The amendment of rice straw to the soil is normally recommended as straw is an important source of soil organic matter and provides nutrients to subsequent crops. Straw-nitrogen (N) together with soil-N are mainly in organic N form, which needs to be mineralized by microbes to be available to crops. However, it is largely unknown on how climate change impacts the straw-N mineralization and relevant microbial attributes.

Recently, researchers at the Northeast Institute of Geography and Agroecology, Key Laboratory of Mollisols Agroecology, Chinese Academy of Sciences (CAS) used ¹⁵N-labeled straw to quantify straw-N mineralization, and deployed ¹⁶S gene sequencing to investigate rice rhizosphere microbial community composition associated with straw-N mineralization when rice plants were grown under elevated CO₂ (700 ppm) and warming (2℃ above ambient).

Related findings were published in Geoderma on 1 March.

Co-elevated CO₂ and temperature had no significant effect on the straw-N-use efficiency, but significantly enhanced the straw-N mineralization with greater increase in the rhizosphere than bulk soil. Climate change resulted in more straw-N transformed into microbial biomass, soluble organic, and mineral N pools (Fig. 1A). Under the straw addition, co-elevated CO₂ and temperature significantly increased the abundance of leucine aminopeptidase gene (pepA), and significantly changed the composition of microbial communities relative to urease (ureC) and pepA, contributing to straw-N mineralization (Fig. 1B).

This study suggested that climate change significantly accelerated the straw-N mineralization by changing the microbial community related to the functional genes of nitrogen mineralization in the rhizosphere of rice. Those results favor the improvement of crop straw management under climate change.