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Free‐Air CO 2 Enrichment of Sorghum: Soil Carbon and Nitrogen Dynamics
Author(s) -
Prior S. A.,
Torbert H. A.,
Runion G. B.,
Rogers H. H.,
Kimball B. A.
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0276
Subject(s) - loam , calcareous , mineralization (soil science) , soil carbon , sorghum , agronomy , chemistry , nitrogen , soil water , environmental chemistry , total organic carbon , incubation , environmental science , soil science , botany , biology , organic chemistry , biochemistry
Abstract The positive impact of elevated atmospheric CO 2 concentration on crop biomass production suggests more carbon inputs to soil. Further study on the effect of elevated CO 2 on soil carbon and nitrogen dynamics is key to understanding the potential for long‐term carbon storage in soil. Soil samples (0‐ to 5‐, 5‐ to 10‐, and 10‐ to 20‐cm depths) were collected after 2 yr of grain sorghum [ Sorghum bicolor (L.) Moench.] production under two atmospheric CO 2 levels: (370 [ambient] and 550 μL L −1 [free‐air CO 2 enrichment; FACE]) and two water treatments (ample water and limited water) on a Trix clay loam (fine, loamy, mixed [calcareous], hyperthermic Typic Torrifluvents) at Maricopa, AZ. In addition to assessing treatment effects on soil organic C and total N, potential C and N mineralization and C turnover were determined in a 60‐d laboratory incubation study. After 2 yr of FACE, soil C and N were significantly increased at all soil depths. Water regime had no effect on these measures. Increased total N in the soil was associated with reduced N mineralization under FACE. Results indicated that potential C turnover was reduced under water deficit conditions at the top soil depth. Carbon turnover was not affected under FACE, implying that the observed increase in soil C with elevated CO 2 may be stable relative to ambient CO 2 conditions. Results suggest that, over the short‐term, a small increase in soil C storage could occur under elevated atmospheric CO 2 conditions in sorghum production systems with differing water regimes.