bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of heterocyclic N compounds in whole soils using N-XANES spectroscopy
Authors: Jokic A. , Cutler J. N. , Anderson D. W. , Walley F. L.
Published: April 2011

The nitrogen (N) cycle is second in importance only to the carbon (C) cycle in natural ecosystems. However, the origin and nature of approximately one-third of total soil N remains poorly understood. We used N-XANES (X-ray absorption near edge structure) spectroscopy, a sensitive, non-destructive synchrotron-based analytical technique, to determine the organic N structures in selected Gleysolic soils of Saskatchewan. Initial results indicate the presence of amide structures and heterocyclic N compounds, which are significant in understanding the transformation of organic N moieties in the soil, both in terms of sources of bio-available N and long-term storage. Key words: Unknown N, amides, heterocyclic N compounds, wetland soils, N-XANES spectroscopy
Digital elevation modelling of soil type and drainage within small forested catchments
Authors: Case Bradley S. , Meng Fan-Rui , Arp Paul A.
Published: April 2011

This paper deals with predicting flow accumulation, drainage class, and soil and vegetation type within small headwater catchments (<20 ha) of two contrasting forested areas in northern New Brunswick, Canada, based on digital elevation modelling. A digital elevation model (DEM), with a point sampling resolution of about 75 m, was used to derive local flow accumulation and slope gradients. These calculations were then compared with direct field mapping of flow accumulation and slope gradients, involving on-site tracking of watershed boundaries, ridges, hummocks, depressions, gullies, and stream channels. In general, the resulting DEM-derived and field-assessed flow accumulation values did not differ statistically from each other. Subsequently, these values were analyzed as potential predictors for soil wetness, drainage, and soil and vegetation type as determined for 77 small forest plots, all scattered throughout the catchments at locations of increasing flow accumulation. In this analysis, the field-assessed flow accumulation values were found to be better predictors than the DEM-derived values . It is suggested that the DEM-derived predictions would be much enhanced by an increased DEM resolution, and that this increase would lead to particularly reliable estimates for local soil wetness, drainage, and soil and vegetation type in catchments with low substrate permeability. Key words: Flow accumulation, soil wetness index, soil taxonomic units, soil drainage, soil permeability, digital elevation model
Fertilizer response of barley grain in south and central Alberta
Authors: McKenzie R. H. , Middleton A. B. , Hall L. , DeMulder J. , Bremer E.
Published: April 2011

The rate of N fertilizer application is among the most critical decisions for barley (Hordeum vulgare L.) grain production because of its large impact on grain yield, protein content and input cost. A field study was conducted to determine the optimum rate of N fertilizer for a range of barley cultivars in south and central Alberta. Experiments were conducted at 20 sites over 3 yr (1997 to 1999). Nitrogen fertilizer was applied at 0, 40, 80, 120, and 160 kg N ha-1 to 10 cultivars. Grain yields were highest for the two semi-dwarf cultivars (CDC Earl and Kasota) and three of the five general-purpose cultivars (AC Harper, AC Lacombe, Leduc) (high-yielding cultivars) and least for the hulless cultivars (Falcon and Phoenix). Grain yields of the two remaining general-purpose cultivars (CDC Fleet and Seebe) and the malt cultivar (Harrington) were intermediate (medium-yielding cultivars). The economic optimum rate of N fertilizer (NFopt) for high-yielding cultivars was 14 kg N ha-1 higher than for medium-yielding cultivars and 24 kg N ha-1 higher than for hulless cultivars. Maximum grain yields for all cultivars were obtained when the ratio of available N (fertilizer + soil-derived N) to maximum grain yield exceeded ~28 kg N Mg-1. Soil-derived N was highly correlated with both pre-seeding soil NO3-N and growing season precipitation. Protein concentrations were highest for hulless cultivars and least for high-yielding cultivars, and increased linearly with increasing N availability. Barley responses to P, K, S and micronutrients were also tested in this study and showed similar responses to earlier studies. The optimum rate of N fertilizer for barley in this study was obtained when the ratio of available N (fertilizer + soil-derived N) to maximum grain yield was 25 to 30 kg N Mg-1. Key words: Hordeum vulgare, nitrogen fertilizer use efficiency, malting barley, protein
Nitrogen mineralization processes of soils from natural saline-alkalined wetlands, Xianghai National Nature Reserve, China
Authors: Bai Junhong , Ouyang Hua , Deng Wei , Wang Qinggai , Chen Hui , Zhou Caiping
Published: April 2011

Nitrogen mineralization was evaluated using a 12-wk anaerobic incubation at 30°C in two wetland soils located in Xianghai National Nature Reserve, China. The Erbaifangzi wetland is an open wetland because it hydrologically connected to the surrounding ecosystem, whereas the Fulaowenpao wetland is a closed wetland, which is not hydrologically connected. Nitrogen mineralization was fitted to an effective cumulative temperature model. Nitrogen mineralization increased gradually with increases in the cumulative temperature and decreased with depth in the soil profile. Nitrogen mineralization was positively correlated with total N (TN) or soil organic matter (SOM), but not with soil pH. Basal N mineralization was found to be greater in the Fulaowenpao wetland (0 .314g N m-2 d-1) than the Erbaifangzi wetland (0.230 g N m-2 d-1). Key words: Saline-alkalined wetland; marsh soils; nitrogen mineralization; anaerobic incubation; the effective cumulative temperature model
Effect of repeated manure application on potassium, calcium and magnesium in soil and cereal crops in Saskatchewan
Authors: Qian P. , Schoenau J J , King T. , Japp M.
Published: April 2011

Increasing use of animal manures in Saskatchewan requires information on the effect of manure addition on the availability of soil K, Ca and Mg and their concentrations in plant tissue. To address these issues, we examined the effects of repeated application of liquid swine and solid cattle manure at low and high rates on extractable K, Ca and Mg in soils from three different long-term field trials in Saskatchewan, and on plant K, Ca and Mg concentrations in cereal straw grown on the soils. After 5 to 7 yr of manure application, extractable potassium in the soils was significantly increased, while extractable Ca and Mg tended to remain similar, or was decreased with swine manure addition. In the cereal straw, concentrations of K, Ca, and Mg were all increased by repeated swine manure application, such that there was no significant increase in the K/(Ca + Mg) ratio. However, the K/(Ca + Mg) ratio in the cereal straw grown on soil amended with the high rate of cattle manure was increased. These findings suggest that increased risk of tetany potential from manure application would mainly be associated with excessive application rates of cattle manure in these soils, but should be monitored in feeds grown on all manured soils.Key words:Soil extractable K, Ca, Mg and Na; cereal K, Ca and Mg concentrations, K/(Ca + Mg) ratio, tetany potential, urea, swine manure, cattle manure
Soil microbial biomass, functional diversity and crop yields following application of cattle manure, hog manure and inorganic fertilizers
Authors: Lupwayi N. Z. , Lea T. , Beaudoin J. L. , Clayton G. W.
Published: April 2011

Soil biological properties can be significantly impacted by land management. Cattle manure, hog manure or inorganic fertilizers were applied annually or triennially in field trials conducted at two sites over 3 yr. A control treatment without manure or fertilizer was also included. Canola (Brassica napus) was grown in year 1, hulless barley (Hordeum vulgare) in year 2, and wheat (Triticum aestivum) in year 3. Where effects were significant, cattle manure increased soil microbial biomass C (MBC) by 26% to three-fold, hog manure by 31% to two-fold, and inorganic fertilizers reduced MBC by 20–64%. Similar effects, except the reduction by inorganic fertilizers, were observed for functional diversity of soil bacteria (Shannon index, H′ ). At one site, where crop yields were recorded for 3 yr, hog manure produced greater grain yields (75% increase over the control) than the rest of the treatments (49% increase by cattle manure) in year 1, but cattle manure out-yielded other treatments thereafter, when it increased yields by 25–50%. Cattle manure out-yielded other treatments even when nutrient uptake from inorganic fertilizers was the highest, implying that other factors also influenced crop yields. At the other site, crop yields were recorded only in year 1, and all soil amendments increased canola yields about three-fold relative to the control. Frequency of application usually had no effects on MBC or H′, but the triennial application rate of inorganic fertilizers or hog manure produced lower crop yields than annual applications in year 1. Key words: Functional diversity, Gray Luvisol, manure quality, NPK fertilizers, soil microbial communities
Estimate of soil erosion on cultivated soils using 137Cs measurements and calibration models: A case study from Nakhla watershed, Morocco
Authors: Hassouni K. , Bouhlassa S.
Published: April 2011

Despite the seriousness of the erosion problem in the Nakhla watershed, there are still only limited data on the rates of soil loss on cultivated land on steep slopes. Thus, there is a need for more information for optimizing strategies for soil conservation. Recent concern over problems of soil degradation and the off-site impacts of accelerated erosion has highlighted the need for improved methods of estimating rates and patterns of soil erosion by water. In this paper, soil erosion and deposition rates have been studied using the 137Cs technique in upstream part in the Nakhla watershed on cultivated soils (Larbaa Beni Hassan area), which is known to suffer soil erosion. Multiple transect sampling was established parallel to the slope, and 137Cs inventories were determined for the sampling points. After establishing the local reference inventory (3073 Bq m-2), soil erosion and deposition rates were estimated using the 137Cs inventories on all the transects with three calibration models: proportional model (PM), mass balance model 1 (MBM1) and mass balance model 2 (MBM2). The magnitude of the soil erosion rates depends on many factors, including the location of sampling, the local topography, and the soil properties. Estimated soil erosion rates for the study area varied from 0.4 to 28.9 t ha-1 yr-1 using PM; from 0.5 to 66.9 t ha-1 yr-1 using MBM1; and from 0.4 to 56.4 t ha-1 yr-1 using MBM2. The deposition ranged, respectively, from 0.3 to 8.0 t ha-1 yr-1 for PM, from 0.4 to 14.5 t ha-1 yr-1 for MBM1, and from 0.3 to 11.5 t ha-1 yr-1 for MBM2. The sediment delivery ratio is about 98%. For one selected plot, L11, the erosion rates show a clear relationship with the range of slopes in its three different horizontal parts. Estimates of soil redistribution rates were interpolated by means of kriging, using Surfer 7.0 software. Two representative transects were selected to identify the contribution of tillage on 137Cs redistribution by using mass balance model 3. It is observed that the pattern of 137Cs redistribution is dominated by water erosion and that the contribution of tillage redistribution remain is smaller. Key words: 137Cs method, soil erosion, erosion rate, soil redistribution, conversion models
Carbon, ash and organic matter relationships for feedlot manures and composts
Authors: Larney Francis J. , Ellert Benjamin H. , Olson Andrew F.
Published: April 2011

Composting is increasingly recognized as a means of handling livestock manure. Using relationships derived from a dataset of >3000 samples representing the decay spectrum from raw manure to mature compost (from unpaved feedlot pens bedded with straw or wood residuals) we propose that measurement of either total carbon or ash content is sufficient to estimate carbon, organic matter and dry matter mass changes during composting of beef feedlot manure. Key words: Compost, carbon, ash content, feedlot manure
Using multivariate adaptive regression splines (MARS) to identify relationships between soil and corn (Zea mays L.) production properties
Authors: Turpin K. M. , Lapen D. R. , Gregorich E. G. , Topp G. C. , Edwards M. , McLaughlin N. B. , Curnoe W. E. , Robin M. J. L.
Published: April 2011

Over-application of agricultural fertilizers can contribute to degradation of surface water quality. Factors governing crop establishment and yield must be identified in order to efficiently manage N application rates in corn (Zea mays L.) production systems. Spatial data sets of corn establishment and grain yields, and soil physical and chemical parameters were obtained for two corn production systems on a poorly drained clay loam soil in eastern Ontario, Canada, during low yielding conditions in 2000. The multivariate adaptive regression splines (MARS) automated regression data mining method was used to determine the dominant factors affecting both crop establishment and yield from these data sets. The analysis using MARS suggests that soil water content and cone penetration resistance are more important than elevation and spring mineral soil N (NH4+ + NO3−) in predicting crop establishment and grain yield. The MARS approach proved to be a useful method for identifying relationships between potential yield-governing variables. It also helped elucidate potential cause and effect processes, and in so doing, helped identify areas within the field where soil physical parameters may have been more important than nutrients in governing corn yield. Key words: Mulitvariate adaptive regression splines, corn yield, cone penetration resistance, soil water content, soil N, topography
Pelletized organo-mineral fertilizer product as a nitrogen source for potato production
Authors: Zebarth B J , Chabot R. , Coulombe J. , Simard R R , Douheret J. , Tremblay N.
Published: April 2011

Replacement of mineral fertilizer with organo-mineral fertilizer products made with animal manures is one strategy for reducing the environmental impact of agricultural production. This study evaluated a pelletized organo-mineral fertilizer product with a nutrient analysis of approximately 7-4-4 produced from composted solid poultry, solid dairy and liquid hog manure as a N source for processing potato (Solanum tuberosum L.) production in Atlantic Canada. The availability of N in the organo-mineral fertilizer product was estimated, and tuber yield, size distribution and quality parameters and soil NO3-N content at harvest were compared at similar application rates of N as mineral or organo-mineral fertilizer. Field trials were conducted in 2000 to 2002 to compare different rates of mineral (0–200 kg N ha-1 as NH4NO3) or organo-mineral (0–3 t product ha-1) fertilizer band-applied at planting, followed by split applications of variable rates of mineral fertilizer. Apparent recovery of N from the mineral fertilizer, estimated as the slope of the regression of plant N accumulation against the rate of N applied and expressed as a percentage, was 65, 33 and 78% in 2000, 2001 and 2002, respectively. Apparent recovery of total N in the organo-mineral fertilizer was 6 0 , 26 and 57% in 2000, 2001 and 2002, respectively. Fertilizer N equivalency of the total N in the organo-mineral fertilizer, estimated as the apparent recovery of organo-mineral fertilizer N divided by apparent recovery of mineral fertilizer N and expressed as a percentage, was 92, 79 and 73% in 2000, 2001 and 2002, respectively. Application of equivalent rates of N as mineral or organo-mineral fertilizer at planting generally resulted in comparable values of tuber yield, size distribution and quality parameters and soil NO3-N content at tuber harvest. We recommend application of 1.5 t ha-1 of organo-mineral fertilizer at planting, with additional mineral fertilizer applied as a split application if warranted, as a suitable N source for processing potato production. Key words: Solanum tuberosum, yield, tuber size, tuber nitrate, tuber specific gravity, soil nitrate
Quantifying spatial uncertainty of soil organic matter content using conditional sequential simulations: A case study in Emilia Romagna Plain (Northern Italy)
Authors: Ungaro F. , Calzolari C. , Tarocco P. , Giapponesi A. , Sarno G.
Published: April 2011

The development and the application of soil organic matter (SOM) indices have recently received much attention by soil scientists. Inventories of soil carbon for modeling, monitoring and mapping programs are currently being realized at different scales, ranging from global to national, to sub-regional, in order to provide operative tools for land use planners and decision makers. This paper presents the results of a research project on the estimation of SOM spatial distribution in the Emilia Romagna Plain, focusing on the effect of spatial uncertainty on the development and mapping of SOM content. In this work, the analysis has been carried out adopting and comparing two distinct geostatistical approaches to assess the uncertainty regarding the content of SOM jointly over several locations on a regular grid: a parametric approach based on the assumption of a multi-gaussian data distribution and a non-parametric approach based on the transformation of data in indicator variables through selection of operatively significant sill values. Two different SOM content class maps are presented with associated uncertainty. The two maps, although almost coincident in terms of SOM content class distribution in the study area, show a significantly different overall degree of spatial uncertainty, with the non-parametric approach based map showing the highest overall accuracy. Key words: Soil organic matter inventory, spatial variability, stochastic simulations, indicators uncertainty
Modelling the evolution of regional carbon stocks in Belgian cropland soils
Authors: Wesemael Bas van , Caroline Roelandt Suzanna Lettens, , Orshoven Jos Van
Published: April 2011

In long-term experiments, it has been demonstrated that management of cropland influences the evolution of soil organic carbon (SOC ) stocks. National inventories of SOC stocks in Belgium have recently been compiled, and show an evolution of SOC stocks of arable land from 1960 to 1990 and 2000. In order to analyse the driving forces of these changes, we concentrate on the SOC evolution in the soil associations of three of the 13 Belgian agricultural regions (Dunes-Polders, Loam belt and Condroz). The small confidence limits around the mean SOC values within some soil associations (0.412.7 t C ha-1) allow us to compare the observed values with the results of the RothC soil carbon model and hence quantify the most important driving forces. After estimating the local parameters by fitting the model to SOC values from a longterm experiment in central Belgium, the model was run from 1960 to 2000 for typical soil profiles of soil associations in the three agricultural regions. The main factors inducing changes in SOC stocks are the increase in plough depth as a result of continued mechanisation in the 1960s and the sustained input of organic amendments in the form of farmyard manure and slurry. In contrast to earlier publications on CO2 emissions from agricultural soils, the model did not predict a decrease in SOC stocks for the period 1990-2000. A slight increase was observed, although this increase is not significant for most soil associations. The comparison between modelled and observed SOC data at two time slices allows the uncertainty of the model results to be estimated. This uncertainty ranges from 7.5 to 14.4% of the SOC stock and is in the same order of magnitude as the uncertainty around SOC modelling for the long-term experiments both in Belgium and elsewhere in Europe. The organic matter concentration in the topsoil, an indicator for soil quality, was in the range of 1.5 to 3.3%. Organic matter content increased in the Dunes-Polders and decreased in the Loam belt and the Condroz from 1960 to 2000. Many soils in the Loam belt are now close to the critical level of 2% under which the soils are vulnerable to compaction and erosion. Key words: Soil organic carbon, regional modelling, soil-land-unit, Belgium
Soil organic carbon as an indicator of environmental quality at the national scale: Inventory monitoring methods and policy relevance
Authors: Ogle Stephen M. , Paustian Keith
Published: April 2011

Soil organic carbon (SOC) storage is an indicator of environmental quality for mineral soils because of the influence that organic matter has on key functional properties, such as fertility, soil structure and water relations. Historically, agricultural management has caused large losses of SOC relative to native ecosystems, leading to degradation. However, new technologies and conservation practices have been developed during the past few decades that can enhance SOC storage, and thus improve environmental quality. Our objective was to describe a national inventory procedure to estimate SOC storage for purposes of monitoring environmental quality. The major steps in this procedure include: (1) model selection/development, (2) model verification, (3) identification of model input data, (4) uncertainty assessment, (5) model implementation, and (6) validation of results. Applying this approach with a simple C accounting method, the upper 30 cm of US agricultural soils were estimated to have accumulated 10.8 Tg C yr-1 between 1982 and 1997, with an uncertainty of ± 40%. A simple index was developed to relate estimated SOC stocks to the potential amounts under native conditions and conventional agricultural management. An index value of 0% on the proposed scale would be equivalent to the SOC under conventional a gricultural use, while an index value of 100% would be equivalent to native levels. With an estimated 1997 stock of 22 400 Tg C, the index value for US agricultural soils was about 60%. Using this inventory procedure, environmental issues related to soil, water and air quality could be informed by SOC in combination with other key indicators, in addition to using the inventory for evaluating sustainability of agricultural lands for food and fiber production. Key words: Natural resource inventory, environmental quality indicators, soil organic carbon, land use and management, national inventory, Organization for Economic Co-operation and Develop
Secondary mineral formation in the White River tephra in grassland and forest soils in central Yukon Territory
Authors: Strickland A. J. , Arocena J. M. , Sanborn P. , Smith C. A. S.
Published: April 2011

Selected surface horizons of grassland and forest soils formed under a cold, semi-arid climate were investigated to evaluate the formation of secondary minerals within the White River tephra, a Late Holocene rhyolitic tephra (~115014C yr BP) veneer that overlies the soil landscapes of central Yukon. Concentrations of extractable Fe (< 0.48%), Al (< 0.26%) and Si (< 0.082%) concentrations in surface tephra-contaning horizons of grassland and forest pedons are low. The high amount of exchangeable calcium in grassland soils is likely due to cycling by vegetation and perhaps, aeolian inputs of Ca and Mg carbonates. Al is incorporated into Al-humus complexes in forest pedons and allophane in grassland pedons. Allophane content is low (< 0.56%) in all soils as is ferrihydrite (< 0.34%). Mineral composition of the sand fraction from tephra horizons is dominated by volcanic glass, plagioclase feldspars, amphiboles, epidote, pyroxenes and very limited quantities of quartz and primary Fe oxides. Chlorite and an expanding phyllosilicate were also detected and are assumed to be of detrital origin. Clay mineralogy is dominated by volcanic glass, quartz, feldspars and minimal quantities of kaolinite and dehydrated halloysite in surficial horizons. Kaolinite is assumed to be of detrital origin while dehydrated halloysite is a product of a low leaching and dry environment where limited resilication occurs. Scanning electronmicroscopy (SEM) investigation indicates the presence of opaline silica in surface horizons from forest pedons which has likely formed due to freezing of the soil solution in combination with dehydration and resilication. Overall, the soil horizons formed within the veneer of White River tephra have experienced minimal weathering and very little silicate clay mineral development. Key words: Tephra, glass, Yukon, minerals (secondary), weathering
Soil oxygen within boreal forests across an age gradient
Authors: Fenton N. , Légaré S. , Bergeron Y. , Paré D.
Published: April 2011

Globally, soil anoxia and water table rise play a role in the development of peatlands from forests. Cited causes have included a diversity of internal and external mechanisms, including Sphagnum and feather mosses, hardpan development, and peatland expansion. The objectives of this study were to examine water table depth in black spruce stands of the Clay Belt of Quebec and Ontario, and to associate changes with potential stand scale causal factors (primarily biological). A methodological issue, the link between oxygen zone and water table, was also addressed. Within stands less than 100 yr post-fire, oxygen zone and water table position were only loosely related, and no other potential factors were significantly correlated. Across a chronosequence of stands, while oxygen zone thickness in the soil profile was relatively constant, its position relative to the mineral soil changed, as it rose from the mineral soil into the forest floor. Forest floor thickness was the dominant explanatory factor in oxygen zone position, suggesting that in these forests other postulated mechanisms are less important. At the landscape level, the movement of the oxygen zone into the forest floor has important consequences for the long-term productivity of this intensively exploited forest region. Key words: Water table, black spruce, paludification, forest floor, Clay Belt, Sphagnum
In-crop application effect of nitrogen fertilizer on grain protein concentration of spring wheat in the Canadian prairies
Authors: McKenzie R H , Bremer E. , Grant C A , Johnston A M , DeMulder J. , Middleton A B
Published: April 2011

Due to the price premium for high-protein wheat (Triticum aestivum L.), many producers are interested in the efficacy of in-crop application of low rates of N fertilizer for increasing grain protein concentration (GPC). We conducted field studies at 26 site-years in Alberta, Saskatchewan and Manitoba from 1998 to 2000 to determine if in-crop application (tillering, boot stage or anthesis) of N fertilizer [broadcast ammonium nitrate (AN) or foliar urea-ammonium-nitrate solution (UAN); 15 kg N ha-1] could economically increase GPC of a Canada Western Red Spring (CWRS) wheat cultivar (AC Barrie). Basal N fertilizer rates were 60 and 120 kg N ha-1. The average increase in GPC due to in-crop N application was 3 g kg-1. The increase in GPC was similar at basal N rates of 60 and 120 kg N ha-1. Broadcast AN and foliar-applied UAN were generally equally effective at increasing GPC, but were not more effective than application at the time of seeding. Late application tended to increase GPC more effectively than early application. The increase in GPC due to application of in-crop N was not economic at most sites in this study, but might be greater if applied under more N deficient conditions. Key words: Split N application, foliar, timing
Determination of exchangeable hydrogen ions in boreal shield soils of Quebec
Authors: Bélanger N. , MacDonald J D , Paré D. , Thiffault E. , Claveau Y. , Hendershot W H
Published: April 2011

An unbuffered BaCl2 extraction for determining effective cation exchange capacity (ECEC) and exchangeable cations is often used for acidic forest soils. However, the contribution of exchangeable H+ to ECEC cannot be assessed using this method as H+ in the extract may be produced/consumed in reactions with free Al3+ and Al-OH complexes, or H+ may be added to the extract via non-exchangeable sources. Fundamentally, any valid measure of ECEC must include some estimate of exchangeable H+ concentration or a demonstration that it is negligible. Unfortunately, this procedure is often neglected in forest soil studies. In this paper, we assessed the significance of the contribution of exchangeable H+ to ECEC for upper soil horizons of three sites of Quebec’s Boreal Shield subject to various disturbance types (i.e., recent harvest, fire and mature forest). We also investigated whether the linear relationships between exchangeable H+ concentrations and soil pH are robust enough to develop regression models capable of predicting exchangeable H+. Exchangeable H+ in the FH samples was higher than that in the podzolic B samples, but the amount of adsorbed H+ relative to ECEC was nevertheless significant in the podzolic B horizons. The general linear relationship (i.e., FH and podzolic B samples as a single data set) developed from soil pH in water explained close to 70% of the variability of log (H+/ECEC). The relationships between log (exchangeable H+) and pH in water in the FH samples were however superior (R2 ≥ 80), either for all sites, disturbance types and sampling strategies (e.g., proportions of F and H horizons in sample). The relationships developed for podzolic B samples alone were not as strong, but ECEC was used efficiently in combination with soil pH to increase prediction capabili ties (R2 ≥ 0.61). Key words: Boreal Shield forest soils, effective cation exchange capacity, exchangeable H+, fire, FH and podzolic B horizons, harvesting, prediction models, soil pH.
Predicting soil organic matter content in southwestern Ontario fields using imagery from high-resolution digital cameras
Authors: Gregory S D.L. , Lauzon J D , O’Halloran I P , Heck R J
Published: April 2011

The spatial pattern of soil organic matter (SOM) content may provide information for variable-rate fertilizer nitrogen recommendations, but often requires intensive soil sampling to be properly characterized. This study evaluated whether imagery of bare soils obtained using a high-resolution digital camera system may be used to predict SOM content in southwestern Ontario fields. Using the camera system, image intensity was measured in near-infrared (0.70–0.80 µm) and visible red (0.60–0.70 µm), green (0.50–0.60 µm), and blue (0.40–0.50 µm) wavebands underboth controlled and field conditions for soil samples representative of the range in SOM typically found in southwestern Ontario fields. Under controlled conditions, SOM content did not relate well to image intensity measured in any waveband when multiple soil types were used (r2 ≤ 0.39). Without multiple soil types, image intensity in all wavebands related to SOM content for soil samples taken from two of the sites (r2 ≥ 0.53 for both sites). Image intensity measured under field conditions related to SOM content for only one site (r2 ≥ 0.54 for all wavebands). Variability between SOM content and image intensity shown in this study is most likely attributed to the relative variability in SOM content and confounding factors such as surface residue. Key words: Soil organic matter, soil reflectance, high-resolution digital camera, aerial imagery
Core aeration of sand-based putting greens in the Lower Fraser Valley of British Columbia
Authors: Sorokovsky P. , Krzic M. , Novak M D
Published: April 2011

Core aeration, a management practice originally developed for soil-based putting greens, is still commonly used on sand-based greens. The study objective was to determine the effects of core aeration on soil properties of sand-based putting greens in the Lower Fraser Valley of British Columbia. The experiment was laid out as a randomized complete block design with three replications. The study treatments were regular management practices, including core aeration (CA) carried out in spring and late summer, and regular management practices, but no core aeration (NCA). Each core aeration event impacted 5% of the surface area. Treatments with and without core aeration had similar soil organic matter content, root weight density, and soil bulk density. The CA treatment was generally drier than NCA. Water infiltration was greater on CA than NCA, but only for 1 mo following core aeration. Core aeration generally reduced soil penetration resistance within the mat layer relative to treatment without this practice. On both treatments, soil penetration resistance consistently exceeded 4000 kPa below about 13 cm depth preventing deeper root growth. The limited benefits of the low-surface-area-impact core aeration on the maturing sand-based putting greens in a humid maritime climate suggest that this practice might not be worth doing (at a low surface area impact); however, additional, more detailed studies are needed to confirm this. Key words: Turf management, golf course management, soil penetration resistance, water infiltration
Carbon stock trends along forested peatland margins in central Saskatchewan
Authors: Bhatti J. S. , Errington R. C. , Bauer I. E. , Hurdle P. A.
Published: April 2011

Forested peatlands store significant amounts of soil carbon (C) compared with upland forests and are strongly influenced by climatic parameters. Carbon stocks at peatland margins, although likely to be most sensitive to changes in climate, have not been well quantified, making it difficult to predict their response to climate change. The purpose of this study was to characterize the physical environment and associated changes in C stocks across the forested margins of two boreal fens. Peat depth increased and water table depth decreased toward the peatland centre, and these parameters acted as the controlling environmental variables. Above-ground biomass C was primarily derived from tree biomass and decreased from upland to peatland, despite an opposite trend in understorey (herbaceous and shrubby) biomass stocks. Leaf area index was related to peat depth through a negative power function and increased linearly with above-ground tree biomass. Total ecosystem C increased from upland to peatland, with minimum and maximum values of 270 and 2100 Mg C ha-1, respectively, and was largely dominated by soil C stocks, even at the upland end of the gradient. Although numerous small trees toward the peatland interior might allow a rapid increase in tree biomass C with lowering water tables, it seems likely that this would be a limited response, overshadowed in the long term by declines in the more substantial soil C stocks. Key words: Peatlands, carbon stocks, biomass, soil, leaf area index, peat depth
Developing statistical models to estimate the carbon density of organic soils
Authors: Bauer Ilka E. , Bhatti Jagtar S. , Cash Kevin J. , Tarnocai Charles , Robinson Stephen D.
Published: April 2011

Carbon density is a key variable in assessments of local or regional soil carbon (C) stocks, but its direct measurement on large numbers of samples is both time-consuming and expensive. To assess whether the C density of organic soils can be inferred from other parameters, we examined the ability of field- (stratigraphic depth and material type) and lab- (bulk density and ash content) based variables to predict the C density of organic soil samples. Candidate models given three different levels of a priori information about samples were developed from data for continental western Canada and examined using Akaike’s information criterion (AIC). Models at each level were then used to predict profile-level C storage in cores from three different regions (continental western Canada, Ontario, and the Northwest Territories). In profiles from western Canada, predictions were unbiased, with mean prediction errors of 0–7% and local precision depending on the amount of a priori information available. Application of models to other regions yielded mixed results, probably reflecting both differences in site characteristics and classification/analytical methods used. Since these error sources are impossible to separate given available data, we recommend that models for C density prediction should be tailored to a given research question and region. The results suggest that simple, field-based variables are sufficient to predict C density for the purpose of regional surveys. To obtain accurate estimates at the profile level, bulk density (and ash or C content) have to be measured in the lab. Key words: Soil (organic), carbon density, bulk density, ash, organic matter, models (predictive)
Influence of climate change factors on carbon dynamics in northern forested peatlands
Authors: Trettin C. C. , Laiho R. , Minkkinen K. , Laine J.
Published: April 2011

Peatlands are carbon-accumulating wetland ecosystems, developed through an imbalance among organic matter production and decomposition processes. Soil saturation is the principal cause of anoxic conditions that constrain organic matter decay. Accordingly, changes in the hydrologic regime will affect the carbon (C) dynamics in forested peatlands. Our objective is to review ecological studies and experiments on managed peatlands that provide a basis for assessing the effects of an altered hydrology on C dynamics. We conclude that climate change influences will be mediated primarily through the hydrologic cycle. A lower water table resulting from altered precipitation patterns and increased atmospheric temperature may be expected to decrease soil CH4 and increase CO2 emissions from the peat surface. Correspondingly, the C balance in forested peatlands is also sensitive to management and restoration prescriptions. Increases in soil CO2 efflux do not necessarily equate with net losses from the soil C pool. While the fundamentals of the C balance in peatlands are well-established, the combined affects of global change stressors and management practices are best considered using process-based biogeochemical models. Long-term studies are needed both for validation and to provide a framework for longitudinal assessments of the peatland C cycle. Key words: Peatland, carbon cycle, methane, forest, wetland.
Decomposition, δ13C, and the “lignin paradox”
Authors: Preston C. M. , Trofymow J. A. , Flanagan L. B.
Published: April 2011

The natural abundance of 13C (δ13C) generally increases with decomposition of organic matter. This is contrary to the expected decrease, as lignin is hypothesized to accumulate relative to isotopically heavier cellulose. Our objective was to test the hypothesis that 13C depletion should be observed for gymnosperm logs that typically develop advanced brown-rot decay with high lignin content. With increasing lignin concentration [previously determined by nuclear magnetic resonance (NMR)], δ13C tended to become more negative for samples of Pseudotsuga menziesii, Tsuga heterophylla, Thuja plicata, and unidentified species from Coastal Forest Chronosequence sites of southern Vancouver Island. For a larger sample set without NMR analysis, δ13C was significantly more depleted for the highest decay classes, and total C was negatively correlated with δ13C, consistent with the higher total C of lignin than of cellulose. Relationships of total C and δ13C with density were much weaker. We discuss causes for the variability of δ13C in coarse woody debrisfrom these sites, and how the apparent paradox in the predicted change of δ13C with decomposition is largely due to the confusion of lignin, the biopolymer produced by higher plants, with the acid-unhydrolyzable residue (AUR) of the proximate analysis procedure commonly used to assess litter quality in decomposition studies. Key words: Coarse woody debris, decomposition, lignin, 13C NMR, δ13C, proximate analysis
Biosolids recycling: Nitrogen management and soil ecology
Authors: Cogger C G , Forge T A , Neilsen G H
Published: April 2011

Biosolids are municipal wastewater treatment solids that meet regulatory standards for land application. Most biosolids are a rich source of N, P, and micronutrients. Although the use of biosolids on food crops remains controversial in the public eye, decades of research have led to the development of regulations for the safe and beneficial use of biosolids in agriculture. Emerging areas of research include biosolids in commercial and home horticulture, the fate of pathogens and organics in biosolids, the use of biosolids in the remediation of contaminated sites, and biosolids effects on soil ecology. Nutrient management remains the most critical day-to-day issue for land application of biosolids. Recent research on plant-available nitrogen (PAN) in biosolids has found that N availability is similar over a range of biosolids processing types, and that growing-season climate is a key factor affecting available N. Regionally based predictions of PAN have been developed for the United States, and could be extended into Canada. Relatively little is known about the effects of biosolids applications on soil ecology, but soil nematodes offer an opportunity to evaluate the structure and function of the soil ecosystem following biosolids applications. We have studied responses of nematode communities to application of municipal biosolids and composts, in forage production systems and orchards. Both types of amendments increased the abundance of enrichment opportunists, for up to 3 yr after single applications. These data on the persistence of increased enrichment opportunists have provided insight into the longevity of amendment-induced enhancement of biological activity and nutrient cycling. Cumulative biosolids applications of 90 Mg ha-1 have caused reductions in abundance of pollutant-sensitive Dorylaimida. The extent to which this change is the result of metal or nutrient loading is unclear and deserves more detailed study. Key words: Biosolids, plant-available nitrogen, soil ecology, nematodes
Influence of tillage and liquid swine manure on productivity of a soybean-barley rotation and some properties of a fine sandy loam in Prince Edward Island
Authors: Carter M R , Campbell A J
Published: April 2011

Interactions between tillage management for manure incorporation and rate of manure application may influence crop productivity and soil properties. This study was conducted to evaluate the effect of liquid swine (Sus scrofa L.) manure (LSM) applied at three N rates (40, 80, 160 kg ha-1), compared with mineral N fertilizer, in a 2-yr barley (Hordeum vulgare L.)-soybean (Glycine max L. Merr.) rotation, incorporated by two tillage methods (chisel plough and disc), on crop yield and quality and some soil properties, especially C parameters. The LSM was applied every second year in the spring, prior to barley seeding. The study was conducted over a 5-yr period on a Charlottetown fine sandy loam (Orthic Humo-Ferric Podzol) in Prince Edward Island. The experimental design was a split-plot with four replicates. Soil samples (0–60 cm) were obtained at the termination of the study to determine residual effects of the LSM on soil properties. The two methods of LSM incorporation had no differential effect on crop response. Generally, increasing the application rate of LSM increased the barley yield, but had no effect on grain N concentration. A residual effect on crop grain yield for the high rate of LSM was evident in the soybean year. Crop response to LSM was similar to that of mineral fertilizer. Application operations for LSM had no adverse effect on soil strength or soil bulk density. Soil properties (microbial biomass C, carbohydrates, water-stable aggregates) were not greatly influenced by LSM application, however, increases in particulate C (POM-C) were evident for the high LSM rate at the 10- to 30-cm soil depth. The study showed that for fine sandy loams in Prince Edward Island low to medium rates of LSM applied every second year could serve as a source of N for barley in barley-soybean rotations. Key words: Barley, soybean, liquid swine manure, fine sandy loam, soil properties, tillage incorporation, eastern Canada
Changes in carbon storage of broadcast burn plantations over 20 years
Authors: Kranabetter J M , Macadam A M
Published: April 2011

The extent of carbon (C) storage in forests and the change in C stocks after harvesting are important considerations in the management of greenhouse gases. We measured changes in C storage over time (from postharvest, postburn, year 5, year 10 and year 20) in logging slash, forest floors, mineral soils and planted lodgepole pine (Pinus contorta var. latifolia) trees from six prescribed-burn plantations in north central British Columbia. After harvest, site C in these pools averaged 139 Mg ha-1, with approximately equal contributions from mineral soils (0–30 cm), forest floors and logging slash. Together these detrital pools declined by 71 Mg C ha-1, or 51% (28% directly from the broadcast burn, and a further 23% postburn), in the subsequent 20 yr. Postburn decay in logging slash was inferred by reductions in wood density (from 0.40 to 0.34 g cm-3), equal to an average k rate of 0.011 yr-1. Losses in forest floor C, amounting to more than 60% of the initial mass, were immediate and continued to year 5, with no reaccumulation evident by year 20. Mineral soil C concentrations initially fluctuated before declining by 25% through years 10 and 20. Overall, the reductions in C storage were offset by biomass accumulation of lodgepole pine, and we estimate these plantations had become a net sink for C before year 20, although total C storage was still less than postharvest levels. Key words: C sequestration, forest floors; coarse woody debris; soil organic matter
The effect of temperature on methane dynamics in soil and peat cores: Calculations from membrane inlet mass spectrometry
Authors: Sheppard Samuel Keir , Beckmann Manfred , Lloyd David
Published: April 2011

Methanogenesis and methane oxidation, fundamental microbial processes in the global carbon cycle, are mediated by numerous factors in terrestrial soil and wetland ecosystems. Accurate quantification of CH4 and CO2 concentrations in soils and wetlands is now possible using membrane inlet mass spectrometry. Below-ground production and headspace exchange of O2, CO2 and CH4 were monitored in microcosms from an upland Soil (Scotland) and three different peat bog systems (Sweden, Iceland and Scotland) by membrane inlet mass spectrometry. A comparison of cores from the different locations revealed that temperature, soil structure, plant cover and water table level are associated with the regulation of the depth of oxygen available for methanotrophic processes in the oxic zone and therefore gas emission rates. In aerobic soil cores, all the methane produced in anaerobic sites is oxidised rather than being emitted from the soil surface. In peat cores, molar CH4:CO2-ratios of around 1:10 indicate the boundary between the oxic and the anoxic zones. Changes in dissolved gas concentrations with depth and especially the molar CH4 :CO2-ratios are discussed. We also demonstrate that inconsistencies in dissolved gas profiles, along with higher localized molar CH4:CO2-ratios, indicate bubble formation at depths greater than 10 cm; gas emission by ebullition was promoted at these sites. Increase in temperature had a particularly strong effect upon gas dynamics in soil and peat cores. Gas solubilities were reduced and elevated CO2 and CH4 emission rates were observed potentially due to increased microbial activity. Key words: Methane, CO2, membrane inlet mass spectrometry, soil
Straw removal increases the light fraction and mineralizable C and N compared with moldboard ploughing
Authors: Soon Y K
Published: April 2011

An earlier study indicated that cereal straw may be removed after harvest without affecting crop production, soil organic matter and microbial biomass. Further measurements of early indicators of changes in soil organic matter, viz., the light fraction and mineralizable C and N, confirm that straw removal is superior to straw incorporation with moldboard ploughing, and comparable to straw incorporation by disking, in C and N retention and turnover. Key words: Carbon, light fraction, mineralization, nitrogen, straw management