Effects of clay on nitrogen cycle related functional genes abundance during chicken manure composting

•Compare the abundance of nitrogen cycling genes during clay amendment co-composting.•Clay addition promote the transformation NH4+-N into NO3−-N.•Clay amendment improve the abundance of nitrogen genes.•8% clay amendment influence the abundance of nifH and nosZ genes efficiently. The objective of this study was to identify the effect of clay additive to explore the nitrogen cycling related ammonification, denitrifying genes and their relation N2O and ammonia emission during the chicken manure (CM) composting. The consequences indicated that the additive clay could optimize the environment and improve the NH4+-N into NO3−-N transformation. Meanwhile, the results observed that 8% clay amendment was significant correlated the abundance of nifH and nosZ genes. Compared with the other treatments, the 6% and 10% clay treatments observed low abundance of nifH. The heat map indicated that clay amendment could enhance the function genes abundance. The redundancy analysis showed that N2O and ammonia emission among all physiochemical parameters had great relationship with functional genes. Therefore, the addition of 10% clay into CM composting system could efficiently enhance the abundance of nirK and narG genes, and improve the composting with its application.