bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of moisture regime, N management, and cultivar on the agronomic performance and yield stability of soft white spring wheat
Authors: Beres B. L. , Sadasivaiah R. S. , McKenzie R. H. , Graf R. J. , Dyck R. J.
Published: April 2011

Field studies were conducted for 4 yr (2000–2003) in southern Alberta to determine the agronomic suitability and yield stability of soft white spring wheat across an array of moisture and fertility regimes. Two soft white spring wheat cultivars (AC Reed and AC Nanda) with contrasting maturity and quality profiles were compared to nine varieties representing the Canada Prairie Spring White, Canada Prairie Spring Red, and Canada Western Extra Strong wheat classes. The cultivars were managed with five varying rates of mid-row banded ammonium nitrate 0, 19, 38, 57, and 76 kg N ha-1. AC Reed matured earlier than most cultivars except AC Vista, and had the highest average yield. Yield stability analyses showed that AC Reed was well adapted to all environments but AC Nanda was less stable. AC Vista, AC Crystal, and AC Karma had average to good stability, but produced less grain than both AC Reed and AC Nanda. For non-irrigated production, yield was generally optimized at the mid-row banded rate 38 kg N ha-1 of ammonium nitrate. Response to N varied at the irrigated sites, but sites with lower initial soil NO3-N levels were responsive through the 76 kg N ha-1 rate. The soft white spring wheat class responded similarly to N in all moisture regimes, but whole-grain protein accumulation was not always lowest in the soft white spring wheat class. This study indicates that long-term sustainable production of soft white spring wheat in semi-arid, non-irrigated environments is possible, and would be most successful if cultivars were selected with yield stability, maturity and protein characteristics similar to AC Reed. Key words: Dry land production, fertility, soft white spring wheat, Triticum aestivum, yield stability, moisture regime
Tourco soybean
Authors: Poysa V. , Woodrow L. , Yu K.
Published: April 2011

Tourco is a large-seeded tofu-type soybean [Glycine max (L.) Merr.] cultiv ar with elevated seed protein content developed at the Agriculture and Agri-Food Canada Research Centre, Harrow, Ontario. Tourco has yellow hila and good tofu processing quality for foreign and domestic markets. Key words: Glycine max (L.) Merr., soybean, cultivar description, tofu
N2O emissions from spring barley production as influenced by fertilizer nitrogen rate
Authors: Zebarth B J , Rochette P. , Burton D L
Published: April 2011

Usage of mineral nitrogen (N) fertilizers for agricultural crop production systems is a major contributor to anthropogenic nitrous oxide (N2O) emissions. As part of a national study to quantify N2O emissions under different cropping systems and in different eco-regions, this study quantified the effect of fertilizer N rate on spring barley (Hordeum vulgare L.) on N2O emissions in 3 yr in a cool maritime climate with humid soil moisture regimes. Treatments were 0, 75 and 150 kg N ha-1 as ammonium nitrate applied as a pre-plant broadcast. N2O emissions were increased by fertilizer N application in each year. In 2003 and 2005, elevated N2O emissions occurred in the 6-wk period following fertilizer application when soil NO3-N concentrations were high. However, in 2004 and 2005, peak N2O emissions occurred near crop harvest. Elevated N2O emissions at this time were attributed to increased carbon availability due to re-wetting of dry soil. Therefore, the effect of fertilizer N management on N2O emissions may not necessarily occur immediately after treatment application. This emphasizes the importance of measuring N2O emissions outside of the crop growth period. Fertilizer-induced cumulative N2O emissions averaged 0.011 and 0.021 kg N kg-1 N when fertilizer N rate was increased from 0 to 75 kg N ha-1 and from 75 to 150 kg N ha-1, respectively, indicating increased N2O emissions when fertilizer is applied at above optimal rates. N2O emissions increased linearly with nitrate intensity, the summation of daily NO3-N concentrations for 0- to 15-cm depth. This suggests that the non-linearity in the relationship between fertilizer N rate and N2O emissions can be explained by the decreasing efficiency in crop NO3-N uptake at high fertilizer N rates. Key words: Hordeum vulgare, soil nitrate, denitrification, carbon availability
Soil micro-arthropod communities and microbial parameters in the potato ridge under two field management systems on sandy loams in Atlantic Canada
Authors: Carter M R , Noronha C.
Published: April 2011

Intensive forms of soil management occur in potato (Solanum tuberosum L.) production systems, but little is known about the influence of such practices on soil biological properties. Microbial biomass C, phosphatase activity, and the abundance (number), richness (family groups), and diversity of soil micro-arthropods (Collembola and mites) were compared in conventional and adjacent integrated pest management (IPM) systems of 3-yr potato rotations, established on fine sandy loams in Prince Edward Island, Atlantic Canada. The study was conducted at two sites over a 2-yr period. Soil microbial parameters were generally similar between management systems. Management differences showed some effect on micro-arthropod abundance and richness in three of the eight comparisons. Under optimum soil-water conditions, both Collembola and mite communities increased over the growing season regardless of management system. Key words: Soil management for potato, Collembola, mites, soil microbial biomass carbon, acid phosphatase, integrated pest management
A comparison of 2D vs. 3D thresholding of X-ray CT imagery
Authors: Elliot Thomas R , Heck Richard J
Published: April 2011

Non-destructive soil constituent analysis has advanced from resin impregnation of intact samples to the utilization of non-destructive imaging devices (i.e., CT scanners) for 3D composition. A difficulty of CT scanning is the finite resolution of such devices and the resulting non-definitive boundaries. Isolation of voxels that contain a single constituent (i.e., low variance voxels) allows for improved segregation of 3D data by histogram thresholding. The results from proposed 2D and 3D low variance voxel segmentation techniques were compared to establish whether or not 3D consideration should be used when analyzing CT and intact soil columns. It was determined that 2D processing in single orientation and as a multiplicative orthogonal process produced dissimilar results to 3D processed data. The authors encourage further exploration of 3D investigation in soil science, particularly related to soil composition and arrangement. Key words: Computed tomography, threshold, segmentation, soil, 3D
The influence of nitrogen, phosphorus and potash fertilizer application on oat yield and quality
Authors: Mohr R M , Grant C A , May W E , Stevenson F C
Published: April 2011

Western Canada has become one of the key production areas for oat (Avena sativa L.) in North America. Limited information is available regarding fertilizer management strategies to optimize yield and quality in this environment. An experiment was conducted at two locations in southern Manitoba in 2000, 2001 and 2002 to assess the impact of factorial combinations of N (0, 40, 80, 120 kg N ha-1 as urea), P (0, 13, 26 kg P ha-1 as monoammonium phosphate), and KCl (0, 33 kg K ha-1) on the growth, yield and quality of AC Assiniboia oat. Low to moderate N rates significantly increased yield, with optimum relative yield achieved with a plant-available N supply of approximately 100 kg N ha-1. Increasing N rate also increased lodging and reduced test weight, kernel weight and kernel plumpness, suggesting that optimal N management must balance yield improvement against reductions in grain quality. Phosphorus application increased yield in 2 of 6 site-years, but had no overall effect on quality. Application of KCl resulted in small increases in yield (88 kg ha-1), kernel weight and kernel plumpness on moderate to high K soils, which were not likely to provide a significant economic benefit. The lack of consistent interactions among N, P, and KCl suggests that these nutrients may be managed individually. Key words: Oat, nitrogen, phosphorus, potassium chloride, yield, quality
Nitrous oxide, carbon dioxide and methane emissions from irrigated cropping systems as influenced by legumes, manure and fertilizer
Authors: Ellert B H , Janzen H H
Published: April 2011

Irrigated land in southern Alberta is intensively managed, producing high yields but also requiring higher inputs, notably of nitrogen (N), than adjacent rainfed lands. The higher N inputs, combined with enhanced soil moisture, might stimulate nitrous oxide (N2O) emissions, but the influence of management on these emissions has not been widely studied. Our objective was to assess soil N2O emissions, along with those of carbon dioxide (CO2) and of methane (CH4), from irrigated cropping systems as influenced by source of N. We used a chamber technique to measure year-round emissions for 3 yr in long-term irrigated crop rotations receiving N as legume crop residues, non-legume crop residues, livestock manure or ammonium nitrate fertilizer. Unlike CO2 fluxes, which peaked during the growing season, those of N2O showed no consistent seasonal trends; emissions occurred sporadically in bursts throughout the year. Depending on management practices, 0.4 to 4.0 kg N2O-N ha-1 yr-1 was emitted to the atmosphere. The amount of N2O emitted from the alfalfa system, averaged over all manure and fertilizer N amendments, was more than twofold that emitted from the corn system. The proportions of fertilizer-N released as N2O were 0.95% for the alfalfa system and 1.30% for the corn system. After livestock manure or legume residues were incorporated, soil CO2 and N2O emissions appeared to be intertwined, but during the early spring N2O emissions were decoupled from CO2. Furthermore, N2O emissions were highly variable in space; at three of 54 chambers, N2O fluxes were consistently 12 to 55 times greater than those for other chambers in the same treatment. Such complexity conceals the underlying processes of net N2O production and transport to the soil surface. Key words: Greenhouse gas, fluxes, carbon dioxide, methane, flux chamber, alfalfa, silage corn, fababean, manure, fertilizer, N inputs, N2O leakage, legumes
Water content as a function of apparent dielectric permittivity in a Fibric Limnic Humisol
Authors: Lange S F , Allaire S E , Juneau V.
Published: April 2011

Volumetric water content (θv) was estimated from time domain reflectometry (TDR) measurementsof apparent dielectric permittivity (Ka) in an organic soil (Humisol). The goals of this study were: (i) to test the accuracy of existing θv-Ka relationships in this soil and if found insufficient (ii) to develop alternative θv-Ka relationships for this organic soil. The Ka values were measured over a wide range of θv in intact soil cores taken from three horizons (Ohp, Of, Oco). Empirical θv-Ka relationships found in the literature for organic porous media could not accurately describe the θv-Ka relationships of any horizon of this Humisol, probably because of the its very large organic matter content (> 75%) of this soil. New θv-Ka relationships for each horizon were consequently developed. Key words: Organic soil, TDR, coprogenic soil, volumetric water content, apparent dielectric permittivity
Carbon dioxide emissions by urban turfgrass areas
Authors: Allaire S E , Dufour-L'Arrivée C. , Lafond J A , Lalancette R. , Brodeur J.
Published: April 2011

This research compared four turfgrass lawn management approaches on CO2 emissions: (1) fertilized and frequently mowed with clippings removal, and unfertilized with clippings left on site and mowed 2) weekly, 3) three times, or 4) once during the growing season. CO2 emissions were measured weekly with flux chambers. Mowing frequency had higher impact on CO2 flux than fertilisation and soil characteristics. Frequently mowed sites emitted CO2 at a maximum rate of 0.63 mg m-2 s-1 and annually up to 2.0 kg m-2, an emission four times higher than lawns mowed infrequently. Differences between treatments mostly occurred during warm weeks. Key words: Lawns, greenhouse gases, carbon cycle, carbon dioxide, net CO2 exchange
The Canadian Journal of Soil Science: Glances through the last half-century and into the next
Authors: Henry Janzen H. , Little Shannan M. , Cramer Leslie J. , Larney Francis J.
Published: April 2011

The Canadian Journal of Soil Science (CJSS) is fifty years old! Here we look back and unearth trends and topics in soil science that have enticed us over those 50 years. Some study areas have stayed prominent throughout (e.g., nitrogen); others flourished then waned (e.g., salinity); and still others are now just ascending (e.g., climate change). And the way the papers look too has changed: they have become longer and with more authors, for example. Having looked briefly at the past half-century, we peer ahead into the one coming, mulling some changes, not necessarily to advocate them, but merely as possible seeds for collective pondering. Key words: History, soil science research, scientific writing
Short-term and long-term effects of tillage and crop rotation on soil physical properties, organic C and N in a Black Chernozem in northeastern Saskatchewan
Authors: Malhi S S , Moulin A P , Johnston A M , Kutcher H R
Published: April 2011

A field experiment was conducted for 8 yr (from 1994 to 2001) in a Black Chernozem (Udic Haploboroll) high in organic C (5.5%) at Melfort, Saskatchewan, Canada, to assess the environmental impact of tillage and crop rotation. Short-term effects on residue cover, soil temperature, moisture, aggregation, bulk density and hydraulic conductivity were measured, and long-term effects on total organic C (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON) were determined. There were two tillage systems [no tillage (NT) and conventional tillage (CT)] and three 4-yr annual crop rotations (canola-wheat-barley-barley,canola-barley-pea-wheat,and canola-pea-flax-barley). Straw was returned to soil every year in all treatments with the exception of flax residue. Soil samples were taken for analysis of organic C and N after the harvest of canola at the end of second 4-yr rotation cycle. Residue cover on soil was higher under NT than CT. Soil temperature was lower and soil moisture was higher in spring, under NT than CT. The proportion of fine aggregates (< 1.3 mm) in soil was lower and that of medium (2.0–12.7 mm) and large aggregates (> 12.7 mm) was generally higher under NT compared with CT. The mean weight diameter (MWD) of aggregates was also larger under NT compared with CT in most cases. The proportion of fine aggregates was higher after canola compared with pea in some cases, but the proportion of medium and large aggregates was higher after pea compared with canola, and in rotations with 50% than 75% broadleaf crops in 2yr. Soil hydraulic conductivity and bulk density were lower under NT than CT in some instances. Compared with CT, NT had greater mass of TOC, TON, LFOC and LFON in soil. However, the differences were significant only for LFOC and LFON, in dicating that light fraction organic C and N was more responsive to NT than CT compared with total organic C and N. In conclusion, the findings suggest that there is no interaction between tillage and rotation, and that light fraction C and N accumulate when tillage is eliminated despite high levels of soil organic C in the soil. Key words: Aggregation, bulk density, crop rotation, hydraulic conductivity, organic C and N, moisture, residue cover soil, temperature, tillage
Test of guidelines for field estimates of water retention properties of soils derived from volcanic materials in northern Tanzania
Authors: McKeague J. A. , Wang C. , Ross G. J. , Modestus W. K.
Published: April 2011

Soil water properties were estimated in the field, using guidelines established in Canada, for five volcanic-derived soils in Tanzania. Many of the estimates for horizons near the surface were satisfactory but those for water retained at − 1500 kPa by horizons below a depth of 1 m were far too low. These low estimates combined with underestimates of air porosity at − 10 kPa for many of the samples resulted in very poor estimates of available water capacity. The guidelines were not directly applicable for estimating water properties of most of the soils studied. The samples had bulk densities of 0.9–1.3 Mg m−3, air porosities at − 10 kPa ranging from 3 to 27%, and available water capacities of 280–116 mm to depths of 140 cm or to a petrocalcic layer. X-ray analysis indicated weakly crystalline clays in all of the soils. Tiron extracted from 7 to 38% of the material from the < 2 mm samples tested but the amounts of extracted material were not closely related to anomalously high water retention values at − 1500 kPa. Specific surface areas, but not clay contents, of these samples were significantly related to their measured water retention values at − 1500 kPa. A high proportion of porous particles in the silt fraction of a sample from a depth of 2 m in one soil indicated that highly porous non-clay sized material may account, in part, for the anomalous water retention and specific surface data. The effect of wetting and drying on the water retention properties of these soils may be important but remains to be clarified. Key words: Available water, air porosity, amorphous material, field estimate
Development of soil structure in some turbic cryosols in the Canadian low Arctic
Authors: Smith C. A. S. , Fox C. A. , Hargrave A. E.
Published: April 2011

This study was undertaken to examine the relationship between periglacial processes and the development of soil structure in some Turbic Cryosols. Three active nonsorted pattern ground features (mud hummocks) were examined for field macrostructure and micromorphological characteristics. The surface of unvegetated mud hummocks exhibited granic fabric expressed as strong granular structure. Cryoturbic movement caused surface materials to be cycled downward toward the permafrost table and upward into the hummock core. Resultant compression caused coalescence of discrete structural units resulting in matrigranodic fabric and subangular blocky structure. Porphyroskelic fabric associated with massive and occasionally prismatic structure was observed in the core of the hummocks although some remnant granularity was evident in thin section. Cycled fragments of surface vegetation 10–1000 μm in length were observed dispersed through all soil horizons. All horizons within the active layer contained more than 2% organic carbon. Key words: Turbic Cryosol, micromorphology, soil structure, cryoturbation
The determination of exchangeable cations in acid soils: Errors caused by weathering reactions during neutral salt extraction
Authors: Rasmussen Pat E. , Schiff Sherry L. , Nesbitt H. Wayne
Published: April 2011

To investigate pH-controlled chemical reactions associated with the neutral salt measurement of exchangeable cations in acid soils, and to estimate the potential error caused by such reactions, a series of experiments was performed which modify an established BaCl2 extraction method. Results showed that dissolution of amorphous silica, aluminum hydroxides and organic material occurs during neutral salt extraction, contributing cations to solution which are indistinguishable from exchangeable cations. As a result overestimates of exchangeable Al and Ca occur, but the error is not significant (> 10%) except in certain Ae horizons which are low in total CEC and high in exchangeable acidity. The 2-h BaCl2 method is recommended over the 4-hour NaCl method to minimize interference from weathering reactions. Key words: Cation exchange, exchangeable acidity, Al, H, acid forest soils, weathering
La fertilisation magnésienne du tabac à cigarette
Authors: Lamarre Michel , Payette Suzanne
Published: April 2011

The effect of magnesium application on the production and chemical composition of flue-cured tobacco was observed over a period of 3 yr to determine the most effective source and the best rate of Mg application. Magnesium increased gross return and magnesium content of the plant while decreasing potassium and zinc contents. Only the Mg applied as double sulfate of potassium and magnesium (Sulpomag) increased yield, gross return and Mg content of the plant. An application of 10 kg ha−1 of Sulpomag is satisfactory to reach a good production on soils low in Mg. Key words: Flue-cured tobacco, magnesium, rate, form, total alkaloids, total nitrogen, reducing sugars
Formation of loose and cemented B horizons in Podzolic soils: evaluation of biological actions from micromorphological features, C/N values and 14C datings
Authors: Pagé F. , Guillet B.
Published: April 2011

Micromorphological observations, C/N values and 14C datings of organic matter were used to evaluate impacts of biological activities on the development of loose and cemented podzolic horizons of a toposequence in the St-Lawrence Lowland. In well-drained soils, the B horizons containing roots have two distinct microstructure types: (1) a microstructure with organic aggregates in root zones (< 5% of the soil volume) resulting from microbial or animal actions, and (2) organo-mineral aggregates and grain coatings in inter-root zones which are due to aggregate transformation of root zones under biological and chemical processes. The organic matter of these loose horizons has C/N values of 23–28, and mean residence time of about 500 yr. The cemented Bfc horizon without roots is characterized almost exclusively by organo-mineral grain coatings, and has a higher C/N ratio (38) and a longer mean residence time (800 yr) indicating weaker biological activities than in loose B horizons. In the poorly drained soil, the cemented horizon has a microstructure with organic grain coatings only. The organic matter has a very high C/N value of 46 and a mean residence time of about 3500 yr. This horizon could represent an older "fossil" situation. Key words: Podzol, biological activity, micromorphology, 14C datings
Impact of a subsurface volcanic-ash layer on the properties of a southern Alberta soil with shallow water table
Authors: Beke G. J. , Sommerfeldt T. G.
Published: April 2011

Two soils from a large depressional area, one with (AL) and one without (NL) a volcanic-ash layer, were investigated to determine the effect of the ash layer on soil properties. The soil parent materials, including the ash layer, were deposited in a lacustrine environment. Both soils had well-developed A and B horizons with secondary salinity. The AL soil contained less Na in the B horizon than the NL soil, resulting in a soil classification of salinized Gleyed Solonetzic Dark Brown Chernozem at the AL site and salinized Gleyed Dark Brown Solonetz at the NL location. Saturated hydraulic conductivity and moisture retention values indicated that the volcanic-ash layer enhanced the depth of effective drainage. This was supported by greater rooting depth, weaker B horizon structure, lower salinity, and dominance of different ions in the upper solum of the AL than in the NL soil. The distribution of soluble ions in the profiles indicated that the ash layer had negligible impact on the height of capillary rise. Lower soluble ion contents in the lower profile of the AL than the NL soil were attributed to the presence of an indurated or cemented layer between the water table and the ash layer in the AL soil. Key words: Soil properties, volcanic-ash, water movement, soluble salt movement, indurated horizon
Long-term effects of preplant liming on apple trees and soil cation levels
Authors: Neilsen G. H. , Hogue E. J. , Hoyt P. B.
Published: April 2011

Nine years after liming a sandy loam orchard soil to pH 6.0 with calcium hydroxide or dolomitic lime, pH and extractable Ca and Mg were still higher where limed than where unlimed. However, pH had decreased below 5.0 in the limed and N-fertilized plots. Delicious (Malus domestica Borkh.) apple tree nutrition benefited from the two soil amendments. Leaf Mg was increased by dolomite. Leaf Ca was increased by calcium hydroxide. Leaf Mn, although highest in unlimed soils, increased over time for both limed and unlimed soil. Key words: Apple, lime application, reacidification
The chemistry of saturation extracts of Solonetzic and associated soils
Authors: Heck R. J. , Mermut A. R.
Published: April 2011

Cation speciation in soil extracts from a catenary sequence of salt-affected soils was studied to understand the chemical evolution of Solonetzic soils in a closed basin. Major changes in cation speciation were found to occur at each phase of soil development. The proportion of thermodynamically active cations was greater in the extracts from the more leached profiles. Saturation indices suggested that the extracts achieved equilibrium with calcite and gypsum, when present in the soil, within 24 h. Accumulations and/or losses of gypsum and calcite from saline layers indicate that there are ongoing changes in their stability. The ratio of Ca2+/Mg2+ suggested a possible equilibrium with Mg-bearing calcites; conditions existed in certain horizons for the formation of this group of minerals. Correlations between exchangeable sodium ratios and sodium adsorption ratios calculated using cation concentration and activity were similar; however, using activities to determine the exchange constants resulted in significant differences.Key words: Cation speciation, saturation indices, cation adsorption, exchange selectivity constants, Solonetzic soils
Formation des horizons diagnostiques argiliques et de fragipan en fonction de la permeabilité des roches
Authors: Bruckert Sylvain , Bekkary Malika
Published: April 2011

Leached soils (Alfisols) with either an argillic horizon or a fragipan were encountered close to each other on the marly-limestone and sandstone plateaus of Haute–Saône (France). Soils have formed under periglacial conditions during the Riss in a similar climatic environment. Because the soils occurring today are in the same geomorphic and topographic position, the objectives of the investigations were to study the influence of other pedogenic factors, such as parent materials and underlying rock type. The soil mantle, above the bedrock, is from one and a half to several meters thick. Four types of materials were identified through the pedons studied: sands, clays, clay-loams, loams. Their location being directly above either a rhetian sandstone or a sinemurian marly-limestone, sandy or clayey materials were accumulated as insoluble residue of the underlying rocks. Related to particle size distribution and mineralogy, the clay loamy materials were identified as eolian dusts. The loamy materials were also eolian deposits, but they were reworked and transported with sandy particles from sandstone of other high landscape positions. The surficial materials, encountered in all the sites studied, were texturally and mineralogically similar, which suggested that the parent materials were not the main factor controlling the formation of argillic horizons or fragipans. On the other hand, the effect of rock type has been established. Our data suggest: (1) significant relationships between the internal drainage of soil and the underlying geological substrata (type, joints and fracture planes, permeability, effect on hydrology), (2) rock effect on formation of an argillic or a fragipan horizon. In the case where meteoric waters can move through fractured rocks, soils can undergo drying and wetting cycles and clays swell and shrink. These processes induce favorable effects on genesis of soil structure, particularly of Bt structure. In the case of low-porosity and low-permeability rocks, soils dry from the surface downward and dessication cycles accomplish a vertical cleavage and polygonal cracking. We have concluded that the rock effect is a major factor involved in the development of leached soils with an argillic horizon or a fragipan. A major advantage of the rock factor hypothesis is that the formation of fragipans is possible in periglacial areas and far from glaciated regions, as proposed by the literature. Key words: Fragipans, argillic horizon, pedogenetic factors, rock effect, Alfisols
Effets d’amendements ligneux sur la disponibilité d’azote dans un sol sableux cultivé en pomme de terre
Authors: Beauchemin Suzanne , Laverdière Marc R. , N’dayegamiye Adrien
Published: April 2011

A field trial with potato (Solanum tuberosum L.) was conducted on a sandy soil to estimate N immobilization after applying tree clippings to the soil. N availability was evaluated by mineralizable N, N recovery coefficients and N derived from fertilizer. Fresh and composted tree clippings (50 t ha−1) were compared with an unamended control. In each principal treatment, nitrogen fertilizer was added at the rates of 0, 150, 200 and 250 kg N ha−1. Mineralizable N was lowest (P ≤ 0.001) in plots amended with wood residues by comparison to the unamended control. N recovery was 0.49 and 0.54 for fresh and composted residues, respectively, which indicates a higher N immobilization for fresh wood residues. N immobilization was estimated at 46 kg N ha−1 and increased in treatments receiving fresh tree clippings and also with increasing N rates. Moreover, a significant linear increase of N derived from fertilizer (P = 0.03) was observed with fertilizer N rates especially in amended treatments. Thus, the incorporation of ligneous material to the soil may have reduced the availability of soil mineralized N and potato growth depended mainly on N fertilizer addition. This study indicates that during the first growing season following the application of ligneous materials, N immobilization remained the main restricting factor on potato production. Key words: N availability, N derived from fertilizer, N immobilization, N recovery coefficient, potato, tree clippings, wood residues
Simulation of protozoa-induced mineralization of bacterial carbon and nitrogen
Authors: Rutherford P. M. , Juma N. G.
Published: April 2011

Modelling in soil ecological research is a means of linking the dynamics of microbial and faunal populations to soil processes. The objectives of this study were (i) to simulate bacterial-protozoan interactions and flows of C and N in clay loam Orthic Black Chernozemic soil under laboratory condtions; and (ii) to quantify the flux of C and N (inputs and outputs) through various pools using the simulation model. The unique features of this model are: (i) it combines the food chain with specific soil C and N pools, and (ii) it simultaneously traces the flows of C, 14C, N and 15N. It was possible to produce a model that fitted the data observed for the soil. The simulated CO2-C evolved during the first 12 d was due mainly to glucose addition (171 μg C g−1 soil) and cycling of C in the soil (160 μg C g−1 soil). During this interval, bacterial C uptake was 5.5-fold greater than the initial bacterial C pool size. In the first 12 d protozoa directly increased total CO2-C evolution by 11% and increased NH4-N mineralization 3-fold, compared to soil containing only bacteria. Mineralization of C and N was rapid when bacterial numbers were increased as a result of glucose addition. Key words: Acanthamoeba sp., modelling, N mineralization-immobilization, organic matter, Pseudomonas sp., Typic Cryoboroll
Performance of a simulation model describing protozoa-induced mineralization of bacterial C and N in a sandy loam
Authors: Rutherford P. M. , Juma N. G.
Published: April 2011

Mathematical modelling of a microcosm experiment provided a rigorous link between soil organism populations and the processes in the C and N cycles for a clay loam soil. In order to check the internal consistency of the model, we tested its performance with the data set obtained for a sandy loam. We empirically lowered the value of the half saturation constant for the protozoan consumption of bacteria from 175 to 50 (μg C g−1 soil) and initialized the state variables with the appropriate values. The model was also used to quantify the effect of texture on bacterial-protozoan interactions and flows of C and N using the simulated data for a clay loam and a sandy loam. The CO2-C evolved during the first 12 d was mainly due to glucose addition (180 μg C g−1 soil) and cycling of C in the soil (130 μg C g−1 soil). During this interval, C inputs into bacteria were 14-fold greater than the initial pool size. Protozoa increased total CO2-C evolution by 16% and increased net NH4-N mineralization 3.5-fold compared with the protozoa-minus treatment. Mineralization of bacterial C and N was more rapid in the sandy loam than in the clay loam. Key words: N mineralization-immobilization, bacteria, model, protozoa, Typic Cryoboroll, sandy loam
Effect of nitrogen and snow management on efficiency of water use by spring wheat grown annually on zero-tillage
Authors: Campbell C. A. , Zentner R. P. , McConkey B. G. , Selles F.
Published: April 2011

Water and N fertility are major limitations to cereal production in southwestern Saskatchewan. Both factors interact to determine grain yield and thus water use efficiency. A 9-yr study to assess the effects of snow management and fertilizer N on yields of spring wheat (Triticum aestivum L.) grown annually under zero-tillage provided an opportunity to quantify water use efficiency and relate this to apparent water used by the crop (WU), years of cropping (Yr) assumed to be 10 or fewer, soil test N (SN), and rate of fertilizer N (FN). The results showed that the estimated initial yield point (IYP) (available water required to produce the first unit of grain) and the yield increase per unit of water used beyond IYP increased with available N. Within the range of available N encountered in this study, IYP ranged between 60 and about 100 mm, values similar to those reported in the literature. However, because IYP is obtained by extrapolation, these values are regarded as first approximations. The yield increase per unit of WU increased with FN, varying between 10 and 14.4 kg ha−1 mm−1 (avg. 12.7) when a simple linear regression model was used to relate yield to WU. When a more accurate multiple regression equation that related yield to WU, SN, FN, and time and placement of fertilizer N was used, the marginal increase in yield per unit increase in available water (∂y/∂WU) ranged between 5 and 23 kg ha−1 mm−1 for assumed combinations of SN ranging between 0 and 50 kg ha−1 and FN ranging between 0 and 100 kg ha−1. The multiple regression model is superior to linear models because it allows the separation of available soil and fertilizer N effects. Key words: Water use efficiency, initial yield point, regression, N fertilizer, soil N
Stability-energy relationships and their application to aggregation studies
Authors: Fuller L.G. , Goh Tee Boon
Published: April 2011

The objective of this study was to develop a method to describe aggregate stability-energy relationships using ultrasonic dispersion and to examine the role played by carbohydrate in soil aggregation. Aggregate size fractions (ASF) from three soils were sonified, and dispersed clay and solubilized carbohydrate measured at energy levels ranging from 0 to 1000 kJ L−1. Study soils included an Orthic Black, Orthic Dark Gray, and Orthic Gray Luvisol, representing the change from a prairie ecosystem to an aspen-forest ecosystem. Ultrasonic dispersion of aggregated clay resulted in characteristic "stability curves" for each ASF which obeyed a first-order decay curve and provided two parameters describing the release of clay from soil aggregates with increasing levels of applied energy: the "stability constant" k and the E1/2 value, which are analogous to a first-order rate constant and half-life, respectively. E1/2 values ranged from 51 to 502 kJ L−1.These values were smallest for the Ae horizon of the Orthic Gray Luvisol and greatest for the macroaggregates of the Ahe horizon of the Orthic Dark Gray. Carbohydrates solubilized upon aggregate destruction generally constituted a minor proportion (10%) of the total ASF carbohydrate, indicating that most of the carbohydrate was strongly adsorbed to surfaces. The development of a stability-energy relationship for aggregates provides a means to study the role of binding agents, such as carbohydrate, in the aggregation process. Key words: Aggregates, ultrasonic dispersion, clay, carbohydrate
Nitrogen-mineralization potential of meadow soils
Authors: Simard Régis R. , N'dayegamiye Adrien
Published: April 2011

An understanding of the mineralization factors in contrasting cultivated soils is necessary for accurate predictions of plant-available N. The objective of this work was to determine the N-mineralization potential and mathematical models that can properly describe the dynamics of the mineralization process in 20 meadow soils from Quebec. The mineralization was monitored over 55.4 wk in a laboratory incubation at 20 °C with intermittent leaching. The cumulative mineralization curves in most soils were characterized by definite lags or a sigmoidal pattern and near-linear release with time after 20 wk. The data were best described by the Gompertz equation; first-order models were inadequate. The total amount of mineralizable N and the potential mineralization rate were very closely correlated with the total amounts of C or N (r > 0.73; P < 0.01). The clay content was also correlated with these mineralization parameters and significantly improved the prediction of the cumulative and potential N-mineralization rate estimated from the total N or C content of soils. The relationships with other soil characteristics such as soil pH and available nutrient contents were weak but significant. The results of this study suggest that textural classes be added in the correction for organic matter content to improve the precision in N-fertilizer recommendation and in soil-quality classifications based on potential mineralization rate. Key words: Soil quality, potentially mineralizable N, Gompertz equation, soil organic matter, soil texture, C, N
Microbial and biochemical changes induced by rotation and tillage in a soil under barley production
Authors: Angers D. A. , Bissonnette N. , Légère A. , Samson N.
Published: April 2011

Crop rotations and tillage practices can modify not only the total amount of organic matter (OM) in soils but also its composition. The objective of this study was to determine the changes in total organic C, microbial biomass C (MBC), carbohydrates and alkaline phosphatase activity induced by 4 yr of different rotation and tillage combinations on a Kamouraska clay in La Pocatière, Quebec. Two rotations (continuous barley (Hordeum vulgare L.) versus a 2-yr barley–red clover (Trifolium pratense L.) rotation) and three tillage treatments (moldboard plowing (MP), chisel plowing (CP) and no-tillage (NT)) were compared in a split-plot design. Total organic C was affected by the tillage treatments but not by the rotations. In the top soil layer (0–7.5 cm), NT and CP treatments had C contents 20% higher than the MP treatment. In the same soil layer, MBC averaged 300 mg C kg−1 in the MP treatment and up to 600 mg C kg−1 in the NT soil. Hot-water-extractable and acid-hydrolyzable carbohydrates were on average 40% greater under reduced tillage than under MP. Both carbohydrate fractions were also slightly larger in the rotation than in the soil under continuous barley. The ratios of MBC and carbohydrate C to total organic C suggested that there was a significant enrichment of the OM in labile forms as tillage intensity was reduced. Alkaline phosphatase activity was 50% higher under NT and 20% higher under CP treatments than under MP treatment and, on average, 15% larger in the rotation than in the continuous barley treatment. Overall, the management-induced differences were slightly greater in the top layer (0–7.5 cm) than in the lower layer of the Ap horizon (7.5–15 cm). All the properties measured were highly correlated with one another. They also showed significant temporal variations that were, in most cases, independent of the treatments. Four years of conservation tillage and, to a lesser extent, rotation with red clover resulted in greater OM in the top soil layer compared with the more intensive systems. This organic matter was enriched in labile forms. Key words: Soil management, soil quality, organic matter, carbohydrates, microbial biomass, phosphatase
Effects of rates and placement methods of urea and potassium chloride on soil nitrogen and potassium and corn dry matter yield
Authors: Chen J. S. , MacKenzie A. F.
Published: April 2011

Placement and interaction of urea and KCl fertilizers for corn production needs to be evaluated to develop rational fertilizer management programs. A field study, involving three rates of urea and KCl with band and broadcast placements, was conducted with corn on two Quebec soils in 1988 and 1989 to determine nutrient interactions on corn (Zea mays L.) dry matter yields, N and P uptake and on soil N and K. In two sites (Chicot 1988 and Ormstown 1989) with dry surface soils, no rainfall for 5 d and significant rainfall after 5 d, broadcast urea resulted in higher dry matter yields and uptake of N than banded urea. In the Chicot 1989 site where urea application was on moist soil and followed by rainfall insufficient to move broadcast urea into the soil, banded urea was more effective than broadcast urea. Banded urea generally resulted in increased inorganic N and fixed [Formula: see text] in soil sampled from within fertilizer bands but lower levels in soil between bands in comparison with broadcast urea. Banding KCl resulted in increased exchangeable K+ in the band. Compared with exchangeable K+, fixed K+ was less affected by placement methods and rates of added N and K. Interactions between rates and placement methods of N and K on dry matter yield, N and K uptake and soil N and K were few and relatively small. Key words: Fertilizer placement, urea, KCl, Zea mays, grain, corn
Caractérisation de l'espace poral d'un sol argileux: effets de ses constituants et du travail du sol
Authors: Derdour H. , Laverdière M. R. , Angers D. A.
Published: April 2011

The objective of this study was to compare the effects of three tillage treatments and soil constituents on soil porosity characteristics. The experiment was initiated in the fall of 1987 on a Kamouraska clay (Orthic Humic Gleysol). Moldboard plowing, chisel plowing and no-till were compared during the fourth growing season of a continuous barley (Hordeum vulgare L.) system. Surface soil samples were taken in late May 1991 after seeding and at the beginning of October before primary tillage. Soil porosity was characterized by measuring the total porosity and its textural, structural and shrinkage components. The tillage treatments had no significant effect on total porosity. In May, however, the structural porosity was 25% larger under moldboard plowing than under no-till. On average for the two sampling dates, the interclod porosity was 51% larger under moldboard plowing than under no-till. In addition, this component of the structural porosity increased during the growing season under all treatments. In May, the shrinkage porosity decreased progressively from moldboard plowing to chisel and to no-till whereas the reverse trend was observed in the fall. Textural porosity was positively correlated with clay and organic carbon contents. This study shows that tillage affects mainly the structural porosity and in particular its interclod and shrinkage components. Key words: Tillage, total porosity, structural porosity, textural porosity, shrinkage porosity
In situ determination of the water desorption characteristics of peat substrates
Authors: Paquet J. M. , Caron J. , Banton O.
Published: April 2011

Knowledge of water desorption characteristics of peat substrates is of primary importance in horticulture. However, these characteristics are difficult to measure as they are influenced by sample preparation, particularly when samples are obtained from potted substrates containing growing plants. The aim of this study was to determine the effect of sample preparation on the water desorption characteristics of peat substrates and to propose an alternative method to limit sample disturbance. This study shows that water desorption characteristics of peat substrates obtained using Tempe cells differ from those obtained using pots and a tension table apparatus. However, the latter method is time and resource consuming. An alternative method for routine and rapid determination of water desorption characteristics of undisturbed samples was tested. Measurements of water potential (ψh) in pots were obtained using tensiometers. Volumetric water content (θ) was measured by time domain reflectometry (TDR), a non-destructive in situ method commonly used for mineral soil characterization. The technique measures the apparent dielectric constant of the soil (ka) and empirically relates it to θ. Empirical relationships between θ and ka were derived for three different peat substrates. Using these relationships, water desorption characteristics (θ versus ψh) were derived for three substrates in laboratory experiments and compared to water desorption characteristics obtained using a tension table to establish different ψh and a gravimetric determination of θ. The approach using TDR and tensiometers appears to be reliable, fast and to allow large number of simultaneous water characteristic determinations. Key words: Water characteristics, water release curve, time domain reflectometry, peat sustrates
Using 137Cs to investigate net soil erosion at two soil benchmark sites in Quebec
Authors: Cao Y. Z. , Coote D. R. , Wang C. , Nolin M. C.
Published: April 2011

137Cs in the soil was used to estimate soil erosion at two National Soil Conservation Program benchmark sites in the province of Quebec (sites 15-QU and 16-QU). The 137Cs baseline in an uneroded forest area was approximately 3100 Bq m−2. The 137Cs content at site 15-QU ranged from 1072 Bq m−2 to 6389 Bq m−2, while at site 16-QU it ranged from 663 Bq m−2 to 5444 Bq m−2. Computed net erosion over the past 30 yr at site 15-QU varied from a loss of 9.65 kg m−2 yr−1 to a gain of 10.88 kg m−2 yr−1 and at site 16-QU from a loss of 6.38 kg m−2 yr−1 to a gain of 1.73 kg m−2 yr−1. The average net erosion rates were 2.43 kg m−2 yr−1 at site 15-QU and 1.29 kg m−2 yr−1 at site 16-QU. Soil samples collected on a grid pattern indicated that 90% and 83% of the area at sites 15-QU and 16-QU, respectively, was subjected to net soil loss. A comparison of total 137Cs movement from eroded areas to depositional areas showed that 24.2% of 137Cs was lost from site 15-QU, while about 17.6% of 137Cs was lost from site 16-QU. Mapping of 137Cs content and calculated soil loss and deposition showed that soil erosion was closely related to topography.Under similar slope conditions, the soil erosion rates were 27–68% higher at site 15-QU than at site 16-QU. Higher tillage frequency and use of silage corn were the suggested reasons for the higher soil erosion rates at site 15-QU compared with site 16-QU, which had been used for hay and small grains. Key words: 137Cs, erosion, deposition, soil conservation