bluuebunny/crossref_metadata_2025 huggingface dataset:
Slope position and subsoiling effects on soil water and spring wheat yield
Authors: McConkey B. G. , Ulrich D. J. , Dyck F. B.
Published: April 2011

A study was conducted on a 4-m-high ridge in southwestern Saskatchewan to determine the relationship of slope position with the soil water regime and spring wheat (Triticumaestivum L.) production and to determine if those relationships were altered by subsoiling. In all years, available soil water in the spring to 120 cm increased significantly with distance upslope. This pattern was attributed to residual subsoil water in the rooting zone that had not been used by previous crops in a long-term crop-fallow rotation. After 3 yr of annual spring wheat production, soil water to 1.2 m at all slope positions approximately equalled the water content wilting point (4.0 MPa) water content, showing this residual water had been largely consumed. Apparent use of soil water between seeding and harvest at the upper slope positions was equal to or greater than that at the lower slope positions. Over-winter soil water conservation, using tall (≥ 30-cm-high) wheat stubble for snow trapping, at the upper slope positions was equal to or greater than that at the lower slope positions. In the non-drought years of 1987 and 1989, wheat yields and crop water use efficiency increased significantly with distance downslope. Since these slope effects were not related to water use or availability, they were attributed to higher soil productivity, probably related to more historical net erosion with distance upslope. During the drought year of 1988, wheat yields and water use efficiency were greatest at the upslope positions, but these results were confounded by uneven crop emergence. Subsoiling to 35 cm or deeper increased the amount and depth of infiltration of water in years with near-average November–April precipitation. Subsoiling had little effect on wheat yields and no effect on crop water use.

Key words: Landscape, wheat, productivity, soil moisture
Utilisation de l'engrais azoté marqué au 15N par le maïs selon les modes d'application et les doses d'azote
Authors: Tran Thi Sen , Giroux Marcel , Cescas Michel P.
Published: April 2011

The main objective of this study was to compare the recovery of 15N-labelled fertilizer by different methods of N application and N rates. Field experiments were carried out for 3 yr at Saint-Hyacinthe (Saint-Damase, Du Contour, Sainte-Rosalie soils) and at Saint-Lambert, Lévis (Le Bras soil). Grain corn (cv. Pride K228, 2700 CHU) and silage corn (cv. Hyland 3251, 2300 CHU) were grown at Saint-Hyacinthe and Saint-Lambert, respectively. In 1988 and 1989, field trials were arranged in a randomized complete bloc design consisting of five treatments in three replications: control 0 N and four split application methods of N fertilizer. Labelled 15NH4 15NO3 fertilizer was applied either banded at planting as starter (D), broadcast and incorporated before planting (Vs) or sidedressing between rows at V6 to V8 stages of corn (Bp). In 1990 field trials, treatments consisted of four N rates (0, 60, 120 and 180 kg N ha−1) labelled with 15NH4 15NO3. The effect of N rates on yield and N uptake by corn was significant in all years. However, the effect of application methods was significant only on the soil Du Contour in 1989 where corn grain yield was highest when N fertilizer was split as starter and sidedress band. The CUR of N fertilizer applied broadcast before planting (42 to 48%) was generally lower than sidedressing band application (43 to 54%). N fertilizer recovery in the starter showed also high CUR values (45 to 60%). Consequently, it is recommended to split N fertilizers and apply in band to increase efficiency for grain corn. The CUR values decreased with N rates only in Le Bras soil in 1990. Residual N fertilizer increased from 27 to 103 kg N ha−1 for 60 and 180 kg N ha−1 rates, respectively. Consequently, the environmental impact of N fertilization may increased with high N rate.

Key words: Grain corn, silage corn, 15N recovery, fertilizer N split application
Nitrogen mineralization and availability in manure composts from Québec biological farms
Authors: N'Dayegamiye Adrien , Royer Raynald , Audesse Pierre
Published: April 2011

The real contribution of composts to N availability depends on their characteristics and maturity. A laboratory incubation experiment (140 d) was conducted parallel to a greenhouse study (330 d) in a split-split-plot design, with, respectively, two peat rates (0, 20 gkg−1 soil), five manure composts and four compost rates (0, 250, 500 and 750 gkg−1 soil). Compost N mineralization, orchardgrass (Dactylis Glomerata L.) yield and N uptake were measured. Total amount of mineralized N and yields and N uptake for six cuts of orchardgrass varied significantly with the type of composts and rate. Peat addition temporarily decreased compost N mineralization rate but significantly increased orchardgrass yields and N uptake as compared to peatless treatments. Mineralized N represented <3% of total N, whereas N uptake by orchardgrass represented 13–40% of total N among composts. This low mineralized N value compared to total N and total N uptake was due to a high maturity of the composts studied. This was shown by high humic acid: fulvic acid fraction ratios (3.1 to 4.8) and low nonhumic fraction:humic acid+fulvic acid ratios (0.10 to 0.12), as well as low C/N ratios, high bulk density, high ash content, pH, NO3-N and CEC values. Even if peat addition decreased mineralized N basically due to temporary N immobilization, its application significantly increased yields and N uptake probably by improving physical conditions in soil-manure compost mixtures. Peat addition to mature manure composts should be considered as an interesting alternative for horticultural plants sensitive to high NO3-N content from mature composts.

Key word: Manure composts, peat, N mineralization, N availability, humification ratios or indexes, yields, orchardgrass
Acidification rate of limed soil in a semiarid environment
Authors: Curtin D. , Ukrainetz H.
Published: April 2011

To evaluate the benefits of liming acid soils, a method is needed to predict the longevity of its effect on soil pH. We coupled a simple index of soil buffering with estimates of the proton budget to predict long-term pH changes in a limed soil (Dark Brown Chernozem) in Saskatchewan. Analysis of published data for Saskatchewan soils showed that acceptable estimates of soil buffering can be obtained from organic matter and clay content. Buffer capacities of organic matter and clay were estimated at 487 and 26 mmol(±) kg−1 (pH unit)−1, respectively. Soil pH, titratable acidity, and effective cation exchange capacity (CEC) were monitored for 18 yr after lime application [Ca(OH)2 at rates of 0, 4.5 and 6.7 t ha−1] to field plots in a wheat (Triticum aestivum L.)-fallow rotation. In limed plots, there was a tendency for pH, exchangeable Ca and effective CEC to decrease with time in the 0–7.5 cm layer and to increase in the 7.5–15 cm layer. This was attributed to mixing of the two layers during cultivation. In the 0–15 cm layer as a whole, there was no discernible change in acidity, Ca, or CEC during the monitoring period. Negligible re-acidification in limed soil was consistent with the estimated H+ budget. External acidification sources were negligible (no N fertilizer was applied). Acidification due to leaching of nitrate and export of cations in grain over 18 yr was estimated at 6–7 kmol(H+) ha−1. This amount of acidity would lower soil pH by less than 0.1 units [buffer capacity of the top 15 cm of soil was ≈70 kmol(±) ha−1 (pH unit)–1], an amount too small to be detectable against background variability.

Key words: Buffer capacity, organic matter, proton budget, titratable acidity
Opportunities for soil science in a milieu of reduced funds
Authors: Mermut A. R. , Eswaran H.
Published: April 2011

not available
Measurement of rill erosion by snowmelt on potato fields under rotation in Prince Edward Island (Canada)
Authors: Edwards Linnell , Richter G. , Bernsdorf B. , Schmidt R.-G. , Burney J.
Published: April 2011

Cool-period soil erosion from farmland in Prince Edward Island occurs predominantly through rilling mainly due to snowmelt. This is mostly evident on fields coming out of potatoes (Solanum tuberosum L.), a crop that is traditionally cultivated as part of a 2-yr rotation with cereal grains, or a 3-yr rotation with cereal grains and a forage crop for hay. Accurate assessment of snowmelt erosion (associated processes and effects) has been historically constrained by data inadequacy, particularly for rilling; and although a number of models have now been developed for estimating cool-period erosion, they still stand to benefit from the generation of actual field data. In the present study, actual volume measurements were made of erosion forms, for about 80 site-years, after the spring snowmelt in fields at various stages of potato rotation. Cool-period erosion, predominantly rills, amounted to about 30 t ha−1 for 2-yr and 3-yr rotations, thus an annual seasonal average of 15 t ha−1 and 10 t ha−1, respectively. Potato fields left untilled over winter averaged about 20 t ha–1 which increased to 36 t ha−1 with fall ploughing. Sediment deposition in fields coming out of potatoes was 13.3 t ha−1 compared with the amount of 0.4 t ha−1 in fields coming out of forages and 1.6 t ha−1 in fields coming out of grain. Fields going into the winter in sod or stubble showed negligible erosion, averaging about 0.1 t ha−1 in spring. The results of this study demonstrate the dominant influence of cropping practice in the erosion process during the cool period, and the tendency for traditional computational procedures to underestimate soil loss. Key words: Cool-period erosion, rilling, rill volume, sediment deposition, soil-loss prediction, erosion mapping, crop rotation
Comparison of acid and base leach for the removal of uranium from contaminated soil and catch-box media
Authors: Duff Martine C. , Mason Caroline F. V. , Hunter Douglas B.
Published: April 2011

Several leach solutions have been developed for the removal of uranium (U) from contaminated media such as soil and military catch-box sand used for the ballistics testing of U-containing projectiles. Leach solutions of concentrated sulfuric acid and of carbonate (with and without oxidants such as peroxides) have also been used in the mining of U from high-grade ore deposits. Many of these solutions have been used at U-contaminated environmental sites with varying degrees of success. Batch leaches with six characterized U-contaminated media and seven leach solutions were conducted. After the leach solutions were reacted with the media (five soils and a catch-box sand), the solutions were analyzed for dissolved U, Ca, Si, Fe, Mn, Pb and Cr. We study the ability of acidic, basic, acidic-oxidizing and basic-oxidizing solutions to leach U from contaminated media. The results suggest the removal efficiency of soil U for each leach solution varies with the nature of the U-contamination in the media and the media composition. It is likely the forms of U in the contaminated media such as reduced, absorbed, complexed and solid species influence the solubilization of U by the leaching agents. Key words: Uranium, synchrotron X-ray fluorescence (SXRF), remediation, chromium, lead, leaching, catch-boxes
Dynamics of soil microbial biomass C, soluble organic C and CO2 evolution after three years of manure application
Authors: Rochette P. , Gregorich E. G.
Published: April 2011

Application of manure and fertilizer affects the rate and extent of mineralization and sequestration of C in soil. The objective of this study was to determine the effects of 3 yr of application of N fertilizer and different manure amendments on CO2 evolution and the dynamics of soil microbial biomass and soluble C in the field. Soil respiration, soluble organic C and microbial biomass C were measured at intervals over the growing season in maize soils amended with stockpiled or rotted manure, N fertilizer (200 kg N ha−1) and with no amendments (control). Manure amendments increased soil respiration and levels of soluble organic C and microbial biomass C by a factor of 2 to 3 compared with the control, whereas the N fertilizer had little effect on any parameter. Soil temperature explained most of the variations in CO2 flux (78 to 95%) in each treatment, but data from all treatments could not be fitted to a unique relationship. Increases in CO2 emission and soluble C resulting from manure amendments were strongly correlated (r2 = 0.75) with soil temperature. This observation confirms that soluble C is an active C pool affected by biological activity. The positive correlation between soluble organic C and soil temperature also suggests that production of soluble C increases more than mineralization of soluble C as temperature increases. The total manure-derived CO2-C was equivalent to 52% of the applied stockpiled-manure C and 67% of the applied rotted-manure C. Estimates of average turnover rates of microbial biomass ranged between 0.72 and 1.22 yr−1 and were lowest in manured soils. Manured soils also had large quantities of soluble C with a slower turnover rate than that in either fertilized or unamended soils. Key words: Soil respiration, greenhouse gas, soil carbon
Coated KCl increases barley K uptake in two Alberta soils in a greenhouse experiment
Authors: Zhang M. , Nyborg M. , Robertson J. A. , Solberg E. D.
Published: April 2011

An experiment was conducted in the greenhouse on two K-responsive soils to determine the effectiveness of coated and non-coated KCl for barley (Hordeum vulgare L. 'Duke'). KCl granules, non-coated and coated with 2.5% and 3.5% polyurethane, were applied at 44 and 132 mg K per pot containing 2000 g of soil. Plant dry matter, K concentration and K uptake were determined on shoot samples taken 40 and 76 d after sowing. While dry matter was unaffected, coated KCl generally reduced plant K concentration and K uptake at 40 d and increased plant K concentration and K uptake at 76 d. We concluded the KCl coated with polyurethane can be more available to crops in K deficient soils. Key words: Coated KCl, KCl, barley K, slow-release fertilizer
Effects of de-inking paper sludges on soil properties and crop yields
Authors: Simard Régis R. , Baziramakenga Régis , Yelle Serge , Coulombe Jean
Published: April 2011

The paper mills in Quebec produce approximately 330 000 Mg of raw de-inking paper sludges (RDS) per year. These residues are rich in cellulose and lignin and may be used as soil conditioner. The effects of RDS on soil chemical properties, barley (Hordeum vulgare L. 'Chapais') growth, nutrient uptake and yields, and their residual effect on a subsequent strawberry (Fragaria × ananassa Duch. 'Kent') crop were investigated on a Tilly silt loam (Gleyed Humo-Ferric Podzol) from 1994 to 1996. Four rates of RDS (0, 15, 30 and 45 Mg ha−1) on a wet-weight basis were combined with four rates of supplemental N-mineral fertilizer (0, 45, 90 and 135 kg ha−1) as NH4NO3 The soluble inorganic N content of soil sampled 30 d after treatment application was significantly lower in plots treated with 45 Mg RDS ha−1 at all N rates. However, soluble inorganic N concentrations increased significantly with RDS rate to 20-cm depth in June 1995. The RDS application increased soil water content and Mehlich-3-extractable P, K, and Ca in the first year. Barley yields were reduced by 50% when 45 Mg RDS ha−1 was applied without supplemental N-mineral fertilizer. The amount of N-mineral fertilizer needed to overcome N immobilization resulting from RDS increased with RDS rates. Strawberry yields were not significantly affected by residual RDS or N-mineral fertilizer. Changes in plant tissue metal contents were not significant. The results of this study indicate that RDS application has a positive short-term effect on soil water, P and K availability but reduces plant-available soil N in the growing season after spring application. The RDS may be used effectively as soil amendment if the crop receives adequate supplemental N-mineral fertilizer. Key words: De-inking paper sludge, N immobilization, barley, strawberry
Nitrogen and carbon mineralization in soil amended with municipal solid waste compost
Authors: Mamo M. , Molina J. A. E. , Rosen C. J. , Halbach T. R.
Published: April 2011

Municipal solid waste (MSW) compost contains large amounts of organic matter that can be beneficial to soil. The objectives of this study were to measure N mineralization and acid hydrolyzable N in soil amended with MSW compost and correlate corn (Zea mays L.) grain yield with acid hydrolyzable N. The soil, an Orthic Black Chernozem (Entic Hapludoll) cropped to corn, was amended with composts at either 90 dry Mg ha−1 yr−1 from 1993 to 1995, or at 270 dry Mg ha−1 in one application in 1993. Soil samples were collected in the fall of 1994 and 1995 to measure C and N mineralization and acid hydrolyzable N. Potentially mineralizable N was estimated with the NCSOIL model after using C and N mineralization observed in the laboratory to calibrate the model. Net N immobilization occurred in compost-amended soils collected in 1994 with less than 0.2% of the total soil N mineralized in the compost treatments. In 1995, there was net mineralization in compost treatments but less than 5% of total soil N mineralized in 120 d. The addition of compost increased the acid hydrolyzable N of soil with 43–63% of the total soil N being acid hydrolyzable. Acid hydrolyzable soil N did not correlate to No but weakly correlated with corn grain yield. The MSW compost source was more important than the timing of application in inducing differences in soil biochemical properties. Keys words: Municipal solid waste compost, organic matter, potentially mineralizable nitrogen, acid hydrolysis
A comparison of methods for gypsum requirement of brine-contaminated soils
Authors: Ashworth John , Keyes Doug , Crépin Jean-Michel
Published: April 2011

An estimate of the gypsum requirement (GR) of soils affected by Na salts has practical value. The estimated GR can indicate both the quantity of any Ca amendment needed and the progress of site remediation. Four published methods to estimate GR use analytical results that do not directly include any Na in excess of the soil's cation exchange capacity (CEC). GR values thus obtained, for a 15-cm soil layer, are at most 20 to 50 t ha−1. We used these four methods to calculate the GR for various soils with known, differing salt contents. The values obtained were often inconsistent with the sodium adsorption ratio (SAR) and electrical conductivity (EC), parameters that indicate the severity of site-contamination. We also used an unpublished method to estimate GR from the amount of Ca required to bring each soil's SAR down to a threshold value of 7, on the basis of concentrations of soluble ions in a saturated paste filtrate. Estimates of GR made in this way often exceeded 50 t ha−1, but were consistent with SAR and EC levels at the various sites. This method may be more appropriate for estimating GR after brine spills on soils where Na is not readily leached and the quantity of Na exceeds the CEC. This situation often applies on the Canadian prairies. Estimating GR from the quantity of Ca required to replace exchangeable Na may be appropriate for sodic, free-draining soils in areas with high rainfall, or on irrigated land. Key words: Gypsum requirement, salt contamination, sodium adsorbtion ratio, electrical conductivity, formation water
Soil solution pH measurements using in-line chambers with tension lysimeters
Authors: Elberling Bo , Jakobsen Bjarne H.
Published: April 2011

During soil water extraction, pH can change as a result of atmospheric gas exchange. The pH change is important for monitoring soil acidification and determination of mineralogic controls on the solution composition. As part of a global change programme in Greenland for monitoring long-term changes in Arctic soil solutions we observed that the pH of extracted soil solutions increased in the order of a half pH unit during traditional sampling and handling of the soil solution. CO2 degassing is often considered the most important factor causing such a pH increase. Thus, traditional as well as in-line pH measurements were performed during the summers 1997 and 1998. The in-line method was designed to eliminate atmospheric contact with soil solutions prior to pH measurements. The time-dependent pH error was quantified based on laboratory experiments with soil solution under controlled temperatures and CO2 partial pressures. Equilibrium speciation modelling was used to predict pH values observed in the field and in the laboratory and the model was found to reproduce the observations well. We conclude that traditional pH measurements on extracted soil solutions in the pH range from 5 to 7 are not appropriate for detailed pH measurements due to errors associated with CO2 degassing. In-line measurements provide more accurate measurement necessary for detailed studies on soil acidification dynamics. Key words: pH, carbon dioxide degassing, soil solution, tension lysimeter, arctic soil
CH4 fluxes and soil CH4 concentration following application of pig slurry for the 19th consecutive year
Authors: Rochette Philippe , Côté Denis
Published: April 2011

Agricultural soils often receive annual manure applications over long periods. The objective of this study was to describe the temporal variations of CH4 fluxes during the growing season in an agricultural soil receiving pig slurry for the 19th consecutive year. In mineral-fertilized control plots, CH4 fluxes were small and negative (uptake) during the experiment. Fluxes were also negative in the manured plots except during the first 4 d following slurry application when net emissions were measured. Despite their short duration, these post-application emissions were almost equivalent to the amount of CH4 taken up by these soils during the rest of the snow-free season. Key words: Geenhouse gases, static chamber, methane concentration in soils
Kinetics of phosphate adsorption on iron oxides formed under the influence of citrate
Authors: Liu C. , Huang P. M.
Published: April 2011

The influence of organic acids on the formation of Fe oxyhydroxides and oxides has been intensively studied. However, scant attention has been paid to the subsequent effect on surface chemistry of the Fe oxides formed. The kinetics and mechanisms of phosphate adsorption by the Fe oxides formed in the presence of citrate ligands at initial citrate/Fe(II) molar ratios (MR) of 0, 0.001, 0.01, and 0.1 were investigated using the conventional batch method. The adsorption studies were conducted at the initial phosphate concentration of 0.5 mM and pH 4.0 during the reaction period from 2 min to 56 h at 278, 288, 298, and 313 K. The results show that the phosphate adsorption followed multiple second-order kinetics and had two distinct rates in each reaction system. The amount, rate coefficient, activation energy and pre-exponential factor of phosphate adsorption by the Fe oxides formed greatly varied with their structural and surface properties. These properties, which included crystal structure, specific surface area, surface porosity, surface geometry, and point of zero salt effect (PZSE), differed significantly with the initial citrate/Fe(II) MR at which Fe oxides were formed. The results of this study have cast the light on the role of organic acids such as citric acid in influencing the surface chemistry of naturally occurring Fe oxides through fundamental structural perturbation and the impact on the dynamics of phosphate in terrestrial and aquatic environments. Key words: Kinetics, activation energy, pre-exponential factor, phosphate, iron oxides, citric acid, structural perturbation
Response of soil CO2 and O2 concentrations to forest soil compaction at the Long-term Soil Productivity sites in central British Columbia
Authors: Conlin T. S. S. , Driessche R. van den
Published: April 2011

The concentrations of soil CO2 and O2 at three Long-term Soil Productivity sites located in the Sub-Boreal Spruce biogeoclimatic zone of British Columbia, Canada, were monitored over several growing seasons. These sites were treated with three levels of soil compaction and three levels of organic material removal following forest harvest. Both compaction and depth had a significant effect upon soil CO2 concentrations and average values increased in response to deeper sampling and compaction. Removal of the forest floor and other organic materials had no significant effect upon soil CO2 and O2 concentrations. Mean soil CO2 concentrations varied from site to site and data collected over three growing seasons also showed that mean CO2 values in response to compaction fluctuated significantly from year to year. The high levels of soil CO2 observed in this study (up to 40 000 µ L L−1), especially in response to the compaction treatments, may have had a substantial effect upon whole plant carbon allocation as well as soil nutrition available to trees growing on the treated plots. Although mean soil O2 also decreased in response to compaction and sampling depth, these lower concentrations did not approach the levels required to influence plant growth. Key words: Soil, compaction, carbon dioxide, oxygen, long-term soil productivity
Soil enzymatic factors expressing the influence of land use, tillage system and texture on soil biochemical quality
Authors: Monreal C. M. , Bergstrom D. W.
Published: April 2011

We identified complexes of soil nutrient mineralising enzymes expressing the influence of land use, tillage system and texture on soil biochemical quality in production systems involving corn, soybean, wheat and oat. The activities of dehydrogenase, β-glucosidase, L-glutaminase, urease, alkaline phosphatase, and arylsulphatase were measured in 760 soil samples taken from the A horizon of uncultivated land and cultivated Gleysols and Luvisols cropped with conventional tillage (CT) and reduced tillage (RT) systems between 1994 and 1996.Discriminant analysis showed that an enzymatic decomposition factor captured 96% of the total dispersion in soil enzyme activity responding to type of land use and tillage system. The soil enzymes β-glucosidase, dehydrogenase and L-glutaminase contributed most to this factor and were sensitive indicators for assessing the health of microbial mineralisation processes of the C and N cycles. Two biochemical factors expressed the influence of texture on soil enzyme activity. The first, a soil organic C and N decomposition factor captured 68% of the dispersion in enzyme activities was influenced mostly by β-glucosidase and dehydrogenase. The second factor, which captured 32% of the dispersion in enzyme activity, was influenced mostly by arylsulphatase and denotes the effects of texture on a pool generally considered to be extracellular in nature. Cluster analysis helped define seven levels of soil enzyme activity ranging from very low (mostly in soils cropped with CT) to very high [mostly in uncultivated (UC) land and soils cropped with RT]. The identification of key enzymatic factors and the definition of seven levels of enzyme activity serve as a basis for developing quantitative systems monitoring the impact of crop production systems on soil enzymes having specific ecological functions in agricultural land. Key words: Soil enzymes, tillage, land use, texture, dehydrogenase, β-glucosidase, glutaminase
Effect of pipeline installation on crop yield and some biological properties of boreal soils
Authors: Soon Y. K. , Rice W. A. , Arshad M. A. , Mills P.
Published: April 2011

Pipeline construction on the Grey soils of the Canadian boreal plains, which have a thin Ah horizon, could have considerable impact on their properties and productivity. This study was conducted because the effects of pipeline installation on crop yield and biological properties of these soils have not been well-documented. Soil was sampled from a Grey Luvisol and a Dark Grey Solod prior to pipeline construction in 1991, and in each of the following 3 yr. The right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic; a trench where the pipeline was buried; and a pile (or spoil) area where soil was stockpiled during construction. The RoW was cropped to barley (Hordeum vulgare L.) in 1992 through 1994. Barley yield was low in 1992 (830–1120 kg ha−1), and near average (2050–3290 kg ha−1) in 1993 and 1994. Except for low shoot P concentration (1.1–1.3 mg g−1) in 1992, macronutrient concentrations (N, P and K) in barley tissues were within normal ranges. Soil organic carbon was reduced by 12–28% in all RoW areas in 1993 and 1994. Soil total N was reduced by 29–49% in all RoWs in 1992 and increased slightly from those levels in 1993 and 1994. Pipeline construction affected soil microbial biomass carbon (MBC) in the three RoW areas differently, and the effect was not consistent from year to year. However, the average level of MBC was not adversely impacted. In 1994, soil phosphatase activity in the RoW zones tended to be lower as compared to pre-pipeline installation, particularly in the pile area of the Dark Grey Solod. It is concluded that although some soil biological properties were degraded by pipeline construction, and barley yield was reduced in 1992, crop production in the following 2 yr was not significantly affected. Key words: Barley, carbon, microbial biomass, nitrogen, phosphatase, pipeline
Soil quality and productivity responses to simulated erosion and restorative amendments
Authors: Larney Francis J. , Janzen H. Henry , Olson Barry M. , Lindwall C. Wayne
Published: April 2011

There is little quantitative information on the interrelatedness of soil erosion, soil quality and soil productivity. A simulated erosion approach was used to quantify erosion and amendment effects on soil quality and subsequent productivity at four southern Alberta sites. Zero, 5, 10, 15 and 20 cm of topsoil were removed (cuts) at each site and subplots were amended with N + P fertilizer, 5 cm topsoil, 70 Mg ha−1 cattle manure or left unamended. Wheat (Triticum aestivum L.) yields in the 2-yr study on the non-amended check plots showed significant correlations with organic C at three of the four sites, and extractable P and inorganic C at all four sites. While manure was the best amendment for enhancing soil productivity, the magnitude of its effect depended on the organic C content of the recipient soil. At an organic C content of 8 g kg−1 on the Lethbridge Dryland site, manure addition increased crop yield by 1.75 Mg ha−1, compared with only 0.27 Mg ha−1 at an organic C content of 15 g kg−1. Our results affirm the benefits of soil management practices that reduce erosion risk, preserve soil quality and sustain productivity. Key words: Soil quality, soil productivity, erosion, manure, topsoil, wheat
Field study of the chemical characterization of the upper ocean surface using various samplers
Authors: Momzikoff André , Brinis Anissa , Dallot Serge , Gondry Geneviève , Saliot Alain , Lebaron Philippe
Published: April 2011

The sea surface microlayer (SML) is the seawater layer (about 100 µm thick) located at the air‐ocean interface, usually enriched in organic and inorganic matter compared to the underlying water (UW) sampled between 5 cm and 50 cm depth. This article is aimed at providing novel data for a better quantification of the SML enrichment and knowledge of associated processes. First, the mean 1 to 100 cm depth profile for dissolved total carbohydrates (DTCHO) established from a set of 10 stations in coastal northwestern Mediterranean waters (off Barcelona and Banyuls‐sur‐mer) indicates that (1) this layer is not necessarily homogeneous as generally admitted and (2) an exploratory survey is needed before undertaking an extensive sampling, to determine the most appropriate depth for sampling UW. Second, two samplers, glass plate (GP) and metal screen (MS), are compared for their ability to collect several classes of biomolecules at the first 50 µm and 440 µm layers below the interface, respectively. GP is shown to collect more efficiently (1) hydrophobic amino acids and phytoplanktonderived detrital matter, as shown by statistical results on a set of eight stations, and (2) fatty acids originating from bacteria and continental higher plants (inferred from a lower number of stations). Thus, it is well adapted for studying interactions between ocean, atmosphere, and continent. On the contrary, MS is better adapted for recovering phytoplankton organisms, as shown by data for chlorophyll a, pheophytin a, and unsaturated fatty acids. DTCHO are equally sampled by GP and MS.
Correcting for slow platform movement in deep‐water ADCP measurements
Authors: Pálmarsson Sveinn Ó. , Steissberg Todd E. , Schladow S. Geoffrey
Published: April 2011

When boat‐mounted acoustic Doppler current profiler (ADCP) velocity measurements are taken in deep water where bottom‐tracking capability no longer exists, navigational data via the Differential Global Positioning System (DGPS) are commonly collected to correct for the boat's contribution to the recorded ADCP velocity. The boat's cruise speed and the desired averaging interval for the water velocity are often great enough for navigational errors to become insignificant contributors to the uncertainty of the resulting water velocity. When the boat or other measurement platform is nearly stationary, navigational errors become significant and lead to an incorrect water velocity when navigational corrections are applied. Furthermore, when the water current is on the same order of magnitude as the slowly moving boat, the boat movement may not be easily distinguished from the fluid velocity. Factors that affect the quality of DGPS navigational estimates include the number of available satellites and their geometric properties in respect to one another. Here we present a method to correct the navigational velocity by developing criteria for geometric properties of the satellites, thus providing more accurate estimates of the water velocity. Assessment of the method indicates that less temporal averaging of the water velocity is needed to obtain a given uncertainty than when the cleaning procedure is not applied. This is an important property for many applications that often require relatively short temporal intervals, such as particle dispersion studies and the investigation of high‐frequency internal waves.
A new method for three‐dimensional visualization and quantification of biogenic structures in aquatic sediments using axial tomodensitometry
Authors: Dufour Suzanne C. , Desrosiers Gaston , Long Bernard , Lajeunesse Patrick , Gagnoud Marie , Labrie Jacques , Archambault Philippe , Stora Georges
Published: April 2011

Biogenic structures formed by the activity of macro‐ and meiobenthic organisms exert a great influence on the physical, chemical, and biological properties of sediments. Although bioturbation processes are recognized as ecologically important, the characterization and quantification of biogenic structures produced by benthic organisms remain difficult. Several techniques (e.g., resin casting, X‐radiography) were previously used to quantify these structures. However, due to a lack of definition, entire burrows, including fine structures created by meiobenthic and small macrobenthic species, could not be identified with precision. Here, we show how axial tomodensitometry (CT scan) can be used to visualize biogenic structures and organic matter in three dimensions with high resolution. Further, a simple method for calculating the space occupied by biogenic structures at given depths is developed, based on comparisons of the densities of biogenic structures with those of surrounding sediments. Other potential uses of the CT scan technique in studying benthic ecology are discussed.
Uncovering hidden species: hatching diapausing eggs for the analysis of cladoceran species richness
Authors: Vandekerkhove Jochen , Declerck Steven , Brendonck Luc , Conde‐Porcuna José Maria , Jeppesen Erik , Johansson Liselotte Sander , De Meester Luc
Published: April 2011

Effective methods for the detection of species are highly needed in biodiversity research. The assessment of richness is especially difficult for short‐lived aquatic organisms, like plankton. Because of the high degree of spatial and temporal variation in plankton community composition, the compilation of complete plankton species lists requires intensive sampling programs. Many large‐scale studies on planktonic organisms are based on single occasion samplings and inevitably fail to detect a substantial fraction of the species. In the present study, we assessed species richness of Cladocera (Branchiopoda, Crustacea) in 88 European lakes by repeated sampling of the active communities and by an alternative method based on the hatching of diapausing eggs from the lake sediments. Identification of hatchlings obtained from egg bank samples enabled the detection of about twice as many cladoceran species than identification of an equal number of individuals retrieved from active community samples. Loglinear analyses revealed a strong species by method interaction, suggesting that both methods are highly complementary and should preferably be applied in combination. Some species were underrepresented in the active community samples, probably because of the lack of spatial and temporal integration in these samples. Other species were underrepresented in the hatching assemblages as a result of species‐specific propensities to produce diapausing eggs or hatch from such eggs.
New applications of a biogenic silica deposition fluorophore in the study of oceanic diatoms
Authors: Leblanc Karine , Hutchins David A.
Published: April 2011

Silicon (Si) availability is known to be one of the main factors controlling the productivity and distribution of diatoms (Dugdale et al. 1995), but current chemical and microscopic methods do not allow discrimination of the key species responsible for Si biomineralization in mixed natural diatom assemblages. In 2001, new insights into biological silicification became available when studies with diatom cultures established that PDMPO [2‐(4‐pyridyl)‐5{[4‐dimethylaminoethyl‐aminocarbamoyl)‐methoxy]phenyl}oxazole] selectively binds to polymerizing silica and emits an intense fluorescence under ultraviolet (UV) excitation wherever newly formed Si is deposited (Shimizu et al. 2001). Here, we focus on adapting the PDMPO method to the study of Si use in natural diatom communities, including identification of individual cells carrying out new Si deposition. Experiments determined a simple and reproducible way to label actively silicifying diatoms, to preserve stained samples and identified the best optical tools to visualize the fluorescence properties of Si‐bound PDMPO. The application of confocal multiphoton microscopy to the PDMPO method revealed unprecedented high‐resolution three‐dimensional (3D) imaging of new Si deposition within diatom cells, which can be used to study biogenic silica deposition in relation to the cell cycle. The quantitative aspects of this method were further explored and resulted in a protocol allowing simultaneous measurement of newly deposited biogenic silica and PDMPO incorporation in the same sample. This aspect was successfully tested on both cultures and field samples. Toxicity assays were also run on a mixed natural diatom community to ensure that the probe presented no deleterious effect on diatom growth, biogenic silica deposition, or silicic acid uptake rates over 24 h incubations and at the recommended concentration. There is also great potential for a better understanding of the biogeochemistry of Si in diatoms through coupling of this method to other quantifying tools, such as UV flow cytometry and image analysis.
Effects of sediment storage conditions on pigment analyses
Authors: Reuss Nina , Conley Daniel J.
Published: April 2011

Sediment pigments as an indicator of water column and benthic processes have become widely used during the last decades. However, the effect of different storage and handling conditions on the accuracy of sediment pigment analyses has not been adequately evaluated. This can potentially make comparisons between studies difficult and, at worst, call into question the validity of some studies. Even though sediment pigment studies often rely on relative changes of individual pigments with depth, the effect of storage and handling is a critical consideration in any investigation. Based on testing of a number of different protocols, this study recommends that all sediment samples should be frozen at −20°C or colder as soon as possible after sampling and stored at this temperature without additional treatment (e.g., freeze‐drying) until just before analysis of pigments. Freezing at a lower temperature than −20°C or flushing with nitrogen gas did not improve preservation. Our results showed that, if dictated by other proxy analyses, raw sediment can be stored at 3°C for up to 6 months, whereas freeze‐dried sediment should always be stored frozen. In addition, the use of an internal standard (for example, β‐apo‐8‐carotenal) for normalizing pigment concentrations is highly recommended as it significantly reduces variability between runs.
I Am Curious About Cannabis Edibles—What Should I Know?
Authors: Zhang Grace Y. , Incze Michael A.
Published: May 2024

This JAMA Internal Medicine Patient Page describes the advantages, risks, and safe use of cannabis edibles.
Mortality Risk Among Women With Premenstrual Disorders in Sweden
Authors: Opatowski Marion , Valdimarsdóttir Unnur Anna , Oberg Anna Sara , Bertone-Johnson Elizabeth R. , Lu Donghao
Published: May 2024

Importance

Premenstrual disorders (PMDs) adversely affect the quality of life of millions of women worldwide, yet research on the long-term consequences of PMDs is limited, and the risk of mortality has not been explored.

Objective

To estimate the associations of PMDs with overall and cause-specific mortality.

Design, Setting, and Participants

This nationwide, population-based, matched cohort study used data from population and health registers in Sweden. Participants included women of reproductive age with a first diagnosis of PMDs between January 1, 2001, and December 31, 2018. Data analysis was performed from September 2022 to April 2023.

Exposures

PMDs were identified through inpatient and outpatient diagnoses and drug dispensing.

Main Outcomes and Measures

Dates of death and underlying causes were ascertained from the National Cause of Death Register. Conditional Cox regression was used to estimate the hazard ratios (HRs) of overall and cause-specific death (eg, death due to natural or nonnatural cause, suicide, or cardiovascular events), adjusting for age, socioeconomic status, and somatic and psychiatric comorbidities; in a separate sibling comparison, models were also adjusted for all factors that sisters share.

Results

A total of 67 748 women with clinically diagnosed PMDs and 338 740 matched unaffected women were included, for a total of 406 488 women. Women with PMDs received a diagnosis at a mean (SD) age of 35.8 (8.2) years. During a mean (SD) follow-up of 6.2 (4.6) years (range, 1-18 years), 367 deaths were observed among women with PMDs (rate, 8.4 deaths per 10 000 person-years; 95% CI, 7.6-9.3 deaths per 10 000 person-years), and 1958 deaths were observed among women without PMDs (rate, 9.1 deaths per 10 000 person-years; 95% CI, 8.7-9.6 deaths per 10 000 person-years). Compared with unaffected women, women with PMDs had increased risk of death due to nonnatural causes (HR, 1.59; 95% CI, 1.25-2.04), particularly suicide (HR, 1.92; 95% CI, 1.43-2.60), but they did not have increased risk of overall mortality (adjusted HR, 0.91; 95% CI, 0.82-1.02). Notably, women who received a diagnosis before the age of 25 years experienced higher all-cause mortality (HR, 2.51; 95% CI, 1.42-4.42) and death from both suicide (HR, 3.84; 95% CI, 1.18-12.45) and natural causes (HR, 2.59; 95% CI, 1.21-5.54).

Conclusions and Relevance

The findings of this matched cohort study suggest that women with PMDs are not at increased risk of early death overall. However, the risk was elevated among young women and for death by suicide. This supports the importance of careful follow-up for young patients and highlights the need to develop suicide prevention strategies for all women with PMDs.
Patterns of Adverse Childhood Experiences and Neurocognitive Development
Authors: Yu Jing , Haynie Denise L. , Gilman Stephen E.
Published: May 2024

Importance

Early life adversity is associated with higher risk of many adult health problems, including mental illness, substance abuse, suicide attempt, and chronic diseases. Many previous studies investigated adversities one at a time or investigated the health toll associated with the cumulative number of adversities.

Objective

To examine the co-occurrence of adversities among children and how specific patterns of adversities are associated with neurocognitive development.

Design, Setting, and Participants

This cohort study used data from the Collaborative Perinatal Project (CPP), which enrolled a national sample of women during pregnancy and followed their offspring to ages 7 to 8 years, between 1959 and 1974. The CPP was a community-based study conducted in 12 US medical centers. The CPP sample was ascertained through prenatal clinics and is diverse with respect to race and socioeconomic status. Data analysis was performed from August 2023 to March 2024.

Exposures

A latent class analysis was conducted of 12 adverse childhood experiences that occurred between birth and 7 years to identify common patterns of childhood adversities.

Main Outcomes and Measures

Five neurocognitive tests were used to measure children’s visual-motor, sensory-motor, auditory-vocal, intelligence quotient, and academic skills.

Results

The analysis sample included 49 853 offspring (25 226 boys [50.6%]); 24 436 children (49.0%) had low probability of experiencing any adversity, whereas the remaining half were classified into 5 groups reflecting distinct patterns of childhood adversities: parental harshness and neglect, 1625 children (3.3%); parental separation and poverty, 8731 children (17.5%); family instability, 3655 children (7.3%); family loss, instability, and poverty, 1505 children (3.0%); and crowded housing and poverty, 9901 children (19.9%). Children in 4 of these groups had lower neurocognitive scores than children with a low probability of experiencing adversity, with standardized mean differences ranging from −0.07 (95% CI, −0.11 to −0.03) to −0.86 (95% CI, −1.06 to −0.65).

Conclusions and Relevance

These findings suggest that adverse childhood experiences are associated with deficits in children’s neurocognitive functions. It is important to understand the complexity in children’s exposure to adversity and the resulting developmental consequences, as well as the underlying mechanisms, to help support children exposed to adversity and foster healthier and resilient trajectories of development.