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Elevated CO 2 enhances below‐ground C allocation in three perennial grass species at different levels of N availability
Author(s) -
COTRUFO M. F.,
GORISSEN A.
Publication year - 1997
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.1997.00839.x
Subject(s) - rhizosphere , lolium perenne , perennial plant , shoot , agronomy , chemistry , festuca rubra , bulk soil , soil carbon , nitrogen , biomass (ecology) , soil water , biology , ecology , bacteria , genetics , organic chemistry
summary Three perennial grass species, Lolium perenne L., Agrottis capillaris L. and Festuca uvina L., were homogeneously labelled in phytotrons with 14 CO 2 at two CO 2 concentrations (350 and 700μl l −1 ). Plants were grown under two nitrogen regimes: one with a minor addition of 8 kg N ha −1 , the other with an addition of 278 kg N ha −1 . Carbon allocation over the different compartments of the plant/soil systems was measured: shoots, roots, rhizosphere soil (soil solution, microbial biomass and soil residue), and bulk soil. Elevated CO., increased total net 14 C recovery in all species by 14%, and significantly enhanced the below‐ground 14 C allocation by 26%, this enhancement was 24%, 39% and 21 % for root, rhizosphere soil and bulk soil, respectively. Within the rhizosphere soil, the 14 C amounts in the soil solution (+ 69%) and soil residue (+ 49%,) increased significantly. Total microbial biomass‐C in the rhizosphere soil was also increased (15 %) by the elevated CO 2 treatment, but only in proportion to the increased root mass. No interactions were observed between the elevated CO 2 , and N treatments. The N treatment increased total net 14 C recovery by more than 300% and 14 C was preferentially allocated to the shoots, leading to a significant increase in shoot‐to‐root ratio. However, N fertilization also increased (+111%) the absolute amount of 14 C in soil. The three species behaved differently, but no interactions were observed between CO 2 treatment and plant species. These results show that elevated CO 2 induces an increased C input into soil for all three grass species at both N levels. However, the highest absolute amounts were found in the soils of the fastest growing species and at the highest N level.