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Topographic contour map showing locations of sampling plots along each depression to upland transect. Relative elevation is the elevation relative to the depression bottom in each depression. Data were obtained from United States Department of Agriculture, Farm Services Agency, National Agricultural Imagery Program, https://geodata.iowa.gov.pages/imagery, accessed on 12/10/2021 and Iowa Department of Natural Resources; https://geodata.iowa.gov/pages/two-foot-contours-county-downloads; accessed on 12/10/2021. The map was created in ArcGIS Pro 2.8.0
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Many productive agricultural soils have naturally poor drainage characteristics and may intermittently pond water even where artificial drainage infrastructure is present, especially in topographic depressions. Soil organic carbon (SOC) is often higher in depressions than uplands, but whether temporary ponding increases SOC by suppressing decomposi...
Citations
... Specific to the Prairie Pothole Region, Euliss et al. (2006) estimated that wetland drainage and subsequent cultivation results in an average loss of 10.1 Mg C ha −1 . Other studies have investigated the effect of time since drainage on carbon storage as well as subsequent land management effects on soil carbon in drained wetlands Bansal et al., 2021;Huang et al., 2023). This research has provided a foundational understanding of the potential influence drainage has on organic carbon storage for the Prairie Pothole Region. ...
Drainage leads to trade-offs between crop production efficiency and wetland conservation, with complex impacts on ecosystem services. In North America’s Prairie Pothole Region, wetland drainage is widespread, often to increase the available land for cultivation, prevent crop loss due to flooding, and manage soil salinity. Wetlands are known for providing key ecosystem services such as improved water quality, flood mitigation, and carbon storage. There is limited research on how changes to soil hydrology and soil redistribution through wetland drainage can impact soil carbon storage and persistence in this region. This research evaluates factors that contribute to soil carbon storage in drained prairie pothole wetland based on 33 drained wetlands in Saskatchewan, Canada. These analyses showed regional differences in the response of soil carbon storage to drainage that are driven by environmental factors such as annual precipitation, temperature, and wetland permanence. We observed increasing soil carbon storage from the Dark Brown to Black soil zones, as well as with longer wetland pond permanence. The sampling depth used for calculating soil carbon storage was especially important when comparing geographically across the soil zones as the Black soil zone had greater soil carbon stored at depth. Soil carbon was also intensively monitored over 2 years following installation of surface drainage across a wetland complex (8 drained wetlands) where water was partially directed to a consolidation wetland. We further assessed changes in soil carbon dynamics and protection from microbial decomposition based on three soil organic matter fractions, ATR-FTIR for organic matter functional groups, and phospholipid fatty acid analysis to understand the microbial community abundance and structure. After 2 years following drainage, ephemeral wetlands with short pond permanence were found to be most sensitive to drainage and the only wetland class with decreases in soil carbon. The temporary and seasonal wetland classes showed no significant differences in soil carbon content but there were changes in the organic matter with depth due to soil redistribution during drainage implementation. Jointly, this research provides region-specific estimates of soil carbon storage in drained prairie pothole wetlands that can be used to inform wetland soil carbon management in cultivated fields.
... In the soils with perennial vegetation, CO 2 is derived partly from recent C 3 plant residues with typical δ 13 C values of − 26‰ to − 30‰, as well from legacy C from mixed C 3 -C 4 crop residues. The CO 2 flux from soil in regional corn-soybean rotations has mean δ 13 C values near − 17‰, with variation (-13‰ to -23‰) according to the most recent crop (Huang et al., 2023). In the perennial and cropland soils used here, higher or lower δ 13 C values of CO 2 likely indicate greater or lesser contributions of C 4 -derived C to respiration in a particular sample, or compound-specific differences in respiration sources (Bowling et al., 2008), given that carbonates were negligible (as quantified according to Huang et al. (2023)). ...
... The CO 2 flux from soil in regional corn-soybean rotations has mean δ 13 C values near − 17‰, with variation (-13‰ to -23‰) according to the most recent crop (Huang et al., 2023). In the perennial and cropland soils used here, higher or lower δ 13 C values of CO 2 likely indicate greater or lesser contributions of C 4 -derived C to respiration in a particular sample, or compound-specific differences in respiration sources (Bowling et al., 2008), given that carbonates were negligible (as quantified according to Huang et al. (2023)). ...
... A h trient content is beneficial for crop growth, allowing more residues to return [51,52]. Therefore, soil nutrients are often positively related with the SOC [53 pared with a high sand content, a high clay content is beneficial for maintainin ture and nutrients, promoting vegetation growth and organic matter ac [55,56]. Consequently, the clay and silt contents often show a positive relatio SOC, while the sand content often shows a negative relation with the SOC [1 this study, the clay content is the second important factor of SOC, and the r portance of the TN and the TK exceeds 5%. ...
... Therefore, soil nutrients are often positively related with the SOC [53,54]. Compared with a high sand content, a high clay content is beneficial for maintaining soil moisture and nutrients, promoting vegetation growth and organic matter accumulation [55,56]. Consequently, the clay and silt contents often show a positive relation with the SOC, while the sand content often shows a negative relation with the SOC [17,57,58]. ...
Accurately mapping soil organic carbon (SOC) is conducive to evaluating carbon storage and soil quality. However, the high spatial heterogeneity of SOC caused by river-related factors and agricultural management brings challenges to digital soil mapping in floodplain farmland. Moreover, current studies focus on the non-linear relationship between SOC and covariates, but ignore the effective range of environmental variables on SOC, which prevents the revelation of the SOC differentiation mechanism. Using the 375 samples collected from the Jiangchang Town near Han River, we aim to determine the main controlling factors of SOC, reveal the effective range of environmental variables, and obtain the spatial map of SOC by using the gradient boosting decision tree (GBDT) model and partial dependence plots. Linear regression was used as a reference. Results showed that GBDT outperformed linear regression. GBDT results show that the distance from the river was the most important SOC factor, confirming the importance of the Han River to the SOC pattern. The partial dependence plots indicate that all environmental variables have their effective ranges, and when their values are extremely high or low, they do not respond to changes in SOC. Specifically, the influential ranges of rivers, irrigation canals, and rural settlements on SOC were within 4000, 200, and 50 m, respectively. The peak SOC was obtained with high clay (≥31%), total nitrogen (≥1.18 g/kg), and total potassium contents (≥11.1 g/kg), but it remained steady when these covariates further increased. These results highlight the importance of revealing the effective range of environmental variables, which provides data support for understanding the spatial pattern of SOC in floodplain farmland, achieving carbon sequestration in farmland and precision agriculture. The GBDT with the partial dependence plot was effective in SOC fitting and mapping.
... Clay and silt particles may further enhance organic carbon burial in restored wetland soils because they are more nutrient rich and have the capacity to adsorb on and stabilize organic carbon (e.g. Yu et al. 2017;Huang et al. 2023). Our results are consistent with several lines of evidence describing parent material and its permeability as key drivers in sustaining hydric soils and soil carbon masses (Richardson & Vepraskas 2000;Mitsch & Gosselink 2015;Byun et al. 2018). ...
Freshwater marsh restoration can be a viable natural climate solution; however, the extent to which marsh soils bury and preserve organic carbon within policy‐relevant timescales remains highly uncertain. Here, we compare organic carbon masses and accumulation rates from an undrained reference marsh, a passively restored freshwater marsh (reflooded after 1954) and a chronosequence of actively restored freshwater marshes (<10 years in age) situated in Lake Erie watersheds in the Long Point Biosphere Reserve of Ontario, Canada. The reference site has sustained the highest rates of short‐term organic carbon accumulation (235 g C m ⁻² yr ⁻¹ ) over the last four decades and has the highest mass of soil organic carbon (122 tC/ha) at 0–30 cm depth. Organic carbon masses are highly variable among all restored wetlands (16–115 tC/ha) at 0–30 cm depth and are not strongly related to time since restoration at least over the last 10 years. Nonetheless, we show that passive wetland restoration generates high rates of organic carbon accumulation (144 g m ⁻² yr ⁻¹ ) on a multidecadal scale where sites are low‐lying, underlain by alluvial deposits and connected to larger ground and surface water networks. Active restoration measures (e.g. excavation, installation of berms) may promote organic carbon preservation, particularly where fine‐grained soil texture promotes waterlogging. We demonstrate the importance of substrate, topographic gradient, and hydrology in selecting sites for marsh restoration to maximize carbon sequestration, and argue that the presettlement context and reference paleorecords provide necessary baselines for directing successful wetland restoration.
