The impact of water hyacinth biochar on maize growth and soil properties: The influence of pyrolysis temperature

IntroductionOptions for managing water hyacinths (WHs) include converting the biomass into biochar for soil amendment. However, less has been known about the impact of WH-based biochar developed in varying pyrolysis temperatures on plant growth and soil qualities.Materials and MethodsA pot experiment was undertaken in a factorial combination of WH biochars (WHBs) developed at three temperatures (350 degrees C, 550 degrees C and 750 degrees C) and two application rates (5 and 20 t ha-1), plus a control without biochar. Maize was grown as a test crop for 2 months under natural conditions.ResultsOur study showed that applying WHB developed between 350 degrees C and 750 degrees C at 20 t ha-1 increased maize shoot and root dry biomass by 47.7% to 17.6% and 78.4% to 54.1%, respectively. Nevertheless, raising the biochar pyrolysis temperature decreased maize growth, whereas increasing the application rate displayed a positive effect. The application of WHB generated at 350 degrees C and 550 degrees C at 20 t ha-1 resulted in significant improvements in soil total nitrogen (17.9% to 25%), cation exchange capacity (27.3% to 20.2%), and ammonium-nitrogen (60.7% to 59.6%), respectively, over the control. Additionally, applying WHB produced from 350 degrees C to 750 degrees C at 20 t ha-1 enhanced soil carbon by 38.5%-56.3%, compared to the control. Conversely, applying biochar produced at 750 degrees C resulted in higher soil pH (6.3 +/- 0.103), electrical conductivity (0.23 +/- 0.01 dS m-1) and available phosphorus (21.8 +/- 2.53 mg kg-1).ConclusionWHBs developed at temperatures of 350 degrees C and 550 degrees C with an application rate of 20 t ha-1 were found to be optimal for growing maize and improving soil characteristics. Our study concludes that pyrolysis temperature significantly governs the effectiveness of biochar produced from a specific biomass source. image