“…Biochar, HH meal, B meal and zeolite were analysed for K, Zn, Na, Mn, Ca and Fe but not for pH, N and P. However, based on the literature, biochar has a pH level of 4.7–11.5 (Alburquerque et al, 2013; Hossain et al, 2020; Silva Gonzaga et al, 2019), HH meal of 6.1–7.9 (Möller & Schultheiß, 2015), B meal of 6.4–6.5 (Möller & Schultheiß, 2015) and zeolite of 7.1–8.0 (Sindesi & Ncube, 2021; Youssef, 2013). Furthermore, biochar has N concentrations of 0.3%–1.4% (Agegnehu et al, 2016; Vitkova et al, 2017), HH meal of 12%–15% (Nordi et al, 2022; Oluwafisayo & Olusegun, 2023), B meal of 3%–6% (Joshi, 2015; Oluwafisayo & Olusegun, 2023) and zeolite of 0.47–0.49 g kg −1 (Głąb et al, 2021). Regarding P, biochar has a P concentration of 0.02%–0.5% (Silva Gonzaga et al, 2019), HH meal of 2% (Oluwafisayo & Olusegun, 2023), B meal of 12%–15% (Joshi, 2015; Oluwafisayo & Olusegun, 2023) and zeolite of 0.01% (Aainaa et al, 2018).…”