The Innovation Team of Soil-Plant Interactions at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has discovered that the low carbon loss in soils with long-term organic fertilizer application during abrupt temperature increases is achieved through the transformation of soil organic carbon recalcitrance, less warm-stimulated microorganisms, more complex microbial community, and the higher CO₂ intercepting capability by Thaumarchaeota. The related research findings were published in "Environmental Science & Technology."

Terrestrial ecosystems constitute the largest global carbon reservoir, wherein soils contain more carbon than aboveground biomass and the atmosphere. Therefore, minor changes in soil carbon can wield substantial influence over the concentration of CO₂, the predominant greenhouse gas in the atmosphere. Manure application stands out as one of the most efficient and widely adopted methods for increasing SOC storage. However, little is known about the response of organic carbon decomposition in soils with organic fertilizer application to abrupt temperature increases, which typically occur during day-night temperature fluctuations.

This study investigated the effects of long-term (23 years) continuous application of manure on SOC chemical composition, soil respiration and microbial communities under temperature shifts (15℃ vs 25℃) in the presence of crop residues. Compared to soil without fertilizer, manure application reduced SOC recalcitrance indexes (i.e. aliphaticity and aromaticity) by 17.45% and 21.77%, and also reduced temperature sensitivity (Q₁₀) of native SOC decomposition, plant residue decomposition and priming effect by 12.98%, 15.98% and 52.83%, respectively. The relative abundances of warm-stimulated chemoheterotrophic bacteria and fungi were lower in the manure-applied soil, whereas that of chemoautotrophic Thaumarchaeota was higher. In addition, the microbial network of the manure-applied soil was more interconnected, with more negative connections with the warm-stimulated taxa than soils without fertilizer or with chemical fertilizer applied. In conclusion, our study demonstrated that the reduced loss of SOC to abrupt warming by manure application arises from C chemistry modification, less warm-stimulated microorganisms, a more complex microbial community and the higher CO₂ intercepting capability by Thaumarchaeota.

The study was led by researcher Fan Fenliang of the Innovation Team of Soil-Plant Interactions at IARRP, with Dr. Enzhao Wang as the first author and associate researcher Alin Song as the corresponding author. This research was supported by the National Key R&D Program and the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences.