pH and exchangeable aluminum are major regulators of microbial energy flow and carbon use efficiency in soil microbial communities

Publication date: Available online 4 September 2019Source: Soil Biology and BiochemistryAuthor(s): Davey L. Jones, Emily C. Cooledge, Frances C. Hoyle, Robert I. Griffiths, Daniel V. MurphyAbstractThe microbial partitioning of organic carbon (C) into either anabolic (i.e. growth) or catabolic (i.e. respiration) metabolic pathways represents a key process regulating the amount of added C that is retained in soil. The factors regulating C use efficiency (CUE) in agricultural soils, however, remain poorly understood. The aim of this study was to investigate substrate CUE from a wide range of soils (n = 970) and geographical area (200,000 km2) to determine which soil properties most influenced C retention within the microbial community. Using a 14C-labeling approach, we showed that the average CUE across all soils was 0.65 ± 0.003, but that the variation in CUE was relatively high within the sample population (CV 14.9%). Of the major properties measured in our soils, we found that pH and exchangeable aluminum (Al) were highly correlated with CUE. We identified a critical pH transition point at which CUE declined (pH 5.5). This coincided exactly with the point at which Al3+ started to become soluble. In contrast, other soil factors [e.g. total C and nitrogen (N), dissolved organic C (DOC), clay content, available calcium, nitrogen, phosphorus (P) and sulfur (S), total base cations] showed little or no relationship with CUE. We also found no evidence to suggest that nutr...
Source: Soil Biology and Biochemistry - Category: Biology Source Type: research