bluuebunny/crossref_metadata_2025 huggingface dataset:
The biology of Canadian weeds. 3. Lepidium draba L., L. chalepense L., L. appelianum Al-Shehbaz (updated)
Authors: Francis A. , Warwick S. I.
Published: April 2011

This paper updates an earlier paper by Mulligan and Findlay (1974) on the cruciferous weeds Lepidium draba, L. chalepense and L. appelianum (treated in the previous paper as Cardaria draba, C. chalepensis and C. pubescens, respectively). Known collectively as hoary cresses, these species reached North America in the 19th and early 20th centuries as contaminants in seed or in ballast. The three species spread extensively in the western parts of the continent by the mid 20th century, partly through seed dissemination, but also by establishment of clonal patches and rhizomatous spread. In the prairie provinces the three species are weeds in grainfields, hayfields and forage crops, and have been largely under control in those crops since the 1970s. By the 1970s all three species had spread into agricultural regions of south central British Columbia and remain a serious problem there. They have also spread into forest, range, and riparian areas of Alberta and British Columbia and are among weedy threats to native ecosystems. Populations in Saskatchewan and Manitoba appear to have stabilized, but remain on noxious weed lists. In the western United States, the species have also spread from cultivated areas into rangelands, and L. draba in particular competes successfully with native vegetation, resulting in reduced local biodiversity. Lepidium draba can also reduce forage production, quality and palatability. Biocontrol measures for L. draba are under investigation. Mechanical controls have proved to be generally ineffective in large populations. Herbicides are effective in the short term in some agricultural crops, but do not provide long-term control, and are of restricted use on rangelands and at riparian sites. Potential beneficial uses of Lepidium draba in phytoremediation and as a source of disease-fighting chemical derivatives are reported. Key words: Lepidium draba, Lepidium chalepense, Lepidium appelianum, Cardaria draba, Cardaria chalepensis, Cardaria pubescens, hoary cress, white-top
Non-indigenous species management using a population prioritization framework
Authors: Rew L. J. , Lehnhoff E. A. , Maxwell B. D.
Published: April 2011

Few agencies or land owners have sufficient resources to target every non-indigenous plant species (NIS) population once they have become established within a management area. Therefore, prioritization of NIS populations for management is a crucial component of the management process. Conceptually, effective management of NIS can be regarded as having four phases that revolve around the land management goals and how best to manage the NIS present in the area to achieve these goals. The key phases are determining the land management goals, inventory/survey, monitoring, evaluation and prioritization. Inventory/survey determines which species are present and their distribution within the landscape. These data can be used to develop probability of occurrence maps, which help in the nonbiased selection of populations for invasiveness and impact monitoring. Monitoring for invasiveness provides information on spatial and temporal changes within a population. Monitoring for impact assesses three types of impact: the impact of the NIS on the ecosystem, the impact of the management/control practices on the NIS, and th e impact of management/control practices on the ecosystem. These data can then be used to evaluate and prioritize which species and populations to manage, and how to manage them, and these decisions should then be extended over the area of interest. The management advantages provided by a population prioritization framework were evaluated with a simulation model and supported the importance of monitoring and prioritization to reduce metapopulation growth. Key words: Invasive species, weeds, survey, monitoring, adaptive management, rangeland, wildlands
RCAT MatRix soybean
Authors: Stirling B. T. , Fischer J. D. , Ablett G. R.
Published: April 2011

RCAT MatRix is a 2850 crop heat unit (CHU) soybean [Glycine max (L.) Merrill] cultivar with excellent yield potential, good lodging resist ance and tolerance to the herbicide glyphosate. It was developed by the Ridgetown Campus, University of Guelph, and is adapted to the 2800–3000 CHU areas of Ontario. RCAT MatRix was issued registration number 6000 on 2005 Nov. 01 by the Variety Registration Office, Plant Production Division of the Canadian Food Inspection Agency. Key words: Soybean, cultivar description
Neural network modelling to predict weekly yields of sweet peppers in a commercial greenhouse
Authors: Lin W. C. , Hill B. D.
Published: April 2011

The production of greenhouse-grown sweet pepper (Capsicum annuum L.) is irregular with a peak-and-valley pattern of weekly yields. We monitored the yields and environment in a commercial greenhouse in British Columbia over six (2000–2005) growing seasons. Light was defined as cumulative light over the current week, with L_1, L_2, L_3, L_4, L _ 5 and L_6 representing light over previous weeks. Temperature (AvgT) was defined as the current weekly average of 24-h air temperatures, with T_1, T_2 and T_3 representing temperatures over previous weeks. Inputs were also created for the current weekly yield (Y) and previous weekly yields (Y_1, Y_2, Y_3 and Y_4). Neural network (NN) modelling with up to 21 inputs was used to predict yields 1 wk (Y + 1) and 2 wk (Y + 2) in advance of the actual fruit harvest. Data for five different years were combined for model training with the year to be predicted held separate as a validation set. The best models used 13 inputs to predict Y + 1 with an average R2 of 0.66 over the 6 yr. Y_4, Y-Y_1, Y_1, L_1, Y, Y_3, Y-Y_3 and wk (of the year) were important inputs. The environmental inputs were of lesser importance, which suggests that the cyclic nature of pepper yields is inherent in the pepper biology. Predicting Y + 2 was more difficult with an average R2 of 0.59 over the 6 yr. NN have good potential for predicting pepper yields. Key words: Capsicum annuum L., flushing, fruit, greenhouse production, neural networks
Reducing the risks of in-crop nitrogen fertilizer applications in spring wheat and canola
Authors: Lafond G. P. , Brandt S. A. , Irvine B. , May W. E. , Holzapfel C. B.
Published: April 2011

Nitrogen is the most limiting nutrient in crop production on the Canadian prairies. There is great interest in managing it more effectively for environmental and economic reasons. Our objective was to study the effectiveness of using different proportions of recommended nitrogen rates at seeding with the balance at different crop growth stages to minimize the risks of potential yield losses from in-crop nitrogen applications in spring wheat and canola. The field trials with wheat were conducted at three locations from 2003 to 2006 and at two locations for canola from 2004 to 2006. The treatments consisted of applying 100, 67, 50, 33 or 0% of the targeted N rate at seeding using urea in mid-row bands and the balance in-crop at the 1.5, 3.5 or 5.5 leaf stages in spring wheat and at the 5-6 leaf stage, bolting or start of flowering stage in canola using surface dribble band of liquid urea-ammonium nitrate. With spring wheat, applying 33% of the recommended N rate at seeding with the balance in-crop resulted in similar yields to when all the nitrogen was applied at seeding in one study while, in the other, some yield loss was observed at the 3.5 leaf stage. This indicates that a higher proportion, such as 50%, would be more appropriate. With canola, a minimum of 50% of the recommended nitrogen rate was required at seeding and the in-crop application at or before the bolting phase to give yields equivalent to when all fertilizer was applied at seeding. Consequently, applying 50% or more of the recommended N at seeding enhances the opportunity for in-crop applications of nitrogen in spring wheat and canola to better match the soil and climatic conditions. Key words: Canola, wheat, split applications, liquid urea-ammonium nitrate, grain yield, grain protein
Hazlet winter rye
Authors: McLeod J. G. , Gan Y.
Published: April 2011

Hazlet is a cultivar of winter rye (Secale cereale L.), developed at the Semiarid Prairie, Agricultural Research Centre, Research Branch, Agriculture and Agri-Food Canada, Swift Current, SK. Straw of Hazlet is about 10% shorter than tall cultivars such as Prima. Lodging resistance is poorer than AC Rifle and similar to Prima and Dakota. Hazlet has good winter survival and is well adapted to the Canadian Prairies. Kernels are about 16% larger and the test weight is significantly greater than the check cultivars. Grain yield is about 16% grater than that of Prima. Key words: Cultivar description, winter rye, straw strength, reduced plant height, test weight, kernel weight, Secale cereale L.
Integrated weed management in white bean production
Authors: Sikkema Peter H , Vyn Richard J , Shropshire Christy , Soltani Nader
Published: April 2011

A study was conducted over a 3-yr period (2004–2006) in Ontario to evaluate various weed management programs in white bean (Phaseolus vulgaris L.). Herbicide treatments evaluated caused no visible injury in white bean. Trifluralin provided 12% (percentage points) greater control of common lambsquarters (Chenopodium album L.) than s-metolachlor. There was no benefit of tank-mixing s-metolachlor and trifluralin for yield and profitability compared with either trifluralin or s-metolachlor alone. The postemergence (POST ) application of bentazon plus fomesafen following a soil-applied herbicide resulted in improved control of common lambsquarters by 15%. Two inter-row cultivations following a soil-applied herbicide resulted in improved control of redroot pigweed (Amaranthus retroflexus L.), common lambsquarters, and green foxtail [Setaria viridis (L.) Beauv.]. The addition of imazethapyr (60% of label dose; 45 g a.i. ha-1) to the soil-applied herbicide resulted in improved control of redroot pigweed (+6%), common lambsquarters (+16%), and green foxtail (+6%). The profit margin tended to increase if more than just a grass preplant-incorporated (PPI) herbicide was used. The best profit margin was with a grass PPI herbicide alone plus cultivation. The profit margin also tended to increase with the use of cultivation rather than a broadleaf POST herbicide. Key words: Bentazon, cultivation, fomesafen, imazethapyr, navy bean, s-metolachlor, trifluralin, Phaseolus vulgaris L.
Use of gross income as a measure of productivity in rice breeding
Authors: Samonte S. O. PB. , Wilson L. T. , Tabien R. E. , McClung A. M.
Published: April 2011

Rice breeders consider grain yield and milled rice percentages in developing cultivars, but usually do not consider gross income. This study’s objectives were to identify rice genotypes that produced high and stable expected gross incomes using genotype plus genotype × environment (GGE) biplot analysis. Uniform Regional Rice Nursery data on 47 long-grain genotypes grown at five locations (AR, LA, MO, MS, and TX) during 2001 to 2003 were analyzed. Gross income of each genotype was estimated based on grain yield, milled rice percentages, market prices, and direct and counter-cyclical payments. Based on GGE biplot analysis, the genotypes with the highest yield and highest gross income for the main crop were different in 12 out of 13 environments. RU0103184, Francis, and RU0003178 were the genotypes with the highest gross income in six, four, and three environments, respectively. Rice breeders should consider gross income as a selection criterion in the release of new cultivars. Key words: Rice, GGE, GE, breeding, gross income
Bruce birdsfoot trefoil
Authors: Papadopoulos Y. A. , McRae K. B. , Gehl D. , Fillmore S. A. E.
Published: April 2011

Bruce birdsfoot trefoil (Lotus corniculatus L.) is a 71-clone synthetic variety developed at the Nappan Research Farm, Agriculture and Agri-Food Canada, Nappan, Nova Scotia. Bruce was developed through two cycles of mass selection for plant vigour (top and root growth) and winterhardiness, and one cycle of mass selection for re-growth vigour under grazing. In Atlantic Canada, Bruce produced more forage than the check cultivar Leo during 3 post-seeding years. It was also superior in spring growth with high first-cut herbage yields. Key words: Birdsfoot trefoil, Lotus corniculatus, cultivar description
Trichothecene-mediated in vitro selection in wheat for reduced mycotoxin accumulation caused by Fusarium graminearum
Authors: Eudes F. , Comeau A. , Rioux S. , Collin J.
Published: April 2011

Trichothecene, a factor of aggressiveness of Fusarium graminearum in wheat fusarium head blight (FHB), was evaluated in an anther co-culture assay for the regeneration of doubled haploid (DH) lines with reduced mycotoxin accumulation. A Fusarium graminearum culture filtrate and a defined mixture of purified trichothecenes were compared with a control treatment in two F1-derived microspores populations. Frontana and Katepwa were the FHB resistant and intermediate resistant sources, respectively, and the cultivar Norseman was the FHB susceptible parent. A preliminary evaluation of the subpopulations of DH lines, using the point inoculation method in the greenhouse, showed selection effects for FHB resistance in the trichothecene co-cultured Frontana/Norseman subpopulation only. Three years of field evaluation using the spray inoculation method revealed that the DH subpopulation from the F1 hybrid Frontana/Norseman co-culture in the presence of trichothecenes accumulated consistently less deoxynivalenol (DON) in the grain than the control subpopulation. The FHB symptoms were also significantly reduced for 1 yr (2001) in the same subpopulation. This subpopulation showed increased test weight, plant height and a 1.1-d delay in heading date when compared with the control subpopulation, under disease pressure. A trichothecene co-cultured DH subpopulation from Katepwa/Norseman also had a significantly lower DON content for 1 yr. Key words: Androgenesis, disease resistance, Gibberella zeae, mycotoxin, Triticum aestivum, wheat scab
Control of common cocklebur (Xanthium strumarium L.) with pre- and postemergence herbicides in soybean
Authors: Sikkema P. H. , Kramer C. , Vyn J. D. , Soltani N.
Published: April 2011

Field trials were conducted in 2006 and 2007 on three Ontario farms with heavy infestations of cocklebur to determine the effectiveness of various preemergence (PRE) and postemergence (POST) herbicides for control of cocklebur in soybean [Glycine max (L.) Merr.]. There was minimal injury (2% or less) to soybean from the PRE and POST herbicides evaluated. Cloransulam applied PRE provided up to 98% visual control, reduced density 93%, and reduced dry weight of cocklebur 96%. Linuron, metribuzin, imazethapyr, and clomazone applied PRE provided 0 to 77% control and reduced density and dry weight of cocklebur minimally (54% or less) compared with the weedy check. Cloransulam applied POST provided as much as 98% control, reduced density up to 96%, and reduced dry weight of cocklebur as much as 98%. Chlorimuron, imazethapyr, imazethapyr plus bentazon, and glyphosate applied POST provided 49 to 90% control, reduced density 62 to 89%, and reduced dry weight of cocklebur 69 to 92%. Acifluorfen, fomesafen, bentazon, and thifensulfuron applied POST provided 1 to 51% control, reduced density 0 to 80%, and reduced dry weight 0 to 74% compared with the weedy check. Soybean yield increased as much as 79% compared with the weedy check as a result of cloransulam applied PRE or POST. Based on these results, cloransulam applied PRE or POST provides excellent control of cocklebur in soybean. Key words: Cocklebur, weed control, soybean, preemergence herbicide, postemergence herbicide
Estimation of ammonia emission episodes for a national inventory using a farmer survey and probable number of field working days
Authors: Sheppard S. C. , De Jong R. , Sheppard M. I. , Bittman S. , Beaulieu M. S.
Published: April 2011

Emissions of ammonia (NH3) and odor from livestock operations, and particularly from the landspreading of manure, are an issue from many aspects. Regional and national issues include production of inhalable aerosols (PM2.5), where NH3 from agriculture is a critical precursor. This process is episodic. As a result, it is important to characterize the episodic nature of NH3 emissions. This paper addresses the fact that weather and soil conditions can focus manure landspreading into a relatively few days each year. The Versatile Soil Moisture Budget (VSMB) was used with 30 yr of weather data on 2576 soil landscape units in Canada to estimate the number of days in each month when manure spreading would be possible. In addition, a national survey of about 3100 livestock farmers was used to quantify common practice. The stochastic information from the VSMB and the survey were applied to an NH3 emissions model. The base case, invoked by most national NH3 emission inventory calculations, is that emissions are uniformly distributed throughout each month. The result of our study was that daily NH3 emission fluxes could be up to 20-fold higher in the spring and fall months when manure landspreading is common but when weather and soil conditions limit the number of days available for field work. This has direct implications for estimating the role of agricultural NH3 on the episodic production of PM2.5, and this approach also has application to odor management. Key words: Modeling, livestock, emission factor, odor, NH3, field working day
Variability of vertical bromide redistribution within hummocky landscape
Authors: Thibodeau J. , Chanasyk D S , Fuller L G
Published: April 2011

Groundwater quality is a major issue for rural communities, and intensive agricultural practices have the potential to contaminate groundwater via leaching. By analysing the movement of a bromide tracer over three slope positions (top, middle and low) within two hummocky landscapes in central Alberta, the intensity of short-term leaching potential was measured, and the accuracy of a leaching potential index was assessed. Concentrations of bromide > 1 mg kg-1 were found at a 120-cm depth at each slope position, from both landscapes, after one snowmelt event and one growing season. However, the depth of a bromide concentration > 100 mg kg-1 varied significantly among slope positions after the snowmelt event, and after the growing season. The leaching potential index successfully distinguished between high leaching potential, and low and very low leaching potential. This index will become a useful tool to determine the variability of leaching within an agricultural landscape. Key words: Soil-landscape, leaching, tracer, soil moisture, soil profile index
Evaluating carbon dynamics and microbial activity in arctic soils under warmer temperatures
Authors: Oelbermann Maren , English Michael , Schiff Sherry L
Published: April 2011

A large portion of carbon (C) is stored in the world’s soils, including those of peatlands, wetlands and permafrost. However, there is disagreement regarding the effects of climate change on the rate of organic matter decomposition in permafrost soils of the arctic. In this study it was hypothesized that soil exposed to a higher ambient temperature would have a greater flux of CO2 as well as a change in the metabolic diversity of culturable soil microorganisms. To evaluate this hypothesis we determined soil C dynamics, soil microbial respiration and activity, and 13C and 15N fractionation in laboratory incubations (at 14 and 21°C) for an organic-rich soil (Mesic Organic Cryosol) and a mineral soil (Turbic Cryosol) collected at the Daring Lake Research Station in Canada’s Northwest Territories. Soil organic C (SOC) and nitrogen (N) stocks (g m-2) and concentration (%) were significantly different (P < 0.05) between soil horizons for both soil types. Stable isotope analysis showed a significant enrichment in δ13C and δ15N with depth and a depletion in δ13C and δ15N with increasing SOC and N concentration. In laboratory incubations, microbial respiration showed three distinct phases of decomposition: a phase with a rapidly increasing rate of respiration (phase 1), a phase in which respiration reached a peak midway through the incubation (phase 2), and a phase in the latter part of the incubation in which respiration stabilized at a lower flux than that of the first phase (phase 3). Fluxes of CO2 were significantly greater at 21°C than at 14°C. The δ13C of the evolved CO2 became significantly enriched with time with the greatest enrichment occurring in phase 2 of the incubation. Soil microbial activity, as measured using Biolog EcoplatesTM, showed a significantly greater average well color development, richness, and Shannon index at 21°C; again the greatest change occurred in phase 2 of the incubation. Principal component analysis (PCA) of the Biolog data also showed a change in the distinct clustering of the soil microbial activity, showing that C sources from the soil were metabolized differently with time at 21 than at 14°C, and between soil horizons. Our results show that Canadian arctic soils contain large stores of C, which readily decompose, and that substantial increases in CO2 emissions and changes in the metabolic diversity of culturable soil microorganisms may occur when ambient temperatures increase from 14 to 21°C. Key words: CO2 flux, C fractionation, global warming, soil organic C and N, stable isotopes
Bromide redistribution as influenced by landscape morphology and pedogenic properties in a variable glacial till landscape: A quantitative examination
Authors: Bullock P R , Whetter D A , Fuller L G
Published: April 2011

The spatial and temporal variability of soil properties with depth in the profile and across landscape positions results in diverse patterns of water and solute distribution over the landscape. Vertical and lateral movement of soluble nutrients within the soil profile influences the availability of nutrients required for crop growth, and the entry of nutrients into groundwater and surface water systems. However, commonly used geomorphic concepts such as crest and depression are not rigorously, quantitatively defined. The objective of this study was to determine the influence of quantitative topographic variables and zones of relative surface flows on vertical and lateral redistribution of a bromide tracer under field conditions in a variable glacial till landscape under zero tillage agricultural management. Tracer plots were established on three representative soil-slope associations and digital terrain models (DTM) were produced for determining slope gradient (G), horizontal curvature (Kh), vertical curvature (Kv), mean curvature (H) and accumulation curvature (Ka). Models of accumulation, transit and dissipation (ATD) zones of surface flows were produced for each digital elevation model (DEM) using data on mean and accumulation curvatures. Topographic variables and soil properties had mixed ability to predict bromide redistribution parameters. Soil profile development indicators were negatively correlated with bromide recovery, indicating that increased profile development resulted in more redistribution and lower recovery rates. Pedogenic indicators were significantly different between ATD zones, with depth to calcium carbonate, A horizon thickness, solum thickness and profile development indicator all significantly greater at accumulation zones relative to dissipation or transit zones, indicating that profile development was greatest at accumulation zones. However, the concept of ATD zones did not correlate significantly with bromide redistribution parameters. The utility of ATD zones as a predictive tool for static soil properties is limited by differing hydrologic regime and pedogenic processes occurring at lower slope positions, as a result of near-surface, dynamic water tables. Previous research, however, has shown that topographic variables and concepts of landscape element complexes have some utility in determining spatial variability of deep solute percolation and determination of potential for groundwater impacts. This study indicates that increased N application in convergent portions of the landscape may result in higher rates of deep percolation and removal of N from the crop rooting zone, in areas of depression-focused recharge, when environmental conditions are favourable for such. Key words: Solute redistribution, bromide tracer, digital terrain model, topography, landscape
Evaluation of fresh and aged clam processing wastes as potential agricultural liming materials for coastal area vegetable production soils
Authors: Owen Josée , LeBlanc Serge , Toner Patrick , Nduwamungu Cargèle , Fava Erica
Published: April 2011

Clam canning in New Brunswick generates 1800 t of clam processing wastes (CPW) annually. Thirty-year-old stockpiles of CPW must now be remediated to satisfy environmental regulations. This study examined fresh and aged CPW as potential agricultural liming materials for acidic coastal vegetable production soils. Clam processing wastes were ground to three size fractions (< 0.250 mm, 0.250 to < 1.00 mm, 1.00 to < 2.00 mm) and analyzed for calcium carbonate equivalent (CCE). They were then mixed with two soils of contrasting textures at three rates, in duplicate, and then placed in a control-plus-factorial pot experiment, with commercial agricultural lime of fine texture (< 0.250 mm) as reference. During an 8-wk incubation, soil water pH and electrical conductivity (EC) were monitored biweekly. At 4 and 8 wk, a soil extract germination test was conducted using cress (Lepidium sativum L.) as an indicator plant. CPW of < 1 mm raised soil pH with effectiveness increasing as particle size decreased. Application rates in function of the fineness to induce a given pH change (ΔpH) could be obtained using prediction graphs with high coefficients of determination (r2: 0.84 to 0.97). The average EC in all treatments to the end of the incubation period was < 2 dS m-1, indicating that salt stress is not a risk following CPW application to soil, since even sensitive crops are capable of withstanding such an EC. Seeding could take place between 4 and 8 wk after the CPW application to loamy sand with no adverse effect on germination index. In the loam soil, this period could safely be shortened. Key words: Clam, liming, soil pH, soil EC, cress, germination index
Potential impacts of climate change on grazing capacity of native grasslands in the Canadian prairies
Authors: Thorpe J. , Wolfe S A , Houston B.
Published: April 2011

Relationships between climate and native grassland production in the Canadian prairies were modelled and used to estimate the potential impacts of climate change on grazing capacity. Field measurements of production were related to climate variables and water balance estimates using regression analysis. Historical time series showed that year-to-year production is most closely correlated with annual actual evapotranspiration, whereas geographic patterns revealed that average production is most closely related to the annual water deficit. Climate and production estimates from the US Great Plains represent potential analogues for the Canadian prairies in the 2050s. Analysis of geographic patterns using Canadian and US data showed that production can be related to actual evapotranspiration (Model 1) or the ratio of actual to potential evapotranspiration (Model 2). The proportion of warm-season (C4) grasses has a significant effect on production in these models. A third independent model (Model 3) using US production data was used for comparison. Five general circulation model (GCM) scenarios covering a range of predictions simulated warmer climates of the 2050s. The production models were used to estimate changes in grassland production. On loamy soils, Model 1 predicts increases in production whereas Models 2 and 3 predict decreases. However, all predicted changes are modest, indicating that Canadian grasslands will probably remain productive over the next 50 yr. In addition, warm-season grasses could increase, particularly on sandy soils, thus benefiting productivity. Key words: Climate change, grazing capacity, grasslands, prairies
Stratifying soils into pedogenically similar categories for modeling forest soil carbon
Authors: Shaw C H , Banfield E. , Kurz W A
Published: April 2011

Most forest ecosystem carbon (C) models are designed to estimate total ecosystem C including soil C stocks and fluxes. Stratification by tree species is often used in these models to reduce uncertainty, but the potential of stratification by soil taxon has received little attention. This potential can be realized only if meaningful modeling strata are identified. Therefore, the objectives of this study were: (a) to distinguish strata of soil C modeling cateogories (SCMC) on the basis of soil C stocks of taxonomic categories that are characterized by similar pedogenic processes important to C dynamics, and (b) to review the literature to test the robustness of the SCMC scheme. Carbon stocks of 1383 forest soil pedons were analyzed by multiple means comparisons for soil orders and by orthogonal contrasts between pedologically related sets of subgroups within soil orders. Eleven SCMCs were distinguished with mean total C stocks varying from 325 ± 37.2 t ha-1 for the gleyed Cryosol SCMC to 94 ± 3.9 t ha-1 for the Brunisolic Gray Luvisol SCMC. A review of the literature relevant to each SCMC demonstrated that there is a scientific basis for using these strata to model forest soil C dynamics. Key words: Forest soil, carbon, modeling, pedology, genesis
Ammonia emission from dairy cow manure stored in a lagoon over summer
Authors: McGinn S M , Coates T. , Flesch T K , Crenna B.
Published: April 2011

It is recognized that volatilized ammonia (NH3) from intensive livestock production can be a significant pathway for nitrogen (N) pollution to land and water, and can contribute to poor air quality. The objectives of our study were to document NH3 emissions from a dairy lagoon and to assess the influence of meteorology on NH3 emissions. Ammonia emissions were determined using a backward Lagrangian Stochastic approach using WindTrax software, an open-path NH3 laser and a sonic anemometer. Results indicate that an average 5.1 ± 1.6 g NH3 m-2 d-1 was released over the summer; however, the emission varied typically over 24 h between 3.6 and 8.6 g NH3 m-2 d-1. Wind speed and surface temperature of the lagoon had similar influences on the magnitude of the release, where their direct impact on NH3 emission accounted for 28 and 31% of the variability, respectively. The main implication of this study is that NH3 losses are significant from dairy lagoons, contributing to the issue of N pollution. As well, NH3 emissions are a loss of valuable N for manure used as fertilizer, which in our study amounted to approximately 13% of the total ammoniacal N content of the manure in the lagoon. Key words: Ammonia, dairy, manure, cattle, dispersion model
Improvements of physical properties of degraded shallow organic soils by admixing organic overlays and mineral sublayers
Authors: Dinel H. , Mathur S. P. , Lévesque M.
Published: April 2011

Twenty-five soil media representing 13 subsoils and organic overlays, and their mixtures, that had been used in pot culture fallow, or for growing root, leafy vegetable and grass crops, were studied to determine if the benefits of organic amendments to crop yields in optimally watered and fertilized soils were due to improvements in soil physical conditions. The soils were subjected to particle and aggregate size fractionation; and the stability of the aggregates was determined. The results suggested that admixing of residual organic overlays improved the structure of all mineral subsoils, except perhaps an alluvial sand. Aggregation and stability of aggregates > 2 mm were improved, thus leading to improved aeration, root proliferation and to increases in crop yields. In addition, grass crops were shown to be more effective than root and leafy crops for improvement of the structure of the various soils. Key words: Organic soils, soil aggregation, soil structure stability
Enumeration of sulfur-oxidizing populations in Saskatchewan agricultural soils
Authors: Lawrence J. R. , Germida J.J.
Published: April 2011

Heterotrophic and autotrophic sulfur-oxidizing populations in 35 Saskatchewan agricultural soils were enumerated. These populations included heterotrophs that produce thiosulfate and or sulfate during elemental sulfur (S°) oxidation, heterotrophic thiosulfate oxidizers, and autotrophic thiosulfate oxidizers. Populations of Thiobacillus thiooxidans and T. ferrooxidans were not detected in any of the soils tested. Heterotrophs that oxidized S° to thiosulfate as the major oxyanion were the most abundant oxidizers enumerated (107–108 cells g−1) and were found in all soils. Autotrophic thiosulfate-oxidizers were detected in 10 of the soils surveyed. Heterotrophic S° and thiosulfate-oxidizing populations exhibited positive trends with soil pH, total-S, hydriodic reducible-S, and clay content, whereas populations of autotrophic thiosulfate oxidizers were negatively correlated with these factors and positively related to sand content and increasing C:S ratios. In soils containing autotrophic thiosulfate oxidizers the amount of thiosulfate relative to sulfate detected was reduced although no effect on S° oxidation rate was detected. Amendment of 15 selected agricultural soils with 0.5% S° significantly reduced total heterotrophic populations, whereas autotrophic thiosulfate oxidizers increased from undetectable levels to 104 cells g−1. Therefore most Saskatchewan soils contain abundant populations of heterotrophic S° oxidizers, and populations of autotrophs that respond to S° applications. Key words: Sulfur oxidation, autotrophic sulfur oxidizers, heterotrophic sulfur oxidizers, soil properties
Lower limit of available water for three plant species grown on a medium-textured soil in southwestern Saskatchewan
Authors: Cutforth H. W. , Jefferson P. G. , Campbell C. A.
Published: April 2011

Numerous researchers estimate and report laboratory-determined lower limit of available water contents using −1.5 MPa water potentials. For medium-textured soils, laboratory-measured lower limits should be determined at potentials of at least −4 MPa, and possibly −10 MPa, when using pressure membrane procedures. However, because the lower limit of available water is dependent upon environmental, plant and soil factors, we agree with Ratliff et al. (1983) that field-measured lower limits are preferable to laboratory-measured lower limits. Field-measured lower limits of available water did not vary markedly between spring wheat, alfalfa and grass. Key words: Lower limit of available water, wheat, alfalfa, grass
Soil water content and stomatal conductance in a mature peach orchard as influenced by various irrigation regimes
Authors: Tan C. S. , Layne R. E. C.
Published: April 2011

Available soil water (ASW) in the rooting zone of mature peach (Prunus persica (L.) Batsch 'Harken/Siberian C.') trees was determined with a neutron probe at incremental depths down to 240 cm between 1979 and 1982. The trees were either not irrigated (I0) or irrigated at a frequency necessary to prevent ASW from falling below 25% (I25) or 50% (I50) in the top 30 cm of soil. Water content in the top 120 cm from May to September for I0 plots was about 37 mm less than I25 plots and 73 mm less than I50 plots. Nonirrigated plots (I0) had the lowest ASW (< 30%) in the soil profile to a depth of 240 cm from mid-growing season onwards. By contrast, irrigated plots (I50) had high ASW (100%) at and below the 100-cm depth during the whole growing season. Leaf stomatal conductance was significantly lower for non-irrigated trees indicating that they were the most severely stressed. The severity of plant water stress increased with decreasing frequency of irrigation as indicated by reduced stomatal conductance. Key words: Prunus persica, available soil water, stomatal conductance
Chemical and biological changes in compost of wood shavings, sawdust and peat moss
Authors: N'Dayegamiye A. , Isfan D.
Published: April 2011

A comparative composting trial with wood shavings (WS), sawdust (SD) and peat moss (PM) was carried out under field conditions. In each, fresh material was mixed with cattle manure in a 2:1 ratio by volume. The initial pH of the WS, SD and PM composts (CST) were 6.2, 5.1 and 5.3, respectively. The chemical and biological changes in CST related to maturity were determined. Samples taken at 0, 12 and 24 mo of composting were also mixed with soil and increasing rates of N and tested as growing media for faba beans (Vicia faba L.) and corn (Zea mays L.) under greenhouse conditions. During composting, the C/N and E4/E6 values decreased in all cases but much more rapidly in WS pile. Thus, after 36 mo of composting, the C/N value decreased from 43 to 17 in WS pile and from 48 to only 35 in PM pile. As indicated by a low C/N ratio (17) and lower humic absorbance values (E4/E6 = 6.4), WS material was practically mature after 24 mo, more rapidly than SD and PM composts which presented initial lowest pH values. The microbial respiration rate (CO2), the pH and N–NO3 values increased during composting in all materials but much more in WS than in SD or PM pile. All composts were not harmful to plant growth even after a short time of composting (12 mo), but yields increased with the duration of composting. These data showed that it was possible to obtain, in field conditions, a compost from ligneous materials in 24 mo. Key words: Compost, composting, corn (Zea mays L.), faba beans (Vicia faba L.), microflora, peat moss, sawdust, wood shavings
Plant availability of Zn fractions in Saskatchewan soils
Authors: Liang J. , Karamanos R. E. , Stewart J. W. B.
Published: April 2011

Two growth chamber experiments were conducted to assess the plant availability of Zn fractions in nine Saskatchewan soils. In one experiment, two rates of Zn (0, and 5 mg kg−1) were applied to navy beans grown on seven soils ranging in pH from 6.2 to 7.8. Most of the applied Zn was recovered in Pb-displaceable and Mn oxide associated fractions after a 7-d incubation. Growth of navy bean plants was normal in all soils and treatments. Dry matter yield did not respond to Zn application. The positive correlations between amounts of Zn in exchangeable, Pb-displaceable and acetic acid soluble fractions and plant uptake indicated the importance of these Zn fractions in influencing availability of Zn. The DTPA soil test was not a successful method for prairie soils with diverse soil properties on the basis of correlations. In the second experiment, three rates of Zn (0, 5 and 10 mg kg−1) were applied to alfalfa grown on two soils with pH of 5.5 and 7.9. The total dry matter yield of alfalfa grown on the calcareous soil was increased significantly by Zn application. No yield response to added Zn was observed in the acidic soil. In both soils, applied Zn increased the Zn concentration and total Zn uptake of alfalfa significantly over the control treatment. Changes in the distribution of applied and native Zn in different fractions before seeding and at second harvest suggest that Zn taken up by plants in the calcareous soil was from exchangeable, acid soluble and possibly residual Zn. Zinc uptake by plants grown on the acid soil was from exchangeable, Pb-displaceable, acid soluble and possibly from Mn oxide associated fractions. Key words: Zn fractions, plant availability, navy beans, alfalfa, pH
Demonstration of spatial heterogeneity in the organic matter of de-ashed humin samples by solid-state 13C CPMAS NMR
Authors: Preston C. M. , Newman R. H.
Published: April 2011

A variant of solid-state 13C CPMAS NMR demonstrated the presence of carbon in spatially distinct domains within three de-ashed samples of humin from a forest soil profile under Douglas-fir near Victoria, British Columbia. Differences in 1H T1 values indicated incomplete spin diffusion in the solid state and separation of organic matter in domains with dimensions of tens of nanometres or more. These relaxation differences were used to separate subspectra of carbons associated with the slower- and faster-relaxing protons. The former were dominated by methylene chains, while the latter contained more aromatic and O-alkyl carbon. Most of the organic matter appears to remain associated with iron even after extensive de-ashing with HCl/HF, but the aromatic and carbohydrate structures appear to be more closely associated with iron than methylene groups in long chains. This NMR technique offers a novel approach to probing the structure of insoluble soil organic matter. Key words: Humin, CPMAS NMR, relaxation, iron, forest soil, Brunisol
Effects of long-chain aliphatic compounds on the germination and initial growth of corn, radish and spinach seedlings, and on hydrological properties of a sand growth medium
Authors: Dinel H. , Lévesque M. , Jambu P.
Published: April 2011

A greenhouse and laboratory study was carried out to determine the effects of various amounts (0.5–2.0%) of long-chain aliphatic compounds (LCA) of beeswax on the germination and initial growth (25 d) of corn, radish and spinach seedlings, and on the hydraulic properties of the sand growth medium. Complete emergence was obtained for corn, irrespective of aliphatic addition, whereas, the germination rate of the other two species decreased gradually as the amount of aliphatics added increased. With 2% LCA, 40 and 60%, respectively, of radish and spinach seeds failed to germinate. Dry matter yields of the three crops were reduced by the incorporation of aliphatics. The inhibitory effect of LCA on radish and spinach seedlings, coupled with a reduced plant density, resulted in a more dramatic yield reduction. Although there was a slight increase in the total porosity of the sand treated with LCA, the addition of LCA markedly decreased amounts of pores in the 25- to 100-μm class. It was concluded that the LCA influenced seed germination to various degrees, depending on the plant species, and that these compounds had a definite inhibitory effect on growth of seedlings, mainly through changes in the hydraulic properties of the sand. Key words: Long-chain aliphatics, germination, hydraulic properties
Prediction of fertilizer requirements for spring wheat grown on stubble in southwestern Saskatchewan
Authors: Selles F. , Zentner R. P. , Read D. W. L. , Campbell C. A.
Published: April 2011

Results of fertilizer trials conducted throughout southwestern Saskatchewan were used to develop a production function relating grain yield increases of stubble-seeded spring wheat (Triticum aestivum L.) to available water, soil NO3-N content to 60 cm depth, soil PO4-P content to 15 cm depth, and fertilizer N and P applications. The trials were carried out from 1967 to 1971 and from 1978 to 1983 on mid-textured Brown Chernozemic soils. The model accounted for 67% of the variability in yield increases, and identified water availability as the single most limiting production factor, which by itself accounted for 15% of the variability in yield increases. Further, the effects of soil and fertilizer N and P were only significant in their interaction with water. Response to N fertilization was adequately described by a second-degree polynomial. The rates of fertilizer N required for maximum economic yield increases were related to the availability of soil NO3-N and PO4-P and to the rate of fertilizer P application, and inversely proportional to available water and the ratio of N cost to wheat price. The model indicated that soil NO3-N was equally effective as fertilizer N in raising yields, but considered soil PO4-P only one-fifth as effective as seed-placed fertilizer P in modifying the rates of fertilizer N required for maximum return. The effect of fertilizer P in the model was only significant in interactions with fertilizer N and soil PO4-P. Water use efficiency was proportional to the availability of soil and fertilizer nutrients. Key words: Fertilizer N, fertilizer P, soil testing, moisture use, soil N, soil P
Spatial interpolation of soil salinity and sodicity for a saline soil in Southern Alberta
Authors: Gallichand Jacques , Buckland Gary D. , Marcotte Denis , Hendry M. J.
Published: April 2011

Soil salinity and sodicity data are usually represented as contour maps based on spatially interpolated data. This study was conducted to assess two commonly used spatial interpolation methods (moving average and weighted moving average) and three forms of two-dimensional (2D) and three-dimensional (3D) kriging. Soil was sampled from two depths on a 25-m grid at 40 sites in a saline and sodic soil of Southern Alberta. Samples were analyzed for electrical conductivity (ECe) and sodium absorption ratio (SARe) of saturation paste extracts. Methods were compared by cross-validation using the mean absolute difference (MAD) between estimated and observed values. Values of MAD resulting from 3D kriging were inferior to those obtained from moving averages. Moving average methods were very sensitive to the number of neighbors used in the estimation. For kriging methods, however, precision remained stable for more than about 10–12 neighbors. Three-dimensional ordinary kriging was the most precise and robust interpolator with a MAD value of 9.74 dS m−1 for ECe. For SARe the lowest MAD value of 10.55 was obtained with 3D ordinary co-kriging. Data representation produced by 3D kriging allowed easy identification of ECe spatial structure. Key words: Spatial interpolation, kriging, moving average, soil, salinity, sodicity
An examination of podzolization near Lake Michigan using chronofunctions
Authors: Barrett L. R. , Schaetzl R. J.
Published: April 2011

A chronosequence of sandy soils was investigated on four terraces near Lake Michigan to assess rates of podzolization and changes in soil properties with age. The terraces ranged in age from 3000 to 10 000 BP. Each surface was systematically sampled to determine the modal profile, which was then described and sampled. Quantities of OC, Fe, and Al in the B horizons of modal soils increased with soil age. Silt content of surface horizons also increased with age, possibly due to eolian input or physical weathering. For weighted profile and B horizon Al and Fe averages and a variety of soil development indices, a single logarithmic model generally gave the highest statistical significance of the three chronofunction models used. All pedons sampled failed to classify as Podzols, but the oldest two met the criteria for the Spodosol order. Thus, more than 4000, but less than 10 000, years are required for the development of a spodic horizon in Michigan. Key words: Soil chronosequence, Podzol development, soil genesis, modal profile
Long-term crop rotation and fertilizer effects on phosphorus transformations: I. In a Chernozemic soil
Authors: McKenzie R. H. , Stewart J. W. B. , Dormaar J. F. , Schaalje G. B.
Published: April 2011

The objective of this study was to determine effects of different cropping systems and nitrogen (N) and phosphorus (P) fertilizers on soil P fractions and transformations in long-term rotation plots on a Chernozemic soil at Lethbridge, Alberta. Continuous wheat, wheat-wheat-fallow, and wheat-fallow crop rotations and fertilizer application significantly affected the amount and distribution of phosphorus among labile and stable inorganic (Pi) and organic (Po) forms as determined by a sequential fractionation procedure. Without N and P fertilizer, the proportion of total soil P in more labile forms that were sequentially extractable with an anion exchange resin (resin-Pi), sodium bicarbonate (bicarb-Pi and Po) and sodium hydroxide (NaOH-Pi and Po) were reduced to a greater extent in continuous wheat than in wheat-wheat-fallow and wheat-fallow rotations. The addition of P fertilizer significantly increased total P and all Pi fractions, with the greatest change in more labile Pi forms (resin, bicarb and NaOH), but had no effect on labile Po forms. In contrast, N fertilizer addition increased the proportion of P in labile Po fractions in all rotations, and decreased the proportion of P in labile Pi forms. The combination of fertilizer N and P generally increased both Pi and Po labile forms. The continuous wheat rotation, coupled with N and P fertilizer inputs, had the most positive effect on P cycling and transformations. Key words: Soil P transformations, Chernozemic soils, P bioavailability, sequential extraction