Summary

This study investigated the use of water hyacinth (Eichhornia crassipes) as an organic mulch for agricultural soils.  Water hyacinth is a nutrient-rich, fast-growing invasive species, and its use as mulch could provide an alternative to traditional amendments.  The research assessed its effects on soil microbial diversity, functional traits, and ecosystem services, such as nutrient cycling, organic matter decomposition, and pathogen suppression.

The study was conducted at three sites in Rockhampton, Queensland: a macadamia orchard, a lychee orchard, and a grazing pasture.  Treatments included water hyacinth mulch, woody mulch, and no-mulch control, with and without urea application.  Soil samples were analysed for microbial diversity, community composition, and functional traits.

Vegetation type strongly influenced microbial diversity and functional traits.  Macadamia orchards supported higher microbial diversity and traits related to nutrient cycling and decomposition.  Lychee orchards had reduced ectomycorrhizal diversity and shifts in decomposition traits, possibly due to competitive interactions or management practices.

Water hyacinth mulch increased microbial traits related to rapid nutrient cycling and decomposition, such as arbuscular mycorrhizal and chitinolytic diversity.  Woody mulch favoured traits associated with organic matter stabilisation and nematode suppression.  Woody mulch also increased the diversity of opportunistic human pathogens, raising biosecurity concerns.