Abstract:
Many lakes, canals and wetlands in Sri Lanka are infested by water hyacinth
(Eichhornia crassipes (Mart.) Solms), which is a non-indigenous invasive aquatic
weed species. It causes a complete blockage of water resources that makes
irrigation and fishing very difficult. Among various eradication methods of
water hyacinth, composting has been extensively used in many countries.
However, the degree of toxicity and the quality of compost are important for
field applications. Therefore, the present study was aimed at transforming
ordinary leaf litter into quality compost using water hyacinth and various other
amendments, and comparing the compost quality in terms of heavy metals, pH,
electrical conductivity (EC) and C: N ratio. The weeds were collected from the
Moragoda canal, Galle, Sri Lanka. The compost trials were prepared using water
hyacinth and different other raw materials and one compost trial was prepared
using water hyacinth alone. The mixtures were decomposed aerobically for 12
weeks by windrow method and prepared composts were analysed for pH, EC,
organic C %, total N %, Cu, Cd, Pb, Zn, Ni, and As. Finally, the obtained results
were compared with the indices given for compost by the Sri Lankan standards.
Considering the C: N ratio, pH, EC which obtained 17.84, 7.5, 1.95 dSm-1,
respectively and heavy metal content less than permissible limit, it revealed
that compost mixture with a composition of water hyacinth and dry leaf litter
was the most suitable mixture to recommend for field application
