Wood base biochar alters inorganic N

Sustainable nut production and supply depend on soil nutrient availability, but current land management practices in macadamia farms, including soil erosion and minimal inter row groundcover in established orchards can reduce soil carbon (C) and impair soil fertility. Therefore, nut production in macadamia orchards relies heavily on inorganic and organic fertiliser application which brings an economic burden for farmers. Biochar, a C rich product from the pyrolysis of organic residues, has been shown to improve soil fertility and fertiliser use efficiency. In the current study, we aimed to explore the effects of a wood-based biochar at two application rates of 10 t/ha (B10) and 30 t/ha (B30) on soil C and nitrogen (N) cycling at months 0, 6, 12, 18 and 24 following its application to a macadamia orchard. No significant effects of biochar on soil soluble organic C and N were observed at months 0, 6 and 12 following biochar application. At months 12, 18 and 24, biochar significantly increased soil nitrate concentration with B30 compared to the control and B10 but differences were significant only at month 12.