| Biochar addition to soils has been proposed as a method to increase soil fertility and carbon sequestration. However, the effect of biochar on nitrogen transformation and availability is poorly understood. This study was conducted to determine how the rice straw biochar affected NH+4-N transformation in two soils with contrasting properties using the NH3 volatilization and chloroform fumigation experiments. The results showed that the biochar reduced NH+4-N concentration in the KCl extract of Gleyi-Stagnic Anthrosols soil by 34%, with 42% of the reduction attributed to microbial activity. Less microbial activity was observed in the biochar-amended Argi-Udic Ferrosols soil, so NH+4-N concentration in the KCl extract was reduced by only 13%, compared to the untreated soil. Biochar elevated pH of both soils, resulting in the accumulated NH3 volatilization in Gleyi-Stagnic Anthrosols and Argi-Udic Ferrosols soils as much as 7.8 times and 1.7 times the untreated soil, respectively. The results obtained from this work are helpful for us to understand the mechanism of biochar-induced nitrogen transformation in soils. |
