Switchgrass cultivars differentially affect soil carbon stabilization
Abstract
Soil organic carbon (SOC) storage depends on the amount and quality of plant-derived carbon (C) inputs to soil, which is largely regulated by plant roots via the processes of root turnover and exudation. While we know that plant roots mediate SOC stabilization, we do not fully understand which root characteristics specifically promote soil C storage. With this study we asked whether roots with coarse root systems versus roots with finely branched root systems differentially affect soil C stabilization. In order to answer this question, we collected soil cores (4.8 cm diameter, to a depth of 30 cm) from directly over the crown of six switchgrass (Panicum virgatum L.) cultivars that differed in root architecture. Specifically, three cultivars had fibrous root systems (i.e. high specific root length) and three had coarse root systems (i.e. low specific root length). The cultivars (C4 species) were grown in a C3 grassland for four years, allowing us to use isotopic fractionation techniques to assess differences in soil C input and stabilization. The cores were divided into depth increments of 10 cm and the soils were sieved (2mm). Soil from each depth increment was dispersed by shaking for 16 hours in a NaHMP solution to isolate coarse particulate organic matter (C-POM), fine particulate organic matter (F-POM), silt, and clay-sized fractions. Samples of soil fractions across all depths were analyzed for C and N contents as well as δ13C signature. We found that the relative abundance of the different soil fractions and associated δ13C signatures differed significantly among cultivars. These results indicate that switchgrass cultivars can differentially impact soil carbon inputs and stabilization. We hypothesize that these differences may be driven by variability in root architectures.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B31E0476A
- Keywords:
-
- 0428 BIOGEOSCIENCES / Carbon cycling