Raw data for 'Water hyacinth (Eichhornia crassipes) mulch and urea interactions shape soil biota and nitrogen cycling'

Water hyacinth (Eichhornia crassipes) mulch and urea interactions shape soil biota and nitrogen retentionAbstractOrganic amendments influence soil health depending on their composition and decomposition rate, and invasive plants such as water hyacinth (Eichhornia crassipes), one of the world’s most widespread aquatic weeds, represent a potential source of nutrient-rich organic matter that can be repurposed as a soil amendment. This study tested the effects of water hyacinth mulch, a nutrient-rich and rapidly decomposable biomass, compared with woody mulch and an unmulched control across macadamia, lychee, and grazing systems in subtropical Queensland, Australia. Plots received mulch with or without ¹⁵N-labelled urea, and soil bacteria, fungi, and nematodes were characterised using metabarcoding to assess treatment effects on microbial communities and nitrogen retention over seven weeks. Water hyacinth mulch reduced bacterial diversity but increased bacterial-feeding nematodes and shifted fungal traits toward chitin degradation, root endophytism, and opportunistic taxa. Bulk soil δ¹⁵N was marginally lower under water hyacinth mulch, indicating reduced nitrogen retention relative to controls. This pattern likely reflects greater nutrient mineralization and turnover, suggesting that combining water hyacinth mulch with more recalcitrant organic inputs may help moderate mineralization rates and improve nitrogen retention. Using water hyacinth as a soil amendment can recycle nutrients and improve fertility, particularly when applied with more stable organic materials. Extended field trials are needed to evaluate whether these short-term microbial and nutrient responses lead to sustained improvements in soil function and long-term fertility.