Residual effects of herbicide-treated Eichhornia crassipes used as a soil amendment

The feasibility of using herbicide-treated water hyacinth (Eichhornia crassipes) as a soil amendment in fruit and vegetable production was examined. Specific impacts of applying shredded water hyacinth treated with diquat, glyphosate, and 2,4-D amine to the potting soil surface of Lycopersicon esculentum seedlings (a sensitive assay species) on subsequent growth of those seedlings were studied. Negative effects of glyphosate and 2,4-D only were observed when shredded, treated E. crassipes was mixed into the top soil. L. esculentum showed reduced biomass and, in some cases, mortality, after some exposure durations. Glyphosate and 2,4-D reduced L. esculentum growth in proportion to the ratio of treated to untreated E. crassipes application.