Evaluation of a Biochar-Based Slow-Release P Fertilizer to Improve Spinacia oleracea P Use, Yield, and Nutritional Quality

Assessment of the application of two amendments (lime and biochar) on the acidification and bioavailability of Ni in a Ni-contaminated agricultural soils of northern Colombia

“…The pyrolysis temperature was raised to 500 °C at a rate of 20 °C min −1 and held constant for 3 h, followed by cooling to room temperature inside a furnace. The biochar was aerated for 24 h at room temperature (25 °C), then sieved (<2mm) and stored in airtight containers ( Morales et al., 2021 ; Sepúlveda-Cadavid et al., 2021 ; Herrera et al., 2022 ). The biochar obtained was named as SP-BC.…”

“…Ash content was measured as the weight of the residue after a SP-BC sample was heated at 700 °C in an open crucible ( López et al., 2020 ). The C and N content were determined using an elemental analyzer (Elemental Analyzer, Germany) ( Sepúlveda-Cadavid et al., 2021 ). Total concentration of Ni was determined by acid digestion and quantified by ICP-OES (Inductively coupled optical emission spectrometry, Agilent Technologies 5100 ICP-OES equipment, Santa Clara, USA).…”

“…Subsequently, the filtrate was used for the determination of elements by ICP-OES ( Table 1 ). Superficial functional groups were determined by FTIR (Fourier-transform infrared spectroscopy) analysis using an infrared spectrometer (Thermo scientific Smart iTR Nicolet iS10, Waltham, USA), which was operating in a 4000-400 cm −1 spectral range with a resolution of 4 cm −1 ( Sepúlveda-Cadavid et al., 2021 ).…”

“…Ash content was measured as the weight of the residue after a SP-J o u r n a l P r e -p r o o f 6 BC sample was heated at 700°C in an open crucible (López et al 2020). The C and N content were determined using an elemental analyzer (Elemental Analyzer, Germany) (Sepúlveda-Cadavid et al 2021).…”

“…Total N was determined for Kjeldhal method (ISO 11261:1995). Bioavailable P concentration was extracted with J o u r n a l P r e -p r o o f 8 Olsen method and estimated using a spectrophotometer (Sepúlveda-Cadavid et al, 2021). Exchangeable base cations (Ca 2+ , Mg 2+ , K + , and Na + ) were extracted with 1 M NH 4 -acetate at pH 7.0 and quantified by ICP-OES according to ISO 11260:2018.…”