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Carbon Dioxide‐Enriched Agroecosystems: Influence of Tillage on Short‐Term Soil Carbon Dioxide Efflux
Author(s) -
Prior S. A.,
Rogers H. H.,
Runion G. B.,
Torbert H. A.,
Reicosky D. C.
Publication year - 1997
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/jeq1997.00472425002600010034x
Subject(s) - tillage , agronomy , carbon dioxide , agroecosystem , loam , conventional tillage , sorghum , chemistry , crop residue , soil carbon , growing season , environmental science , environmental chemistry , soil water , biology , ecology , soil science , agriculture , organic chemistry
Increasing atmospheric carbon dioxide (CO 2 ) concentration can increase biomass production that may influence carbon (C) dynamics in terrestrial ecosystems. Soil CO 2 efflux as affected by crop residues from high CO 2 environments managed under different tillage systems has not been explored. This study examined the effects of tillage systems in a legume [soybean [ Glycine max (L.) Merr.]] and nonlegume [grain sorghum [ Sorghum bicolor ] (L.) Moench.] CO 2 ‐enriched agroecosystem on the rates of short‐term CO 2 evolution from a Blanton loamy sand (loamy siliceous, thermic Grossarenic Paleudults). In the spring of 1994, CO 2 efflux observations initiated within 5 s after a tillage event were compared to no‐tillage conditions for 8 d in plots where both crop species had been grown in open top field chambers under two CO 2 conditions (ambient and twice ambient) for two seasons (1992 and 1993). Added CO 2 increased yields, residue, and root biomass; higher percent ground cover was also observed in CO 2 ‐enriched plots prior to the tillage treatment. Differences in C/N ratio of the residue may have influenced CO 2 efflux rates; C/N ratio was highest for sorghum and was increased by elevated CO 2 . Efflux patterns were characterized by flushes of CO 2 following initial tillage and rainfall events. Species × tillage and CO 2 × species interactions were noted on several days and for total CO 2 efflux values. Our results suggest that short‐term CO 2 fluxes may be greater for tilled soybean and for soybean grown under elevated CO 2 ; however, short‐term flux rates in the sorghum crop were affected by tillage, but not by CO 2 level. These short‐term results should be viewed with caution when predicting long‐term C turnover in agroecosystems.