Co-application of biochar with non-pyrolyzed organic material accelerates carbon accrual and nutrient availability in soil

Abstract The impact of biochar on C storage and nutrient cycling when co-applied with other non-pyrolyzed organic amendments is still uncertain. Therefore, an incubation experiment for 120 days was conducted to attain an improved understanding of the capability of biochar for C accretions and nutrient release when co-applied with non-pyrolyzed organic materials like crop-residue (rice-residue) and manure (animal-manure). The results of the study showed that the individual application of biochar (RB), rice residue (RR), animal-manure (AM), or their co-application (RB+RR and RB+AM) enhanced C mineralization by 10%, 85%, 59%, 63%, and, 37%, respectively than the unamended control. Even though the input of C in RB+RR and RB+AM was 82% and 75% more compared with the sole biochar amended soil, comparatively, percentage C loss per g of C added in RB+RR and RB+AM were only 12% and 5% greater than biochar amended soil. Therefore, the results of the study indicate stabilization of C released from labile sources (RR or AM) on the biochar surface that reiterates its greater C accretion potential. Furthermore, soil available nutrients showed no significant difference between the control and sole biochar amended soil, thus validating the limitations of applying biochar individually. On the other hand, a considerable correlation between microbial biomass with plant-available nutrients in the soil co-amended with biochar and non-pyrolyzed organic materials ensured greater availability of nutrients for crop uptake. Thus, co-application of biochar with non-pyrolyzed organic materials could be more beneficial for C accretion and release of nutrients compared with their individual application to soil.