Nitrogen (N) and phosphorus (P) are two most commonly limiting nutrients for the growth and reproduction of photosynthetic biota. Increased supplies of N, P, or both are expected to exert substantial impacts on growth and metabolism of plants and soil microbes, therefore terrestrial carbon (C)-cycling. While responses of aboveground C processes to interactions between N and P additions have been widely studied, how the interactions in?uence belowground C-cycling processes are still unclear.

A research team from South China Botanical Garden of Chinese Academy of Sciences recently made a meta-analysis of 1928 observations from 158 experimental studies to quantify the different interactions (i.e., additive, synergistic, and antagonistic) between N and P additions on eight variables related to belowground C-cycling processes. They found that the interactions were mainly antagonistic and additive for most belowground C-cycling variables. The relative contribution of microbial biomass to soil organic C pool increased in response to both N and P additions, as indicated by the positive interactive responses of microbial biomass C, and fungal/bacterial/total microbial biomass. The observed results were mainly due to the increased microbial C-use efficiency (CUE) with increased availabilities of N and P, and thus an increased potential for soil C uptake. In addition, the relative contribution of microbial biomass to soil organic C pool in low-latitude regions was lower than that in high-latitude regions due to the differences in CUE, soil nutrient status, and environmental conditions.

This meta-analysis highlights the interactions between N and P additions are likely to change microbial processes, thus potentially affecting terrestrial C uptake, and also provides some new insights into understanding terrestrial C-cycling processes under increasing anthropogenic N and P depositions. This study entitled “Antagonistic and additive interactions dominate the responses of belowground carbon-cycling processes to nitrogen and phosphorus additions”, and was published online in Soil Biology and Biochemistry. JIANG Jun was the first author, and Professor YAN Junhua was the corresponding author.

For more details, please refer to: https://doi.org/10.1016/j.soilbio.2021.108216.