"People know more about the movement of celestial bodies than about the soil underfoot." Leonardo da Vinci once said. For example, few people noticed that rice paddy fields are often in phosphorus (P) deficiency, especially those located in the red-soil region of southern China.

Scientists from the Institute of Subtropical Agriculture of the Chinese Academy of Sciences (ISA) had a brainstorm that it may be possible to combine irrigation management together with P fertilizer, maybe in this way activity, biomass and composition of soil microbial communities will be well affected.

The research group tried to investigate the interactive effect of P fertilizer and irrigation management on CO₂ fixation autotrophs in a P-limited paddy soil.

They first conducted rice microcosms using a P-limited paddy soil under continuous flooding (CF) or alternative wetting and drying (AWD) treatments.

Then, they quantified the copy numbers of the bacterial 16S rRNA gene, archaeal 16S rRNA gene and four functional genes for three CO₂-fiation pathways in both bulk and rhizosphere soils under two irrigation managements.

In addition, they assessed the soil physicochemical properties and their potential influence on CO₂-fixing autotrophic microorganisms.

Based on qPCR, CCA and variation partitioning analysis, they found that the response of CO₂-fixing autotrophs to P fertilizer depended on the irrigation management methods.

P application combining with continuous flooding showed a positive effect on the abundance of CO₂-fixing autotrophs, suggesting that this combined management may potentially be more effective in increasing soil C sequestration than other tested conditions in P-limited paddy soils.

The study entitled "Irrigation management and phosphorus addition alter the abundance of carbon dioxide-fixing autotrophs in phosphorus-limited paddy soil" can be accessed online in FEMs Microbiology and Ecology.

This study was supported financially by the National Natural Science Foundation of China, National key research and development program and Youth Innovation Team Project of ISA, CAS.