[Effects of biochar and biochar compound fertilizer on the communities of nitrifier and denitrifier in a reclaimed soil from coal-mining area].

As a new soil amendment strategy, the effects of biochar application on soil microbial community have been reported in literature, but little information is available on the response of nitrogen-related microbial communities to biochar application in the reclaimed soil from coal-mining area. Through an outdoor pot experiment with reclaimed soil from coal-mining area of Huaibei, the effects of biochar and biochar compound fertilizer on nitrifier and denitrifier communities were investigated by real time PCR (qPCR) and terminal-restricted fragment length polymorphism (T-RFLP). There were five treatments: control (CK), NPK fertilizer (CF), biochar compound fertili-zer (BF), 2% biochar and NPK fertilizer (LB), 4% biochar and NPK fertilizer (HB). Results showed that compared with the CK, the treatments CF, BF, LB and HB significantly increased the abundance of ammonia oxidizing archaea (AOA), ammonia oxidizing bacteria (AOB), nirK and nirS genes of denitrifier. Compared with the CF treatment, BF, LB and HB significantly increased the abundance of AOB and nirK genes by 42.9%-82.1% and 33.5%-62.7%, respectively. Results of redundancy analysis showed that soil organic carbon, pH, NH4+-N and available potassium significantly affected AOB community structure, while soil organic carbon concentration, pH and NO3--N concentration significantly altered nirK-denitrifier community structure. Therefore, the application of biochar and biochar compound fertilizer could improve soil quality of the reclaimed soil from coal-mining area, and increase the abundances of nitrifier and denitrifier and alter community structure of AOB and nirK-denitrifier.