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Although crop and crop residue management practices are mainly used for increasing crop yield, they and the resulting changes in crop growth affect one or more hydrological components, including runoff. Based on published research in the Canadian Prairies, this paper reviews the effects of crop type, quantity of crops and crop residues, crop variability within landscapes, tillage, and stubble management practices on crop water use (termed including evaporation, transpiration and interception), snow trapping, and water infiltration, with the aim to discuss major impacts of crop and residue management on runoff. Rainfall runoff is influenced by rain interception and crop water use, and it can be reduced by choosing appropriate crop types, increasing above-ground biomass, or increasing coverage on the soil surface, activities which coincide with the farmer’s efforts of increasing crop productivity. However, although high stubble and reduced tillage for maintaining good residue cover help conserve soil moisture and improve soil health, they increase snowmelt runoff potential. The review emphasizes the need of future research to assess the agronomic and environmental trade-offs of crop residue management, the linkage between crop water use and runoff, and the impacts of crop and residue management on runoff across various temporal and spatial scales.

Increasing complexity in human-environment interactions at multiple watershed scales presents major challenges to sediment source apportionment data acquisition and analysis. Herein, we present a step-change in the application of Bayesian mixing models: Deconvolutional-MixSIAR (D-MIXSIAR) to underpin sustainable management of soil and sediment. This new mixing model approach allows users to directly account for the ‘structural hierarchy’ of a river basin in terms of sub-watershed distribution. It works by deconvoluting apportionment data derived for multiple nodes along the stream-river network where sources are stratified by sub-watershed. Source and mixture samples were collected from two watersheds that represented (i) a longitudinal mixed agricultural watershed in the south west of England which had a distinct upper and lower zone related to topography and (ii) a distributed mixed agricultural and forested watershed in the mid-hills of Nepal with two distinct sub-watersheds. In the former, geochemical fingerprints were based upon weathering profiles and anthropogenic soil amendments. In the latter compound-specific stable isotope markers based on soil vegetation cover were applied. Mixing model posterior distributions of proportional sediment source contributions differed when sources were pooled across the watersheds (pooled-MixSIAR) compared to those where source terms were stratified by sub-watershed and the outputs deconvoluted (D-MixSIAR). In the first example, the stratified source data and the deconvolutional approach provided greater distinction between pasture and cultivated topsoil source signatures resulting in a different posterior distribution to non-deconvolutional model (conventional approaches over-estimated the contribution of cultivated land to downstream sediment by 2 to 5 times). In the second example, the deconvolutional model elucidated a large input of sediment delivered from a small tributary resulting in differences in the reported contribution of a discrete mixed forest source. Overall D-MixSIAR model posterior distributions had lower (by ca 25–50%) uncertainty and quicker model run times. In both cases, the structured, deconvoluted output cohered more closely with field observations and local knowledge underpinning the need for closer attention to hierarchy in source and mixture terms in river basin source apportionment. Soil erosion and siltation challenge the energy-food-water-environment nexus. This new tool for source apportionment offers wider application across complex environmental systems affected by natural and human-induced change and the lessons learned are relevant to source apportionment applications in other disciplines.

Rewetting drained wetlands restores long-term carbon storage by reviving organic carbon burial in sediments and rebuilding carbon stocks, but the decades-long recovery pathway is uncertain. Sediment cores were dated using naturally occurring radioactive lead-210, verified with cesium-137 from past nuclear testing, to reconstruct organic carbon burial rates before drainage and for 4–40 years after rewetting across two restoration chronosequences in dry and wet climate zones; undisturbed wetlands provided benchmarks. Burial rates in undisturbed wetlands (median: 0.60 Mg C ha -1 yr -1 ) were comparable to pre-drainage rates in rewetted wetlands (median: 0.53), suggesting pre-drainage conditions can guide site-specific recovery targets. After ditch plugging, burial rates increased rapidly (net change: 0.28–1.01 Mg C ha -1 yr -1 within 14 years) but then declined and converged on the baseline by about 40 years. Meanwhile, total organic carbon stored in sediments rose steadily, reaching 24.6 Mg C ha -1 after four decades. Organic carbon sequestration rates in rewetted wetlands increase during early restoration and then stabilize within ~40 years, while organic carbon stocks accumulate steadily, according to radiometric dating and organic matter quantification in Canadian wetlands

Soil color has long been used as an indicator for soil properties such as soil organic carbon and soil moisture. Recent developments in citizen science have seen the increased use of smartphone cameras for soil color measurements. However, there are high errors associated with this technique. Two major sources of errors are smartphone cameras and lighting conditions. These errors limit the applicability of this technique in citizen science. Existing correction methods for reducing these errors are either ineffective or too complicated or difficult to apply. There is also a lack of systematic analysis on how these correction methods can reduce errors. In this study, we tested the effectiveness of using a color plate as a reference to reduce the errors on color measurements due to the use of different smartphones and taking photos under different lighting conditions. Three types of objects were tested, including the squares on the color plate itself, the color chips in a Munsell soil color book, and soil samples. The results show that the raw values of color parameters showed different patterns of biases with different smartphones and lighting conditions. The calibration reduced the errors consistently for all smartphones under all lighting conditions for the color plate squares. For the Munsell book chips or the soil samples, the calibration did not always reduce the bias but it did reduce the variations in all color parameters among smartphones and lighting conditions and, therefore, improved the precision of color measurements.

Vegetated filter strips (VFS) are a best management practice, designed to reduce sediment and nutrient runoff to surface waters in agricultural landscapes. In cold climates, phosphorus (P) can be released from VFS vegetation when it undergoes freeze–thaw cycles, making their utility in these regions an area needing further study. Research in Manitoba, Canada, investigated temporal changes in soil P concentrations and potential P loss from VFS from 2015 to 2017. Soil, harvestable vegetation, and residue samples were collected within VFS and control strips, and soils were analysed for Olsen P and Total P (TP). Harvestable vegetation and residue samples were analysed for TP. Results showed increases in Olsen P each spring and reductions each fall in soils at all sites. There was substantial loss of TP from the harvestable vegetation samples at all sites from November 2016 to May 2017, but residues in the VFS and control sites had a lower loss of TP over the same period. Vegetation was shown to release P over the winter into surface soils, and harvestable vegetation released significantly more P than residue, potentially leading to P loss from soils through surface runoff or leaching. Thus, harvesting vegetation may be a suitable VFS management strategy in cold climates.

Canada is known for its massive and fertile landscape, and one of the biggest industries in Canada is crop production, which is responsible for contributing to the national economy as well as the global food supply. Soil erosion is considered the top challenge facing Canadian farmers in the 21st century. This study aims to evaluate soil erosion’s impact on Canadian crop production, assessed based on the integration of soil erosion analysis and multitemporal crop market values from 1971 to 2015. Soil Erosion Risk Indicator models were used to assess soil erosion’s impact on crop productivity using the relationship of soil organic carbon with crop yield gain/loss. The total soil erosion cost of yield losses in the 44 years leading up to 2015 is estimated to be CAD 33.51 billion. 2013 was found to show the highest loss, with CAD 1.93 billion. Oilseeds, small grains, and potatoes were the major crop commodities that were impacted by yield loss as a direct result of soil erosion, the costs being 41%, 37%, and 15%, respectively. Ontario and Saskatchewan were the most impacted provinces, with costs of 45.25% and 22.50%, respectively. Four eras were detected in this research, each having unique soil erosion costs, which reflect different agriculture policy and soil conservation efforts: Era 1 (1971–1988), Era 2 (1989–1995), Era 3 (1996–2007), and Era 4 (2008–2015). This research is the beginning of exploring the cost of the environmental impacts on agriculture sustainability in Canada and supporting decision makers in adopting effective soil conservation strategies to mitigate these impacts.

For wetlands to serve as natural climate solutions, accurate estimates of organic carbon (OC) sequestration rates in wetland sediments are needed. Dating using cesium-137 (137Cs) and lead-210 (210Pb) radioisotopes is commonly used for measuring OC sequestration rates in wetland sediments. 137Cs radioisotope dating is relatively simple, with calculations based on a single point representing the onset (1954) or peak (1963) of the 137Cs fallout. 210Pb radioisotope dating is more complex, as the calculations are based on multiple points. Here, we show that reliable dating of sediment cores collected from wetlands can be achieved using either 137Cs or 210Pb dating or their combination. However, 137Cs and 210Pb profiles along the depth of sediment cores need to be screened, analyzed, and interpreted carefully to estimate OC sequestration rates with high precision. To this end, we propose a decision framework for screening 137Cs and 210Pb profiles into high- and low-quality sediment profiles, and we compare dating using the 1954 and 1963 time markers, i.e., the rates of sedimentation and, consequently, OC sequestration over the past ∼ 60 years. Our findings suggest that 137Cs- and 210Pb-based OC sequestration rates are comparable, especially when using the 1963 (vs. 1954) time marker.

The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.

Purpose The characterization of soil properties is an important part of many different types of agri-environmental research including inventory, comparison, and manipulation studies. Sediment source fingerprinting is a method that is increasingly being used to link sediment sources to downstream sediment. Characterization of sediment sources is a key part of this method as it serves as the base to identify and quantify soil properties (fingerprints) that can discriminate between sources. There is currently not a standard approach to characterizing sources and the different approaches to sampling have not been well assessed. Methods Grid (n = 49), transect (n = 14), and likely to erode (n = 8) sampling designs were used to characterize the geochemical, colour, grain size distribution, and soil organic matter content at two sites under contrasting land uses (agricultural and forested). The impact of the three sampling designs on characterization of fingerprint properties, the relationship between particle size and organic matter content on fingerprint properties, fingerprint selection, source discrimination, and mixing apportionment results were evaluated using a range of methods including 21 virtual mixtures. Results The likely to erode design resulted in a unique fingerprint signature compared to the other two sampling designs. The correlation between particle size and organic matter varied between fingerprint, source, and sampling design. While the number and composition of the fingerprints selected varied between sampling designs there was a strong (100%) discrimination between sources regardless of the sampling approach. The maximum absolute difference between the virtual mixtures and the modeled proportions was 7.7%, 7.8%, and 8.9% for the grid, transect, and likely to erode sampling designs, respectively. Conclusions The likely to erode sampling design was not representative of the upslope areas as characterized by the grid and transect methods. Despite these differences the final apportionment results using virtual mixtures were qualitatively similar between the three sampling designs. Continued work at the watershed scale is needed to fully evaluate the importance of source sampling design on the sediment source fingerprinting approach.

The movement of excess phosphorus (P) into streams, rivers and lakes poses a significant threat to water quality and the health of aquatic ecosystems and thus P has been targeted for reduction. In landscapes dominated by agriculture, P is primarily transported through non-point sources which a number of best management practices aim to target. One such practice is vegetated buffer strips (VBS), which are designed to use dense vegetation above the surface and extensive root systems below the surface to reduce runoff velocity, trap sediments, increase infiltration, and increase plant uptake of nutrients. The effectiveness of VBS in reducing P concentrations has been studied and reviewed, but most studies have been undertaken in warm or temperate climates, where runoff is primarily driven through summer rainfall events, and when vegetation is actively growing. In cold climates, the majority of runoff occurs during the snowmelt period when vegetation is not actively taking up nutrients, has been flattened by snow and ice over the winter period, and when soils are frozen. These conditions hinder the ability for VBS to work as designed. Additionally, frozen vegetation can release P after undergoing freeze-thaw cycles (FTCs). Thus, this review aimed to: i) summarize research designed to determine the effectiveness of VBS to reduce P transport undertaken in cold climates; ii) collate research on the potential for vegetation to release P after undergoing FTCs; and iii) identify research gaps to be addressed in determining VBS effectiveness in cold climates. Cold climate VBS implemented in Canada, the northern United States, and northern Europe have shown P removal efficiencies ranging from -36% to +89%, a range that pinpoints the uncertainty surrounding the use of VBS in these landscapes. However, there is consensus in research globally that vegetation does release P after undergoing FTCs, though P concentrations from different species vary across studies. The design and management of VBS in cold climates requires careful consideration and may not always be the best management strategy to reduce P transport. Future research should be undertaken at a larger scale in natural systems and focus on VBS design and management strategies.