Assessment of Water Hyacinth Biochar as a Soil Amendment for Sandy Soils

Abstract

Soil application of water hyacinth biochar as a source of nutrient- and carbon-rich biomass may be an effective ploy to eradicate this invasive aquatic weed. Incubation trial was conducted to assess effects of water hyacinth biochar addition on some sandy soil biochemical and biological properties and potential carbon sequestration at different application rates and methods. Results demonstrated that pyrolysis of water hyacinth at temperature of 300 °C and 30 min furnace residence time produced biochar with coveted physicochemical properties. Field emission scanning electronic microscopy (FE-SEM) images obtained for water hyacinth biochar showed major macroscopic changes caused by substantial changes in pore structure, surface area and surface morphology due to insufficient carbonization. Soil biochemical and microbiological characteristics after incubation exposed obvious significant improvements at all rates compared to control and varied markedly between addition of biochar as incorporation and broadcasting. Among different treatments, biochar addition as incorporation at the rate of 3% resulted in higher significant increases in most tested soil parameters. Water hyacinth biochar provided nitrogen and carbon immediately via SOC, DOC and DON in treated sandy soils providing energy for microbial biomass compared to control and this reflected by increases in soil values of C-MIC N-MIC and P-MIC. In addition, water hyacinth biocharring would greatly improve sandy soil carbon sequestration at high application rates. It could be concluded that water hyacinth transformation into biochar represents a sustainable strategy for managing these weeds and thus become a valuable organic source for sandy soils and will boost carbon sequestration.