Maize residue decomposition measurement using soil surface carbon dioxide fluxes and natural abundance of carbon-13

• Published in: Soil Science Society of America journal Vol. 63; no. 5; pp. 1385 - 1396
• Main Authors: Rochette, P, Angers, D.A, Flanagan, L.B
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.09.1999; Soil Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; biological activity in soil; Biological and medical sciences; biomass; carbon; Carbon 13; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; Corn; Crop residues; Decomposition; degradation; Fundamental and applied biological sciences. Psychology; immobilization; measurement; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; ratios; respiration; soil microorganisms; soil respiration; Soil science; Soil surfaces; soil temperature; soil water content; Soils; stable isotopes; Zea mays; Quebec; Monocotyledones; Zea mays; Material flow; Cultivated soil; Carbon dioxide; Isotopic composition; Decomposition; Vegetal waste; Measurement in situ; C-13; Gramineae; Ground surface; Angiospermae; Spermatophyta; Measurement method
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1999.6351385x

The decomposition rate of crop residues in soils directly impacts organic matter content and nutrient cycling. We hypothesized that natural abundance (13)C analyses could be used with soil CO(2) flux measurements to quantify the short-term decomposition rates of maize (Zea mays L.) residues under undisturbed field conditions. For this purpose, maize was grown in a sandy loam (Umbric Dystrochrept) that developed under C3 vegetation. Residues were returned to the field at the end of the growing season. During the following snowfree period (May to November), the maize residue decomposition rate was calculated for plots that were either under no-till or moldboard plowed, using the C isotope ratio ((13)C/(12)C) of the soil CO(2), the C isotope ratio of the plant and soil substrates, and the soil respiration rate. The incorporation of residue-derived C into the soil microbial biomass was also evaluated. Maize residue decomposition increased the C isotope ratio of the soil CO(2) by 2 to 7 ppt relative to unamended control plots. Decomposition rates peaked in June (2-3 g C m(-2) d(-1)) and were low at both the beginning and end of the growing season (< 0.5 g C m(-2) d(-1)). For a given soil temperature, the decomposition was more active early than late in the season because of decreased substrate availability as decomposition proceeded. The decomposition rate of maize-derived C correlated with the fraction of the microbial biomass derived from maize residues. This active pool represented 9% of microbial biomass and showed a high level of specific activity. The total maize residue-C losses during the study corresponded with 35% of the added residue C under no-till plots and 40% with moldboard plowing. Natural abundance (13)C analyses may be successfully used with respiration measurements to quantify crop residue decomposition rates under undisturbed field conditions.