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In Situ Decomposition of Grass Roots as Affected by Elevated Atmospheric Carbon Dioxide
Author(s) -
Ginkel J. H.,
Gorissen A.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200040015x
Subject(s) - lolium perenne , perennial plant , incubation , decomposition , chemistry , carbon dioxide , soil water , lolium , biomass (ecology) , organic matter , agronomy , environmental chemistry , soil carbon , soil science , biology , poaceae , environmental science , biochemistry , organic chemistry
The effects of elevated CO 2 on belowground C input, on decomposition of roots in situ vs. decomposition of disturbed roots, and on soil microbial biomass were investigated in a perennial grass species. Forty ryegrass ( Lolium perenne L.) plants were homogeneously 14 C‐labeled in two controlled environments for 115 d in a continuous 14 CO 2 atmosphere at 350 and 700 µL CO 2 L ‐1 and two soil N levels (low, LN, and high, HN). Thereafter, some of the plants were destructively harvested. Undisturbed root systems of the remaining plants were incubated in situ (IRS) for comparison with a disturbed incubation of the dried and ground roots (DRS) in their original soils. At the start of the incubation, elevated CO 2 had increased total 14 C‐labeled soil C input by 44 and 27% at LN and HN, respectively, compared with input at ambient CO 2 . After incubation for 230 d, 40% of 14 C soil content was mineralized to 14 CO 2 in the disturbed system and 52% in the intact system. Native soil organic matter (SOM) decomposition of the DRS was lower than the SOM decomposition of the IRS. The formation of 14 C‐labeled soil microbial biomass ( 14 C‐SMB) in the soil with DRS was 130% higher than in the soil with the IRS. Elevated CO 2 decreased the decomposition of roots and root‐derived products by 10% and increased the size of the 14 C‐SMB by 28% for both IRS and DRS, whereas the decomposition of SOM was not affected by CO 2 at either LN or HN. After plant growth and in situ incubation, the 14 C‐labeled C in the soil solution showed a highly positive correlation with the amount of 14 C‐SMB. The ratio between 14 C‐labeled microorganisms and total 14 CO 2 evolved was not affected by elevated CO 2 . It seems that microorganisms adapt to changing soil C input under elevated CO 2 and there is no effect on their turnover and behavior.