Long-term integrated soil-crop system management promoted rhizosphere nitrogen cycling and reduced N2O emission of maize

Context

Agricultural management practices are changing from the high-yield production to high-efficient production and now sustainable production in order to satisfy the increasing demand for food. We attempted to establish a high-yielding and high-efficient maize production practice, Integrated Soil-Crop System Management (ISCM). The ISCM increased yield and nitrogen use efficiency (NUE), which could be due to changes in the composition and function of the rhizosphere bacterial community, and consequently nutrient utilization.

Objectives

To investigate the rhizosphere microbial community composition response to different production practices and explore the impact of changes in rhizosphere microbes on nitrogen metabolism and yield of maize.

Methods

Based on long-term treatment, optimizing aboveground population canopy and belowground nutrient management to set ISCM. A 12-year treatment was conducted in Tai'an City, Shandong Province, China, with four treatments.

Results

The grain yield and dry matter increment of ISCM were increased by 42.7 % and 36.6 %, compared to farmers practices (FP), respectively, while reducing N₂O emissions by 27.8 % and increasing nitrogen use efficiency by 63.7 %, mainly due to improved rhizosphere environments. The soil nitrogen cycle-related microorganisms under FP was decreased compared to ISCM. However, FP enhanced the function of microorganisms associated with gaseous nitrogen loss, resulting in higher N₂O emissions and low NUE. The ISCM enriched a wider range of rhizosphere bacterial OTU species, including many nitrogen metabolism-related microorganisms, e.g., Nitrosomonadaceae and Nitrococcales. This leads to faster soil N avalibilty to plants, maintain higher productivity, and reduce N losses. However, a super high-yield system (SY) had the highest yield and lowest NUE. Additinally, SY reduced the expression abundance of most microorganisms associated with the nitrogen cycle, but increased microorganisms gaseous of nitrogen loss function to increased N₂O emission.

Conclusions

The improved rhizosphere N metabolism promoted N uptake and reduced N₂O emissions. These findings emphasize the availability of ISCM for sustainable agricultural development.