The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Jizhong Zhou - One of the best experts on this subject based on the ideXlab platform.
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denitrifying and diazotrophic community responses to artificial warming in permafrost and tallgrass Prairie Soils
Frontiers in Microbiology, 2015Co-Authors: Derek St Louis, James R Cole, Liyou Wu, Edward A G Schuur, Jizhong Zhou, Christopher Ryan Penton, Amanda PhamAbstract:Increasing temperatures have been shown to impact soil biogeochemical processes, although the corresponding changes to the underlying microbial functional communities are not well understood. Alterations in the nitrogen (N) cycling functional component are particularly important as N availability can affect microbial decomposition rates of soil organic matter and influence plant productivity. To assess changes in the microbial component responsible for these changes, the composition of the N-fixing (nifH), and denitrifying (nirS, nirK, nosZ) soil microbial communities was assessed by targeted pyrosequencing of functional genes involved in N cycling in two major biomes where the experimental effect of climate warming is under investigation, a tallgrass Prairie in Oklahoma (OK) and the active layer above permafrost in Alaska (AK). Raw reads were processed for quality, translated with frameshift correction, and a total of 313,842 amino acid sequences were clustered and linked to a nearest neighbor using reference datasets. The number of OTUs recovered ranged from 231 (NifH) to 862 (NirK). The N functional microbial communities of the Prairie, which had experienced a decade of experimental warming were the most affected with changes in the richness and/or overall structure of NifH, NirS, NirK and NosZ. In contrast, the AK permafrost communities, which had experienced only one year of warming, showed decreased richness and a structural change only with the nirK-harboring bacterial community. A highly divergent nirK-harboring bacterial community was identified in the permafrost Soils, suggesting much novelty, while other N functional communities exhibited similar relatedness to the reference databases, regardless of site. Prairie and permafrost Soils also harbored highly divergent communities due mostly to differing major populations
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fungal diversity in permafrost and tallgrass Prairie Soils under experimental warming conditions
Applied and Environmental Microbiology, 2013Co-Authors: Ryan C Penton, Derek St Louis, James R Cole, Liyou Wu, Edward A G Schuur, Jizhong Zhou, James M TiedjeAbstract:ABSTRACT Soil fungi play a major role in terrestrial ecosystem functioning through interactions with soil structure, plants, micro- and mesofauna, and nutrient cycling through predation, pathogenesis, mutualistic, and saprotrophic roles. The diversity of soil fungi was assessed by sequencing their 28S rRNA gene in Alaskan permafrost and Oklahoma tallgrass Prairie Soils at experimental sites where the effect of climate warming is under investigation. A total of 226,695 reads were classified into 1,063 genera, covering 62% of the reference data set. Using the Bayesian Classifier offered by the Ribosomal Database Project (RDP) with 50% bootstrapping classification confidence, approximately 70% of sequences were returned as “unclassified” at the genus level, although the majority (∼65%) were classified at the class level, which provided insight into these lesser-known fungal lineages. Those unclassified at the genus level were subjected to BLAST analysis against the ARB-SILVA database, where ∼50% most closely matched nonfungal taxa. Compared to the more abundant sequences, a higher proportion of rare operational taxonomic units (OTU) were successfully classified to genera at 50% bootstrap confidence, indicating that the fungal rare biosphere in these sites is not composed of sequencing artifacts. There was no significant effect after 1 year of warming on the fungal community structure at both sites, except perhaps for a few minor members, but there was a significant effect of sample depth in the permafrost Soils. Despite overall significant community structure differences driven by variations in OTU dominance, the Prairie and permafrost Soils shared 90% and 63% of all fungal sequences, respectively, indicating a fungal “seed bank” common between both sites.
P. Dahl - One of the best experts on this subject based on the ideXlab platform.
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freeze thaw classification for Prairie Soils using ssm i radiobrightnesses
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:Data from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) have been used to classify snow-free Soils in the northern Great Plains as either frozen or thawed. The technique is based on differing sensitivities among SMMR radiobrightness frequencies to liquid moisture and volume scattering in the upper few millimeters of bare soil. The SMMR is no longer active. A current near-equivalent is the Special Sensor Microwave/Imager (SSM/I). The authors demonstrate that SSM/I radiobrightnesses also exhibit differential sensitivities to liquid water and volume scattering in frozen soil despite their higher frequencies. They find that the best classification discriminants for SSM/I data are a combination of the 37-GHz V-pol radiobrightnesses and the 19-to-37-GHz V-pol spectral gradients. They also examine the sensitivity of the classification to atmospheric emission and absorption and find little effect.
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Freeze/thaw classification for Prairie Soils using SSM/I radiobrightnesses
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:Data from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) have been used to classify snow-free Soils in the northern Great Plains as either frozen or thawed. The technique is based on differing sensitivities among SMMR radiobrightness frequencies to liquid moisture and volume scattering in the upper few millimeters of bare soil. The SMMR is no longer active. A current near-equivalent is the Special Sensor Microwave/Imager (SSM/I). The authors demonstrate that SSM/I radiobrightnesses also exhibit differential sensitivities to liquid water and volume scattering in frozen soil despite their higher frequencies. They find that the best classification discriminants for SSM/I data are a combination of the 37-GHz V-pol radiobrightnesses and the 19-to-37-GHz V-pol spectral gradients. They also examine the sensitivity of the classification to atmospheric emission and absorption and find little effect.
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Freeze/thaw classification for Prairie Soils using SSM/I radiobrightnesses
IGARSS '96. 1996 International Geoscience and Remote Sensing Symposium, 1996Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:The state of soil moisture is an important variable in land surface processes. Moist Soils can be classified as frozen or thawed using SSM/I radiobrightness signatures. Though the lowest frequency of SSM/I, 19.35 GHz, is above the Debye relaxation frequency of liquid water, the spectral gradient remains sensitive to the state of soil moisture. Frozen soil was classified as such by a negative 19.35 to 37 GHz or 19.35 to 85 GHz spectral gradient and a low 37 GHz radiobrightness.
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freeze thaw classification for Prairie Soils using ssm i radiobrightnesses
International Geoscience and Remote Sensing Symposium, 1996Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:The state of soil moisture is an important variable in land surface processes. Moist Soils can be classified as frozen or thawed using SSM/I radiobrightness signatures. Though the lowest frequency of SSM/I, 19.35 GHz, is above the Debye relaxation frequency of liquid water, the spectral gradient remains sensitive to the state of soil moisture. Frozen soil was classified as such by a negative 19.35 to 37 GHz or 19.35 to 85 GHz spectral gradient and a low 37 GHz radiobrightness.
Randall D Jackson - One of the best experts on this subject based on the ideXlab platform.
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microbial community structure and functional potential in cultivated and native tallgrass Prairie Soils of the midwestern united states
Frontiers in Microbiology, 2018Co-Authors: Rachel Mackelprang, Alyssa M Grube, Regina Lamendella, Ederson Da Conceicao Jesus, Alex Copeland, Chao Liang, Randall D JacksonAbstract:Author(s): Mackelprang, Rachel; Grube, Alyssa M; Lamendella, Regina; Jesus, Ederson da C; Copeland, Alex; Liang, Chao; Jackson, Randall D; Rice, Charles W; Kapucija, Stefanie; Parsa, Bayan; Tringe, Susannah G; Tiedje, James M; Jansson, Janet K | Abstract: The North American Prairie covered about 3.6 million-km2 of the continent prior to European contact. Only 1-2% of the original Prairie remains, but the Soils that developed under these Prairies are some of the most productive and fertile in the world, containing over 35% of the soil carbon in the continental United States. Cultivation may alter microbial diversity and composition, influencing the metabolism of carbon, nitrogen, and other elements. Here, we explored the structure and functional potential of the soil microbiome in paired cultivated-corn (at the time of sampling) and never-cultivated native Prairie Soils across a three-states transect (Wisconsin, Iowa, and Kansas) using metagenomic and 16S rRNA gene sequencing and lipid analysis. At the Wisconsin site, we also sampled adjacent restored Prairie and switchgrass plots. We found that agricultural practices drove differences in community composition and diversity across the transect. Microbial biomass in Prairie samples was twice that of cultivated Soils, but alpha diversity was higher with cultivation. Metagenome analyses revealed denitrification and starch degradation genes were abundant across all Soils, as were core genes involved in response to osmotic stress, resource transport, and environmental sensing. Together, these data indicate that cultivation shifted the microbiome in consistent ways across different regions of the Prairie, but also suggest that many functions are resilient to changes caused by land management practices - perhaps reflecting adaptations to conditions common to tallgrass Prairie Soils in the region (e.g., soil type, parent material, development under grasses, temperature and rainfall patterns, and annual freeze-thaw cycles). These findings are important for understanding the long-term consequences of land management practices to Prairie soil microbial communities and their genetic potential to carry out key functions.
J. Judge - One of the best experts on this subject based on the ideXlab platform.
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freeze thaw classification for Prairie Soils using ssm i radiobrightnesses
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:Data from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) have been used to classify snow-free Soils in the northern Great Plains as either frozen or thawed. The technique is based on differing sensitivities among SMMR radiobrightness frequencies to liquid moisture and volume scattering in the upper few millimeters of bare soil. The SMMR is no longer active. A current near-equivalent is the Special Sensor Microwave/Imager (SSM/I). The authors demonstrate that SSM/I radiobrightnesses also exhibit differential sensitivities to liquid water and volume scattering in frozen soil despite their higher frequencies. They find that the best classification discriminants for SSM/I data are a combination of the 37-GHz V-pol radiobrightnesses and the 19-to-37-GHz V-pol spectral gradients. They also examine the sensitivity of the classification to atmospheric emission and absorption and find little effect.
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Freeze/thaw classification for Prairie Soils using SSM/I radiobrightnesses
IEEE Transactions on Geoscience and Remote Sensing, 1997Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:Data from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) have been used to classify snow-free Soils in the northern Great Plains as either frozen or thawed. The technique is based on differing sensitivities among SMMR radiobrightness frequencies to liquid moisture and volume scattering in the upper few millimeters of bare soil. The SMMR is no longer active. A current near-equivalent is the Special Sensor Microwave/Imager (SSM/I). The authors demonstrate that SSM/I radiobrightnesses also exhibit differential sensitivities to liquid water and volume scattering in frozen soil despite their higher frequencies. They find that the best classification discriminants for SSM/I data are a combination of the 37-GHz V-pol radiobrightnesses and the 19-to-37-GHz V-pol spectral gradients. They also examine the sensitivity of the classification to atmospheric emission and absorption and find little effect.
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Freeze/thaw classification for Prairie Soils using SSM/I radiobrightnesses
IGARSS '96. 1996 International Geoscience and Remote Sensing Symposium, 1996Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:The state of soil moisture is an important variable in land surface processes. Moist Soils can be classified as frozen or thawed using SSM/I radiobrightness signatures. Though the lowest frequency of SSM/I, 19.35 GHz, is above the Debye relaxation frequency of liquid water, the spectral gradient remains sensitive to the state of soil moisture. Frozen soil was classified as such by a negative 19.35 to 37 GHz or 19.35 to 85 GHz spectral gradient and a low 37 GHz radiobrightness.
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freeze thaw classification for Prairie Soils using ssm i radiobrightnesses
International Geoscience and Remote Sensing Symposium, 1996Co-Authors: J. Judge, J.f. Galantowicz, A.w. England, P. DahlAbstract:The state of soil moisture is an important variable in land surface processes. Moist Soils can be classified as frozen or thawed using SSM/I radiobrightness signatures. Though the lowest frequency of SSM/I, 19.35 GHz, is above the Debye relaxation frequency of liquid water, the spectral gradient remains sensitive to the state of soil moisture. Frozen soil was classified as such by a negative 19.35 to 37 GHz or 19.35 to 85 GHz spectral gradient and a low 37 GHz radiobrightness.
J. J. Schoenau - One of the best experts on this subject based on the ideXlab platform.
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Influence of Willow Biochar Amendment on Soil Nitrogen Availability and Greenhouse Gas Production in Two Fertilized Temperate Prairie Soils
BioEnergy Research, 2016Co-Authors: R. D. Hangs, H. P. Ahmed, J. J. SchoenauAbstract:The potential of biochar to improve numerous soil physical, chemical and biological properties is well known. However, previous research has concentrated on old and highly weathered tropical Soils with poor fertility, while reports regarding the influence of biochar application on relatively young and fertile temperate Prairie Soils are limited. Furthermore, the mechanism(s) underlying biochar-induced effects on the plant availability of inorganic nitrogen (N) fertilizers and their relationship to greenhouse gas production is not well understood. The objective of this study was to determine the effect of a biochar soil amendment, produced by slow pyrolysis using shrub willow ( Salix spp.) bioenergy feedstock, on CO_2, N_2O and CH_4 fluxes by two contrasting marginal Soils from Saskatchewan, Canada with and without added urea, over a 6-week incubation period. Biochar decreased soil N availability after 6 weeks only in the lower organic matter (Brown) soil, with no effect on the Black soil, regardless of fertilizer N addition, which was attributed to soil N immobilization by heterotrophs mineralizing the labile biochar-carbon. There appeared to be a synergistic effect when combining biochar and urea, evidenced by enhanced urease activity and higher initial nitrification rates compared to biochar or fertilization alone. The accelerated urea hydrolysis in the presence of biochar may increase NH_3 volatilization losses associated with urea fertilization and, therefore, warrants further investigation. The decreased N_2O emissions following biochar addition, with (both Soils) or without (Black soil) fertilizer N, could be due to decreased ammonium and nitrate availability, along with changes in denitrification potential as related to improved aeration. Biochar significantly reduced the water-filled pore space, which concurrently increased CH_4 consumption in both Soils. The lack of biochar effect on CO_2 emissions from either soil, with or without fertilizer N, suggests enhanced CO_2 consumption by autotrophic nitrifiers. Biochar application appears to be an effective management approach for improving N_2O and CH_4 fluxes in temperate Prairie Soils.
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development of a laboratory bioassay and effect of soil properties on sulfentrazone phytotoxicity in soil
Weed Technology, 2009Co-Authors: Anna M Szmigielski, F. A. Holm, Eric N Johnson, J. J. Schoenau, Ken L SapsfordAbstract:Abstract Sulfentrazone is a phenyl triazolinone herbicide used for control of certain broadleaf and grass weed species. Sulfentrazone persists in soil and has residual activity beyond the season of application. A laboratory bioassay was developed for the detection of sulfentrazone in soil using root and shoot response of several crops. Shoot length inhibition of sugar beet was found to be the most sensitive and reproducible parameter for measurement of soil-incorporated sulfentrazone. The sugar beet bioassay was then used to examine the effect of soil properties on sulfentrazone phytotoxicity using 10 different Canadian Prairie Soils. Concentrations corresponding to 50% inhibition (I50 values) were obtained from the dose–response curves constructed for the Soils. Sulfentrazone phytotoxicity was strongly correlated to the percentage organic carbon (P = 0.01) and also to percentage clay content (P = 0.05), whereas correlation with soil pH was nonsignificant (P = 0.21). Because sulfentrazone phytotoxic...
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Nitrogen balance and accumulation pattern in three contrasting Prairie Soils receiving repeated applications of liquid swine and solid cattle manure
Nutrient Cycling in Agroecosystems, 2007Co-Authors: C. Stumborg, J. J. Schoenau, S S MalhiAbstract:The expansion of intensive livestock operations in western Canada has increased concerns about overloading of nutrients in manured lands. The magnitude of nutrient accumulation and its distribution in the soil profile varies with soil-climatic conditions. The objective of this study was to determine loading and distribution of manure-derived nitrogen (N) in the soil profile as influenced by repeated manure applications. Four field experiments were conducted at three sites (Dixon, Melfort and Plenty) in Saskatchewan under longer-term manure management. The four field experiments provide contrasts in soil type, climatic conditions, manure type, application and cropping history to enable the effect of these factors to be evaluated. Liquid hog manure (LHM—Experiment 1) and solid cattle manure (SCM—Experiment 2) treatments were applied annually over 8 years at Dixon (Black Chernozemic loam soil—Udic Boroll in sub-humid climate), while only LHM was applied at Plenty (Dark Brown Chernozemic heavy clay soil—Typic Boroll in semi-arid climate) over 6 years (Experiment 3), and at Melfort (Dark Gray Luvisol silty clay loam soil—Mollic Cryoboralf in humid climate) over 5 years (Experiment 4). Soil samples were collected in the spring and autumn of 2003 and 2004, and were analyzed for organic N, ammonium-N (NH _4 ^+ -N) and nitrate-N (NO _3 ^− -N) concentrations. Plant samples were collected to determine the impact of manure application rate on plant N uptake and crop N removal. The annual application of LHM (37,000 L ha^−1 yr^−1) and SCM (7.6 Mg ha^−1 yr^−1) at agronomic rates at Dixon (added N balances crop demand for that year), or larger rates of LHM (111,000 L ha^−1) applied once every 3 years (Melfort) did not significantly elevate NO _3 ^− -N in soil compared to the unfertilized control. Lower crop removal and reduced leaching of NO _3 ^− -N due to drier conditions as occurred at the Plenty site contributed to greater accumulation of nitrate in the top 60 cm at equivalent rates compared to the other two sites. At large manure rates, excess N from the balance estimates could not be accounted for in soil organic N and was assumed to be lost from the soil-plant system. At the Dixon LHM site, deep leaching of NO _3 ^− -N was observed at the excessive rate (148,000 L ha^−1 yr^−1) up to the 150 cm depth, compared to the control. At Dixon, the large annual application rate of SCM (30.4 Mg ha^−1 yr^−1) did not significantly increase NO _3 ^− -N in the 0–60 cm soil compared to the control, which was attributed to lower mineralization of organic N from the SCM. Over the short and medium term, LHM application at large rates every year poses a greater risk for loading and deep migration of NO _3 ^− -N in soil than large rates of SCM. Larger single applications made once every 3 years were not associated with accumulation or deep leaching. To prevent loading, rates of applied manure nitrogen should be reduced when crop N removal potential is diminished by high frequency of drought.