Analysis on Seedling Substrate of Water Hyacinth and Its Heavy Metal Contents

【Objective】Water hyacinth was fermented to produce solanaceous vegetable seedling substrate in order to explore the ways of water hyacinth resource utilization. 【Method】Water hyacinth was treated by sorting, crushing, air drying and fermentation. The nutrient and heavy metal content of the fermentation were analyzed. The fermentation of water hyacinth was crushed and then mixed with perlite and vermiculite to prepare seedling substrate at a ratio of 3∶1∶1. . Tomato, pepper and eggplant seeds were used to study the seedling-raising effect of the substrate. 【Result】The contents of total nitrogen, total phosphorus (P2O5) and total potassium (K2O) in the fermentation of water hyacinth were 1.75(±0.08)%, 0.74(±0.09)% and 7.87 (±0.40)%, respectively. Compared with the loss of nutrients before fermentation, the contents of five heavy metals, mercury, lead, arsenic, cadmium and chromium, increased by 23.09%-38.52%, nevertheless, their contents were only the standard of organic fertilizer industry ranging from 15.85% to 36.10%. Nevertheless, the content of heavy metals in fermentation was only 1.25%-13.33% of the maximum limit of organic fertilizer industry standard. The 50- day seedling-raising experiment of tomato, pepper and eggplant showed that the seedling emergence rate and root growth of three solanaceous vegetables on this substrate were not significantly different from those on high-quality peat soil, but significantly better than those on ordinary peat soil. The seedling height, fresh weight and dry weight were significantly higher than those on high-quality peat soil or ordinary peat soil. 【Conclusion】 After fermentation, water hyacinth can be used to produce safe and high quality seedling substrate for solanaceous vegetables.