Aquaculture wastewater reuse for horticulture (integrated farming)

Aquaculture wastewater reuse routes nitrogen- and phosphorus-rich pond effluent through drip or furrow systems to dyke-grown banana, papaya, coconut, guava and lemon. The technique converts what would otherwise be discharged pond water into an irrigation-plus-nutrition stream for horticulture, while pond-bund land that is otherwise unproductive is brought into cropping.

Principle

Intensive fish or shrimp culture concentrates nutrients in pond water from uneaten feed and excreta. Direct discharge causes downstream eutrophication; the integrated alternative routes the same effluent to perennial fruit crops that can absorb the dissolved N and P. The dyke or pond bund supports the trees and the crops in turn shade and stabilise the embankment.

Implementation

ICAR-CIFA Bhubaneswar promotes integrated fish-horticulture systems on pond bunds, with banana, lemon, papaya, coconut and guava as documented dyke crops. Pond water is either pumped through drip lines or routed by gravity to furrows around the trees. Stocking density, feed rate and pond exchange schedule are tuned so that effluent nutrient load matches crop demand rather than being a pollutant.

Adoption context

The system suits small and marginal holdings in coastal and deltaic Andhra Pradesh, Odisha, West Bengal and Kerala where fish ponds and banana or coconut blocks already co-exist on the same farm. Integration is most efficient when the pond is upslope of the horticulture so that effluent flows under gravity.

Limitations

Salinity, heavy-metal load from feed sources and pathogenic organisms can transfer from pond to crop if water quality is not monitored. Bund width must be sized to support root systems without compromising pond integrity, and tree roots can damage clay-puddled pond liners over time.

References

ICAR-CIFA Research. ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar.
Multiple Uses of Water in Aquaculture-Integrated Agriculture. MDPI Water, 2023.