Soil respiration before and after 22 years of no-till management
Peer Reviewed StatusNon-Peer Reviewed
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Soils are the largest terrestrial carbon sink on Earth and increasing soil organic carbon (SOC) content is a means of sequestering atmospheric CO2. Adoption of no-till management can contribute to long-term soil carbon storage by increasing the level of stable recalcitrant SOC, which is resistant to loss as CO2 via heterotrophic respiration. However, limited work has been done to examine the effect of long-term reduced tillage practices on the permanence of SOC in surface soil. The objective of this study is to assess the nature and permanence of sequestered SOC in contrasting Saskatchewan soils after 22 years of conservation agriculture practices. Ninety fields under continuous direct-seeded annual crop production were sampled in 1996 and again at the same locations in 2018. The fields represent a diverse collection of soil types from within the five Soil Zones of Saskatchewan. Comparisons were made between the 1996 and 2018 soils (0-10 cm) in the respirable carbon fraction of soil organic matter during a six-weekend incubation. Regardless of soil type and sampling year, there were few differences in CO2 emissions among the sampled pairs. Respiration was lowest in soils from the Brown Soil Zone, reflecting the lower organic matter content of these soils. The similar cumulative CO2-C emissions between the 1996 and 2018 soils in the six-week respiration measurements, despite presumably greater SOC levels in the 2018 soils, may indicate similar or greater permanence of the SOC following 22 years of conservation management compared to the SOC in the 1996 soils.
Part OfSoils and Crops Workshop
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