Abstract:
Alligator weed (Alternanthera philoxeroides) is a highly invasive species causing severe ecological
and economic consequences by affecting water quality, hydrological flow, and the growth of native flora and
fauna due to its rapid growth and dense mat formation. It thrives in both aquatic and terrestrial habitats
and has become a significant ecological concern in Sri Lanka. In Trincomalee, a two-hectare farm pond
in Anpuvalipuram has been infested annually, typically from November to May (up to 1.5-hectare level),
disrupting fishing and irrigation activities. Although local communities have attempted control measures
such as mulching and feeding it to poultry because of its high nutrient availability, these practices have
further encouraged its spread into surrounding terrestrial areas. This study was conducted to evaluate the
potential of alligator weed as an organic liquid fertilizer and to compare its effectiveness on the growth and
yield of the okra crop with that of a conventional organic fertilizer mix and an inorganic fertilizer. Liquid
fertilizers were prepared using four concentrations of alligator weed (25%, 50%, 75% and 100%). A traditional
organic mixture of Gliricidia and neem leaves, an inorganic fertilizer treatment, and an untreated control
were also included. The experiment was arranged in a Completely Randomized Design with four replicates.
Fertilizer samples were analyzed for nitrogen, phosphorus, potassium (NPK), pH, and electrical conductivity
(EC). Growth and yield performance were evaluated by measuring crop height, stem circumference, total
pod number and total pod weight. Despite relatively low NPK concentrations, the 50% alligator weed liquid
fertilizer treatment achieved the highest yield performance (1,145.26 g and 64 pods), which was comparable
to inorganic fertilizer and superior to both the organic mixture and the control. Utilizing alligator weed
not only provides a sustainable alternative to inorganic fertilizers but also offers an eco-friendly strategy for
managing a problematic invasive species while recycling nutrients within agricultural areas.
