Key points are not available for this paper at this time.
Abstract Nitrogen (N) fertilization is the major contributor to nitrous oxide (N 2 O) emissions from agricultural soil, especially in post‐harvest seasons. This study was carried out to investigate whether ryegrass serving as cover crop affects soil N 2 O emissions and denitrifier community size. A microcosm experiment was conducted with soil planted with perennial ryegrass ( Lolium perenne L.) and bare soil, each with four levels of N fertilizer (0, 5, 10 and 20 g N m −2 ; applied as calcium ammonium nitrate). The closed‐chamber approach was used to measure soil N 2 O fluxes. Real‐time PCR was used to estimate the biomass of bacteria and fungi and the abundance of genes involved in denitrification in soil. The results showed that the presence of ryegrass decreased the nitrate content in soil. Cumulative N 2 O emissions of soil with grass were lower than in bare soil at 5 and 10 g N m −2 . Fertilization levels did not affect the abundance of soil bacteria and fungi. Soil with grass showed greater abundances of bacteria and fungi, as well as microorganisms carrying narG , napA , nirK , nirS and nosZ clade I genes. It is concluded that ryegrass serving as a cover crop holds the potential to mitigate soil N 2 O emissions in soils with moderate or high NO 3 − concentrations. This highlights the importance of cover crops for the reduction of N 2 O emissions from soil, particularly following N fertilization. Future research should explore the full potential of ryegrass to reduce soil N 2 O emissions under field conditions as well as in different soils. Highlights This study was to investigate whether ryegrass serving as cover crop affects soil N 2 O emissions and denitrifier community size; Plant reduced soil N substrates on one side, but their root exudates stimulated denitrification on the other side; N 2 O emissions were lower in soil with grass than bare soil at medium fertilizer levels, and growing grass stimulated the proliferation of almost all the denitrifying bacteria except nosZ clade II; Ryegrass serving as a cover crop holds the potential to mitigate soil N2O emissions.
Wang et al. (Thu,) studied this question.