化肥和有机肥配施生物炭对根际土壤反硝化势和反硝化细菌群落的影响

为明确化肥和有机肥配施生物炭对根际土壤反硝化细菌和反硝化势的影响，以柠檬根际土为研究对象，设置不施肥(CK)、化肥(CF)、有机肥(M)、化肥配施生物炭(CFBC)和有机肥配施生物炭(MBC)等5个处理，通过测定根际nirS型、nirK型和nosZ型反硝化菌群落特征、反硝化势和土壤环境因子，明确化肥和有机肥配施生物炭对根际反硝化作用的影响.结果表明，与CK相比，CF处理显著降低根际土壤反硝化势47.7%,M和MBC处理分别显著增加反硝化势的2 192.7%和1 989.9%; M和MBC处理显著增加nirS型和nosZ型反硝化菌的基因拷贝数，CF和CFBC处理显著降低nirS型和nosZ型反硝化菌基因拷贝数，而4个施肥处理均显著增加nirK型反硝化菌基因拷贝数.逐步回归分析结果表明：pH是nirS型反硝化菌丰度的主要影响因子，有机质(SOM)和铵态氮(NH⁺₄-N)是nirK型反硝化菌的主要影响因子，pH、硝态氮(NO^-₃-N)和氮磷比(N/P)则是nosZ型反硝化菌的主要影响因子.偏最小二乘法分析...

Effect of Chemical Fertilizer and Manure Combined with Biochar on Denitrification Potential and Denitrifying Bacterial Community in Rhizosphere Soil

To clarify the effect of chemical fertilizer and manure combined with biochar on denitrifying microorganisms and denitrification potential of rhizosphere soil, a pot experiment growing lemon was conducted involving five treatments, namely no fertilization (CK), chemical fertilizer (CF), manure (M), chemical fertilizer combined with biochar (CFBC), and manure combined with biochar (MBC). We determined the characteristics of the rhizosphere soil nirS-, nirK-, and nosZ-type denitrifying bacteria populations; denitrification potential; and soil environmental factors to clarify the effects of chemical and manure combined with biochar on denitrification. Our results showed that compared with that in CK, the CF treatment reduced the rhizosphere soil denitrification potential by 47.7%, whereas the M and MBC treatments increased the denitrification potential by 2192.7% and 1989.9%, respectively. The M and MBC treatments increased the gene copy number of nirS and nosZ, the CF and CFBC treatments decreased the gene copy number of nirS and nosZ, and all four fertilization treatments increased the gene copy number of nirK. Stepwise regression analysis showed that pH was the main factor for the abundance of nirS-type denitrifying bacteria and SOM and NH⁺₄-N were the main factors for the abundance of nirK-type denitrifying bacteria, whereas pH, NO^-₃-N, and N/P were main factors for the abundance of nosZ-type denitrifying bacteria. The results of partial least squares analysis indicated that the abundance of nirS-and nosZ-type denitrifying bacteria, pH, TN, and N/P were the main factors affecting rhizosphere denitrification potential. Therefore, in acidic purple soil, nirS- and nosZ-type denitrifying bacteria were the main drivers of the soil denitrification process in lemon rhizospheres under chemical fertilizer and pig manure combined with biochar, whereas fertilizer affected the rhizosphere soil denitrification process by regulating soil pH, TN, and N/P.