Does added plant residue interfere with profiling soil bacterial community by 16S rRNA gene sequencing and qPCR?

This project aimed to investigate whether the introduction of plant residue interferes with characterizing bacterial community. We added plant residue to soil and extracted soil DNA immediately, and then performed 16S rRNA gene sequencing and quantitative PCR (qPCR) to determine bacterial community structure and abundance. Unamended soil served as a control. Five DNA extraction kits, five 16S rRNA gene primer pairs, five soils, as well as two types (rice straw and alfalfa) and three addition rates (2%, 4%, and 6%; w/w) of plant residue were tested.