Changes in soil C‐isotopic composition in an agroecosystem under Free Air Carbon dioxide Enrichment (FACE) treatment during a crop rotation period

Abstract

FACE (Free Air Carbon dioxide Enrichment) has been used since 1999 to evaluate the effects of future atmospheric CO(2) concentrations on an arable crop agroecosystem. The experiment conducted at the Institute of Agroecology at the Federal Research Centre in Braunschweig consists of a typical local crop rotation of winter barley, a cover crop, sugar beet and winter wheat. The atmospheric CO2 concentration of ambient air is about 375 ppm with a delta13C value of -7 to -9 per thousand, and 550 ppm (delta13C value = -20.2 per thousand) during daylight hours in the rings fumigated with additional CO2. Thus, the surplus C can be traced in the agricultural system. Over the course of the first experimental period (3-year crop rotation period), the C-isotopic composition and the C concentration in soil were monitored monthly. Plant samples were analysed according to the relevant developmental stages of the crop under cultivation. A 13C depletion was observed in plant parts, as well as in soil samples from the FACE rings under CO2 enrichment, indicating that labelled C has reached both respective ecosystem compartments. Albeit farming management practice (especially ploughing) leads to a mixing of 'old' and 'new' C compounds throughout all soil horizons down to the end of the ploughing layer and resulted in a heterogeneous distribution of newly formed C compounds in the soil, isotope analysis of soil C reflected where the surplus C went.

Canopy CO2 exchange of sugar beet under different CO2 concentrations and nitrogen supply: results from a free‐air CO2 enrichment study

“…2002; Weigel et al. 2005, 2008), an increase in soil organic C and a decrease of δ 13 C (Giesemann 2005; Giesemann & Weigel 2008), as well as an increase in soil respiration (Soe et al. 2004).…”

Preface

“…The Joint European Stable Isotope Users Group Meeting (JESIUM) 2004 was the first formal gathering of European stable isotope scientists, receiving support from the respective isotope users groups in Austria (SINA), Germany (GASIR), France (SFIS), Benelux (BIG) and the UK (SIMSUG), with additional speakers and participants from Europe (Italy and Poland), the Americas (USA and Canada) and Australasia (Australia and New Zealand). A selection of ten papers presented at the meeting are published in this issue 1–10…”

Genetische Analysen für eine markergestützte Verbesserung der Trockenstresstoleranz von Winterackerbohnen

“…Die Proben wurden vermahlen und massenspektrometrisch auf ihren Gehalt der relevanten Kohlenstoffisotope am Johann-Heinrich-von-Thünen-Institut für Agrarklimaschutz in der Arbeitsgruppe von Anette Giesemann untersucht. Die Methodik folgte Giesemann (2005).…”