Algae as a natural fertiliser for pineapples

Fresh Del Monte is researching the use of algae as a natural fertiliser for pineapple production. The work asks whether a carefully processed biological input can support soil condition, plant resilience and fruit quality while reducing reliance on synthetic fertiliser.

Rather than treating algae as a stand-alone source of nutrition, the programme evaluates it within a broader soil-management system. Controlled field work, food-safety checks and an assessment of realistic farm economics will determine where it can add value.

Why algae is being investigated

Algae-based inputs are attracting interest because they can combine mineral nutrients with organic compounds that may help roots and leaves respond to nutrient availability. Seaweed-derived products are already used as biostimulants in some cropping systems, but that does not mean any algal material can be applied safely or profitably to a pineapple crop.

Our research therefore begins with a practical question: can an appropriately processed algal input improve pineapple performance under Australian conditions? Background on biological crop inputs is available through Shoku-e’s research resources, which provides useful context, although it does not replace replicated field testing.

What algae can do in pineapple soil

Seaweed and other approved algal materials can contribute small amounts of nitrogen, phosphorus, potassium and trace elements. When they break down in soil, their organic matter can improve aggregation and water retention, which matters for pineapple’s relatively shallow rooting system. This is a supplementary role, and algae should not be described as a complete replacement for balanced nutrition.

Extracts act differently from whole biomass. At low concentrations, they may act as biostimulants, helping plants manage environmental stress. At higher concentrations, salts or unwanted compounds can inhibit growth. The research compares application rates and timing so that a promising laboratory result does not become a field risk.

Fresh Del Monte has experience testing biological uses for agricultural residues. Its coffee-ground mushroom pilot demonstrated how spent coffee grounds can support mushroom cultivation. The pineapple research examines a different material and objective, but it shares the principle that a biological input earns its place only when controlled evidence shows a reliable benefit.

Designing a controlled field trial

The programme sets replicated plots with untreated controls and conventional fertiliser treatments as benchmarks. Researchers keep planting material, variety, irrigation, crop protection and routine field work consistent, changing only the algal treatment. Seasonal rainfall, plant age and soil variation can otherwise obscure the effect being measured.

Measurements follow the crop through its growth. These include leaf condition, root development, soil moisture, organic matter and nutrient availability. At harvest, researchers assess fruit mass, shape, sugar and acidity, the condition of the “eyes”, crown quality and defects. Results must be repeated across sites and seasons before a yield benefit can be claimed.

Food-safety requirements are built into the work. Harvested fruit undergoes appropriate chemical and microbiological testing, including checks for heavy metals and, where relevant, cyanobacterial toxins. Algal materials are also assessed for salts, pathogens and other contaminants. Passing food-safety requirements matters as much as demonstrating agronomic value.

Australian conditions and market realities

Australia’s commercial pineapple industry is concentrated in Queensland, particularly the Gold Coast and Sunshine Coast hinterlands. The subtropical coastal climate provides warm growing conditions, wet summers and periods that may still require irrigation. Sandy, well-drained soils make water management a constant consideration. Local quality discussions focus on the fruit’s “eyes” and the condition of its crown, rather than size alone.

Fresh retailers and wholesalers expect pineapples throughout the year, with Queensland fruit sitting alongside imports from Costa Rica, Kenya and the Philippines. Imported fruit must meet Australian biosecurity and food-safety requirements, while domestic producers compete on consistency, flavour, shelf life and reliable delivery. These conditions make commercial viability an essential part of the research.

Quarantine also applies to experimental inputs. Any live or unprocessed algal material entering Australia must be checked against the conditions published in the Department of Agriculture, Fisheries and Forestry’s BICON system before movement. Relevant state quarantine rules must also be followed, making biosecurity part of the trial design rather than an administrative afterthought.

Measuring value and managing risk

The business case is as important as the crop response. Algae collection, drying, extraction, transport and storage all carry costs and environmental impacts. A treatment that improves soil condition but adds excessive labour, water demand or processing requirements may not suit Australian farms. Researchers therefore compare the cost of each treatment with its effect on marketable fruit.

Environmental safeguards need equal attention. Excess nutrients can reach rivers and estuaries, while some algal materials may contain unsuitable organisms or compounds. Application rates must be calibrated to soil tests and crop requirements. Identity documentation, contaminant screening and restrictions on releasing live experimental strains help prevent unintended effects beyond the trial site.

The research fits within the company’s sustainability commitments, which cover responsible sourcing, environmental protection and community development across global agricultural operations. Any approach tested in Costa Rica, Kenya or the Philippines would need local validation before its results were applied in Queensland, since soils, climates and production systems differ considerably.

Comparing the main treatment options

Before any algal input is recommended, the research compares it with the choices a Queensland grower already manages. This keeps the evaluation grounded in farm practice and makes clear which benefits are additional, which are simply nutritional and which may not justify the extra cost.

These options answer different questions. A treatment that changes soil structure cannot be judged only by leaf colour, while a biostimulant cannot be credited with replacing base nutrition. The most useful trial records both crop response and input costs, then checks whether the treatment remains effective under wet summers, dry irrigation periods and different soil types.

A practical path to field adoption

The strongest pathway from research to farm use is staged: verify the algal material, test it against untreated and conventional-fertiliser plots, review safety results, and assess costs per hectare and per unit of marketable fruit. Any recommendation must fit irrigation schedules, existing soil tests and the grower’s harvest plan.

The practical takeaway is simple: algae belongs in the toolbox as a measured soil input, not a guaranteed replacement for nutrition. Wider adoption is justified only when replicated evidence shows better soil condition, acceptable fruit quality and a workable cost across Australian growing conditions.