Details

Autor(en) / Beteiligte

• Kumar, Amit
• Kuzyakov, Yakov
• Pausch, Johanna

Titel

Maize rhizosphere priming: field estimates using ¹³C natural abundance

Ist Teil von

• Plant and soil, 2016-12, Vol.409 (1/2), p.87-97

Ort / Verlag

Cham: Springer

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Introduction Root-mediated changes in soil organic matter (SOM) decomposition, termed rhizosphere priming effects (RPE), play crucial roles in the global carbon (C) cycle, but their mechanisms and field relevance remain ambiguous. We hypothesize that nitrogen (N) shortages may intensify SOM decomposition in the rhizosphere because of increase of fine roots and rhizodeposition. Methods RPE and their dependence on N-fertilization were studied using a C₃-to-C₄ vegetation change. Nfertilized and unfertilized soil cores, with and without maize, were incubated in the field for 50 days. Soil CO₂ efflux was measured, partitioned for SOM-and rootderived CO₂, and RPE was calculated. Plant biomass, microbial biomass (MBC) and N (MBN), and enzyme activities (ß-1, 4-glucosidase; N-acetylglucosaminidase; L-leucine aminopeptidase) were analyzed. Results Roots enhanced SOM mineralization by 35 % and 126 % with and without N, respectively. This was accompanied by higher specific root-derived CO₂ in unfertilized soils. MBC, MBN and enzyme activities increased in planted soils, indicating microbial activation, causing positive RPE. N-fertilization had minor effects on MBC and MBN, but it reduced ß-1, 4-glucosidase and L-leucine aminopeptidase activities under maize through lower root-exudation. In contrast, Nacetylglucosaminidase activity increased with Nfertilization in planted and unplanted soils. Conclusions This study showed the field relevance of RPE and confirmed that, despite higher root biomass, N availability reduces RPE by lowering root and microbial activity.