Ha. Torbert et al., ELEVATED ATMOSPHERIC CARBON-DIOXIDE EFFECTS ON COTTON PLANT RESIDUE DECOMPOSITION, Soil Science Society of America journal, 59(5), 1995, pp. 1321-1328
Assessing the impact of elevated atmospheric CO2 concentration on the
global environment is hampered due to a lack of understanding of globa
l C cycling. Carbon fixed within plant biomass ultimately enters the s
oil via plant residues, but the effects of elevated-CO2-grown plant ma
terial on decomposition rates and long-term soil C storage are unknown
. The objective of this study was to determine the decomposition rate
of plant residues grown under an elevated CO2 environment as affected
by soil type. Cotton (Gossypium hirsuturn L. 'Delta Pine 77') samples
were collected from a free-air CO2 enrichment (550 mu L L(-1)) experim
ent. The plant residues were incubated under ambient CO2 conditions to
determine decomposition rates of leaves, stems, and roots and potenti
al N and P mineralization-immobilization in three soil series: a Blant
on loamy sand (loamy siliceous, thermic Grossarenic Paleudult), a Deca
tur silt loam (clayey, kaolinitic, thermic Rhodic Paleudult), and a Ho
uston clay loam (very fine, montmorillonitic Typic Chromudert). No sig
nificant difference was observed between plant residue grown under CO2
enrichment vs. ambient CO2 conditions for soil respiration or P miner
alization-immobilization. Significantly greater net N immobilization w
as observed during the incubation in all soil types for plant residue
grown at elevated CO2. These results indicate that while decomposition
of plant residue may not be reduced by CO2 enrichment, N dynamics may
be markedly changed.