Water hyacinth [Eichhornia crassipes (Mart.) Solms.] engineered soil nutrient availability in a low-land rain-fed rice farming system of north-east India

A study was conducted to investigate the mulch role of water hyacinth (Eichhornia crassipes) on soil properties of a lowland rain-fed rice farming system in north-east India. The green mulch had higher carbon and nutrient contents as compared to its compost and vermicompost forms, and so were the hemicellulose, cellulose and lignin. Significant reduction in C/N ratio from fresh water hyacinth indicated rapid N release while composting. Over all, mulching significantly (p < 0.05) increased soil C, total N, available P and K as compared to the non-mulched plots. Nonetheless, soil C was greater in the green mulch plots, followed by compost and vermicompost plots. Net N mineralization rate also followed similar patterns. Upon comparison with other aquatic weedy species, E. crassipes had 20-50% more C and 10-40% more N in its residues. Likewise, the compost prepared out of E. crassipes also seems to be of good quality as indicated by a C/N ratio less than 25, as compared to Hydrilla spp., Najas spp., Ottelia spp. and Pistia stratiotes. It is therefore suggested that recycling of water hyacinth can be an ecofriendly aquatic weed management strategy to improve soil health and nutrient redistribution through a faster turnover that can engineer sustainable agricultural production in the tropical soils.