bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil respiration in barley (Hordeum vulgare L.) and fallow fields
Authors: Rochette P. , Desjardins R. L. , Gregorich E. G. , Pattey E. , Lessard R.
Published: April 2011

A study was carried out to quantify the diurnal variation of soil respiration in fallow and barley fields and to assess the impact of atmospheric CO2 concentration (C) and crop photosynthesis on soil respiration rates under field conditions. Soil respiration rate was measured twice a day (06:00 and 13:00 h EST) for 69 consecutive days at Ottawa, Ontario, Canada, during the 1990 growing season. Measurements were taken on fallow and under a barley (Hordeum vulgare L. ’Léger’) crop using a dynamic closed chamber system. Crop net photosynthesis was obtained by substracting soil respiration from the vertical CO2 fluxes above the crop which was obtained using the eddy correlation technique. Afternoon soil respiration averaged 22 and 17% more than that in the morning on fallow and barley soils, respectively. No correlation was found between atmospheric CO2 concentration and morning respiration rates. The two daily respiration measurements on fallow soil could be fit to the same function of soil temperature despite important differences in C at the time of measurement. These results indicate that soil temperature might account for the differences in R between morning and afternoon, and that the effect of C need not be considered for the modelling of the soil respiration diurnal cycle. Respiration in soil under barley was 25% lower than in fallow soil. Soil under barley was estimated to have at least 199 g C m−2 more than fallow soil at the time of harvest due to the lower soil respiration and to the input of carbon by barley root residues. High correlations were obtained between crop photosynthesis and soil respiration rates during vegetative and reproductive periods, confirming that the biotic plant component is an important factor controlling soil respiration rates in cropped fields. Key words: Root respiration, chamber measurements, CO2 flux, crop net photosynthesis, greenhouse gas, soil organic matter.
Reflectance characteristics of southern Alberta soils
Authors: Major D. J. , Janzen H. H. , McGinn S. M. , Olson B. M.
Published: April 2011

The reliability of reflectivity measurements for the remote sensing of crop productivity may be compromised by possible confounding effects of variation in soil color. An experiment was conducted to determine the influence of selected soil characteristics on reflectance in a broad range of soils typical of those found in southern Alberta. The reflectance of ground (< 2 mm) subsamples of 36 soils previously relocated to a common field site at Lethbridge Alberta was measured indoors with an artificial light source and a 60° field of view. Reflectance was measured between 400 and 1100 nm at 5-nm intervals. Reflectance of ground soils was strongly correlated to that of measurements in the field (r2 = 0.99), though values from the former were consistently higher. Soil reflectance declined with increasing organic carbon content in a quadratic relationship. Furthermore, there was a positive linear correlation between reflectance and soil carbonate content. Variation in organic C and carbonate accounted for 60% of the variability in reflectance among soils, based on multiple regression analysis. These findings confirm that soil carbon exerts a significant effect on reflectance and that reliable estimates of crop productivity by remote sensing requires correction for variable soil reflectance. Key words: Remote sensing, visible infrared reflectance, organic carbon
Nitrogen availability and nitrate leaching from organo-mineral fertilizers
Authors: Richards J. E. , Daigle J.-Y. , LeBlanc P. , Paulin R. , Ghanem I.
Published: April 2011

Greenhouse, field and laboratory studies were conducted to determine if N availability to corn (Zea mays L.) and NO3 leaching were affected by encapsulating conventional granular fertilizer within peat pellets (organo-mineral fertilizers or OMF). In the greenhouse, total N uptake by three 6-wk crops of corn from soil fertilized with NH4NO3 was 9.1% higher than the mean from soils fertilized with OMF made with urea (OMF-urea) or with NH4NO3 (OMF-AN). Total N uptake was 5.1% higher from soils fertilized with OMF-AN than OMF-urea. Differences in total N uptake among the fertilizers were constant across crops. In two field trials, total N uptake was slightly higher (4%) from soil fertilized with commercial NH4NO3 than with OMF-AN. In a laboratory experiment, NO3 from commercial NH4NO3 fertilizer leached more readily from soil than NO3 from OMF-AN. Approximately 95% of the NO3 from commercial NH4NO3 fertilizer leached from 3-cm soil cores in the first 50 mL of leachate whereas only 26% of the NO3 contained in OMF-AN leached. In another trial, NO3 from commercial NH4NO3 fertilizer leached more deeply than NO3 from OMF-AN after application of 2.5 cm irrigation water to soil in 63-cm leaching columns. Virtually no NO3 was retained within the OMF-AN pellet after leaching, suggesting that the retention of NO3 by OMF-AN used in our work is of limited duration. The OMF is an effective source of N to crops and is less prone to NO3 leaching losses than commercial NH4NO3 fertilizer when rain occurs soon after application. More work is required to determine the effect of pellet size and composition on NO3 retention, NO3 leaching losses and crop availability of N. Key words: Nitrate leaching, corn, organo-mineral fertilizers
Nitrogen availability for corn in soils amended with urea, cattle slurry, and solid and composted manures
Authors: Paul J. W. , Beauchamp E. G.
Published: April 2011

This study was conducted to determine whether manure N availability for corn (Zea mays L.) was best estimated by a component of the manure N or by soil inorganic N in May or June. Liquid dairy cattle manure, solid beef cattle manure, and composted beef cattle manure were applied in the spring of 1988, 1989 and 1990 at rates of 100, 200 and 300 kg N ha−1. Urea was applied at rates of 50, 100 and 150 kg N ha−1 for comparison. The N recovery by the harvested portion of the corn (grain + stover) in 1988 and 1990 averaged 49, 18, and 5% of the total N in urea, liquid dairy cattle manure, and solid or composted beef cattle manure, respectively. There was no yield response to any N source in 1989 because of high soil fertility. Relative nitrogen uptake by the corn grain + stover in 1988 and 1990 was significantly correlated with inorganic N applied as manure or fertilizer (r2 = 0.56), but not with total N applied (r2 = 0.02). When the data from all 3 years were analyzed, relative nitrogen uptake was better correlated with soil NH4 + NO3 in mid-May and soil NO3 in early-June (r2 = 0.83 and 0.76, respectively), than with inorganic N applied as manure or fertilizer (r2 = 0.20). A soil N test after manure application in mid-May to early June may be the best N management tool for corn production on livestock farms in Ontario. Key words: Animal manure, fertilizer, corn yields, soil nitrate test, nitrogen availability
Activity of arylsulfatase in Saskatchewan soils
Authors: Gupta V. V. S. R. , Farrell R. E. , Germida J. J.
Published: April 2011

In this study we investigated the occurrence of arylsulfatase activity in Saskatchewan soils and assessed the relationships between enzyme activity and soil properties. Thirty-nine soils representative of the five soil zones in Saskatchewan, and exhibiting a wide range of physical, chemical, and biological characteristics were studied. Arylsulfatase was detected in all the soils. Enzyme activity ranged from 14 to 770 μg ρ-nitrophenol released g−1 soil h−1. Arylsulfatase activity was highly correlated with levels of organic C (r = 0.73***), total S (r = 0.74***), HI-S (r = 0.60***), and microbial biomass C (MB-C; r = 0.56***). There was a relatively weak positive correlation (r = 0.48**) between arylsulfatase activity and the amount of SO4-S in the soils, indicating that end-product inhibition of the enzyme was not a factor at the low levels of SO4 commonly found in Saskatchewan soils. Key words: Sulfur, HI-reducible S, microbial biomass, organic C
Short-range variability of fallout 137Cs in an uneroded forest soil
Authors: Nolin M. C. , Cao Y. Z. , Coote D. R. , Wang C.
Published: April 2011

Use of fallout 137Cs for measuring soil erosion rates requires an accurate estimate of the mean areal activity of 137Cs of an uneroded reference site. To study the short-range variability of 137Cs in a forest soil, 16 profiles were sampled in a small area (8 × 8 m). Variability was relatively low (CV = 16%), so that the mean areal activity (3163 Bq m−2) at this reference site was estimated with a relatively low allowable error (< 10%) at relatively high confidence level (95%). To obtain a satisfactory estimate of the mean areal activity of 137Cs of reference sites, particularly those located in forest areas, it is suggested to collect at least five subsamples, 1–10 m apart and composite them into a single sample for analysis. Key words: 137Cs, short-range variability, water erosion
An empirical model of denitrification
Authors: Bergstrom D. W. , Beauchamp E. G.
Published: April 2011

We used a simple empirical model to predict denitrification rates from measurements of bulk soil properties. Boundary analysis was used to define relationships between denitrification rate and each of air-filled porosity, respiration rate and mineralizable-C content. The ratio of measured denitrifying enzyme activity to the maximum measured value was used to account for variation in amounts of enzymes and numbers of denitrifiers in soil. Nitrate content had little effect on denitrification rate and was excluded from the model. Because the model did not account for microscale variability, it did not accurately predict rates in individual soil cores. Nevertheless, population means and distributions of predicted and measured values were similar. The seasonal patterns of mean values of predicted and measured denitrification rates were also similar over the second half of the sampling period, which extended from May to November. The model did not account for appreciable denitrification on three dates in May. This discrepancy indicated that environmental regulation of denitrification may not be uniform over the season. The model was not sufficiently sensitive to factors influencing episodic events. Key words: Denitrification rate, model, boundary line
Clay mineralogy of parent materials derived from uppermost Cretaceous and Tertiary sedimentary rocks in southern Saskatchewan
Authors: Dubbin W. E. , Mermut A. R. , Rostad H. P. W.
Published: April 2011

Soils developed from parent materials derived from uppermost Cretaceous and Tertiary sedimentary rocks have been delineated from those which do not contain any of these younger sediments. The present study was initiated to determine the validity of this delineation. Parent materials from six locations in southwestern Saskatchewan were collected to determine their general chemical and physical properties. Clay fractions from each of these six parent materials were then subjected to detailed chemical and mineralogical analyses. The two parent materials containing the greatest amount of post-Bearpaw bedrock sediments (Jones Creek, Scotsguard) were characterized by substantially more organic carbon and less CaCO3. The presence of coal and the absence of carbonates in local bedrocks were considered to be the source of these deviations. In general, fine clays were comprised of 64–69% smectite, 14–21% illite and 10–13% kaolinite and coarse clay contained 32–39% smectite, 25–34% illite and 11–14% kaolinite. An exception was found in two fine clays which had less smectite but 3–6% vermiculite. Total iron content of the fine clays ranged from 7.16 to 8.11% expressed as Fe2O3. However, only a small fraction of this iron was extractable using the CDB technique. There were no substantial differences in surface areas or CECs of the clay fractions. Despite minor differences in the chemistry and mineralogy of these six parent materials, a separation of the soil associations does not appear to be warranted. Key words: Parent materials, uppermost Cretaceous, Tertiary, bedrock, clay mineralogy
Rapid changes of sandy soils caused by vegetation changes
Authors: Nørnberg P. , Sloth L. , Nielsen K. E.
Published: April 2011

Development of Typic Haplorthods in a heathland area in Denmark responded over a short period of time (decades) to changes of vegetation. Part of the heath, Hjelm Hede, was left undisturbed and was invaded by trees, mainly oak and a few aspen and conifers. Another part of the heath was planted with Norway and Sitka spruce 60–70 yr ago. The soils under heath, oak and spruce were studied. Major differences were found, some visible in the field and others detectable in the laboratory. Under oak, relative to heath, horizon boundaries were less distinct, pH increased in the top horizons, organic carbon and C/N ratio decreased, and iron and aluminum contents in the upper B horizons decreased. Compared with the original heath podzol, the soil under spruce had a lower pH in the O, E and upper B horizons, higher organic carbon content and C/N ratio in the top horizons, increased cementation, and a placic horizon. However the pyrophosphate-extractable iron and aluminum content was significantly lower than in any of the other soils. The soil under oak showed "depodzolization" features, whereas the soil under spruce was increasingly podzolized, though the podzolization mechanism might be different from that under heath. Analyses of phenolic compounds in the soil water were consistent with these conclusions. The three main components of substituted benzoic acids were gallic acid, protocatechuic acid and coumaric acid, which are all strongly complexing agents believed to take part in the podzolization process. Generally, the highest concentrations were found under spruce and the lowest under oak.Key words: Vegetation-induced soil changes, Spodosols, phenolic compounds
Effects of three tillage treatments on seasonal runoff and soil loss in the Peace River region
Authors: Vliet L. J. P. van , Kline R. , Hall J. W.
Published: April 2011

Three tillage treatments were evaluated over a 4-yr period for their effects on runoff and soil loss under natural precipitation on a Donnelly silt loam soil (Solonetzic Gray Luvisol) near Dawson Creek in the Peace River region of British Columbia. Conventional-tilled (CT) plots (spring or fall cultivation) received twice the amount of tillage as the reduced-tilled (RT) plots, while the zero-tilled (ZT) plots were only disturbed at seeding once a year. The plots were seeded to barley (Hordeum vulgare L.). Rainfall and snowmelt runoff were collected throughout the year to determine seasonal runoff and soil losses. The effects of the tillage treatments on runoff and soil loss depended on the season (whether caused by rainfall or snowmelt) and the crop year. Mean snowmelt runoff was ZT > CT > RT. Conventional tillage had significantly higher rainfall runoff and soil loss from snowmelt than the other two tillage treatments, with no significant differences between RT and ZT. Mean rainfall-induced soil loss was significantly different for each tillage treatment, with CT > RT > ZT. Soil losses from snowmelt were low, less than 30% of those from rainfall, since snowfall was 45% below normal. Soil losses from rainfall were consistently higher than from snowmelt for each tillage treatment in each of the four crop years and provided over 75% of the 4-yr total annual soil loss. Tillage effects were more pronounced in years with low runoff and soil loss than in years with high runoff and soil loss. Zero tillage and RT are effective in reducing average annual soil losses by 81 and 53%, respectively, of those observed under conventional tillage. Key words: Runoff, soil loss, erosion plots, seasons, tillage
Nitrous and nitric oxide emissions during nitrification and denitrification from manure-amended soil in the laboratory
Authors: Paul J. W. , Beauchamp E. G. , Zhang X.
Published: April 2011

Denitrification and nitrification processes in soil produce significant amounts of atmospheric N2O and NO. Laboratory experiments were designed to measure N2O and NO emissions from an agricultural soil shortly after manure addition. Nitrous oxide emissions were higher from soil following addition of manure slurries than following addition of composted manure. Emissions of both N2O and NO were highest between 1 and 4 d after manure addition. Nitrous oxide emission following manure application was the result of both denitrification and nitrification, which occurred simultaneously in soil. Denitrification was a major producer of N2O because both denitrification rates and N2O emission increased dramatically at higher soil-moisture contents and increased manure concentration. Nitric oxide production occurred during nitrification. Nitrous oxide emitted during the 6 d after manure addition ranged from 0.025 to 0.85% of the manure N. Nitric oxide emissions were approximately 0.26% of the amount of added manure N.Key words: Nitrous oxide, nitric oxide, manure, denitrification, nitrification
Micromorphological and 13C NMR characterization of a Humic, Lignic, and Histic Folisol from British Columbia
Authors: Fox C. A. , Preston C. M. , Fyfe C. A.
Published: April 2011

The thick folic (mainly upland forest) materials (> 40 cm of accumulated organic material) that occur in the Coastal Western Hemlock Biogeoclimatic Zone in British Columbia have not been described with regard to the spatial interrelationships of the soil constituents in context with the chemical composition of the different horizons. Micromorphological assessment and solid-state 13C NMR were used to characterize the accumulated folic materials from a Lignic Folisol (northern Vancouver Island), Histic Folisol (Prince Rupert, BC) and a Humic Folisol (Queen Charlotte Islands, BC). Micromorphology provided information on the spatial relationships of the soil constituents and 13C NMR provided data on the chemical components of the folic materials. Soil faunal activity, primarily from mites, was the dominant soil-forming process observed in the organic horizons of the Folisols, being especially prominent in the Lignic Folisol with the breakdown of woody materials. Solid state 13C CPMAS NMR spectra facilitated distinguishing three main types of horizons: (1) Horizons derived from accumulated residues (L, Fr, and Hr) showing higher carbohydrate-like C and O-alkyl C values and lower total aromatics; (2) Horizons with advanced decomposition (Hr2, Oh1, and Hd) which were higher in alkyl C; and (3) Horizons derived from ligneous material (Fw and Hdw) where carbohydrate-like C was less than total aromatic C. Implications for adequate nutrient content and forest growth were inferred from the observed micromorphology and chemical composition of the folic materials. Key words: Folisol, forest soils, micromorphology, 13C NMR, faunal activity
Naturally occurring gamma-emitting isotopes, radon release and properties of parent materials of Saskatchewan soils
Authors: Jong E. de , Acton D. F. , Kozak L. M.
Published: April 2011

Mineral composition of the parent material is a major factor controlling natural radioactivity of soils. The objective of this study was to investigate the relationship between the natural radioactivity of 18 till and six lacustrine parent materials and their properties measured during soil surveys. Gamma spectroscopy was used to estimate 40K and daughters of 238U and 232Th; neutron activation analysis was used to determine total U; and alpha counting was used to measure 222Rn release from the soil. The amounts of the various radioisotopes were positively correlated with each other and with clay content; the correlation with sand content was negative; and the correlations with silt and inorganic C content were generally not significant. Adding the fine/total clay ratio as a further independent variable considerably improved the correlation between 40K and clay content. The data suggested considerable disequilibrium in the 238U decay chain, which appeared to be in part related to the mode of deposition of the parent materials. Soil survey information — in particular, texture — thus appears a readily available tool for preliminary screening of terrestrial radiation in Saskatchewan. Key words: Radioactivity, 40K, uranium, thorium, radon, texture
Improved soil quality and barley yields with fababeans, manure, forages and crop rotation on a Gray Luvisol
Authors: Wani S. P. , McGill W. B. , Haugen-Kozyra K. L. , Robertson J. A. , Thurston J. J.
Published: April 2011

There exists a need (i) to test, whether equal or better cereal yields could be obtained using cropping systems which rely on renewable resources rather than on fertilizer nitrogen; and (ii) to discover the condition of the soil resource under these systems.The long-term cropping systems on a Gray Luvisol at Breton were studied. They included: (i) an agro-ecological 8-yr rotation (AER), established in 1981, which involved addition of both fababean green manure and manure from livestock fed with forages and fababeans grown in the rotation: (ii) a continuous grain (barley) system (CG), with fertilizer N at 90 kg ha−1 y−1, established in 1981; (iii) a classical Breton 5-yr rotation (CBR) involving forages and cereals, with no return of crop residues or manure, established in 1930. Mean barley yields were 16–19% higher in the AER (P ≤ 0.05) than in the CG system, and yield on either was about double that of the CBR. Within 9 yr, there was evidence of increased total C, N, and P; available N, P and K, CEC; microbial biomass, microbial respiration; and counts of bacteria, fungi, and mycorrhizae in the AER compared with the CG system.We conclude that biological fixation of N by legumes can be used as the sole source of N for barley production on Luvisolic soils of low fertility such as the Breton loam, without sacrificing yield or soil quality. Barley yields in the AER (38% of the rotation time) exceeded those of barley grown under continuous cereal cropping. The soil resource was maintained or improved during a 10-yr period under AER compared to the CG or CBR systems. Further research is needed to discover the mechanisms involved in regulating biological activity and availability of plant nutrients other than N in the AER system. Key words: Barley, Breton loam, cropping systems, Gray Luvisol, soil quality, fababeans
Pedogenic and geochemical processes of ultramafic soils along a climatic gradient in southwestern British Columbia
Authors: Bulmer C. E. , Lavkulich L. M.
Published: April 2011

This paper presents information on pedogenic processes, weathering status and geochemical evolution of ultramafic soils at three areas in southwestern British Columbia characterized by climatic conditions ranging from relatively wet–cool to relatively dry–cool. The soils of the Coquihalla serpentine belt have Podzolic profiles that resulted from intense weathering in a moist environment. The Tulameen area has a moderately dry climate, and Brunisolic soils have developed in serpentinized peridotite and dunite. Brunisolic soils with composite profiles of tephra overlying serpenite developed in a dry environment at the Shulaps area. We investigated the weathering status of five soils using a variety of chemical and mineralogical techniques. Chlorite and mica weathering was indicated by XRD analysis of clay fractions for the Podzolic soils at the Coquihalla area. Serpentine dissolution was also indicated by geochemical analysis of these upland soil profiles. Weathering and leaching depleted Mg from B horizons relative to parent materials. Chromium accumulated in B horizons of the soils, and was associated with high levels of Fed. The distribution of total and extractable Ni and Co indicated that these elements were transported to the C horizons in all but the driest environments. Redistribution of Mn also occurred, but to a lesser extent. The distribution patterns of Cr, Mn, Co, and Ni were useful indicators during the early stages of ultramafic pedogenesis. Key words: Serpentine, ultramafic rocks, mineralogy, soil processes, trace minerals
Genesis of Solonetzic soils as a function of topography and seasonal dynamics
Authors: Miller J. J. , Pawluk S.
Published: April 2011

A Gleyed Black Solonetz at a depressional slope position, a Black Solonetz at a lower slope position, a Black Solodized Solonetz at a mid-slope position, and a Black Solod at an upper slope position in central Alberta, were investigated using chemical, physical and mineralogical techniques to determine the role of topographic position and season in their genesis. Solonization, as indicated by electrical conductivity (EC) values < 4 dS m−1 and exchangeable sodium percent (ESP) values > 15% in the B horizon, was greatest in the Gleyed Black Solonetz, and then decreased in the soils upslope. Solonization occurred during the spring, summer and fall in the B horizon of the Gleyed Black Solonetz and Bnt1 horizon of the Black Solod, and during the spring in the B horizon of the Black Solonetz, Bnt1 horizon of the Black Solodized Solonetz, and Bnt2 horizon of the Black Solod. Solodization, as indicated by the development of Ae and AB horizons, acidic conditions and higher dithionite-extractable Al in the upper sola, and high exchangeable acidity in the upper B horizons, was greatest in the Black Solod at the upper slope position, moderate in the Black Solodized Solonetz at the mid-slope position, and absent in the two soils at the lower slope positions. Solodization as reflected by exchangeable acidity, also exhibited seasonal fluctuations, particularly in the upper B horizons. Seasonal variations of exchangeable Na, Ca and Mg in the B horizons, however, were slight to nonexistent. Topographic position and seasonal fluctuations of soluble salts and exchangeable acidity in the B horizons played a major role in the genesis of soils in this Solonetzic catena. Key words: Solonetzic catena, solonization, solodization, topography, seasonal dynamics
Laboratory calibration of pressure transducer-tensiometer system for hydraulic studies
Authors: Azooz R. H. , Arshad M. A.
Published: April 2011

Pressure transducer-tensiometer (PTT) systems can be used to continuously monitor soil pore water pressure and the hydraulic gradient distribution in a field, and under laboratory conditions over relatively short time intervals. A reliable laboratory calibration of a PTT system can determine the effects of temperature fluctuations on output readings in the field. Laboratory calibrations of 20 PTTs were conducted under constant pressures of 0, − 25, − 50 and − 75 kPa and constant temperatures of 5, 15, 25 and 48 °C. Twenty Bourdon gauge tensiometers (BGTs) and pressure transducers (PTs) were also calibrated to check changes in the sensitivity and effectiveness of the PTT system, when the Bourdon gauge of the tensiometer is replaced by a PT. Readings of all the three systems revealed that pressure values gradually declined with an increase in temperature. With a temperature change from 5 to 48 °C, the pressure values at constant pressures of 0, − 25, − 50 and − 75 kPa decreased by 0, 3.7, 4.1 and 4.5 kPa for the BGT; 2.05, 2.16, 2.23 and 2.44 kPa for PT and 2.53, 2.87, 2.88 and 3.17 kPa for PTT. As the influence of temperature on the calibration curve of the PTT and PT systems was different, it is recommended that the complete PTT system should be calibrated in the laboratory to adjust the output readings to the anticipated temperature in the field. Key words: Tensiometer, tensiometer-pressure transducer, soil pore water pressure, hydraulic gradient
Towards a minimum data set to assess soil organic matter quality in agricultural soils
Authors: Gregorich E. G. , Carter M. R. , Angers D. A. , Monreal C. M. , Ellert B. H.
Published: April 2011

Soil quality is a composite measure of both a soil’s ability to function and how well it functions, relative to a specific use. Soil quality can be assessed using a minimum data set comprising soil attributes such as texture, organic matter, pH, bulk density, and rooting depth. Soil organic matter has particular significance for soil quality as it can influence many different soil properties including other attributes of the minimum data set. Assessment of soil organic matter is a valuable step towards identifying the overall quality of a soil and may be so informative as to be included in minimum data sets used to evaluate the world’s soils.In this review, soil organic matter is considered to encompass a set of attributes rather than being a single entity. Included among the attributes and discussed here are total soil organic carbon and nitrogen, light fraction and macroorganic (particulate) matter, mineralizable carbon and nitrogen, microbial biomass, soil carbohydrates and enzymes. These attributes are involved in various soil processes, such as those related to nutrient storage, biological activity, and soil structure, and can be used to establish different minimum data sets for the evaluation of soil organic matter quality. Key words: Biological activity, minimum data set, nutrient storage, soil organic matter, soil quality, soil structure
Winter wheat growth and nitrogen demand in south coastal British Columbia
Authors: Bomke A. A. , Temple W. D. , Yu S.
Published: April 2011

Winter wheat, Triticum aestivum, is a new crop in south coastal British Columbia. The purposes of this study were to characterize plant development, dry matter accumulation and N uptake under low input and intensively managed systems as well as to assess the capability of some of the region’s soils to supply N to the crop. Grain yields, crop development and dry matter and N accumulation were similar to those reported from southern England. High amounts of winter rainfall (November–April precipitation ranged from 523 to 1111 mm) leach virtually all residual NO3 from south coastal B.C. soils and, without N fertilization, result in uniformly N deficient winter wheat. The low input N regime, 75 kg N ha−1 at Zadoks growth stage 31, plus soil N mineralized subsequent to the winter leaching period were sufficient in this study to maximize grain and total aboveground crop dry matter yields, but not to achieve adequate grain protein contents. The soils in the study were capable of supplying N in amounts sufficient to support only 30–53% of the maximum N uptake between growth stages 31 and 78. Appropriate quantities and timing of N are critical to successful production of high-yielding, good-quality wheat in south coastal British Columbia. Nitrogen management is likely to be most efficient when guided by the stage of crop development and demand and not by spring soil sampling and mineral N analysis. Key words: Winter wheat, N demand, soil N supply, crop development, intensive crop management, low input
Quantification des processus de minéralisation et d’organisation de l’azote dans un sol en présence d’amendements organiques
Authors: Jedidi N. , Cleemput O. Van , M’Hiri A.
Published: April 2011

Quantification of the processes of gross mineralization and immobilization is very important to make full nitrogen balances. These processes were quantified in a clay loam soil (S) after application of nitrogen K15NO3 (N) and four organic amendments (two composts of domestic waste of different ages (C1 and C3), residual waste from a treatment plant (B) and farmyard manure (F) as a control). This study was carried out during a 1–2 mo incubation at a temperature of 25 °C and a moisture content of 2/3 of the field capacity. The mineralization and immobilization processes depended on the nature of the organic amendments, their degree of stability and their nitrogen content. N mineralization was correlated with C/N ratios (r = 0.936), N contents (r = 0.880), hemicellulose contents (NDF – ADF) (r = 0.869), (hemicellulose + cellulose + lignin)/N ratios (NDF/N) (r = 0.886) and (cellulose + lignin)/N ratios (ADF/N) (r = 0.869). The immobilization of N was correlated to (cellulose + lignin) contents (ADF) (r = 0.607). The amount of mineralized N (mg kg−1) during this month was in the following decreasing order: S + N + B (94.3) > S + N + F (14.3) > S + N + C3 (4.92) > S + N (− 0.31) > S + N + C1 (−20.1). Organic amendments application favored the process of N immobilization which decreased with the degree of stability of organic materials. The amount of N immobilization (mg kg−1) was in the following decreasing order: S + N + B (53.3), S + N + C1 (49.1), S + N + F (36.72), S + N + C3 (35.6) and S + N (29.1). The loss of nitrogen (between 2 and 20%) was attributed to dénitrification or volatilization. Key words: Mineralization, immobilization, organic amendments, 15N
The role of long-term sites in agroecological research: A case study
Authors: Janzen H. H.
Published: April 2011

Gradual, episodic or subtle changes in agroecosystems can be definitively measured only in long-term studies. The objective of this paper is to illustrate the benefits and limitations of long-term agroecological sites using a crop rotation study (Rotation ABC) established at Lethbridge, Alberta in 1910. Long-term agroecological sites, envisioned as part of a continuum of research levels, seek to determine the persistence of cropping systems with respect to their effects on soil resources and the larger environment. Examples of research findings arising from such sites include the documentation of long-term changes in agricultural productivity, measurement of organic matter changes over time, calculation of long-term nutrient budgets, and verification of simulation models. For example, soil organic matter concentrations in Rotation ABC were found to decline abruptly within the first few decades of cultivation and then approach a new steady state. Despite the continual removal of N in harvested grain, soil N concentrations also appear to have stabilized, suggesting an accession of N approximately equivalent to the amount harvested. Common limitations of long-term sites like that at Lethbridge include: rudimentary experimental design, evolving management practices, incidental changes at the sites, and variation in sampling protocols. The successful use of long-term agroecological sites depends on well-defined objectives, simplicity of design, adequate scale, consistent data and sample collection, and collaboration among sites. The primary justification for the establishment and maintenance of long-term agroecological sites may be their future role in answering questions not yet envisioned. Key words: Soil organic matter, long-term studies, crop rotations, sustainability, fertilizer
Spatial variability of soil porosity under reduced tillage in a Humo-Ferric Podzol
Authors: Carter M. R.
Published: April 2011

The spatial and random variability of soil bulk density, water-filled pore space and macroporosity, which are important indices of soil physical quality in a humid soil moisture regime, were studied in soil samples taken from direct-drilled rotations at Charlottetown, Prince Edward Island. Classical statistics indicated variation was low for bulk density (CV = 3.0–5.8%) and water-filled pore space (CV = 7.4–10.3%), and medium (CV = 15.7–29.6%) for macropore volume. Spatial variation determined using variograms indicated some degree of spatial structure. The ability of variograms to divide sample variance into random and spatial components allows improved estimation of soil sampling size and spacing. Key words: Geostatistics, soil sampling, direct-drilling, humid climate
Foliar deficiencies of sugar maple stands associated with soil cation imbalances in the Quebec Appalachians
Authors: Ouimet Rock , Camiré Claude
Published: April 2011

Widespread symptoms of foliar deficiency of P and K have been observed for almost a decade in most of the declining hardwood forest in the Quebec Appalachians. We hypothesized that the foliar nutrient disturbances were related to the chemical equilibrium of exchangeable soil cations. Mature sugar maple (Acer saccharum Marsh.) foliage, and soil H-Ah and B horizon from 246 hardwood stands located in the Quebec Appalachians were sampled and analyzed. A cluster analysis using the Diagnosis and Recommendation Integrated System (DRIS) indices of the foliar data permitted the identification of six different nutritional groups: one slightly and one strongly deficient group in P-K, three groups having a K-Ca deficiency at different intensities from weak to strong, and one group having a strong P-K-Ca deficiency. These foliar nutrient status were strongly related to some soil properties. The P-K deficient groups had a 30% lower K saturation in the H-Ah horizon than the average level of the other groups, but a higher proportion of exchangeable Ca in the H-Ah and B horizon. For the four groups that were K-Ca deficient, increased nutrient stress was associated with reductions in soil Ca saturation and pH, and, particularly, increases in soil Mg saturation. Also, the Ca/(H+Al) ratio of exchangeable cations in the B horizon was ≤ 0.6 for these groups. High soil Mg saturation, potential soil Al toxicity related to low Ca saturation, and unfavorable soil humus properties were associated with the severity of nutrient stress. To obtain a balanced nutrition for sugar maple in this region, the forest humus should have less than 10% of Mg on exchange sites, a Ca/Mg ratio of exchangeable cations > 6, and a K/Mg ratio > 0.5. The values in the mineral B horizon should be < 10% for Mg/CEC, > 4 for the Ca/Mg ratio, > 1 for the K/Mg ratio, and > 1 for the Ca/(H+Al) ratio. Key words:Acer saccharum, cation saturation, Diagnosis and Recommendation Integrated System, forest decline, nutrient status, soil properties
Sodicity in irrigated soils in Saskatchewan: Chemistry and structural stability
Authors: Curtin D. , Steppuhn H. , Selles F. , Mermut A. R.
Published: April 2011

Irrigation with sodic waters may damage soil structure, but neither the processes involved nor the critical levels of exchangeable Na have been well defined for prairie soils. We examined two irrigated soils from southern Saskatchewan on which sodicity damage had occurred to determine the processes and the chemical conditions (exchangeable Na and electrolyte concentration) that cause structural damage. Dispersion of clays in the upper 20 cm of the profile seemed to be the primary cause of structural deterioration. Examination of irrigated soil by scanning electron microscopy (SEM) showed that sand- and silt-size grains were stripped of binding colloidal particles and that large pore spaces had formed, creating very loose aggregates. In one of the soils, physical instability was observed at an exchangeable-Na percentage (ESP) of only about 10%, indicating that some soils in Saskatchewan are relatively sensitive to sodicity. With a 1:5 (wt vol−1) soil/water extract, the electrical conductivity (EC) needed to prevent clay dispersion when soil suspensions were mechanically agitated was about 0.2 dS m−1 in the absence of Na, increasing to 1.5–2 dS m−1 at a sodium adsorption ratio of 20 (mmolc L−1)0.5. Sodic conditions greatly altered soil chemical behavior, with the most sodic soil having an extremely high level of water-extractable P. In a laboratory experiment, addition of Ca (as CaCl2 or gypsum) to replace Na reduced water-extractable P from 78 mg kg−1 to less than 20 mg kg−1. The effect of sodicity on P solubility was likely due to a decrease in surface electrostatic potential as exchangeable Na increased. Increased solubility of P along with the potential for runoff and erosion from Na-affected soils could result in increased inputs of P to surface waters. Key words: Sodicity hazard, clay disperson, phosphate solubility
SHORT COMMUNICATION: Methane emission from a usually well-drained prairie soil after snowmelt and precipitation
Authors: Wang F. L. , Bettany J. R.
Published: April 2011

Usually well-drained soils, when they are flooded periodically, are a sporadic source for greenhouse gases such as methane. Using a static chamber technique in the field, we found methane emission, which ranged from 7.8 (cultivated site) to 10.5 mg m−2 d−1 (grassland site), from the lower slope positions after snowmelt in the spring. Smaller methane emission was also observed after rainfall in the summer: 0.02–0.64 mg m−2 d−1 after 23–79 mm of precipitation. Key words: Methane emission, spring snowmelt, short-term flooding
Changes in the forms and distribution of soil phosphorus due to long-term corn production
Authors: Richards John E. , Bates Thomas E. , Sheppard S. C.
Published: April 2011

Long-term fertilizer-P application affects soil-P distribution and forms. These effects must be characterized to use fertilizer P most efficiently. In three southern Ontario soils of varying texture, we determined changes in soil organic P (Po) and inorganic P (Pi) caused by fertilizer P application (0–90 kg broadcast P ha−1 yr−1 during 10 yr of corn production. Soil P was characterized by (1) annual measurement of 0.5 M NaHCO3-extractable P (Olsen-P) and (2) sequential extraction from soil taken at the beginning of the experiment and after receiving 0 to 90 kg broadcast P ha−1 yr−1 for 10 yr. Fertilizer P increased Olsen-P concentrations in all soils. The increases were proportional to the cumulative amount of P applied. Based on all three soils, 16 kg P ha−1 was required to increase Olsen-P concentrations by 1 mg L−1 soil. After 10 yr of 90 kg broadcast P ha−1 yr−1, labile Pi fractions (resin P and NaHCO3 P) were increased, as was NaOH-extractable Pi in all soils. On the most P-deficient soil (Conestogo SiL), where corn grain yields were increased by fertilizer P, P fertilization also increased HCl-Pi, residual P (H2O2-H2SO4 extractable P) and labile Po (NaHCO3-Po and NaOH-Po). A P balance was calculated, which accounted for additions to, removals from, and changes in the total P status of the 0–20 cm layer. When no broadcast P was applied, there was an unaccounted-for input (possibly from the subsoil), of 20.9 kg P ha−1 yr−1 on the Conestogo SiL. When 90 kg broadcast P ha−1 yr−1 was applied to the Fox SL, the coarsest soil studied, there was a deficit of 30.9 kg P ha−1 yr−1 and elevated Olsen-P concentrations in the 25–36 cm depth, suggesting downward movement on fertilizer P. It appears that subsoil P was involved in the P cycle of these two soils. Key words: Continuous corn, P fertilization, sequential extraction, organic phosphorus, inorganic phosphorus, labile phosphorus, subsoil P, leaching
Soil amendments and water-stable aggregation of a desurfaced Dark Brown Chernozem
Authors: Sun Haiguo , Larney Francis J. , Bullock Murray S.
Published: April 2011

Aggregate stability, which influences soil resistance to wind and water erosion, can be improved by the application of organic amendments. In spring 1992, a desurfaced Dark Brown Chernozem in southern Alberta was amended with six animal manures, four crop residues and two rates of phosphate fertilizer, to determine their efficacy in restoring soil productivity. Eroded check (no amendment) and topsoil check (no desurfacing) treatments were left for comparison. One year later, wet aggregate stability at five levels of aggregate pre-wetting was determined. Aggregate stabilities of crop residue-amended soils were significantly higher (P < 0.01) than those of soils treated with animal manures or fertilizer/checks at all wetness levels. Significant (P < 0.01) quadratic response and plateau relationships between aggregate stability and soil water content showed that there was a threshold moisture content for maximum stability. With the onset of rainfall, aggregates on the crop residue-amended treatments would reach maximum stability sooner than those on the fertilizer/check treatments, thereby decreasing the potential for water erosion. Stability of air-dry aggregates showed weak positive relationships with organic and inorganic C. Amendment of eroded soils with crop residues is likely more effective in limiting erosion than amendment with animal manures or chemical fertilizers, at least in the first year after incorporation. Key words: Soil erosion, aggregate stability, animal manure, crop residue
Residue detections in soil and shallow groundwater after long-term herbicide applications in southern Alberta
Authors: Miller J. J. , Hill B. D. , Chang C. , Lindwall C. W.
Published: April 2011

After herbicide applications for 1–24 yr, there were no detectable residues of glyphosate, dicamba, 2,4-D, bromoxynil or methylchlorophenoxyacetic acid (MCPA) in soil at two long-term tillage sites and one long-term manured site. The only detectable residues in soil were of diclofop and triallate. Residues of bromoxynil, diclofop and MCPA but not dicamba, 2,4-D or triallate, were detected in the groundwater at the manured site. Diclofop was detected in 6% and bromoxynil and MCPA in 2% of 84 water samples collected at the manured site. Maximum concentrations of bromoxynil (6.5 μg L−1) and diclofop (47 μg L−1) in the groundwater at the manured site exceeded levels set by the Canadian drinking water guidelines. Long-term application of herbicides has not caused accumulation of harmful residues in southern Alberta soils, but the presence of certain herbicides in the groundwater at concentrations above the level set by the drinking water guidelines is cause for concern. Key words: Herbicide residues, tillage, manure, soil, groundwater
Long-term changes in Mehlich-3 extractable P and K in a sandy clay loam soil under continuous corn (Zea mays L.)
Authors: Zhang T. Q. , MacKenzie A. F. , Liang B. C.
Published: April 2011

Rates of change of soil nutrient levels during crop production can be used to evaluate the long-term economic value and sustainability of fertilizer practices. Objectives were to quantify changes in Mehlich-3 extractable P and K due to additions of inorganic and manure P and K in corn (Zea mays L.) production. Surface (0–20 cm) and subsoil (20–40 cm) samples were collected after harvest from 1984 to 1993 on a Chicot sandy clay loam soil (Grey Brown Luvisol) fertilized with two rates of inorganic P and K and with dairy manure. Manure P at 60 kg P ha−1 plus inorganic fertilizer P at 132 kg ha−1 yr−1 increased extractable P 1.0 kg for every 4.2 kg added P if only topsoil was considered, for every 3.2 kg added P if corn grain P removal was deducted, and for every 2.8 kg added P if subsoil increases were included but corn P uptake excluded, and 2.1 kg added P with subsoil P included and corn P removal deducted. Without manure, 132 kg P ha−1 yr−1 increased Mehlich-3 extractable P by 1.0 kg for every 8.1 kg P added, or 5.3 kg P added if corn P removal was deducted from added fertilizer P. At the low rate of 44 kg P ha−1 with manure P, Mehlich-3 levels increased by 1.0 kg P for every 5.2 kg added fertilizer P. Extractable P remained constant when inorganic fertilizer P was added without manure, probably because crop removals equalled fertilizer additions. Mehlich-3 extractable K increased in both top soil and subsoil at rates of 141 and 332 kg ha−1 yr−1 inorganic K except for the 141 K rate in the final four years when no manure was applied. When both soil depths were included and summed over all years, values of added K to increase extractable K by 1.0 kg ranged from 4.2 to 5.5 kg, regardless of source or rate of added K. To increase soil test P, manure combined with high P rates was more effective per unit added P than low P rates or added P without manure. Either form or rate of added K was equivalent in increasing extractable K. Key words: Long-term fertilization, continuous corn, organic manure P, inorganic P, Mehlich-3 extractable P, Mehlich-3 extractable K