Carbon input to soil may decrease soil carbon content

TL;DR: The results of this study suggest that the wetland degradation would decrease soil PDA, and abundance and structural diversity of the denitrifying bacteria with nirS genes in alpine wetlands.

Abstract: The Loess Plateau soil in northwest China originated from wind sediments and is characterized by deep soil profiles and large organic carbon (C) content. Severe soil erosion constantly exposes deep soils to the surface, making the organic C vulnerable to microbial decomposition. Few, however, have so far examined how soil microbial activity and community composition in the deep loess soil respond to perturbations. We examined microbial responses in three layers of a clay‐loam loess (topsoil, 0–20 cm; midsoil, 40–60 cm; subsoil, 80–100 cm) to substrate additions (0.8 g glucose‐C kg−1 soil) under two temperature regimes (25 and 35°C). Soil C:N ratio was significantly larger in the subsoil (20.3) than topsoil (7.4). Glucose addition significantly increased CO2 efflux during a 30‐day incubation period and the relative magnitude of the increase was four times larger in the subsoil than topsoil. The temperature sensitivity (Q10) of soil CO2 efflux increased significantly with soil depth in the absence of glucose addition (i.e., ambient soil), but it decreased under glucose addition. Also, glucose addition significantly increased phenol oxidase and peroxidase activities in the subsoil, which might contribute to the stimulation of microbial CO2 efflux. Composition of the microbial community was more affected by temperature increase in the topsoil, but more responsive to labile C addition in the subsoil. Together, these results indicated that the composition of soil communities and microbial activities in the topsoil and deep soil responded differently to warming and labile C input. Our findings suggest that organic C in deep loess soils can be highly sensitive to environmental changes, emphasizing the need for more long‐term monitoring and quantitative assessment of organic C release from this important C pool.

TL;DR: In this article, the effect of inorganic nitrogen (N) and root carbon (C) addition on decomposition of organic matter (OM) was investigated for 200 days with nine treatments.

TL;DR: In this article, three experiments were performed with bathypelagic Atlantic waters to experimentally test how the chemical quality of available organic compounds influenced the production of new fluorescent humic-like material, which is relatively difficult to metabolize by deep water prokaryotes.

TL;DR: In this paper, the authors build a conceptual model of the priming effect based on the contradictory results available in the literature adopting the concept of nutritional competition, and they postulate that priming results from the competition for energy and nutrient acquisition between the microorganisms specialized in the decomposition of fresh organic matter and those feeding on polymerised SOM.

TL;DR: In this article, the authors present an analysis of Soil organic matter storage in Agroecosystems. But their focus is on the storage of organic matter in Soil Fraction and Aggregates.