Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution w... more Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution where topsoil is depleted from convex slope positions and deposited in concave positions. In these experiments, the variation in erosion estimates, properties of the surface soil, and crop yield (four years) were determined in an undulating landscape that is subject to annual moldboard plowing. Results indicated that areas with high tillage erosion (shoulder slope positions) had high inorganic carbon contents in the surface soil due to the incorporation of calcareous subsoil material. Wheat yields in 2000, 2001, and 2003 were lowest in these areas, demonstrating yield reductions of 50 percent or more. Conversely, wheat yields were highest in areas in which soil translocation by tillage and water results in a net deposition of soil (depressions). These areas had a deeper A horizon, and the surface soils had higher organic carbon contents, lower pH and lower inorganic carbon contents. Soybe...
Determining soil redistribution and sediment budgets in watersheds is often challenging. One of t... more Determining soil redistribution and sediment budgets in watersheds is often challenging. One of the methods for making such determinations employs soil and sediment fingerprinting techniques, using sediment properties such as geochemistry, fallout radionuclides, and mineral magnetism. These methods greatly improve the estimation of erosion and deposition within a watershed, but are limited when determining land use-based soil and sediment movement. Recently, compound-specific stable isotopes (CSSIs), which employ fatty acids naturally occurring in the vegetative cover of soils, offer the possibility of refining fingerprinting techniques based on land use, complementing other methods that are currently in use. The CSSI method has been met with some success; however, challenges still remain with respect to scale and resolution due to a potentially large degree of biological, environmental and analytical uncertainty. By better understanding the source of tracers used in CSSI work and the inherent biochemical variability in those tracers, improvement in sample design and tracer selection is possible. Furthermore, an understanding of environmental and analytical factors affecting the CSSI signal will lead to refinement of the approach and the ability to generate more robust data. This review focuses on sources of biological, environmental and analytical variability in applying CSSI to soil and sediment fingerprinting, and presents recommendations based on past work and current research in this area for improving the CSSI technique. A recommendation, based on current information available in the literature, is to use very-long chain saturated fatty acids and to avoid the use of the ubiquitous saturated fatty acids, C16 and C18.
In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of... more In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. One approach to remediate these eroded landforms is moving soil from areas of topsoil accumulation to areas of topsoil depletion, termed here soil-landscape rehabilitation. These experiments were conducted in an eroded undulating landform typical of the prairie pothole region. The summit, shoulder, upper and lower backslope were depleted in soil nutrients and organic carbon and had enriched inorganic carbon contents through the incorporation of calcareous subsoil material into the tilled layer. Surface soil organic carbon contents in lower slope positions were at least twice that in the most eroded positions. Six replicate plots were established that extended from the summit to the toeslope of the test area. Soil-landscape rehabilitation was performed on three plots by moving 15-20 cm of soil from the lower slope (footslope and toeslope) to the upper slope (summit, shoulder, and upper backslope) positions. The three remaining plots were undisturbed. In lower slope positions, soil properties were shifted upwards with respect to the soil surface by 15-20 cm in rehabilitated plots (where soil was removed). In upper slope positions, soil properties were shifted downwards by 15-20 cm in rehabilitated plots (where soil was applied, original soil was buried). After rehabilitation, the top 15 cm of soil in rehabilitated plots had characteristics similar to the footslope and toeslope, from which the soil was taken. Thus, soil properties were much more uniform from summit to toeslope in rehabilitated plots compared to undisturbed plots. Productivity was measured in two cropping years characterized by summer drought conditions. In rehabilitated plots, yields were relatively consistent across landscape positions, whereas in undisturbed plots, yields were depressed in eroded landscape positions. Grain yields in rehabilitated plots were increased by 30% in areas of soil addition. These yield increases were accompanied by yield decreases of 50% (year 1) and 20% (year 2) in areas of soil removal. Results indicate that movement of accumulated topsoil from lower slope positions to eroded upper slope positions can result in large yield increases in upper slope positions and more consistency in crop yields across the landscape, but additional research is needed to provide a more complete analysis of the soil productivity impacts of this approach.
Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution w... more Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution where topsoil is depleted from convex slope positions and deposited in concave positions. In these experiments, the variation in erosion estimates, properties of the surface soil, and crop yield (four years) were determined in an undulating landscape that is subject to annual moldboard plowing. Results indicated
Using established erosion models and national databases, A Soil Erosion Risk Indicator (SoilERI) ... more Using established erosion models and national databases, A Soil Erosion Risk Indicator (SoilERI) was developed under the National Agri-Environmental Health Analysis and Reporting Program (NAHARP) in Canada to assess the risk of soil erosion in agricultural land from the combined effects of tillage, water and wind erosion processes. The indicator was build upon the Soil Landscape of Canada (SLC) polygon and was then aggregated to the province and national scale. It reflects the characteristics of the climate, soil and topography and responds to changes in land use over the 25-year period between 1981 and 2006. The results showed that the risk of soil erosion on Canadian cropland has steadily declined with time since the 1980s, largely due to the adoption of the conservation tillage, particularly no-till systems. However, there are still areas in every province with risks of unsustainable soil erosion. The risk of soil erosion was greatest under potato and sugar beet production and co...
Little is known about the impact of tillage methods on soil movement resulting from hoeing tillag... more Little is known about the impact of tillage methods on soil movement resulting from hoeing tillage operations in the Sichuan Basin, China. Effects of tiered ridge and contour tillage on soil movement (translocation and erosion) were examined in the steep hillslopes of this basin using a physical tracer method. Stone chips were used as tracers, having a contrasting color from the surrounding soil, and were incorporated into each experimental plot. Net mean downslope displacement distance by contour tillage was much shorter (P<0.0001) than that by downslope tillage (5 times for tiered ridge tillage, 3 times for flat tillage). Soil displacement distance was positively correlated to slope gradient for downslope tillage (R2 = 0.6303 – 0.8282, P = 0.0002 – <0.0001), whereas slope gradient was not significantly correlated to soil downslope displacement by contour tillage (R2 = 0.2421-0.3142, P = 0.0529-0.0239). Tillage transport coefficients were 25.5 and 30.7 kg m−1 tillage pass−1 f...
ABSTRACT: Tillage translocation is measured in the studies of soil dispersion and soil crosion. T... more ABSTRACT: Tillage translocation is measured in the studies of soil dispersion and soil crosion. The translocation of soil by tillage is normally measured with a tracer. Using plots, a volume of soil is labelled and then tilled. There are two methods of calculating translocation using plot-tracers. For the more common method, translocation is calculated directly from the distributions of tracer before and after tillage (Distribution-Curve Method). For the less common method, a summation curve is generated from the distribution of tracer after tillage by employing convolution, and translocation is calculated from this curve (Summation-Curve Method). In this paper, the two methods are described and compared using hypothetical and experimental data. Both methods provide accurate measures of gross translocation. The Summation-Curve Method provides a measure of error associated with gross translocation and a more thorough characterization of the dispersion of translocated soil; therefore,...
Complete List of Authors: Kieta, Kristen A.; University of Northern British Columbia, Natural Res... more Complete List of Authors: Kieta, Kristen A.; University of Northern British Columbia, Natural Resources and Environmental Studies Owens, Philip N.; University of Northern British Columbia, Natural Resources and Environmental Studies Lobb, David A.; University of Manitoba, Dept. of Soil Science Vanrobaeys, Jason A.; Agriculture and Agri-Food Canada Flaten, Don N.; University of Manitoba, Dept. of Soil Science
Journal of Environmental Quality AGRICULTURAL WATER QUALITY IN COLD ENVIRONMENTS SPECIAL SECTION ... more Journal of Environmental Quality AGRICULTURAL WATER QUALITY IN COLD ENVIRONMENTS SPECIAL SECTION Core Ideas • Vegetated filter strips are dynamic in cold climates and P retention capacity changes seasonally. • Vegetated filter strips were not effective at retaining P outside the growing season. • New designs and management are required for vegetated filter strips for P retention in cold climates.
Many agricultural activities result in the movement of soil. Tillage is the most prevalent of the... more Many agricultural activities result in the movement of soil. Tillage is the most prevalent of these activities as it is used extensively throughout crop production. Land improvement and management practices, such as land forming and land leveling, also result in soil movement. Tillage disturbs the soil, causing it to move vertically and horizontally, often making it more susceptible to further movement by wind and water. The horizontal movement of soil can lead to tillage erosion. Conservation tillage practices can be used to reduce severe soil erosion by wind, water, and tillage erosion and the practice of soil-landscape restoration can be used to reverse soil erosion.
Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution w... more Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution where topsoil is depleted from convex slope positions and deposited in concave positions. In these experiments, the variation in erosion estimates, properties of the surface soil, and crop yield (four years) were determined in an undulating landscape that is subject to annual moldboard plowing. Results indicated that areas with high tillage erosion (shoulder slope positions) had high inorganic carbon contents in the surface soil due to the incorporation of calcareous subsoil material. Wheat yields in 2000, 2001, and 2003 were lowest in these areas, demonstrating yield reductions of 50 percent or more. Conversely, wheat yields were highest in areas in which soil translocation by tillage and water results in a net deposition of soil (depressions). These areas had a deeper A horizon, and the surface soils had higher organic carbon contents, lower pH and lower inorganic carbon contents. Soybe...
Determining soil redistribution and sediment budgets in watersheds is often challenging. One of t... more Determining soil redistribution and sediment budgets in watersheds is often challenging. One of the methods for making such determinations employs soil and sediment fingerprinting techniques, using sediment properties such as geochemistry, fallout radionuclides, and mineral magnetism. These methods greatly improve the estimation of erosion and deposition within a watershed, but are limited when determining land use-based soil and sediment movement. Recently, compound-specific stable isotopes (CSSIs), which employ fatty acids naturally occurring in the vegetative cover of soils, offer the possibility of refining fingerprinting techniques based on land use, complementing other methods that are currently in use. The CSSI method has been met with some success; however, challenges still remain with respect to scale and resolution due to a potentially large degree of biological, environmental and analytical uncertainty. By better understanding the source of tracers used in CSSI work and the inherent biochemical variability in those tracers, improvement in sample design and tracer selection is possible. Furthermore, an understanding of environmental and analytical factors affecting the CSSI signal will lead to refinement of the approach and the ability to generate more robust data. This review focuses on sources of biological, environmental and analytical variability in applying CSSI to soil and sediment fingerprinting, and presents recommendations based on past work and current research in this area for improving the CSSI technique. A recommendation, based on current information available in the literature, is to use very-long chain saturated fatty acids and to avoid the use of the ubiquitous saturated fatty acids, C16 and C18.
In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of... more In hilly landforms subject to long-term cultivation, erosion has denuded upper slope positions of topsoil and accumulated topsoil in lower slope positions. One approach to remediate these eroded landforms is moving soil from areas of topsoil accumulation to areas of topsoil depletion, termed here soil-landscape rehabilitation. These experiments were conducted in an eroded undulating landform typical of the prairie pothole region. The summit, shoulder, upper and lower backslope were depleted in soil nutrients and organic carbon and had enriched inorganic carbon contents through the incorporation of calcareous subsoil material into the tilled layer. Surface soil organic carbon contents in lower slope positions were at least twice that in the most eroded positions. Six replicate plots were established that extended from the summit to the toeslope of the test area. Soil-landscape rehabilitation was performed on three plots by moving 15-20 cm of soil from the lower slope (footslope and toeslope) to the upper slope (summit, shoulder, and upper backslope) positions. The three remaining plots were undisturbed. In lower slope positions, soil properties were shifted upwards with respect to the soil surface by 15-20 cm in rehabilitated plots (where soil was removed). In upper slope positions, soil properties were shifted downwards by 15-20 cm in rehabilitated plots (where soil was applied, original soil was buried). After rehabilitation, the top 15 cm of soil in rehabilitated plots had characteristics similar to the footslope and toeslope, from which the soil was taken. Thus, soil properties were much more uniform from summit to toeslope in rehabilitated plots compared to undisturbed plots. Productivity was measured in two cropping years characterized by summer drought conditions. In rehabilitated plots, yields were relatively consistent across landscape positions, whereas in undisturbed plots, yields were depressed in eroded landscape positions. Grain yields in rehabilitated plots were increased by 30% in areas of soil addition. These yield increases were accompanied by yield decreases of 50% (year 1) and 20% (year 2) in areas of soil removal. Results indicate that movement of accumulated topsoil from lower slope positions to eroded upper slope positions can result in large yield increases in upper slope positions and more consistency in crop yields across the landscape, but additional research is needed to provide a more complete analysis of the soil productivity impacts of this approach.
Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution w... more Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution where topsoil is depleted from convex slope positions and deposited in concave positions. In these experiments, the variation in erosion estimates, properties of the surface soil, and crop yield (four years) were determined in an undulating landscape that is subject to annual moldboard plowing. Results indicated
Using established erosion models and national databases, A Soil Erosion Risk Indicator (SoilERI) ... more Using established erosion models and national databases, A Soil Erosion Risk Indicator (SoilERI) was developed under the National Agri-Environmental Health Analysis and Reporting Program (NAHARP) in Canada to assess the risk of soil erosion in agricultural land from the combined effects of tillage, water and wind erosion processes. The indicator was build upon the Soil Landscape of Canada (SLC) polygon and was then aggregated to the province and national scale. It reflects the characteristics of the climate, soil and topography and responds to changes in land use over the 25-year period between 1981 and 2006. The results showed that the risk of soil erosion on Canadian cropland has steadily declined with time since the 1980s, largely due to the adoption of the conservation tillage, particularly no-till systems. However, there are still areas in every province with risks of unsustainable soil erosion. The risk of soil erosion was greatest under potato and sugar beet production and co...
Little is known about the impact of tillage methods on soil movement resulting from hoeing tillag... more Little is known about the impact of tillage methods on soil movement resulting from hoeing tillage operations in the Sichuan Basin, China. Effects of tiered ridge and contour tillage on soil movement (translocation and erosion) were examined in the steep hillslopes of this basin using a physical tracer method. Stone chips were used as tracers, having a contrasting color from the surrounding soil, and were incorporated into each experimental plot. Net mean downslope displacement distance by contour tillage was much shorter (P<0.0001) than that by downslope tillage (5 times for tiered ridge tillage, 3 times for flat tillage). Soil displacement distance was positively correlated to slope gradient for downslope tillage (R2 = 0.6303 – 0.8282, P = 0.0002 – <0.0001), whereas slope gradient was not significantly correlated to soil downslope displacement by contour tillage (R2 = 0.2421-0.3142, P = 0.0529-0.0239). Tillage transport coefficients were 25.5 and 30.7 kg m−1 tillage pass−1 f...
ABSTRACT: Tillage translocation is measured in the studies of soil dispersion and soil crosion. T... more ABSTRACT: Tillage translocation is measured in the studies of soil dispersion and soil crosion. The translocation of soil by tillage is normally measured with a tracer. Using plots, a volume of soil is labelled and then tilled. There are two methods of calculating translocation using plot-tracers. For the more common method, translocation is calculated directly from the distributions of tracer before and after tillage (Distribution-Curve Method). For the less common method, a summation curve is generated from the distribution of tracer after tillage by employing convolution, and translocation is calculated from this curve (Summation-Curve Method). In this paper, the two methods are described and compared using hypothetical and experimental data. Both methods provide accurate measures of gross translocation. The Summation-Curve Method provides a measure of error associated with gross translocation and a more thorough characterization of the dispersion of translocated soil; therefore,...
Complete List of Authors: Kieta, Kristen A.; University of Northern British Columbia, Natural Res... more Complete List of Authors: Kieta, Kristen A.; University of Northern British Columbia, Natural Resources and Environmental Studies Owens, Philip N.; University of Northern British Columbia, Natural Resources and Environmental Studies Lobb, David A.; University of Manitoba, Dept. of Soil Science Vanrobaeys, Jason A.; Agriculture and Agri-Food Canada Flaten, Don N.; University of Manitoba, Dept. of Soil Science
Journal of Environmental Quality AGRICULTURAL WATER QUALITY IN COLD ENVIRONMENTS SPECIAL SECTION ... more Journal of Environmental Quality AGRICULTURAL WATER QUALITY IN COLD ENVIRONMENTS SPECIAL SECTION Core Ideas • Vegetated filter strips are dynamic in cold climates and P retention capacity changes seasonally. • Vegetated filter strips were not effective at retaining P outside the growing season. • New designs and management are required for vegetated filter strips for P retention in cold climates.
Many agricultural activities result in the movement of soil. Tillage is the most prevalent of the... more Many agricultural activities result in the movement of soil. Tillage is the most prevalent of these activities as it is used extensively throughout crop production. Land improvement and management practices, such as land forming and land leveling, also result in soil movement. Tillage disturbs the soil, causing it to move vertically and horizontally, often making it more susceptible to further movement by wind and water. The horizontal movement of soil can lead to tillage erosion. Conservation tillage practices can be used to reduce severe soil erosion by wind, water, and tillage erosion and the practice of soil-landscape restoration can be used to reverse soil erosion.
Uploads
Papers by David A Lobb