[Effects of physico-chemical parameters on the abundance of the denitrification-associated genes nirK, nirS and nosZ during agricultural waste composting].

The abundance variation of the functional genes (nirK, nirS and nosZ) involved in denitrification was investigated using the real-time polymerase chain reaction (real-time PCR) at different locations (top, center and bottom) of the compost pile during the agricultural waste composting. The changes in pile temperature, pH, moisture content, soluble NH4(+) -N, NO3(-) -N and water soluble carbon (WSC) were measured. The results showed that the abundance of those genes varied among the samples collected in different zones. Redundancy analysis (RDA) was applied to explore the correlations between the abundance of nirK, nirS and nosZ and the composting physic-chemical parameters. The results suggested that water soluble carbon (WSC), pile temperature and nitrate had the most significant impacts on the abundance of the three genes. The t-value biplots for each environmental variable indicated that nirK was positively related with temperature and pH (P < 0.05), nirS was positively related with temperature (P < 0.05), and nosZ was positively related with NH4(+) -N while negatively with WSC.