”

Either apply the organic liquid fertilizer to the soil or the leaves directly to allow uptake through the leaves, in a method known as foliar feeding. Molloy recommends foliar feeding gardens in the early morning when dew is still on the plants to promote plant uptake of nutrients.

“Plants with big leaves like pumpkins really thrive with the foliar feeding,” says Molloy. “Neptune’s Harvest has a cult-like following of giant pumpkin growers, and last year a grower in Minnesota grew a 2,560-pound pumpkin using our products. It was the largest pumpkin ever grown in North America!”

Powdered Garden Fertilizers

Neptune’s Harvest Crab and Lobster Shell fertilizer has an NPK ratio of 5-3-0, so it is rich in nitrogen, and contains 17% calcium, yet has little potassium. Molloy recommends using the crab and lobster shell powder in the garden in the spring when preparing beds, as she said it helps minimize insect damage and blossom end rot, while promoting moisture retention and deep root growth.

Neptune’s Harvest continues to be a locally-owned business with 45 employees and now has a full line of garden fertilizers. Many of its products take what would otherwise be an environmental hazard and transform it into something that helps organic farmers and gardeners produce healthy vegetable crops, fruit trees, ornamentals, and flowers.