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Dyck MS Thesis 2022.pdf (1.99 MB)

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50 years of change: Quantifying soil C stability under long-term tillage and cropping systems in Ohio

Dyck, Ashly
http://orcid.org/0000-0003-3076-6309
http://rave.ohiolink.edu/etdc/view?acc_num=osu1657909715320021

Abstract Details

2022, Master of Science, Ohio State University, Environment and Natural Resources.
Soils represent one of the largest terrestrial stocks of carbon (C) and adopting land management techniques that increase soil C has the potential to off-set rising atmospheric CO2. Yet in order to recommend land management techniques that maximize soil C sequestration, researchers must look beyond bulk soil C budgets to investigate where, how, and for how long soil C is stored. Soil organic matter (SOM) fractionation separates bulk SOM into portions of varying stability and permanence associated with different C turnover times – including particulate organic matter (POM) (active), silt and clay (SiC) (intermediate), and resistant soil organic carbon (rSOC) (refractory) – and provides a mechanistic understanding of soil organic C (SOC) decomposition and stabilization. Changes to intermediate and refractory pools can take decades to appear, and very few studies longer than 5 years exist. Here, we seek to determine the effects of disturbance and crop diversity on the accumulation of new, corn-derived C (herein referred to as C4-C vs. “old” C3-C) in three soil fractions over 50 years of cultivation in a long-term experiment with repeated samplings. We employed size, density, and chemical fractionation, natural 13C abundance, and MIRS specific peak area analysis to identify changes in SOM composition, SOC stock (Mg ha-1), and C4-derived C stocks (Mg ha-1) of surface soil samples (0-15 cm) from the Triplett-Van Doren long-term no-tillage experiment in Wooster, OH from 1971, 2003, and 2020. Land use treatments examined were moldboard plow (PL) and no-tillage (NT), combined with continuous corn (Zea mays) (CC) and corn-soy (Glycine max) (CS) crop rotations in a full-factorial randomized complete block design. A mixed modeling approach revealed that NT and CC increased SOC stocks in POM and SiC fractions compared to PL and CS. POM made up 16.7% of total SOC, SiC 56.0%, and rSOC 4.5%. C4-derived C stocks in the SiC fraction increased over time under NT (p < 0.0001) and plateaued under PL, confirming the importance of this fraction for intermediate C storage and its vulnerability to disturbance. POM CN ratio increased over time under NT compared to PL (p < 0.0001), suggesting that disturbance is causing faster residue decay and reduced protection of POM-C in soil aggregates. The proportion of C4-C within a given fraction was greatest in POM, intermediate in SiC, and very low in rSOC. The fact that there was measurable C3-C in POM and C4-C in rSOC after 50 years of CC indicates that these fractions may not directly relate to theoretical pools of a very fast and very slow turnover. The 2:1 alumino-silicate clay mineral peak at 3630 cm-1 was important for stabilizing C4-C in the SiC (p = 0.014) and rSOC (p = 0.02) fractions in our results, while the phenolic -OH peak at 3400 cm-1 was positively correlated with C3-C storage in the rSOC fraction (p = 0.00083). Aromatic peaks at 1530 cm-1 and 1620 cm-1 were inversely correlated with the persistence of older C3-C in the rSOC fraction (p < 0.0001 for both), supporting recent theories that the innate chemical recalcitrance of inputs does not guarantee long-term soil C stabilization.
M. Scott Demyan (Advisor)
Steve Culman (Committee Member)
Christine Sprunger (Committee Member)
114 p.
Soil Sciences
fractionation; soil carbon; C sequestration; no-till; crop rotation; natural abundance; MIRS

Recommended Citations

Citations

  • Dyck, A. (2022). 50 years of change: Quantifying soil C stability under long-term tillage and cropping systems in Ohio [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1657909715320021

    APA Style (7th edition)

  • Dyck, Ashly. 50 years of change: Quantifying soil C stability under long-term tillage and cropping systems in Ohio. 2022. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1657909715320021.

    MLA Style (8th edition)

  • Dyck, Ashly. "50 years of change: Quantifying soil C stability under long-term tillage and cropping systems in Ohio." Master's thesis, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1657909715320021

    Chicago Manual of Style (17th edition)

osu1657909715320021
71
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