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Effects of elevated atmospheric CO 2 in agro‐ecosystems on soil carbon storage
Author(s) -
TORBERT H,
ROGERS HUGO,
PRIOR STEPHEN,
SCHLESINGER WILLIAM,
BRETT RUNION G.
Publication year - 1997
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1046/j.1365-2486.1997.d01-173.x
Subject(s) - loam , soil carbon , environmental science , agronomy , organic matter , terrestrial ecosystem , sorghum , soil organic matter , ecosystem , total organic carbon , environmental chemistry , soil water , chemistry , soil science , ecology , biology , organic chemistry
Increasing global atmospheric CO 2 concentration has led to concerns regarding its potential effects on the terrestrial environment. Attempts to balance the atmospheric carbon (C) budget have met with a large shortfall in C accounting (≈1.4 × 10 15 g C y –1 ) and this has led to the hypothesis that C is being stored in the soil of terrestrial ecosystems. This study examined the effects of CO 2 enrichment on soil C storage in C3 soybean ( Glycine max L.) Merr. and C4 grain sorghum ( Sorghum bicolor L.) Moench. agro‐ecosystems established on a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). The study was a split‐plot design replicated three times with two crop species (soybean and grain sorghum) as the main plots and two CO 2 concentration (ambient and twice ambient) as subplots using open top field chambers. Carbon isotopic techniques using δ 13 C were used to track the input of new C into the soil system. At the end of two years, shifts in δ 13 C content of soil organic matter carbon were observed to a depth of 30 cm. Calculated new C in soil organic matter with grain sorghum was greater for elevated CO 2 vs. ambient CO 2 (162 and 29 g m –2 , respectively), but with soybean the new C in soil organic matter was less for elevated CO 2 vs. ambient CO 2 (120 and 291 g m –2 , respectively). A significant increase in mineral associated organic C was observed in 1993 which may result in increased soil C storage over the long‐term, however, little change in total soil organic C was observed under either plant species. These data indicate that elevated atmospheric CO 2 resulted in changes in soil C dynamics in agro‐ecosystems that are crop species dependent.