Mineralization of Carbon-14-Labeled Plant Residues in Conventional Tillage and No-Till Systems
- Mehdi Sharifia,
- Bernie J. Zebarth *b,
- David L. Burtonc,
- Craig F. Druryd and
- Cynthia A. Grante
- a Environmental and Resource Science/Studies Program, Trent Univ., 1600 West Bank Drive, Peterborough, ON, Canada K9J 7B8
b Agriculture and Agri-Food Canada, Potato Research Centre, PO Box 20280, Fredericton, NB, Canada E3B 4Z7
c Dep. of Environmental Sciences, Nova Scotia Agricultural College, PO Box 550, 21 Cox Rd., Truro, NS, Canada B2N 5E3
d Agriculture and Agri-Food Canada, Greenhouse and Processing Crop Research Centre, Harrow, ON, Canada N0R 1G0
e Agriculture and Agri-Food Canada, Brandon Research Centre, Grand Valley Road, Brandon, MB, Canada R7A 5Y3
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 14C-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 (14C-labeled wheat residues) either surface applied or incorporated into the soil. Decomposition of the 14C-labeled residues, soil mineral N concentration, and soil microbial biomass 14C (MB14C) were monitored for 86 d at 25°C. Respiration of 12CO2 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 14CO2. Incorporation of 14C residues increased MB14C 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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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