bluuebunny/crossref_metadata_2025 huggingface dataset:
Impacts of grazing systems on soil compaction and pasture production in Alberta
Authors: Donkor N. T. , Gedir J. V. , Hudson R. J. , Bork E. W. , Chanasyk D. S. , Naeth M. A.
Published: April 2011

Livestock trampling impacts have been assessed in many Alberta grassland ecosystems, but the impacts of animal trampling on Aspen Boreal ecosystems have not been documented. This study compared the effects of high intensity [4.16 animal unit month per ha (AUM) ha-1] short-duration grazing (SDG) versus moderate intensity (2.08 AUM ha-1) continuous grazing (CG) by wapiti (Cervus elaphus canadensis) on soil compaction as measured by bulk density at field moist condition (Dbf) and penetration resistance (PR). Herbage phytomass was also measured on grazed pastures and compared to an ungrazed control (UNG). The study was conducted at Edmonton, Alberta, on a Dark Gray Luvisolic soil of loam texture. Sampling was conducted in the spring and fall of 1997 and 1998. Soil cores were collected at 2.5-cm intervals to a depth of 15-cm for measurement of bulk density (Dbf) and moisture content. Penetration resistance to 15 cm at 2.5-cm intervals was measured with a hand-pushed cone penetrometer. The Dbf and PR of the top 10-cm of soil were significantly (P ≤ 0.05) greater by 15 and 17% under SDG than CG, respectively, by wapiti. Generally, Dbf in both grazing treatments decreased over winter at the 0-7.5 cm and 12.5-15 cm depths, suggesting that freeze-thaw cycles over the winter alleviated compaction. Soil water content under SDG was significantly (P < 0.05) lower than CG. Total standing crop and fallen litter were significantly (P ≤ 0.05) greater in CG treatment than the SDG. The SDG treatment had significantly (P ≤ 0.05) less pasture herbage than CG areas in the spring (16%) and fall (26%) of 1997, and in the spring (22%) and fall (24%) of 1998, respectively. The SDG did not show any advantage over CG in improving soil physical characteristics and herbage production. Key Words: Bulk density, Cervus elaphus, moisture content, penetration resistance, pasture production
Soil microbial biomass and diversity respond to tillage and sulphur fertilizers
Authors: Lupwayi N. Z. , Monreal M. A. , Clayton G. W. , Grant C. A. , Johnston A. M. , Rice W. A.
Published: April 2011

There is little information on the effects of S management strategies on soil microorganisms under zero tillage systems o n the North American Prairies. Experiments were conducted to examine the effects of tillage and source and placement of S on soil microbial biomass (substrate induced respiration) and functional diversity (substrate utilization patterns) in a canola-wheat rotation under conventional and zero tillage systems at three sites in Gray Luvisolic and Black Chernozemic soils. Conventional tillage significantly reduced microbial biomass and diversity on an acidic and C-poor Luvisolic soil, but it had mostly no significant effects on the near-neutral, C-rich Luvisolic and Chernozemic soils, which underlines the importance of soil C in maintaining a healthy soil. Sulphur had no significant effects on soil microbial biomass, and its effects on microbial diversity were more frequent on the near-neutral Luvisol, which was more S-deficient, than on the acidic Luvisol or the Chernozem. Significant S effects on microbial diversity were observed both in the bulk soil (negative effects, compared with the control) and rhizosphere (positive effects) of the acidic Luvisol, but all significant effects (positive) were observed in root rhizospheres in the other soils. Sulphur by tillage interactions on acidic Luvisolic soil indicated that the negative effects of S in bulk soil occurred mostly under zero tillage, presumably because the fertilizer is concentrated in a smaller volume of soil than under conventional tillage. Sulphate S effects, either negative or positive, on microbial diversity were usually greater than elemental S effects. Therefore, S application can have direct, deleterious effects on soil microorganisms or indirect, beneficial effects through crop growth, the latter presumably due to increased root exudation in the rhizosphere of healthy crops. Key Words: Biolog, conservation tillage, microbial biodiversity, rhizosphere, soil biological quality, S fertilizer type and placement
Decomposition of grain-corn residues (Zea mays L.): A litterbag study under three tillage systems
Authors: Burgess M. S. , Mehuys G. R. , Madramootoo C. A.
Published: April 2011

This study was undertaken to obtain litterbag decomposition data for grain-corn residues in eastern Canadian conditions, to determine tillage and/or depth effects on residue mass loss, and to compare decomposition patterns for the different plant parts that constitute the residue (cobs, stems, leaves, husks). Mesh bags containing residues were buried or left on the soil surface in grain-corn plots under no-till, reduced tillage, and conventional tillage, and retrieved over a 2-yr period. Data were obtained separately for each plant part, then used to calculate pooled totals for all residues combined, for all residues except cobs, or for stems and leaves only, to facilitate comparison with studies based on different residue mixes. Buried residues lost mass faster than surface residues. Despite low overwinter temperatures, residue mass decreased substantially between placement in November and first sampling in mid- May. Surface litterbag residues lost 20% of initial mass during this period, residues buried at 5 cm lost 33%, and those at 20 cm lost 41%. Corresponding losses from mid-May to mid-October were 21, 42 and 32%, respectively. Mass loss was fastest for buried leaves, husks and stems (89-98% loss in 2 yr) and slowest for surface cobs (32% loss in 2 yr). Key words: Corn, maize, crop residue decomposition, litterbag, no-till, tillage
Effects of two silvicultural practices on soil fauna abundance in a northern hardwood forest, Québec, Canada
Authors: Moore Jean-David , Ouimet Rock , Camiré Claude , Houle Daniel
Published: April 2011

Soil fauna play a key role in soil fertility and productivity of forest ecosystems and represent an important base of terrestrial food chains. The impact of forest management on soil fauna should be considered when sustainable forest management and conservation of biodiversity are desired. We evaluated the impact of selective cutting and strip clearcutting on soil fauna abundance in a northern hardwood forest of the Lower Laurentians of Québec. Twelve years after strip clearcutting, the abundance of carabid beetles (Coleoptera: Carabidae), collembolans (Hexapoda: Collembola) and snails (Stylommatophora: Sigmurethra) was greater in the strip clearcuts than the adjacent undisturbed strips. Snails and millipedes (Polydesmida: Polydesmidae) were more abundant in the selective cuts 6 to 8 yr after treatment. Spiders (Arachnida) were the only organism whose abundance was lower in the selective cuts than in the adjacent undisturbed forest . No significant negative effect of the silvicultural treatments was noted for the abundance of other caught organisms. This one-season sampling suggests there are few negative impacts associated with low intensity selective cutting and strip clearcutting on the abundance of soil fauna in this northern hardwood forest stands 6 to 12 yr after harvest. Key Words: Salamander, arthropod, shrew, northern hardwood, selective cutting, strip clearcutting
Controlled-release P fertilizer concept evaluation using growth and P uptake of barley from three soils in greenhouse
Authors: Pauly D G , Malhi S S , Nyborg M.
Published: April 2011

Use of controlled-release P fertilizers to match the fertilizer P availability to crop requirement has potential for improvement of P uptake and crop production. Greenhouse experiments were conducted to evaluate the concept of controlled-release P fertilizer by using different coatings to regulate the release of P and to compare the growth and P uptake of barley (Hordeum vulgare L.) in three Alberta soils. Testing of different coatings in one experiment was followed by further evaluation of the promising treatments in two experiments. Commercial monoammonium phosphate (MAP) and diammonium phosphate (DAP) were coated with a polymer (thin-coated, 1.8% by weight or thick-coated, 2.2%) or enveloped in commercial packaging polyethylene film (shrink wrap, SW) with two, four or six pin-holes to control P release. Thin-coated treatment showed greater dry matter yield (DMY), P uptake (PU), net fertilizer P efficiency (NFPE) and net fertilizer releases efficiency of MAP compared to the uncoated, thick-coated or SW treatments in many cases. Coating of DAP did not consistently improve any of the above-mentioned parameters. In some cases, uncoated fertilizer had greater DMY, PU and NFPE than the polymer-coated treatments in early stages of crop growth (at the 13th, 26th, and 30th days), but coated treatments generally performed better during later stages of crop (at the 39th, 45th, 60th and 90th days). At 31.4 mg P pot-1 for example, thick-coated treatment had about 25% of its total PU during the 60th to 90th day, which resulted in greater spike yield accumulation in this treatment (8.4 g pot-1) compared to uncoated fertilizer (5.0 g pot-1). The P release rate was greater with thin-coated fertilizer than with thick-coated fertilizer during the 0 to 13th days (by 0.199 mg P kg-1d-1) and the 13th to 26th days (by 0.084 mg P kg-1d-1), but the opposite was true during the 26th to 39th days (by 0.112 mg P kg-1d-1) and the 39th to 52th days (by 0.064 mg P kg-1d-1). The polymer-coated, in particular the thin-coated, fertilizers delivered P in a manner that allowed the plants to use it more effectively than the uncoated MAP in several cases, which indicated a potential for improvement of fertilizer P efficiency and crop production. Key words: Barley growth, controlled-release P fertilizer, P uptake, yield
Biodiversity of ground beetles (Coleoptera: Carabidae) in Canadian agricultural soils
Authors: Goulet H.
Published: April 2011

In Canada, ground beetles (Carabidae) are abundant and diverse in agricultural ecosystems. Adults of all species are well characterized, but only 10% are known in the immature stages. In a typical agricultural site, one could find 40 to 60 species. While the ground beetle species composition consists mainly of native species in agriculture sites in the Prairie regions, a mixture of local and accidentally introduced species is the norm elsewhere. Although the diversity of introduced European species is not as great as that of native of ground beetles, the absolute number of European species may dominate an agricultural site. The basic biology and habitat requirements of almost all species occurring in agricultural habitats are known. Each species of beetle has special requirements based on soil type, moisture, pH, and light exposure. They are excellent indicators of habitat modification and of the quality of the environment. Although, most species of ground beetles are predators or scavengers, some are seed feeders. Because of their positive contribution to agricultural ecosystems, maintaining and developing their diversity by providing refuge habitats is recommended. Cropping sequence and type of crop influence ground beetle populations. More important, pesticides of all kinds reduce to various degrees the number of species and specimens. Female fecundity is a most sensitive test of sublethal pesticide effects on groun d beetles and should be considered in future studies of non-target insects. Key words: Ground beetles, carabidae, diversity, ground beetles and agriculture, ground beetles and pesticides, ground beetle extirpation
Cultivation and grassland type effects on light fraction and total organic C and N in a Dark Brown Chernozemic soil
Authors: Malhi S. S. , Brandt S. , Gill K. S.
Published: April 2011

Light fraction of organic matter is a source of nutrients for plants and a substrate for microbes, while total organic matter is critical for optimum physical conditions and retention of nutrients and other chemicals in soil. The objective of this study was to evaluate the effects of cultivation and grassland type on light fraction and total C and N in a Dark Brown Chernozemic soil. Three paired-sets of soil samples, in five replications, were collected from three cultivated field areas under annual crops [mostly wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.)] and from three adjacent grassland areas. The three sets were a 30-yr-old bromegrass (Bromus inermis Leyss.)/alfalfa (Medicago sativa L.) dominated stand cut annually for hay (Lm) and cultivated area 1 (Ct1), an unbroken native grass stand having no vegetation removed (Ng) and cultivated area 2 (Ct2) and a bromegrass/crested wheatgrass (A gropyron cristatum L. Gaertn.) dominated stand on a land reverted to grassland 60 yr ago having no vegetation removed (Og) and cultivated area 3 (Ct3). Soil samples from the 0- to 5-cm, 5- to 10-cm, 10- to 15-cm, 15- to 20-cm and 20- to 30-cm depths were taken using a 4-cm-diameter coring tube sampler. Total organic C (TOC), total N (TN), light fraction organic C (LFOC) and light fraction N (LFN) in soil were determined and the equivalent mass technique was used to calculate their masses in different soil layers. Total mass (for all soil layers) was less in the cultivated areas compared to the grassland areas by 31 to 43% for TOC, by 84 to 85% for LFOC, by 15 to 34% for TN and by 82 to 84% for LFN. The effect of cultivation was much greater in the surface 5-cm depth compared to deeper soil layers. The proportions of LFOC in TOC and LFN in TN as well as the TOC:TN ratios were lower in the cultivated areas than in the grassland areas, whereas the LFOC:LFN ratios were similar in cultivated and grassland areas. The light fractions of C and N were thus more responsive to change from grassland to cultivation of annual crops compared to the total C and N. Within the grassland areas, the mass of TOC and TN in most of the soil layers was greater in the Lm compared to both Ng and Og areas, while the LFOC and LFN did not show the effect of grassland type. The differences in the mass of both total and light fraction C and N in the cultivated areas were small and generally not significant. The findings suggest that including legume in grassland stands can sequester more organic C and N into the soil even when used for hay production. Key words: Cultivated land, light fraction C and N, native grassland, total organic C and N
Soil dissolved organic carbon: Influences of water-filled pore space and red clover addition and relationships with microbial biomass carbon
Authors: Zhang T. Q. , Drury C. F. , Kay B. D.
Published: April 2011

Soil dissolved organic carbon (SDOC) plays an important role in organic C cycling and translocation of nutrients and pollutants in the soil profile. Soil microbial biomass C (MBC) has been used as an indicator of soil quality. Both SDOC and MBC may be affected by management practices and indigenous soil properties, which however are not fully understood. Using a laboratory incubation technique, we determined the effects of red clover (Trifolium pratense L.) addition and soil water saturation as expressed in water-filled pore space (WFPS, 20-95%) on soil SDOC and MBC in three soils from Ontario. The levels of SDOC were the greatest at 20% WFPS, and decreased with increase s in WFPS up to 95%. In comparison with the control, addition of red clover increased SDOC by up to 72% at 20% WFPS, but the effect was minimal or insignificant at WFPS above 50%. Reduction of SDOC with increases of WFPS both with and without red clover was attributed to the increased mineralization of labile organic C, as indicated by CO2 production. Regardless of the legume amendment, soil available N (e.g., mineral N), labile organic C (e.g. initial level of SDOC) or the variable derived from these two measurements, available C:N ratio, were the factors predominately affecting dynamics of SDOC at WPFS from 20 to 50% after 1-mo incubation and at WFPS from 20 to 65% with extended incubation to 3-mo. Soil factors affecting SDOC at WFPS above 85% were total N and pH without red clover, but changed to organic C and soil labile organic C with red clover. High levels of MBC were found to occur mostly with the high WFPS, and were enhanced by red clover addition only in the Perth silt loam. Soil dissolved organic C was significantly related to MBC with WFPS from 20 to 65% without red clover. No relationships between SDOC and MBC were found at WFPS above 65% without red clover and at WFPS from 20 to 95% with red clover. Soil factors affecting SDOC and the availabili ty of SDOC to microbial activity are WFPS dependent and related to soil legume amendment. Key words: Red clover, water-filled pore space, dissolved organic C, microbial biomass C, CO2 emission
Determining wheat responses to copper in prairie soils
Authors: Karamanos R. E. , Goh T. B. , Harapiak J. T.
Published: April 2011

Criteria for assessment of the Cu status of prairie soils were developed in the early 1980s and are currently in use with some modifications. Although there appears to be a reasonable agreement on the soil critical value of 0.4 mg kg-1 soil based on DTPA-extractable Cu, a marginal range that extends between 0.4 and 1.2 mg DTPA-Cu kg-1 soil is used to generate fertilizer recommendations. The objective of this study was to verify the existing soil critical value and identify the frequency of agronomic as well as economic response of spring wheat to Cu fertilization on soils with levels both below and above the critical value. We carried out a large number (52) of trials with spring wheat (Triticum aestivum L.) between 1991 and 2000 in all three Prairie Provinces and compiled a large number of spring wheat experiments conducted in western Canada (63) by a number of researchers. Fifty-nine trials carried out on soils containing marginal and sufficient Cu levels were evaluated and were compared to 56 experiments on soils containing deficient levels. A number of methods of placement and products were compared. Agronomic responses were obtained in 41 of the 115 experiments and only by broadcasting either 3 to 5.5 kg Cu ha-1 as CuSO4·5H2O or 0.5 to 2 kg Cu ha-1 as Cu-sulphonate and incorporating the product or by foliar application of 0.22 kg Cu ha-1. Calibration of the DTPA-extractable Cu test using a Mitscherlich type of function verified the soil critical value of 0.4 mg Cu kg-1 soil. Statistically significant grain yield responses were obtained in 87, 16 and 0% of trials carried out on soils containing <0.4, 0.4 to 0.8 and >0.8 mg DTPA-extractable Cu kg-1 soil. Economic responses, defined as those where Cu application yielded a 2:1 return on the cost of fertilizer in the year of application, varied depending on the price of wheat and ranged between 19 to 45% in deficient soils for a price range of $100 to $200 t-1 of wheat grain; economic responses on marginal and sufficient soils occurred in 6% and none of the cases, respectively. Hence, fertilization of soils with DTPA-extractable Cu levels >0.4 mg kg-1 is associated with very high risk. Key words: DTPA-extractable, calibration, soil critical value, deficient, marginal, agronomic, economic
Effects of selected conditioners and tillage on the physical quality of a clay loam soil
Authors: Reynolds W. D. , Yang X. M. , Drury C. F. , Zhang T. Q. , Tan C. S.
Published: April 2011

Field-crop yields are below their genetic and climatic potentials on many fine-textured soils due to low organic carbon content (OC), high bulk density (ρb), low hydraulic conductivity (Ks), insufficient air capacity (AC) and low plant-available water capacity (PAWC). Although soil conditioners derived from municipal, agricultural and industrial wastes are frequently used to improve soils, their effects on overall soil physical quality are still poorly understood. Hence, the objective of this laboratory soil core study was to determine for a Brookston clay loam the effectiveness of masonry sand, greenhouse rockwool waste, yard waste compost and swine manure compost for improving soil physical quality relative to “ideal” levels proposed in the literature, and relative to “benchmark” levels found in the soil under virgin conditions, long-term conventional tillage and long-term no-tillage. The virgin soil produced near-surface (0.05–0.15 m depth) values for ρb(0.88 Mg m-3), AC (0.19 m3m-3) and PAWC (0.22 m3m-3) that fell within the optimal ranges proposed in the literature, while OC (68.2 g C kg-1) was slightly above optimal. The soil under long-term conventional tillage and no-tillage (cornsoybean rotation) produced below-optimal organic carbon content (21.9–22.5 g C kg-1), excessive ρb (1.45–1.47 Mg m-3), insufficient AC (0.06 m3m-3) and low PAWC (0.14–0.19 m3m-3). Conventional tillage also produced below-optimal Ks (10−6 m s-1). Each conditioner could improve one or more of the above parameters, but not all five. Adding sand at 20–100 wt. % improved AC, but caused excessive reductions in OC and PAWC, and excessive increases in ρb and Ks. Greenhouse rockwool waste added at 2.5–10 wt. % improved AC and ρb, but did not improve OC and PAWC. Yard waste compost added at 3.8–20 wt. % improved OC, ρb and PAWC, but did not improve AC. Adding swine manure compost at 3.8–20 wt. % improved OC and ρb, but did not improve AC or PAWC, and decreased Ks. As no single conditioner could optimize all soil physical quality parameters, future studies using combinations of conditioners are proposed. Key words: Soil physical quality, tillage, soil conditioners, clay loam, sand, rockwool, compos
Formation of iron nodules in a Hapludult of central Taiwan
Authors: Pai C. W. , Wang M. K. , Chiang H. C. , King H. B. , Hwong J. -L. , Hu H. T.
Published: April 2011

This study compared iron nodules with their matrix materials in a Hapludult from central Taiwan. Mineralogy and 14C ages of the iron nodules were compared with their associated matrix materials. The samples were analyzed by X-ray diffraction (XRD) and accelerated mass spectroscopy (AMS). Hydroxy-interlayered vermiculite (HIV) and illite were the major clay minerals in the soil matrix, but illite and kaolinite were dominant in the iron nodules. Clay mineralogy of iron nodules revealed more intense weathering process than the surrounding soil matrix. 14C dates showed that the age of saprolite and iron nodules were similar, and were both much older than those of the soil matrix. It is suggested that iron nodules developed from residuum of the Tertiary shale (saprolite). During pedogenesis, saprolite acted as a nucleus, where Fe coated on its surface was transferred to form iron nodules. Key words: 14C dates, iron nodules, saprolite, soil matrix, Ultisol
Patterns of water movement on a logged Gray Luvisolic hillslope during the snowmelt period
Authors: Whitson I. R. , Chanasyk D. S. , Prepas E. E.
Published: April 2011

Hillslope flow processes during the snowmelt period were studied at a logged site in the Boreal Plain Ecozone of western Canada. Fine-textured subsoils of Gray Luvisolic soils and soil frost were hypothesized to reduce infiltration capacity and promote interflow. Liquid soil water content, saturated flow through upper horizons, and soil temperature were monitored by Time Domain Reflectometry probes, zero-tension flow collectors, and thermocouples, respectively, on a 0.5-ha site with a 13% slope. Soil water content increased abruptly during snowmelt while soil temperature in the upper 65 cm was near 0°C, indicating that infiltration capacity was high despite frost. Mineral soil thawed 2 wk after snowmelt. Less than 0.1 mm of the 87 mm snow water equivalent became interflow. Size and timing of interflow events were variable and related to increased soil water content. The largest event occurred during soil thaw, and contributed 84% of total interflow. The lower Ae horizon was the preferred route for this flow, suggesting that the flowpath was not influenced by frost. Low pre-melt soil moisture probably reduced interflow volume. Interflow in Gray Luvisols is likely an infrequent happening due to high profile moisture storage capacity and rare development of the necessary saturated conditions. Key words: Snowmelt, infiltration, frozen soil, boreal, hydrologic flowpath, Luvisol
Influence of agricultural management on soil organic carbon: A compendium and assessment of Canadian studies
Authors: VandenBygaart A. J. , Gregorich E. G. , Angers D. A.
Published: April 2011

To fulfill commitments under the Kyoto Protocol, Canada is required to provide verifiable estimates and uncertainties for soil organic carbon (SOC) stocks, and for changes in those stocks over time. Estimates and uncertainties for agricultural soils can be derived from long-term studies that have measured differences in SOC between different management practices. We compiled published data from long-term studies in Canada to assess the effect of agricultural management on SOC. A total of 62 studies were compiled, in which the difference in SOC was determined for conversion from native land to cropland, and for different tillage, crop rotation and fertilizer management practices. There was a loss of 24 ± 6% of the SOC after native land was converted to agricultural land. No-till (NT) increased the storage of SOC in western Canada by 2.9 ± 1.3 Mg ha-1; however, in eastern Canada conversion to NT did not increase SOC. In general, the potential to store SOC when NT was adopted decreased with increasing background levels of SOC. Using no-tillage, reducing summer fallow, including hay in rotation with wheat (Triticum aestivum L.), plowing green manures into the soil, and applying N and organic fertilizers were the practices that tended to show the most consistent in creases in SOC storage. By relating treatment SOC levels to those in the control treatments, SOC stock change factors and their levels of uncertainty were derived for use in empirical models, such as the United Nations Intergovernmental Panel on Climate Change (IPCC). Guidelines model for C stock changes. However, we must be careful when attempting to extrapolate research plot data to farmers’ fields since the history of soil and crop management has a significant influence on existing and future SOC stocks. Key words: C sequestration, tillage, crop rotations, fertilizer, cropping intensity, Canada
Multi-site assessment of cultivation-induced soil change using revised landform segmentation procedures
Authors: Pennock D. J.
Published: April 2011

The range of soil properties associated with soil taxonomic class results from natural soil formation and soil-changing effects of human activity. My goal was to assess cultivation effects on soil formation and soil organic carbon (SOC) at four cultivated and two native hummocky till sites from the same climatic region of Saskatchewan. A revised landform segmentation procedure was used for comparisons across sites. Neither A horizon thickness nor SOC was related to topographical attributes at the native sites, but both had significant relationships (P = 0.001) with profile curvature (Pearson r= −0.53 and −0.57 for A horizon thickness and SOC, respectively), specific dispersal area (r = −0.40 and −0.54) and plan curvature (r = −0.24 and −0.34) at the cultivated sites. The greatest decreases in A horizon thickness (16 cm) and SOC (56 Mg ha-1) at the cultivated sites occurred in divergent shoulder elements, which have high rates of tillage-induced soil loss. Increases in soil thickness (including depth to calcium carbonate) occurred in concave footslope and depressional elements, but in situ losses of SOC outweighed the effects of SOC deposition. Soil thinning caused increases in the proportion of Orthic Regosols and decreases in the proportion of Calcareous Chernozems, but horizonation changes in the dominant Orthic Chernozems were minor. The self-terminating nature of the horizonation changes and improved conservation measures suggest that the future rate of soil change in these landscapes may be lower than in the past. Key words: organic carbon, topography, landscape-scale, erosion, tillage redistribution, digital elevation model, cesium
Winter wheat response to nitrogen fertilizer form and placement in southern Alberta
Authors: Middleton A. B. , Bremer E. , McKenzie R. H.
Published: April 2011

The recommended method for N fertilization to winter wheat (Triticum aestivum L.) on the Canadian prairies has been to broadcast ammonium nitrate (AN) during early spring. In the Chinook region of southern Alberta, considerable interest exists in alternative formulations (particularly urea), times of application and placements. To determine the effect of alternative N fertilizer practices on winter wheat in southern Alberta, two field experiments were conducted over 2 consecutive years (1998-1999 and 1999-2000) at three locations. In the first experiment, fall applications of urea or coated urea, seed-placed or banded, were compared to the standard practice of spring-broadcast AN. At five of six sites, there was no difference between fall-banded urea and coated urea in plant stand, grain yield or protein concentrations when compared to spring-broadcast AN. In 1998-1999, fall-banded urea reduced grain yield by 13% at the site in the Brown soil. Seed-placed N was only safe for urea at 30 kg N ha-1 and for coated urea at rates up to 60 kg N ha-1. In the second experiment, urea and coated urea were broadcast in spring for comparison with AN. Coated urea was ineffective in dry years due to poor N release. Urea was equally effective as AN in this study, possibly due to the cool, dry conditions at the time of application and the relatively low surface soil pH levels at these reduced tillage sites. Further research will be required to confirm the effectiveness of this practice for this region. Key words: Ammonium nitrate, urea, coated urea, nitrogen fertilizer placement, nitrogen timing, grain protein
Enzyme activity and C and N pools in soil following application of mulches
Authors: Masciandaro G. , Ceccanti B. , Benedicto S. , Lee H. C. , Cook H. F.
Published: April 2011

A field experiment was carried out to evaluate the effects of some mulching materials on soil biochemical properties that represent a component of soil quality and functionality. Wheat straw, dairy manure compost, and black polyethylene were used in the mulching experiments of a soil seeded with forage maize. Soil samples were taken from the surface (0–10 cm) and subsurface (10–20 cm) layers 1 and 4 mo after treatments were applied. Soil productivity, biochemical and chemical properties were determined. Compost treatment showed the highest agronomic yield due to the release of nutrients for plant nutrition and soil metabolism. Dehydrogenase activity was used as a measurement of overall microbial activity, whereas β-glucosidase and urease hydrolase activities were determined as an expression of C and N cycles. In addition, a ratio between dehydrogenase activity and water soluble carbon (defined as “metabolic potential index”) was calculated, in order to better represent soil metabolic potential. Compost-mulch treatment showed the lowest ratio values, while straw mulch had the highest value. A similar trend was found for β-glucosidase activity. The data confirmed the validity and sensitivity of the metabolic potential index and β-glucosidase enzyme in monitoring the change of soil biochemical properties and of soil quality during soil management practices. Key words: Soil enzyme activities, mulching practice, soil quality
Arbuscular mycorrhizae and soil/plant water relations
Authors: Augé Robert M.
Published: April 2011

The water relations of arbuscular mycorrhizal (AM) plants have been compared often. However, virtually nothing is known about the comparative water relations of AM and nonAM soils or about the relative influence of AM colonization of soil vs. AM colonization of plants on host water balance. In this review, I summarize findings that support the assertion that colonization of soil may play as important a role as colonization of roots regarding how AM symbiosis affects the water relations of host plants. We observed a slight but significant AM effect on the soil moisture characteristic curve of a Sequatchie fine sandy loam following 7 mo of mycorrhization by Glomus intraradices/Vigna unguiculata. In a separate study, few AM effects on either the wet or dry hysteretic curves were discernible after 12 mo of mycorrhization by G. intraradices or Gigaspora margarita on roots of Phaseolus vulgaris. Using myc- bean mutants, we determined that about half of the considerable promotion of stomatal conductance by G. intraradices and Gi. margarita was attributable to soil colonization and about half to plant colonization. A path analysis modeling approach revealed that soil hyphal colonization had larger direct and total effects on dehydration tolerance of bean than did root hyphal colonization or several other soil or plant variables. Key words: Mycorrhizal symbiosis, soil moisture characteristic, stomatal conductance, water relations
Potential impacts of climate change on corn, soybeans and barley yields in Atlantic Canada
Authors: Bootsma A. , Gameda S. , McKenney D. W.
Published: April 2011

In this paper, relationships between agroclimatic indices and average yields of grain corn (Zea mays L.), soybeans (Glycine max L. Merr.) and barley (Hordeum vulgare L.) in field trials conducted in eastern Canada are explored and then used to estimate potential impacts of climate change scenarios on anticipated average yields and total production of these commodities for the Atlantic region for the 2040 to 2069 period. Average yields of grain corn and soybeans were highly correlated (R2 = 0.86 and 0.74, respectively) with average available crop heat units (CHU), with yields increasing by about 0.006 t ha-1 CHU-1 for corn and 0.0013 t ha-1 CHU-1 for soybeans. The explained variance was not improved significantly when water deficit (DEFICIT) was included as an independent variable in regression. Correlations between average yields of barley and effective growing degree-days (EGDD) were low (R2 ≤ 0.26) and negative, i.e., there was a tendency for slightly lower yields at higher EGDD values. Including a second-order polynomial for DEFICIT in the regression increased the R2 to ≥ 0.58, indicating a tendency for lower barley yields in areas with high water deficits and with water surpluses. Based on a range of available heat units projected by multiple General Circulation Model (GCM) experiments, average yields achievable in field trials could increase by about 2.6 to 7.5 t ha-1 (40 to 115%) for corn, and by 0.6 to 1.5 t ha-1 (21 to 50%) for soybeans by 2040 to 2069, not including the direct effect of increased atmospheric CO2 concentrations, advances in plant breeding and crop production practices or changes in impacts of weeds, insects and diseases on yield. Anticipated reductions in barley yields are likely to be more than offset by the direct effect of increased CO2 concentrations. As a result of changes in potential yields, there will likely be significant shifts away from production of barley to high-energy and high-protein crops (corn and soybeans) that are better adapted to the warmer climate. However, barley and other small grain cereals will likely remain as important crops as they are very suited for rotation with potatoes. There is a need to evaluate the potential environmental impacts of these possible shifts in crop production, particularly with respect to soil erosion in the region. Key words: Crop heat units, growing degree-days, water deficits, crop yields, climate change, Atlantic region
Magnetic susceptibility of soil separates of Gleysolic and Chernozemic soils
Authors: de Jong E. , Heck R. J. , Ponomarenko E. V.
Published: April 2011

The major horizons of Gleysolic and Chernozemic soils and the underlying deep till of five cores were separated into sand-, silt- and clay-sized fractions. Pedogenesis increased the ranges of magnetic susceptibility (χ) and oxalate (Feo) and dithionite-citrate extractable (Fed) iron in bulk samples and size separates of the A, B and IC horizons compared to the deep till. In the A, B and IC horizons the relationships between χ of the bulk (< 2 mm diameter) soil and χ of the sand and silt fractions was much stronger than in the deep till. Generally, χ of the clay was much lower than that of the coarser fractions, whose χ was similar or slightly larger than that of the bulk samples, except for two buried, burned horizons. Treatment of the sand fraction of 15 soils with dithionite -citrate to remove pedogenic ferrimagnetics showed that the latter decreased in the order: burned, buried horizons > gleysolic and chernozemic A horizons > gleysolic B horizons > IC horizons. The low χ of the gleysolic horizons cannot be attributed to a decrease in pedogenetically formed ferrimagnetics; they must have lost part of their inherited ferrimagnetics, possibly sand-sized magnetite. Key words: Magnetic susceptibility, soil separates, extractable iron, gleysols, chernozems
Soil responses to topsoil replacement depth and organic amendments in wellsite reclamation
Authors: Larney Francis J. , Akinremi Olalekan O. , Lemke Reynald L. , Klaassen Vasile E. , Henry Janzen H.
Published: April 2011

Changes in soil properties reflect the success or failure of reclamation practices on abandoned wellsites. We examined the effect on soil properties of four (0, 50, 100 and 150%) topsoil replacement depths (TRD) and five amendment treatments [compost, manure, wheat (Triticum aestivum L.) straw, alfalfa (Medicago sativa L.) hay, check] aimed at reclaiming three wellsites (Strathmore, Hesketh and Rosedale) in southcentral Alberta. TRD treatment differences were consistent across all wellsites, with 30 to 32% higher soil organic carbon (SOC) on the 150% TRD compared to the 0% TRD. Initially, the alfalfa treatment showed higher levels of nitrate-nitrogen (e.g., 26 mg kg-1 vs. 3 to 7 mg kg-1 for the other amendment treatments in the 15- to 30-cm depth at Strathmore in fall 1998), which was related to its rapid breakdown and mineralization of organic N. After 40 mo (June 1997-October 2000), the average amounts (n = 3 wellsites) of added C conserved near the soil surface were: compost (65 ±10% SE) > manure (45 ±16% SE) > alfalfa (28 ±11% SE) > straw (23 ± 6% SE). Our results show that organic amendments play an important role in improving soil properties related to long-term productivity of reclaimed wellsites, especially where topsoil is scarce or absent. Key words: Wellsite reclamation, topsoil depth, organic amendments, soil quality
Effectiveness of seedrow placement of granular copper products for wheat
Authors: Karamanos R. E. , Walley F. L. , Flaten P. L.
Published: April 2011

The practice of placing granular Cu fertilizers with the seed of cereals and oilseeds has been expanding in western Canada mainly due to the high cost of applying the minimum suggested broadcast and incorporation rate of 3.5 kg Cu ha-1. The hypothesis made is that annual applications of small amounts of Cu in the order of 1 kg Cu ha-1 will satisfy the Cu requirement of a crop and, over a period of years, have the same effect as a single broadcast and incorporated application. We tested this hypothesis in a number of experiments aimed at assessing the effectiveness of seedrow placement of a variety of Cu products (sulphate, oxysulphate and chelated) at various rates (0 to 4 kg Cu ha-1) in the year of application, its residual effect after four annual applications and whether it can be combined with foliar Cu applications to provide an agronomic and economic solution both in the short and longer terms. Annual seedrow applications of up to 4 kg ha-1 were both agronomically and economically inferior to broadcasting and incorporation of 4 kg ha-1 as Cu sulphate; the former provided a statistically significant grain yield increase only in 3 of 10 site-years and only when the Cu fertilizer was in sulphate or chelated forms. However, yield increases thus obtained were neither economical nor as good as those obtained with broadcast and incorporated copper sulphate. The residual effects of seedrow-applied Cu at rates up to 4 kg ha-1 were very small compared to a single, 4-yr old broadcasting and incorporation of 4 kg Cu ha-1, and were obtained primarily after 3 yr of annual applications and with sulphate or chelated products only. However, average yield increases as a result of residual effects in the fifth year were approximately 35% of those obtained with broadcasting and incorporation. Combining seedrow with foliar applications did not have any agronomic or economic advantage, since most benefit arose from the latter. Key words: Broadcast and incorporation, sulphate, oxysulphate, chelate, residual
Using measurements of soil CO2 efflux and concentrations to infer the depth distribution of CO2 production in a forest soil
Authors: Drewitt G. B. , Black T. A. , Jassal R. S.
Published: April 2011

Carbon dioxide (CO2) from soil respiration is the focus of many ecosystem-atmosphere studies. However, due to the difficulty in obtaining measurements, there is a relative lack of information on the behavior of CO2 in the soil. This paper describes an accurate method that can be used in the field to measure CO2 concentration in small (10-cm) samples of soil air using an infrared gas analyzer. Measurements on samples drawn by syringe from different depths are compared to those calculated using a simple steady-state model derived from the conservation equation for soil CO2 and Fick’s law of diffusion. The study site is a second growth coastal temperate Douglas-fir forest plantation (53 yr old) located on the eastern slope of Vancouver Island, Canada. Measurements of CO2 concentrations were obtained from two locations at six soil depths between 0.02 and 1 m at various times of the year in 2000 and 2001. The vertical profiles of CO2 concentrations generally had similar shapes throughout the year although there was considerably more short-term variability in the shallow layers. Below-ground CO2 concentrations were higher during summer and decreased during the winter. Non-zero CO2 concentration gradients between the 0.5- and 1-m depths suggested some CO2 production below the 1-m depth. By matching modelled CO2 concentrations with measured values and using measured CO2 efflux, we used the model to determine the CO2 production profile. Calculations of CO2 production profiles indicated that more than 85% of the CO2 efflux from this forest soil originates at depths shallower than 30 cm. Key words: Soil carbon dioxide, CO2, soil respiration, steady-state model
Base cation mineral weathering and total release rates from soils in three calibrated forest watersheds on the Canadian Boreal Shield
Authors: Ouimet Rock , Duchesne Louis
Published: April 2011

Total release rates of base cations (Ca, Mg, K, and Na) from soils and from watersheds were evaluated using three methods. Three methods, one of which is new, were also used to evaluate mineral weathering rates of soils for three calibrated forest watersheds in the forest ministry’s monitoring network (Réseau d’étude et de surveillance des eco ystems forestiers: Quebec Forest Ecosystem Research and Monitoring Network; RESEF) on the Canadian Boreal Shield. We also compiled an extensive literature review of forest soil base cation release rates, focussed on northeastern North American forest soils of granitic lithology. With the exception of the total release and mineral weathering of Ca from soils at the Lake Laflamme Watershed site, and the total release of K from the three watersheds, soils and watershed release rates for the three watersheds were within the confidence interval of release rates compiled for forest ecosystems with similar granitic environment (compiled data for solum [mmol (+) m-2 yr-1 ± 95% CI], Ca: 33.8 ± 16.3, Mg: 16.8 ± 4.2, K: 13.0 ± 5.6, Na: 11.1 ± 3.0, and sum of base cations (BC): 61.2 ± 11.0; compiled data from watersheds, Ca: 82.8 ± 24.6, Mg: 50.8 ± 17.0, K: 7.8 ± 2.2, Na: 44.7 ± 12.8, and BC: 186.0 ± 49.9). Given the uncertainties associated with the calculations, there was little overall difference between total release rates and weathering release rates from soils for two of the three watersheds. Key words: Weathering rate, forest soil, granitic environment, watershed, PMB method, compositional trends
Soil salinity and sodicity after application of fresh and composted manure with straw or wood-chips
Authors: Miller J J , Beasley B W , Larney F J , Olson B M
Published: April 2011

Limited information exists on the effect of fresh versus composted beef cattle manure containing straw or wood chips on salinity (EC), soluble salts (Ca, Mg, Na, K, Cl, SO4), sodicity (sodium adsorption ratio, SAR), and potassium adsorption ratio (PAR) status of soil in the Great Plains region of North America. A site on a clay loam soil under irrigated barley (Hordeum vulgare) in southern Alberta was used for this study. The treatments were three rates (13, 39, 77 Mg ha-1 dry material) of fresh manure (FM) or composted manure (CM) containing either straw (ST) or wood-chip (WD) bedding, one inorganic (IN) fertilizer treatment, and a control (CON) treatment. All treatments were applied in the fall of 1998, 1999, and 2000. Soil sampling was conducted in the fall of 1998, 1999, 2000, and 2001 prior to manure and fertilizer application. Our results indicated that applying CM to irrigated barley for 3 yr at rates up to 77 Mg ha-1 should not cause an increase in any of the salinity variables compared with FM. Calcium, Mg, K, Cl, EC, and PAR were significantly higher for ST than WD bedding at certain rates and years. Year of sampling had a significant effect on Ca, K, Cl, SO4, EC, SAR and PAR. Salt distribution profiles indicated no accumulation of Ca, Mg, and SO4 in the soil profile relative to the control, increases in K and PAR at the 0- to 15-cm depth, increases in Na, Cl, EC, and SAR at the 0- to 30-cm depth, and accumulation of Cl at all depths. Overall, CM should not increase soil salinity and sodicity compared with FM, and bedding material may be a potential tool to manage certain salinity variables in the soil. Key words: Soluble salts, electrical conductivity, sodium adsorption ratio, fresh manure, compost, bedding
Soil nitrogen dynamics as affected by landscape position and nitrogen fertilizer
Authors: Soon Y. K. , Malhi S. S.
Published: April 2011

The influence o f landscape position on the dynamics of N in the soil-plant system has not been adequately studied. Our aim with this study on a predominantly Black Chernozem soil was to evaluate the effect of slope position (upper vs. lower) and N fertilizer application (none vs. 60 kg N ha-1) on soil and wheat (Triticum aestivum L.) N through the growing season. Landscape position had a dominant effect on soil NO3− and soluble organic N (SON) concentrations, especially in the surface 15 cm. These pools of soil N and net N mineralization were greater at the lower than at the upper slope position. The landscape effect is attributed to higher organic matter content (as measured by organic C) and water availability in lower compared with upper slope positions. Nitrogen application had no measurable effect on soil NO3− and SON concentrations. Exchangeable and non-exchangeable NH4+ were little affected by slope position or N fertilization. Nitrogen application increased wheat N uptake; however, its influence was less than that of slope position, especially on N accumulation in wheat heads during grain-filling. Although N application increased wheat yields, landscape position exerted the greater influence: grain yield was less on upper than lower slope positions due to earlier onset of crop maturity. During grain filling, net N mineralization was suppressed at the upper slope position and by N application. The increase in crop yield and N uptake due to N application was not significantly different between slope positions. This study demonstrated that landscape position had a greater influence on N dynamics and availability than the application of typical amounts of fertilizer N and that the two effects were mostly independent of each other. Key words: Available N, landscape position, N uptake, net N mineralization, soluble organic N