Eroded Critical Zone Carbon and Where to Find It: Examples from the IML-CZO

Blair, Neal E.; Hayes, John M.; Grimley, David A.; Anders, Alison M.

doi:10.1007/978-3-030-95921-0_5

Cited by 4 publications

(5 citation statements)

References 72 publications

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“…Whereas in topographic concavities where flow accumulates, water erosion has the potential to remove soils from the field to the stream network, decreasing SOC burial within fields. However, the majority of eroded soil is likely stored locally with fields (Blair et al., 2022; Stallard, 1998) because soil deposition due to agricultural erosion outpaces soil export via water erosion (Pennock & De Jong, 1987; Van Oost et al., 2000). Rill and gully erosion can also increase rates of hillslope erosion by drainage network expansion and local base‐level lowering, but their effect would be small within our simulation's timescales (Text S3 in Supporting Information S1) (Fernandes & Dietrich, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…Our model differs from soil erosion models that estimate the export of sediment, that is, sediment yield (Arnold et al., 1998; Laflen et al., 1991; Van Oost et al., 2000); instead, LEM‐SOC predicts the internal redistribution of soil and SOC. In the Midwestern U.S., the majority of soil that is eroded is transported only a short distance before it is deposited, or redistributed; less than 10% of eroded soil is estimated to be exported from watersheds (Blair et al., 2022). Hence, our modeling focusses on the redistribution of soil and SOC that occurs within agricultural fields.…”

Section: Midwestern United States (Us) Soils and Erosion Modelingmentioning

confidence: 99%

“…However, if SOC transported with soil is buried before it can mineralize, and dynamic replacement of carbon occurs where soils have been eroded (Harden et al., 1999), CO 2 is sequestered (Berhe et al., 2007; Liu et al., 2003). Therefore, to assess whether agricultural soil erosion acts as a net sink or source of atmospheric CO 2 , the transport and fate of SOC in the landscape must be considered (Amundson et al., 2015; Billings et al., 2019; Blair et al., 2022; Doetterl et al., 2016; Lal, 2003; Van Oost et al., 2007). Hence, understanding the potential impacts of future soil erosion on the global carbon cycle requires detailed predictions of SOC redistribution.…”

Section: Introductionmentioning

confidence: 99%

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The Future of Soils in the Midwestern United States

2023

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Soil is the source of the vast majority of food consumed on Earth, and soils constitute the largest terrestrial carbon pool. Soil erosion associated with agriculture reduces crop productivity, and the redistribution of soil organic carbon (SOC) by erosion has potential to influence the global carbon cycle. Tillage strongly influences the erosion and redistribution of soil and SOC. However, tillage is rarely considered in predictions of soil erosion in the U.S.; hence regionwide estimates of both the current magnitude and future trends of soil redistribution by tillage are unknown. Here we use a landscape evolution model to forecast soil and SOC redistribution in the Midwestern United States over centennial timescales. We predict that present‐day rates of soil and SOC erosion are 1.1 ± 0.4 kg ⋅ m−‐2 ⋅ yr−‐1 and 12 ± 4 g ⋅ m−2 ⋅ yr−1, respectively, but these rates will rapidly decelerate due to diffusive evolution of topography and the progressive depletion of SOC in eroding soil profiles. After 100 years, we forecast that 8.8 (+1.9/−2.1) Pg of soil and 0.17 (+0.03/−0.04) Pg of SOC will have eroded, causing the surface concentration of SOC to decrease by 4.4% (+0.9/−1.1%). Model simulations that include more widespread adoption of low‐intensity tillage (i.e., no‐till farming) determine that soil redistribution, SOC redistribution, and surficial SOC loss after 100 years would decrease by ∼95% if low‐intensity tillage is fully adopted. Our findings indicate that low‐intensity tillage could greatly decrease soil degradation and that the potential for agricultural soil erosion to influence the global carbon cycle will diminish with time due to a reduction in SOC burial.

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Section: Discussionmentioning

confidence: 99%

Section: Midwestern United States (Us) Soils and Erosion Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Future of Soils in the Midwestern United States

2023

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“…Currently, there is a strong bias in our data collection toward minimally impacted, pristine sites, often in the northern hemisphere, often in temperate climates. Human‐impacted systems such as urban and agricultural systems are underrepresented in CZ studies but are obviously essential to understand (e.g., Blair et al, 2022; Kumar et al, 2018). We also note that many CZ sites within the international network are established on colonial vestiges, particularly in North and South America and Africa.…”

Section: Looking Forwardmentioning

confidence: 99%

Expanding the Spatial Reach and Human Impacts of Critical Zone Science

Singha,

Sullivan,

Billings

et al. 2024

Earth's Future

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Two major barriers hinder the holistic understanding of subsurface critical zone (CZ) evolution and its impacts: (a) an inability to measure, define, and share information and (b) a societal structure that inhibits inclusivity and creativity. In contrast to the aboveground portion of the CZ, which is visible and measurable, the bottom boundary is difficult to access and quantify. In the context of these barriers, we aim to expand the spatial reach of the CZ by highlighting existing and effective tools for research as well as the “human reach” of CZ science by expanding who performs such science and who it benefits. We do so by exploring the diversity of vocabularies and techniques used in relevant disciplines, defining terminology, and prioritizing research questions that can be addressed. Specifically, we explore geochemical, geomorphological, geophysical, and ecological measurements and modeling tools to estimate CZ base and thickness. We also outline the importance of and approaches to developing a diverse CZ workforce that looks like and harnesses the creativity of the society it serves, addressing historical legacies of exclusion. Looking forward, we suggest that to grow CZ science, we must broaden the physical spaces studied and their relationships with inhabitants, measure the “deep” CZ and make data accessible, and address the bottlenecks of scaling and data‐model integration. What is needed—and what we have tried to outline—are common and fundamental structures that can be applied anywhere and used by the diversity of researchers involved in investigating and recording CZ processes from a myriad of perspectives.

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“…For example, prior to the conversion to intensive agriculture in northern and central Iowa, 44% of the region was occupied by wetlands (Miller et al, 2009), many of which were not connected by surface pathways to externally‐draining rivers. Closed depressions were estimated to occupy 40% of the area of the Upper Sangamon River Basin in east‐central Illinois (Blair et al, 2021), which lies in the heart of the Grand Prairie, an extensive area dominated by wet prairie that was drained and converted to row crop agriculture in the late 19th century (Urban, 2005). Groundwater in low‐relief post‐glacial areas has been observed to cross subtle topographic divides, for example in the Prairie Potholes of North Dakota (Winter & Rosenberry, 1998), glacial sediments in Wisconsin and Minnesota (Winter et al, 2003), and the sandy glacial lowlands of the Netherlands (De Vries, 1994).…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of groundwater‐driven stream network evolution in low‐relief post‐glacial landscapes

Cullen

Anders

Lai

et al. 2021

Earth Surf Processes Landf

Self Cite

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In the low-relief post-glacial landscapes of the Central Lowlands of the United States, fluvial networks formed and expanded following deglaciation despite the low slopes and large fraction of the land surface occupied by closed depressions.Low relief topography allows for subtle surface water divides and increases the likelihood that groundwater divides do not coincide with surface water divides. We investigate how groundwater transfer across subtle surface water divides facilitates channel network expansion using a numerical model built on the Landlab platform.Our model simulates surface and subsurface water routing and fluvial erosion. We consider two end-member scenarios for surface water routing, one in which surface water in closed depressions is forced to connect to basin outlets (routing) and one in which surface water in closed depressions is lost to evapotranspiration (no routing).Groundwater is modeled as fully saturated flow within a confined aquifer. Groundwater emerges as surface water where the landscape has eroded to a specified depth. We held the total water flux constant and varied the fraction of water introduced as groundwater versus precipitation. Channel growth is significantly faster in routing cases than no-routing cases given identical groundwater fractions. In both routing and no-routing cases, channel expansion is fastest when $30% of the total water enters the system as groundwater. Groundwater contributions also produce distinctive morphology including steepened channel profiles below groundwater seeps. Groundwater head gradients evolve with topography and groundwater-fed channels can grow more quickly than channels with larger surface water catchments. We conclude that rates of channel network growth in low-relief post-glacial areas are sensitive to groundwater contributions. More broadly, our findings suggest that landscape evolution models may benefit from more detailed representation of hydrologic processes.

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Eroded Critical Zone Carbon and Where to Find It: Examples from the IML-CZO

Cited by 4 publications

References 72 publications

The Future of Soils in the Midwestern United States

The Future of Soils in the Midwestern United States

Expanding the Spatial Reach and Human Impacts of Critical Zone Science

Numerical modeling of groundwater‐driven stream network evolution in low‐relief post‐glacial landscapes

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