Relevance of substrate quality and nutrients for microbial C-turnover in top- and subsoil of a Dystric Cambisol

摘要: Abstract The generally high apparent 14C age of soil organic carbon (SOC) in subsoils suggests a stability against microbial degradation. However, the SOC decomposition may also be limited by easily available substrates and nutrients, such as N P. In topsoils, priming effects response to substrate additions are largely determined quality which differently affects community, while knowledge for deep layers is very scarce. order gain further insight into processes controlling subsoils, we conducted laboratory incubation experiment 105 days investigate impact different mineral P on mineralization Dystric Cambisol sampled at 2–12, 35–65 135–165 cm. We studied impacts 14C-labeled citric, vanillic palmitic acid or alone combination with two changes mineralization. choice was based their nominal oxidation state carbon, reflects energy yield biogeochemical reactivity compound. Further, treatments activity six extracellular enzymes involved C-, N-, P- S-acquisition, peroxidase phenoloxidase intracellular dehydrogenase investigated clarify if qualities nutrients affect potential nutrient demand community. Our results show that metabolism both subsoil layers, although upper (35–65 cm) have become during later stage incubation. Even after 105 days, C-cycling were highly elevated lower (135–165 cm) indicates sustained higher community once N-limitation overcome. (35–65 cm), found amounts labile C, indicating proportion fast cycling SOC. Furthermore, all added induced negative effects, positive only addition related limiting metabolism. suppressed likely occurred because present adapted more compounds, resulting preferential utilization. (135–165 cm), real acid, citric had no effect This clearly matters inducing this subsoil. Altogether, study evidently shows consequence altered input storage destabilized forest soils.