Characteristics and inorganic N holding ability of biochar derived from the pyrolysis of agricultural and forestal residues in the southern China

Biochar not only provides an important way to utilize agricultural and forestry waste, but also plays an important role in soil improvement and soil carbon sequestration. This study mainly investigated the effect of pyrolysis temperatures(300, 500 and 650 °C) and feedstock types including Banana Leaf (BL), Banana Stalk (BS), Banana Pseudo stem (BP), Sugarcane Leaf (SL), Sugarcane Stalk (SS), Cassava Stem (CS), Mulberry Stalk (MS), and Eucalyptus Branches (EB) on the biochar properties an its inorganic N holding ability. The results showed that the physical properties of biochar were more affected by agricultural and forestal residues types e.g.; herbaceous feedstock materials resulted in lower surface area (2-70 m2/g) while woody materials obtained relatively higher surface area (200-380 m2/g). However, the chemical properties of biochar were affected by pyrolysis temperature, as results indicated that BL biochar obtained pH 10.0 at 650 °C, while 8.45 at 300 °C, BS got highest CEC value 13.79 cmol kg−1 at 650 °C, while 6.83 cmol kg−1at 300 °C. NH4+-N sorption amount was ranging from 609.59 to 2040.40 mg/kg by different biochars, BS biochar adsorbed the highest amount of NH4+-N (1668.11 to 2040.4 mg/kg) among all the feedstock materials. Biochar derived from herbaceous biomass had relatively lower yield and C content as compared with that of wooden biomass. However, herbaceous biochars showed relatively better chemical properties than that of wooden biochars. The inorganic nitrogen holding ability of biochar was significantly affected by feedstock resources.