Effects of Exogenous Silicon Addition on Nitrification and Denitrification-Derived N2O Emissions from Moso Bamboo (Phyllostachys edulis) Forest Soil

It has been reported that applying silicon (Si) to agricultural soils can reduce N2O emissions. But, we do not fully understand how this might work in forest ecosystems, especially in Phyllostachys edulis plantations. This study set out to determine how exogenous Si impacts soil nitrification and denitrification. Also, it aimed to assess their separate contributions to N2O emissions. A pot incubation experiment that lasted 28 days was carried out under controlled conditions. The soil used was collected from a bamboo plantation that is intensively managed. The treatments included adding silicon. Also, 3,4-dimethylpyrazole phosphate (DMPP) and acetylene (C2H2) were applied to specifically hold back nitrification and denitrification. We measured the rates of soil N2O emissions, the cumulative fluxes, and the concentrations of NH4+-N, NO3−-N, and NO2−-N. A positive correlation that was significant (p < 0.05) was found between N2O emissions and the levels of soil NO3−-N. Adding Si continued to reduce both the emission rate and the cumulative flux in all of the treatment groups. Also worth mentioning is that the relative contribution of denitrification to N2O emissions dropped from 38.2% to 11.4%. Meanwhile, nitrification’s contribution went up from 61.8% to 88.6%. These findings show that adding Si mainly suppresses denitrification. And, by doing so, it lessens N2O emissions in bamboo plantations. This study underlines the potential of Si amendments. They could be used as an effective management strategy to reduce greenhouse-gas emissions in forest soils. It also provides a scientific basis for making Phyllostachys edulis ecosystems more sustainable.