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Mineralization of Carbon‐14‐Labeled Plant Residues in Conventional Tillage and No‐Till Systems
Author(s) -
Sharifi Mehdi,
Zebarth Bernie J.,
Burton David L.,
Drury Craig F.,
Grant Cynthia A.
Publication year - 2013
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/sssaj2011.0064
Subject(s) - tillage , mineralization (soil science) , agronomy , crop residue , conventional tillage , chemistry , soil water , soil carbon , residue (chemistry) , soil respiration , soil science , environmental science , biology , ecology , biochemistry , agriculture
Tillage systems are known to influence the quantity and quality of soil organic C (SOC); however, it is unclear if tillage also changes the soil catabolic capacity (the ability to decompose C substrates). This study compared soils from two contrasting tillage systems, no‐till (NT) vs. conventional tillage (CT), with respect to their ability to catabolize a common 14 C‐labeled substrate. Intact core samples from the 0‐ to 5‐cm soil depth under CT and the 0‐ to 5‐ and 10‐ to 15‐cm depths under NT were collected after 14 yr of winter wheat ( Triticum aestivum L.)–corn ( Zea mays L.)–soybean [ Glycine max (L.) Merr.] rotation. Soil cores received a common substrate ( 14 C‐labeled wheat residues) either surface applied or incorporated into the soil. Decomposition of the 14 C‐labeled residues, soil mineral N concentration, and soil microbial biomass 14 C (MB 14 C) were monitored for 86 d at 25°C. Respiration of 12 CO 2 from native SOC was greater at 0 to 5 cm under NT than CT but did not vary with depth under NT; there was no significant effect of tillage system or depth under NT or residue placement on respiration of residue 14 CO 2 . Incorporation of 14 C residues increased MB 14 C compared with surface application, indicating a greater efficiency of C utilization. For the soils and residues used in this experiment, there was no evidence of an effect of tillage system on soil catabolic capacity, and differences in soil microbial activity between tillage systems were attributed only to differences in the quantity and quality of C substrates.