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    Soil denitrification response to increased urea concentration constrains nitrous oxide emissions in a simulated cattle urine patch
    (Springer, 2023-05-24) Reimer, Jesse C.; Arcand, Melissa; Helgason, Bobbi
    Aim Incorporating non-bloat legumes into grass pastures can reduce enteric methane and alter cattle urinary urea N output by increasing protein intake. Deposition of high urea N urine influences soil N-cycling microbes and potentially N2O production. We studied how urine urea N concentration affects soil nitrifier and denitrifier abundances, activities, and N2O production. Methods 15N13C-labelled urea dissolved in cattle urine was added at 3.5 and 7.0 g L−1 to soils from a grazed, non-bloat legume pasture and incubated under controlled conditions. CO2, N2O, 13C-CO2, and 15N-N2O production were quantified over 240 h, along with nitrifier and denitrifier N-cycling genes and mRNA transcripts. Results High urea urine increased total N2O relative to the control; low urea was not significantly different from the control or the high urea treatment. As a result, N2O-N emission factors were not significantly different between the low urea treatment (1.17%) and high urea treatment (0.94%). Doubling urea concentration doubled CO2-Curea and N2O-Nurea but not total N2O-N. Urine addition initially inhibited then increased AOB transcripts and gene abundances. nirK and nirS transcript abundances indicated that denitrification by ammonia oxidizers and/or heterotrophic denitrifiers dominated N2O production. Urine addition increased nosZ-II vs. nosZ-I transcripts, improving soil N2O reduction potential. Conclusion Characterizing this interplay between nitrifiers and denitrifiers improves the understanding of urine patch N2O sinks and source dynamics. This mechanistic information helps to explain the constrained short-term N2O emissions observed in response to excess urine N excretion from cattle consuming high protein diets, e.g. non-bloat legumes.
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    Land use in the Prairie Pothole Region influences the soil bacterial community composition and relative abundance of nitrogen cycling genes
    (Canadian Science Publishing, 2023) Town, Jennifer; Yu, Min; Lemke, Reynald; Helgason, Bobbi
    The undulating topography of Prairie Pothole Region of North America creates spatial and temporal variability in soil moisture and nutrient levels, affecting microbial community processes and greenhouse gas emissions. By identifying differences in soil bacterial and archaeal community composition and the abundance of nitrogen cycling genes in permanent cover versus annual crop land over two growing seasons (2017 and 2018), we were able to assess the effects of topography and land use on the functional capacity of the soil microbiome. Permanent grassland cover was associated with higher bacterial diversity in upland positions and lower diversity in low-lying depressions. Bacterial community composition was also significantly different between cultivated and permanent cover at all points along the topographic slope, with the largest effects seen in the footslope and backslope positions. Compared to permanent cover, soil from annual cropland had consistently more abundant nitrifiers, including Nitrospira in the toeslope and backslope, and Nitrososphaeraceae in the shoulder and knoll samples while soils from permanent cover had a greater abundance of several Alphaproteobacteria from Rhodospirillales and Hyphomicrobiaceae across multiple upland positions. Upland soils from annual cropland also had consistently higher abundance of both bacterial and archaeal ammonia oxidizing (amoA) genes and a higher ratio of nirK:nirS genes compared to those from permanent cover. These differences in microbial community composition were associated with higher N2O and CO2 emissions in upland soils in annual cropland; however, there were no differences in GHG emissions between the two systems in low-lying positions.
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    Contrasting Nitrogen Fertilization and Brassica napus (Canola) Variety Development Impact Recruitment of the Root-Associated Microbiome
    (APS Publications, 2023) Li, Yunliang; Vail, Sally L.; Arcand, Melissa M.; Helgason, Bobbi
    Canola (Brassica napus) is an important broadacre crop, produced under high nitrogen (N) fertilizer application. Modern canola varieties are developed under high N rates but the impacts on root-associated microbiomes of different varieties are unknown. We studied eight canola varieties spanning historical Canadian spring canola development at two sites under high and low N fertility and characterized bacterial and fungal microbiomes in the root and rhizosphere using amplicon sequencing. Environmental conditions and the resulting canola varietal responses strongly affected the root-associated bacterial and fungal microbiomes. Microbes regulated by N fertility in each canola variety were mainly Gammaproteobacteria, Bacteroidia, Actinobacteria, Sordariomycetes, Dothideomycetes, and Agaricomycetes classes. Differentially abundant (DA) microbial taxa showed that N more strongly enriched bacteria in the roots and fungi in the rhizosphere. Each variety had its specific pattern of DA amplicon sequence variants (ASVs) responding to soil N availability, and the profile of DA-ASVs in paired canola varieties were also altered by soil N availability, especially bacteria in the rhizosphere. The yield was strongly associated with a subset of microbial taxa, mainly from Proteobacteria, Actinobacteriota, and Ascomycota. These variety-dependent responses to N and links to yield performance make the root-associated microbiome a promising target for improving the agronomic performance of canola by manipulating microorganisms tailored to soil fertility and plant genotype.
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    Crop rotation significantly influences the composition of soil, rhizosphere, and root microbiota in canola (Brassica napus L.)
    (BMC (part of Springer Nature), 2023) Town, Jennifer R.; Dumonceaux, Tim; Tidemann, Breanne; Helgason, Bobbi
    Background: Crop rotation is an agronomic practice that is known to enhance productivity and yield, and decrease pest and disease pressure. Economic and other factors have increased the frequency of certain crops, including canola, with unknown effects on the below ground microbial communities that impact plant health and performance. This study investigated the effect of 12 years of crop rotation including canola-wheat; canola-pea-barley; and unrotated canola across three geographic sites in Western Canada with diverse soil types and environmental conditions. To provide data on mature, established crop rotation strategies, root exudate profiles, soil nutrient fluxes, and bacterial and fungal microbial community profiles were determined at the flowering stage in the final two (canola) years of the 12-year rotations. Results: After 12 years of rotation, nutrient fluxes were affected in the soil in an inconsistent manner, with K, NO3, Mg, Ca, P, and Fe fluxes variably impacted by rotation depending on the year and site of sampling. As expected, rotation positively influenced yield and oil content, and decreased disease pressure from Leptosphaeria and Alternaria. In two of the three sites, root exudate profiles were significantly influenced by crop rotation. Bacterial soil, root, and rhizosphere communities were less impacted by crop rotation than the fungal communities. Fungal sequences that were associated with specific rotation strategies were identified in the bulk soil, and included known fungal pathogens in the canola-only strategy. Two closely related fungal sequences identified as Olpidium brassicae were extremely abundant at all sites in both years. One of these sequences was observed uniquely at a single site and was significantly associated with monocropped canola; moreover, its abundance correlated negatively with yield in both years. Conclusions: Long-term canola monoculture affected root exudate profiles and soil nutrient fluxes differently in the three geographic locations. Bacterial communities were less impacted by rotation compared to the fungal communities, which consistently exhibited changes in composition in all ecological niches at all sites, in both years. Fungal sequences identified as O. brassicae were highly abundant at all sites, one of which was strongly associated with canola monoculture. Soil management decisions should include consideration of the effects on the microbial ecosystems associated with the plants in order to inform best management practices.
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    A 1000-Year Record of Temperature From Isotopic Analysis of the Deep Critical Zone in Central China
    (Wiley Open Access [Commercial Publisher]; American Geophysical Union [Client Organisation], 2023) Wang, Hongxiu; Li, Han; Xiang, Wei; Lu, Yanwei; Wang, Huanhuan; Hu, Wei; Si, Bing Cheng; Jasechko, Scott; Mcdonnell, Jeffrey
    Temperature proxies for paleoclimate reconstruction have been made typically via ice cores, tree rings, stalagmites, and lake sediments. While extremely useful, these proxies can be limited spatially. Here we sampled a 98 m “soil core” from Loess Plateau of China and examined the relationship between pore water isotopic values and hydroclimate history. We extracted soil pore water for δ 18O, δ 2H, and 3H and measured chloride concentration. The 3H-peak at 6 m and chloride mass balance were used to turn depth into calendar year. A 1000 year span was revealed. δ 18O and δ 2H values between 14–50 m were anomalously low—bracketing well the Little Ice Age period from 1420 to 1870. The identification was consistent with other standard proxies in the region and showed the same temporal dynamics of temperature anomalies. Our study shows the potential of stable isotopes of soil water for paleoclimate reconstruction in deep soils.
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    Spatiotemporal Variation in Driving Factors of Vegetation Dynamics in the Yellow River Delta Estuarine Wetlands from 2000 to 2020
    (MDPI, 2023) Niu, Zhongen; Si, Bing Cheng; Li, Dong; Zhao, Ying; Hou, Xiyong; Li, Linlin; Wang, Bin; Song, Bing; Zhang, Mengyu; Li, Xiyu; Zeng, Na; Zhu, Xiaobo; Lv, Yan; Mai, Ziqi
    Previous studies of vegetation dynamics in the Yellow River Delta (YRD) predominantly relied on sparse time series or coarse-resolution images, which not only overlooked the rapid and spatially heterogeneous changes, but also limited our understanding of driving mechanisms. Here, employing spatiotemporal data fusion methods, we constructed a novel fused enhanced vegetation index (EVI) dataset with a high spatiotemporal resolution (30-meter and 8-day resolution) for the YRD from 2000 to 2020, and we analyzed the vegetation variations and their driving factors within and outside the YRD Nation Natural Reserve (YRDNRR). The fused EVI effectively captured spatiotemporal vegetation dynamics. Notably, within the YRDNRR core area, the fused EVI showed no significant trend before 2010, while a significant increase emerged post-2010, with an annual growth of 7%, the invasion of Spartina alterniflora explained 78% of this EVI increment. In the YRDNRR experimental area, the fused EVI exhibited a distinct interannual trend, which was characterized by an initial increase (2000–2006, p < 0.01), followed by a subsequent decrease (2006–2011, p < 0.01) and, ultimately, a renewed increase (2011–2020, p > 0.05); the dynamics of the fused EVI were mainly affected by the spring runoff (R2 = 0.71), while in years with lower runoff, it was also affected by the spring precipitation (R2 = 0.70). Outside of the protected area, the fused EVI demonstrated a substantial increase from 2000 to 2010 due to agricultural land expansion and human management practices, followed by stabilization post-2010. These findings enhance our comprehension of intricate vegetation dynamics in the YRD, holding significant relevance in terms of wetland preservation and management.
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    Characterization of problem soils in and around the south central Ethiopian Rift Valley
    (Academic Journals, 2016) Alemayehu, Kiflu; Sheleme, Beyene; Schoenau, Jeffrey
    Some soils in Ethiopia reduce plant productivity due to physical and/or chemical limitations. The morphological, physical and chemical properties of problem soils, including sodic, acidic, and saline soils, around southern Ethiopia were characterized and are described in this chapter. The intention is to characterize the soils and better understand the specific nature of the limitations. Sodic soils of Alage, acid soils of Hagereselam, and saline soils of Zeway areas were sampled to represent the problem soils. The soil properties determined included color, electrical conductivity (EC), structure, consistency, bulk density, texture, pH, organic carbon (OC), total nitrogen, available phosphorus (P) and K, exchangeable bases and available micro-nutrients. The soils had considerable heterogeneity in solum and regolith thickness, horizon depth, structural development in surface soils and subsurface horizons, pH, EC and available nutrients. The classification of these soils was made according to Soil Taxonomy and World Reference Base for Soil Resources systems. The sodic soils of Alage had high pH and sodium (Na) content, and low level of OC, available P, copper (Cu) and zinc (Zn). The epipedon was classified as an ochric and the profile also had variation in clay content down the profile to satisfy the requirements of having an argilic horizon and therefore these soils were classified as Typic Natragids. Soils of Hagereselam had very low available P. Available Cu and Zn contents were found to be at the marginal levels for production of most crops. The Hagereselam profile had an argilic horizon with umbric epipedon and was classified as Typic Paleustults. The saline soils in Zeway area had relatively high amounts of calcium and low OC. The profile was found to have ochric epipedon and these soils are classified as Typic Haplocambids. Application of fertilizer including P, Cu and Zn, and removal of sodium and salts from the soil profile may be means of improving the productivity of these soils. Application of organic amendments including manures and crop residues may also be beneficial in increasing the fertility as well as organic carbon content.
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    Addition of Biochar to a Sandy Desert Soil: Effect on Crop Growth,Water Retention and Selected Properties
    (MDPI, 2019) Alotaibi, Khaled D.; Schoenau, Jeffrey
    Agricultural and environmental applications of biochar (BC) to soils have received increasing attention as a possible means of improving productivity and sustainability. Most previous studies have focused on tropical soils and more recently temperate soils. However, benefits of BC addition to desert soils where many productivity constraints exist, especially water limitations, have not been widely explored. Thus, three experiments were designed using a desert soil from Saudi Arabia to address three objectives: (1) to evaluate the effect of BCs produced from date palm residues added at 8 t ha−1 on wheat growth, (2) to determine the effect of BC addition and BC aging in soil on water retention, and (3) to reveal the effect of BC on selected soil physical (bulk density, BD; total porosity; TP) and chemical (pH; electrical conductivity, EC; organic matter, OM; cation exchange capacity, CEC) properties. The feedstock (FS) of date palm residues were pyrolyzed at 300, 400, 500, and 600 °C, referred to here as BC300, BC400, BC500, and BC600, respectively. The BC products produced at low temperatures were the most effective in promoting wheat growth when applied with the NPK fertilizer and in enhancing soil water retention, particularly with aging in soil, whereas high -temperature BCs better improved the selected soil physical properties. The low-temperature BCs increased the yield approximately by 19% and improved water retention by 46% when averaged across the incubation period. Higher water retention observed with low-temperature BCs can be related to an increased amount of oxygen-containing functional groups in the low-temperature BCs, rendering BC surfaces less hydrophobic. Only the BC300 treatment showed a consistent positive impact on pH, OM, and CEC. Pyrolysis temperature of date palm residue along with aging are key factors in determining the potential benefit of BC derived from date palm residues added to sandy desert soil.
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    Demonstration and Testing of the Improved Shelterbelt Component in the Holos Model
    (Frontiers Media SA, 2020) Kröbel, Roland; Moore, Julius; Ni, Yu Zhao; McPherson, Aaron; Poppy, Laura; Soolanayakanahally, Raju Y.; Amichev, Beyhan Y.; Ward, Tricia; Laroque, Colin; Rees, Ken C. J. Van; Akhter, Fardausi
    The shelterbelt component of Canada’s whole-farm model Holos was upgraded from an age-determined to a circumference-determined (at breast height) calculation using a multi-stem averaging approach. The model interface was developed around the idea that a shelterbelt could have multiple rows, and a variable species composition within each row. With this, the model calculates the accumulated aboveground carbon in the standing biomass and a lookup table of modeled tree growth is used to add estimates of the belowground carbon. Going from an initial interface that asks for the current state, the model also incorporates an option of past and future shelterbelt plantings. In order to test the model’s suitability, we measured diverse shelterbelts (evergreen, deciduous, shrub type) in southern Saskatchewan, Canada representing commonly planted woody species. By making use of Caragana, Green Ash, Colorado Spruce, Siberian Elm, and a mixed Caragana/Green Ash tree row, we tested how many tree circumference measurements would be required to yield a representative average. Later, these results were incorporated in the Holos model to estimate the accumulated above-and below-ground carbon in each shelterbelt type.
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    Multi-Horizon Predictive Soil Mapping of Historical Soil Properties Using Remote Sensing Imagery
    (MDPI, 2022) Sorenson, Preston; Kiss, Jeremy; Bedard-Haughn, Angela; Shirtliffe, Steve
    There is increasing demand for more detailed soil maps to support fine-scale land use planning, soil carbon management, and precision agriculture in Saskatchewan. Predictive soil mapping that incorporates a combination of environmental covariates provides a cost-effective tool for generating finer resolution soil maps. This study focused on mapping soil properties for multiple soil horizons in Saskatchewan using historical legacy soil data in combination with remote sensing band indices, bare soil composite imagery, climate data, and terrain attributes. Mapped soil properties included soil organic carbon content (SOC), total nitrogen, cation exchange capacity (CEC), electrical conductivity (EC), inorganic carbon (IOC), sand and clay content, and total profile soil organic carbon stocks. For each of these soil properties, a recursive feature elimination was undertaken to reduce the number of features in the overall model. This process involved iteratively removing features such that random forest out-of-bag error was minimized. Final random forest models were built for each property and evaluated using an independent test dataset. Overall, predictive models were successful for SOC (R2 = 0.71), total nitrogen (R2 = 0.65), CEC (R2 = 0.46), sand content (R2 = 0.44) and clay content (R2 = 0.55). The methods used in this study enable mapping of a greater geographic region of Saskatchewan compared to those previously established that relied solely on bare soil composite imagery.
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    1981 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1982) Henry, J.L.; Hogg, T.J.
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    1980 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1981) Henry, J.L.; Hogg, T.J.
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    1979 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1980) Henry, J.L.; Hogg, T.J.
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    1978 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1979) Henry, J.L.; Hogg, T.J.
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    1977 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1978) Henry, J.L.; Hogg, T.J.
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    1976 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1977) Hogg, T.J.; Henry, J.L.
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    1975 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1976) Henry, J.L.; McGill, K.S.
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    1974 Soil Plant Nutrient Research Report
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 3/1/1975) McGill, K.S.; Henry, J.L.
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    Water infiltration and evaporation from the soil surface under reduced tillage
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 8/1/1992) Grevers, M.C.J.; Foster, R.K.
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    Modulus of rupture test for determining soil strength of surface soils
    (Department of Soil Science, University of Saskatchewan, Saskatoon, SK, 8/1/1992) Grevers, M.C.J.