Amelioration in nutrient mineralization and microbial activities of sandy loam soil by short term field aged biochar

The aging of biochar is an important parameter for its sustainable application. However, data on the impact of field-aging biochar on soil biological properties is limited. In this study, the impact of three months aged biochar soil mixture and fresh biochar soil mixture on the physico-chemical characteristics (morphology, functional groups, cation exchange and water holding capacities) and biological activity (microbial and soil enzymes) was compared. Cymbopogon winterianus-derived biochar was used for the experiment at three different application rates. The physico-chemical properties of soil collected at different time points suggested that weathering of biochar soil mixture significantly increases the labile organic carbon and cation exchange capacity. However, a decrease in pH and water holding capacity was also observed. In the aged biochar-soil mixture, the rate of mineralization was higher as compared to the fresh biochar-soil mixture. It provided better sites for adsorption of NH4-N and NO3-N. Aged soil biochar mixture had higher microbial and enzymatic activities (dehydrogenase, acidic and alkaline phosphatase and urease) as compared to fresh biochar soil mixture except for beta-glucosidase. Our results suggest that short-term field weathering of biochar would be able to improve the soil biological properties significantly.