High carbon use efficiency and low priming effect promote soil C stabilization under reduced tillage. (August 2018)

• Record Type: Journal Article
• Authors: Sauvadet, Marie; Lashermes, Gwenaëlle; Alavoine, Gonzague; Recous, Sylvie; Chauvat, Matthieu; Maron, Pierre-Alain; Bertrand, Isabelle
• Is Part Of: Soil biology and biochemistry. Volume 123(2018)
• Page Start: 64
• Page End: 73
• Publication Date: 2018-08
• Subjects: Soil -- Decomposition -- Litter -- CUE -- Enzymes -- Priming effect -- 13C; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2018.04.026
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Increasing the accumulation of organic carbon (C) in soils is a crucial challenge both for soil fertility and for climate change mitigation. Heterotrophic microbial communities are key drivers of C cycling in the soil and are influenced by cultural practices, among other factors. However, whether changes in microbial communities in turn affect their C degradation functions is not well understood. Here, we studied the effects of prior soil management on the microbial taxonomic composition and activity of soils amended with wheat litter. Prior soil management was either conventional (CONV) (i.e., full inversion ploughing) or reduced tillage (RT) during a 5-year period in the same loamy soil in northern France. Soil samples taken from the top 5 cm of field plots were incubated with 13 C-labelled litter of either flowering wheat or mature wheat for 29 days at 15 °C. We measured the C-CO2 and 13 C-CO2, microbial biomass C (MBC) and 13 C, and hydrolytic enzyme activities during decomposition. The initial bacterial and fungal community diversity was studied via high-throughput sequencing of ribosomal genes. The results showed that the MBC in the RT soil was initially 1.5-fold greater than that in the CONV soil; contrasting taxonomic compositions were also recorded. The soil biotic legacy impacted the degradation functions when the soils were amended with wheat litter. Compared with that in the CONV soil, the enzymatic efficiency of microorganisms in the RT soil increased by 49% and 61% in the presence of mature and flowering wheat litter, respectively. Enzyme efficiency was positively correlated with microbial litter C use efficiency (CUE) (r = 0.92, P-Value < 0.001) but negatively associated with the priming effect (PE) (r = −0.85, P-value < 0.001) across all soils and litter treatments. These findings demonstrated that the RT soil benefited both from an increase in litter C incorporated in the microbial biomass and from a reduction in soil C loss due to the PE, regardless of the quality of the decomposed litter. Our study indicated that agricultural practices such as RT, which enriches the amount of soil organic C (SOC) in the topsoil layer, can lead to positive feedback against C stabilization functions. Highlights: The contrasting 5-year tillage practices induced changes in soil microbial biomass and taxonomy. Soil biotic legacy impacted microbial functions during litter degradation. Soil microorganisms under reduced tillage had higher C use and enzyme efficiencies. Conventional tillage led to greater priming effects than did reduced tillage. High CUE and low priming effects promoted soil C stabilization under reduced tillage.