bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between denitrification rate and determinant soil properties under barley
Authors: Bergstrom D. W. , Beauchamp E. G.
Published: April 2011

To better understand environmental regulation of denitrification, we examined relationships between denitrification rate and six determinant soil properties: moisture content, air-filled porosity, NO3− content, respiration rate, mineralizable-C concentration and denitrifying enzyme activity (DEA). Soil cores were collected on 27 sampling dates over a growing season at a site seeded to barley (Hordeum vulgare). Denitrification rate was measured using a static core technique and acetylene blockage. Moisture content and air-filled porosity and, to a lesser extent, mineralizable-C concentration and respiration rate were more strongly related to denitrification rate than was DEA. Denitrification rate was unrelated to NO3− content. On most sampling dates, mean denitrification rate increased substantially only below an air-filled porosity of 0.3. Moreover, the distribution of individual measurements of denitrification rate was less skewed at lower air-filled porosities. Approximately 60% of variation in mean values of denitrification rate for each sampling date could be accounted for by measurements of bulk soil properties, of which moisture content and air-filled porosity were most important. Measurements of bulk soil properties did not account for nil values of denitrification rate at low air-filled porosities or for small-scale spatial variability. Such measurements were better indicators of temporal variation — that is, when denitrification occurred — than of actual rates. Key words: Denitrification, air-filled porosity, denitrifying enzyme activity
Sulfur and oxygen isotopic composition of sulfates at two saline sites in southern Alberta
Authors: Miller J. J. , Beke G. J. , Pawluk S. , Krouse H. R.
Published: April 2011

Possible sources of SO4 in soil, drift and bedrock at two saline sites in southern Alberta were investigated using sulfur and oxygen isotope analyses. Slight differences (0.6–5.2 per mil) between δ34S values of SO4 and insoluble S in the geologic material were attributed to kinetic fractionation during oxidation of organic S. Negative δ18O values of SO4 in the shallow (<6 m) bedrock, drift and soil reflected oxidation of reduced S. In contrast, positive δ18O values in the deep (>6 m) bedrock indicated sulfate reduction. The exact source of SO4 could not be determined in this preliminary study. The isotope approach, however, shows promise and warrants more detailed study. Key words: Salinization, sulfates, sulfur isotopes, oxygen isotopes
Relations of shoot C, root C and root length with root-released C of two barley cultivars and the decomposition of root-released C in soil
Authors: Xu J. G. , Juma N. G.
Published: April 2011

The production and utilization of root-derived C is fundamental to the functioning of ecosystems. The objectives of this experiment were to quantify the amount of root-released C produced by two barley (Hordeum vulgare L.) cultivars, to evaluate the direct and indirect effects of shoot C, root C and root length on the root-released C and to quantify the kinetics of the decomposition of root-released C in soil for two barley cultivars. Seedlings of two barley cultivars, Abee and Samson, were cultured in nutrient solution for 20 d and then pulse-labelled with 14C for 5 d. Samson released more C than Abee during the entire experimental period. Root length had the greatest direct effect on root-released C for the two barley cultivars. Kinetics analysis of the decomposition of root-released C added to soil showed that the labile components of the added material was 87.3% for Abee and 74.4% for Samson with half-lives of 4.3 d and 4.5 d, respectively. The half-lives of the resistant components of the root-released C added to soil and microbially-derived material were 37.7 d for Abee and 29.6 d for Samson, respectively. The amount of root-released C and its decomposition rate in soil varied with cultivars used. Key words: Root-released C, path analysis, direct effect, indirect effect, 14C, decomposition, Typic Cryoboroll
Organic and inorganic nitrogen leaching from incubated soils subjected to freeze-thaw and flooding conditions
Authors: Wang F. L. , Bettany J. R.
Published: April 2011

Freeze-thaw and flooding of usually well-drained soils occur in the spring in the prairie and boreal regions of Canada. We studied the impact of these conditions on nitrogen leaching in a Black Chernozemic soil (Udic Boroll). Soil samples, subjected to different treatments, were incubated for 12 wk in the laboratory and leached every 2 wk with 0.001 M CaCl2 solution. The cumulative leaching loss of total N (mg kg−1 soil) was reduced by freeze-thaw (76.0), flooding (41.4) and a superimposition of the two treatments (28.8) compared to the control (109). All treatments affected the distribution of the forms of N leached. The total loss of water soluble organic N (SON) and ammonium-N was in the order of flooded > flooded-freeze-thaw > freeze-thaw = control. In the leachates from the flooded treatments, SON accounted for 71.5–77.4% of the total N leached. Nitrate- and nitrite-N dominated the total leachable N in the unflooded treatments following an order of control > freeze-thaw > flooded = flooded-freeze-thaw. During the incubation, the Eh of the flooded soils decreased from 344 to −46 mV, compared to a variation in Eh from 355 to 301 mV for the unflooded soils. The maximum rate of leaching of organic nitrogen from the flooded treatment (0.53 mg N kg−1 d−1) coincided with a sharp decrease in Eh, from 131 to 42 mV. It is concluded that climatic events will have a significant impact on the dynamics of soil nitrogen. Flooding, in particular, may promote the loss of N in water soluble organic matter. Key words: Flooding, freeze-thaw, organic and inorganic nitrogen leaching, redox potential
Les extraits de sols saturés à l’eau et le suivi des nutriments dans l’érablière dépérissante
Authors: Marquis F. , Camiré C.
Published: April 2011

The soil solution provides the majority of essential nutrients needed for plant growth. Obtaining this solution in situ presents logistic problems and therefore most results are obtained from air-dried soils, even though chemical properties of soils can be substantially modified by drying. Water-saturated extracts obtained from dried soils were tested for their efficiency to detect the effects of in situ fertilization with P-TSP, K-K2SO4 and Ca-Ca(OH)2 on the Ahe horizon of a maple stand. Results obtained with water-saturated extracts on dried soils were compared with those obtained from conventional (exchangeable) extraction on dried soils and to those obtained from extraction with a soil:water ratio of 1:5 on dried soils. A similar experiment comparing water-saturated extracts with the soil:water ratio of 1:5 was carried out using soils fertilized in vitro. The effects of fertilization were clearly evident with saturated extracts when these could be observed by conventional analysis. Furthermore, the saturated extract indicated potential toxicity of Al in relation to pH. For the same samples, the saturated extracts were more sensitive than the extracts with a soil:solution ratio of 1:5, especially with regard to element ratios not easily expressed by conventional analysis. The originality of this method rests on a combination of efficient centrifugation with a double bottom container, the convenience in the utilization of air-dried soils and the use of near water field capacity as a representative water content. Key words: Saturated extracts, fertilization, toxicity, maple stand
Layer charge of expandable 2:1 phyllosilicates in selected parent materials of some Canadian soils
Authors: Arocena J. M. , Pawluk S. , Dudas M. J.
Published: April 2011

We investigated the nature of the layer charge of the different expandable 2:1 phyllosilicates present in glacial till, marine sediment, beach sand, loess, weathered sandstone and acid shale parent materials of selected soils from the arctic, alpine and interior plateau regions of Canada. Detailed characterization of 2:1 clay minerals, using the layer charge, was done by intercalation of the clay fractions with different chains (nc = 6 to 18) of n-alkylammonium cations (AC).Results indicated that AC were able to detect a mixture of smectite and vermiculite that was not detected by previous studies, using the glycerol (GLY) and ethylene glycol (EG) solvation techniques. The mean unit cell layer charge [in mol(+)/Si,Al)4O10)] varies from 0.30 to 0.39 for the smectite and from 0.71 to 0.74 for vermiculite. Vermiculite from the beach sand is trioctahedral in which most of the charge is located in the tetrahedral sheet, while vermiculite in the weathered sandstone is dioctahedral in which part of the charge originates from the octahedral layers. The presence of smectite, associated with the weathering of chlorite and an expanding component associated with the degradation of biotite, was also observed. Key words:n-alkylammonium cations, mean layer charge, 2:1 phyllosilicates
Effect of long-term applications of copper on soil and grape copper (Vitis vinifera)
Authors: Renan Li
Published: April 2011

The purpose of this research was to examine the residual effect of long-term Bordeaux mixture application on grapes grown on soils of a coastal plain in eastern China, and to investigate the effect of Bordeaux mixture application on total copper in the leaf and pulp of grape. The results showed that the DTPA extractable Cu was high as 34.2 mg kg−1 in the topsoil for growing grapes in the 10th year. Copper concentrations in grape leaves were within the range of 753–9845 mg kg−1. Concentrations of Cu in grape pulp were between 0.33 and 1.71 mg kg−1 which is slightly higher than the value reported for pulp in U.S.A. The well water near the soil sampling sites has not been contaminated by copper. Key words: Copper, grape, soil
Forest floor and soil nutrient status under Norway spruce and red pine in a plantation in southern Quebec
Authors: Fyles J. W. , Côté B.
Published: April 2011

The influence of 40 years of red pine and Norway spruce growth on forest floor and soil nutrient status was examined in a well-replicated series of plantation blocks established on abandoned agricultural land. Concentrations of N, P, K and Ca, and mass of organic matter and all nutrients in the forest floor were higher under spruce than under pine. In the mineral soil, concentrations of exchangeable K and Ca were higher under spruce whereas Mg, extractable P and mineralizable N did not differ between the species. Forest floor pH was higher under spruce but mineral soil pH did not differ between the species. The soil characteristics reflected litter chemistry of the two species. Relative to pine, spruce foliage litter was consistently higher in nutrient concentration and had lower acidity and higher ash bases. The results are inconsistent with the reputation of Norway spruce as a species that strongly acidifies soils, an observation that may be the result of elevated levels of Ca and K in our soils relative to those in other studies where acidification has been observed. This research demonstrates that soil fertility can be altered significantly by tree species effects over the period of a single rotation. Key words: Forest soil fertility, plantation, acidity, forest floor, leaf litter
SHORT COMMUNICATION: Resin-based extractor for multiple-element determinations of availability in soils
Authors: Olness Alan , Rinke Jana
Published: April 2011

Multi-element extractors were prepared by encasing cation and anion exchange resin beads in dialysis tubing. Extractors were inserted in soil suspensions, equilibrated for 168 h and eluted with 0.1 M HNO3. Eluted volumes were adjusted to 1.2 M in HCl, diluted to volume and directly analyzed using ICP methods. Key words: Extraction, resin, soil
Effect of chloride fertilization on Bedford barley and Katepwa wheat
Authors: Mohr R. M. , Bernier C. C. , Flaten D. N. , Racz G. J.
Published: April 2011

Recent studies in the northern Great Plains have confirmed that the chloride (Cl−) component of fertilizers can reduce disease severity and increase grain yield for wheat (Triticum aestivum) and barley (Hordeum vulgare). Field studies were conducted in Manitoba in 1989 and 1990 to determine the effect of rates of 25 and 50 kg Cl− ha−1 (applied as KCl or NaCl) applied with or without Cochliobolus sativus inoculum on plant nutrient status, disease severity and grain yield for Katepwa wheat and Bedford barley. Chloride application, regardless of placement or source, increased the Cl− concentration in plant tissue sampled at the boot to heading stages. Rates of 25 and 50 kg Cl− ha−1 resulted in significant reductions in the severity of common root rot for barley in two of six experiments and for wheat in one of four experiments. Chloride applications did not reduce spot blotch severity on barley in either of two experiments conducted. Inoculum did not have a consistent effect on any of the parameters measured. The application of 50 kg Cl− ha−1 significantly increased grain yield for barley by an average 393 kg ha−1 in two of eight experiments, but did not increase grain yield for wheat in any of eight experiments. Yield responses to Cl− were not related to soil Cl− content, Cl− concentration in plant tissue or observed reductions in disease. Key words: Chloride, fertilizers, barley, wheat, disease, yield
The toxicity of banded urea to corn growth and yield as influenced by triple superphosphate
Authors: Fan M. X. , MacKenzie A. F.
Published: April 2011

Banding of urea in corn (Zea mays L.) production is restricted by toxic conditions from urea hydrolysis, but higher urea rates could reduce application cost. A growth chamber experiment and a field experiment were conducted to study toxicity of banded urea when applied with triple super-phosphate (TSP). In the growth chamber experiment, surface samples from a Ste. Rosalie clay (Humic Gleysol), a Chicot sandy clay loam (Grey-brown Podzol), and an Uplands sandy soil (Humo Ferric, Podzol), were used. The field experiment was conducted on a Ste. Rosalie clay, a St. Bernard loam (Eutric Brunisol), and a Chicot sandy clay loam soil. In the growth chamber experiment, banded urea increased soil pH to 7.2–7.5 at a distance of up to 4 cm from the fertilizer band, and NH3 concentrations were as high as 2.1 mM at 2 cm from the fertilizer band after 20 d. The high pH and NH3 concentrations from urea hydrolysis inhibited corn root and seedling growth. Banding TSP with urea reduced soil pH increases from urea hydrolysis and reduced NH3 concentrations. Root weights increased with added TSP in urea bands. In the field experiment, banding urea at > 40 kg N ha−1 reduced plant density and shoot dry weight in early growth stages. Banding TSP with urea increased seedling growth in all soils. Maximum rates of urea compatible with increased corn yield could be increased from 40 to 80 kg ha−1 when banded with TSP. Key words: Urea, nitrogen, ammonia, triple superphosphate, phosphorus, pH, fertilization, corn (Zea mays L.)
Long-term effects of fertilizers and manure application on the forms and availability of soil phosphorus
Authors: Tran Thi Sen , N’dayegamiye Adrien
Published: April 2011

Long-term application of cattle manure and fertilizer can affect the forms and availability of soil phosphorus. This cumulative effect was evaluated on Le Bras silt loam (Humic Gleysol) cultivated with silage corn (Zea mays L.). In this long-term trial, treatments were arranged in a split-plot design, with dairy cattle manure applied at 0 and 20 Mg ha−1 as the main factor. The subplots consisted of six fertilizer treatments (NK, PK, NP, NPK, NPKMg and the unfertilized check). Fertilizer rates for silage corn were 150, 100, 150 and 40 kg ha−1 N, P205, K20 and Mg, respectively. The N fertilizer rate was reduced to 100 kg N ha−1 in manured plots. Soil inorganic P (Pi) and organic P (Po) fractions were sequentially extracted by resin, NaHCO3, NaOH, HCl and a final H2SO4 wet digestion of the residue. On average, labile P extracted by resin and NaHCO3 represented 17% of the total P (Pt); moderately labile NaOH-Pi and Po more than 40%; and stable P 36%. Application of manure and fertilizers increased significantly resin-, NaHCO3-, NaOH-Pi and Pt. However, NaOH-Po was decreased by P fertilizer application in NPK and NPKMg treatments, while long-term manure application maintained this Po pool in the soil. Stable P fractions were not affected by fertilization or by manuring. In all 6 yr of the study, P uptake by silage corn was significantly increased both by long-term N and P fertilizer application and also by manure incorporation. Phosphorus uptake by corn was highly related to all labile and moderately labile Pi fractions and Pt. Long-term application of dairy manure at a rate of 20 t ha−1 increased soil Pi forms and maintained Po fractions. Key words: Inorganic labile P, organic P, soil-P fractionation, P uptake, silage corn
Soil hydraulic properties of an Orthic Black Chernozem under long-term tillage and residue management
Authors: Singh Baldev , Chanasyk D. S. , McGill W. B.
Published: April 2011

The effects of tillage on soil hydraulic properties are unclear from the literature and residue effects are little reported. The hydraulic properties of an Orthic Black Chernozem under three tillage-residue systems in central Alberta — tillage with straw incorporated (till+straw) or removed (till−straw) — and no tillage with straw on the surface (no till+straw) — were studied for 2 yr. Measurements began in the 9th year of continuous barley (Hordeum vulgare L.).Plant-available water capacity differed among treatments only in the 0–2.5 cm layer, due to differences in water retention at −1500 kPa. Pore size partitioning revealed relatively high macroporosities (14–18% of total porosity) and residual porosity (34–41% of total porosity), but no treatment differences in the tillage layer. Saturated hydraulic conductivity (Ksat), infiltration rate and cumulative infiltration at 1 h followed the trend: no till+straw > till+straw > till−straw. Infiltration characteristics and hydraulic conductivity had considerable temporal variation. Interestingly, field and laboratory measurements gave the same order of magnitude of transmission characteristics. The common similarity of the no till+straw and the till+straw treatments and their usual difference from the till−straw treatment, especially in the water transmission characteristics, indicate the importance of the return of residue to the soil. The influence of straw on soil hydraulic properties does not appear to depend on whether it was incorporated or not. Key words: tillage, straw, residue, soil hydraulic properties, infiltration, pore size distribution
Short-range variability of fallout Pb in a contaminated soil
Authors: Arrouays D. , Mench M. , Gomez A. , Amans V.
Published: April 2011

Studies about Pb variability in contaminated soils, especially in the case of fallout from smelters or facilities, are few and the relevance of geostatistical technique for studying contaminated soil as well as the surface area required for investigation are unclear. Few studies have been conducted on short-range variability of trace elements in soils, and some of them have shown these elements to be randomly distributed while others pointed out the spatial dependence between sample locations. Therefore the main objective of this study is to document the short-range variability of Pb in an area contaminated by fallout, using a case study in France. Soil lead in this site arises from a history of industrial use. No other metals were detected in Pb emissions. On this site, we conducted a statistical and a geostatistical study of Pb content in soil, and of soil characteristics that may affect it. The aims of this work are (i) to separate the spatial structure due to high Pb fallout from a content and diffuse pollution, (ii) to separate the variability due to analytical measurements from ones related to spatial variations, (iii) to point out the soil characteristics correlated with Pb, (iv) to optimize sampling design for monitoring the long-term changes following remedial action. Results demonstrated that in this highly contaminated soil, fallout Pb was mainly located in the surface layer (0–0.2 m depth). The geostatistical study suggested that the study of the spatial structure may help in discriminating fallout Pb from Pb coming from diffuse pollution or geochemical content. However, the large spatial variability of Pb, partly due to microheterogeneity made the monitoring of this toxic element very difficult, and required a larger surface for sampling. Using correlation techniques to detect causations appeared not to be relevant. Therefore, other statistical techniques such as path analysis should be tested. Additionally, microanalysis, mobility and bioavailability studies, as well as lab or bench scale remediation studies should be conducted. Key words: Contaminated soils, fallout Pb, short-range variability, geostatistics
Influence of vegetation on microbial degradation of atrazine and 2,4-dichlorophenoxyacetic acid in riparian soils
Authors: Entry James A. , Emmingham William H.
Published: April 2011

Mineralization of atrazine (2 chloro-4 [ethylamino]-6[isopropylamino]-s-triazine) and 2,4-D (2,4-dichlorophenoxyacetic acid) in the organic layer and the top 10 cm of mineral soil was measured with radiometric techniques seasonally in coniferous forests and deciduous forests and grassland riparian soils. Active bacterial biomass and active fungal biomass, total carbon, total nitrogen, and total phosphorus were also measured. In the organic horizon, atrazine mineralization was higher in conifer than in deciduous forests during all seasons. Mineralization of 2,4-D was higher in coniferous than deciduous forests in autumn and spring. Grassland vegetation did not form an organic horizon. In mineral soil, atrazine mineralization was higher in coniferous than deciduous forests in the spring and higher in grassland soils in all seasons of the year. In mineral soil, 2,4-D mineralization was higher in coniferous and deciduous forests than grassland soils in autumn, winter, and spring. 2,4-D mineralization in mineral soils did not differ between coniferous and deciduous forest soils. We found no abiotic variables or active fungal or bacterial biomass that correlated with atrazine or 2,4-D mineralization. We hypothesize that the soil microbial communities that develop under coniferous forests are capable of mineralizing greater amounts of atrazine and 2,4-D than those that develop under deciduous forests or grassland ecosystems. Key words: Forest riparian soils, forest soils, herbicides, microbial biomass
Review of recent developments in soil water simulation models
Authors: Jong R. de , Bootsma A.
Published: April 2011

Soil water is of great importance to agricultural and hydrological systems, affecting crop yields, agricultural management practices and a wide range of physical and chemical processes in soils. Many models have been developed over the years to simulate soil water, ranging from simple water balance procedures to complex deterministic models. In this paper, some of the basic concepts, strengths, weaknesses and input requirements of soil water models are reviewed. Simple budget models which require only available water-holding capacity, based on the concepts of field capacity and wilting point, and monthly average values of precipitation and potential evapotranspiration (PET) are often adequate for climatic characterizations. However, detailed deterministic models are useful for investigating more complex processes such as solute movement, soil degradation and crop growth. These models are based on Richards’ equation, with an added term for root water extraction. They generally require daily or hourly meteorological data and detailed hydraulic conductivity and water potential functions for various soil layers.Meteorological data for input into models are widely available in Canada from a network of climate stations. However, the network density is sparse for those models which use the most accurate procedures for estimating PET, requiring parameters such as wind, solar radiation and/or humidity. Moreover, pedotransfer functions generally need to be used to estimate, from existing soil databases, the required soil inputs for sophisticated models.To demonstrate a practical application, a soil water model was used in conjunction with simple crop yield/water use relationships to characterize soil water regimes and crop production risks. The probability of obtaining break-even yields (PBEY) for continuous spring wheat was calculated and mapped for the Canadian prairie region. PBEY ranged from less than 20% in the most arid region of the prairies to between 60 and 100% in most humid areas. An estimate of PBEY based on modelled yields was in close agreement with that based on long-term measured yields in the sub-arid region. With increasing availability of integrated multi-process based models, this technique has potential for studying the effects of soil characteristics and crop management techniques on PBEY. Key words: Soil water, simulation models, review, spring wheat, break-even yield, Canadian prairies
Long-term effects of tillage and crop rotations on soil organic C and total N in a clay soil in southwestern Saskatchewan
Authors: Campbell C. A. , McConkey B. G. , Zentner R. P. , Selles F. , Curtin D.
Published: April 2011

Soil organic matter contributes to the productivity and physical well-being of soils. An 11-yr study was conducted on a clay soil in the Brown soil zone in southwestern Saskatchewan to determine the influence of tillage and cropping frequency on soil organic C and total N content. Carbon and N behaved in a similar manner. Cropping frequency did not affect soil organic C or total N content, but soil C and N were greater under no-tillage (NT) than under mechanically tilled continuous wheat (Triticum aestivum L.) (Cont W) and fallow-wheat (F-W) rotations. Effects were apparent in the 0– to 7.5– and 7.5– to 15-cm depths. Over the 11-yr period, F-W (minimum tillage) gained no additional C; Cont W (conventional tillage) gained 2 t C ha−1, and both Cont W (NT) and F-W (NT) gained 5 t C ha−1. Changes in organic C and N were greatest in the final 4 yr of the experiment when crop residue production was greatest. Using data from two similar experiments conducted during the same period on soils differing in texture, we demonstrated that C gains were directly related to clay content of the soils. Thus, when attempting to estimate C storage in soils, we must consider both residue input and soil clay content. Key words: Organic C, total N, organic matter, soil texture, bulk density
SHORT COMMUNICATION: Volatile losses of NH3 from surface-applied urea and urea ammonium nitrate with and without the urease inhibitors NBPT or ammonium thiosulphate
Authors: Grant C. A. , Brown K. R. , Bailey L. D. , Jia S.
Published: April 2011

Field microplot studies were conducted under zero-till conditions on a fine sandy loam (Orthic Black Chernozem) to determine the effect of the urease inhibitors N-(n-butyl) thiophosphoric triamide (NBPT) and ammonium thiosulphate (ATS) on volatile losses of NH3 from urea and urea ammonium nitrate (UAN). Two studies were conducted, one in late May and one in early August. Losses of NH3 were measured on days 1, 2, 4 and 7 after fertilizer application, using ammonia traps. Ammonia losses were higher in the second study due to the higher soil temperatures and lower soil moisture later in the growing season. Total NH3 losses increased in the order Control < UAN + NBPT = Urea + NBPT < UAN + ATS = UAN < Urea. Total loss of NH3 during the 7 d after fertilizer application was higher from urea than from UAN, particularly in the first study. Use of NBPT was effective in reducing NH3 volatilization from both UAN and urea during 7 d after fertilizer application while use of ATS had little influence on NH3 loss from UAN. The NBPT may delay losses by slowing the hydrolysis of urea, but volatilization may persist for a longer duration. The delay in urea hydrolysis could allow time for rainfall to carry the urea into the soil, thus reducing total volatilization losses from surface fertilizer application. Key words: N-(n-butyl) thiophosphoric triamide, zero tillage
Field pea response to liming of an acid soil under two tillage systems
Authors: Arshad M. A. , Gill K. S.
Published: April 2011

There is an increased use of no-tillage (NT) methods in soils of the Peace River region of Alberta–British Columbia where a good proportion of acid soils exist. There is little information, however, on how crops, soils, and weeds respond to liming under different tillage intensities. A Hythe clay loam (Gray Luvisol; initial pH in CaCl2 ≈ 5) was limed (7.5 t ha−1) in May 1991. Field pea (Pisum sativum L.) yield, soil properties, and weed populations under conventional tillage (CT) and NT were monitored during three growing seasons (1993–1995). The pH of limed soil in the 0–10 cm layer ranged from 6.0 to 6.3. Liming slightly increased NO3-N, P and bulk density of soil, lowered exchangeable Al concentration and wet aggregate stability, and had no effect on NH4-N and penetration resistance. Liming increased the grain yield by 0.50 (22%) t ha−1 yr−1 in CT and by 0.55 (18%) t ha−1 yr−1 in NT. Aboveground dry matter (DM) increase of 1.37 (27%) t ha−1 yr−1 in CT and 1.72 (25%) t ha−1 yr−1 in NT was obtained due to liming. Populations of annual broadleaf, annual grass and perennial weeds were not affected by either liming or tillage. Reduced soil acidity and exchangeable Al in conjunction with increased NO3-N and P contributed to increased crop yield by liming under both CT and NT. Higher soil moisture in the NT contributed to increased yield in comparison to CT system, as other soil properties and weed population were not significantly affected by tillage. Key words: No tillage, Pisum sativum L., exchangeable aluminium, wet aggregate stability
The impact of kaolin clay sprays on leaf gas exchange of Ginger Gold apple trees in New Brunswick
Authors: Privé J. P. , Russell L. , LeBlanc A.
Published: April 2011

A field trial was conducted over two growing seasons in a Ginger Gold apple orchard in Bouctouche, New Brunswick, Canada to examine the impact of Surround (95% kaolin clay) on leaf gas exchange [net photosynthesis (Pn), stomatal conductance (gs), intercellular CO2 (Ci) and transpiration (E)]. In 2004, a greater rate of Pn and gs was achieved at the higher than at the lower frequency of Surround applications. This was particularly notable at leaf temperatures exceeding 35°C. In 2005, no significant (P ≤ 0.05) differences among leaf residue groupings [Trace (< 0.5 g m-2), Low (0.5 to 2 g m-2), and High (≥ 2 g m-2)] were found for the four leaf gas exchange parameters at leaf temperatures ranging from 25 to 40°C. It would appear that under New Brunswick commercial orchard conditions, the application of Surround favours or has no effect on leaf gas exchange. Key words: Surround, particle film, leaf physiology, photosynthesis, stomatal conductance, intercellular CO2, transpiration
Comparative assessments of seedling runner and adult-plant resistance to leaf scorch in strawberry
Authors: Xue A. G. , Sutton J. C. , Dale A.
Published: April 2011

Nine progeny populations, derived from a half-diallel and self-crosses of strawberry cultivars Vantage, Scotland, Governor Simcoe and Kent were evaluated for resistance to leaf scorch (Diplocarpon earlianum) as seedling runners and at the adult-plant stage. At both stages selfed Vantage and selfed Scotland were resistant; crosses between Vantage and Kent and between Governor Simcoe and Kent were susceptible; and remaining progeny populations were of intermediate resistance. A strong correlation (r = 0.970, P < 0.01) was observed between resistance of seedling runners and adult-plants of the nine S1 and F1 populations. The results suggest that strawberry genotypes can be evaluated effectively at the seedling stage in a breeding program for resistance to leaf scorch. Key words: Leaf scorch, Diplocarpon earlianum, strawberry, Fragaria × ananassa, seedling-runner, adult plant, resistance
AC Hercule soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

AC Hercule is a 2600 crop heat unit soybean (Glycine max [L.] Merr.) cultivar with seed protein levels about 3–4% higher than oilseed cultivars. AC Hercule is intended for whole-seed use in livestock rations. AC Hercule has field tolerance to phytophthora root rot. Key words: Soybean, cultivar description, high protein cultivar
The biology of Canadian weeds. 108. Erucastrum gallicum (Willd.) O.E. Schulz
Authors: Warwick Suzanne I. , Wall David A.
Published: April 2011

A review of biological information is provided for Erucastrum gallicum (Willd.) O.E. Schulz. A European native, it was introduced into Canada and the United States in the early 1900s and spread rapidly along the railroads. The species occurs in all the provinces and the Northwest Territories and is particularly abundant in the Prairie provinces and mid-western United States. It is a summer annual, rarely a winter annual or biennial species, and is characterized by high reproductive output. Plants occur most commonly on waste ground and along roadsides and railroads, followed by agricultural fields. Erucastrum gallicum is of allopolyploid origins (n = 15, 7 + 8 chromosomes), and contains a single multi-locus isozyme genotype. The species is a close relative of Brassica and is capable of limited genetic exchange with the canola species, B. rapa and B. napus. The possible transfer of genes from transgenic canola varieties to Erucastrum gallicum poses a remote, but potential, environmental risk. Populations of Erucastrum gallicum, including both Old World and North American populations, constitute a valuable germplasm resource as potential sources of beneficial agronomic traits, such as disease resistance for canola crop improvement. Key words: Dog mustard, Erucastrum gallicum, weed biology, risk assessment, germplasm, canola
Root-to-straw ratios - influence of moisture and rate of N fertilizer
Authors: Campbell C A , de Jong R.
Published: April 2011

Root/straw ratios for crops are urgently required by scientists wishing to estimate crop residue inputs to soil and for modeling C and N dynamics in the soil-plant-atmosphere system. In this paper we discuss the influence of moisture and rates of N application on such ratios for wheat (Triticum aestivum L.) grown in the semi-arid region of the Canadian prairies. Under natural rainfall root/straw (nongrain aboveground material), ratios decreased with increasing rates of N, but under irrigation these ratios were generally constant. We estimated root/straw ratios for roots measured at anthesis (their maximum mass) and straw measured at maturity, under natural rainfall conditions, to be 0.36–0.58 if roots are assessed for the 0 - to 120-cm depth, 0.21–0.34 for the 0 - to 30-cm depth, and 0.15–0.26 for the 0- to 15-cm depth. Under natural rainfall, if roots are measured at maturity (as is commonly done), the corresponding ratios were 0.29–0.37, 0.15–0.21, and 0.10–0.15, for the respective depths. Under irrigation, the ratios when roots were measured at anthesis were 0.36, 0.24 and 0.19 for 0- to 120-cm, 0- to 30-cm and 0- to 15-cm rooting depths, respectively; but when roots were measured at maturity these ratios were 0.30, 0.17 and 0.13, respectively. We suggest that the values based on roots measured at anthesis provide a more accurate estimate of root C available for decomposition. We propose that the ratio used should be dependent on the depth to which changes in soil C or N are being measured. Key words: Soil organic C, roots, straw, fertilizer N, moisture
Effects of Cedrus atlantica and Pinus halepensis on the chemistry and fertility of a Mediterranean soil after 40 years
Authors: Pinzari F. , Dell’Abate M. T. , Benedetti A. , Dazzi C.
Published: April 2011

In this study, a comparison between Pinus halepensis Miller and Cedrus atlantica (Endl) Carrière in reforested sites was carried out. Our major objectives were to study soil organic matter in the two stands to determine whether significant biochemical modifications of the C cycle occurred since stand establishment, and to evaluate the effect of the two tree species on soil formation.The study area is part of the Sicani range (western Sicily, Italy), and is characterised by homogeneous environmental features (topography, geology, slope, exposition, climate, etc.). Ten profiles were sampled in a plantation of Pinus halepensisand one of Cedrus atlanticafor each stand. Microbial biomass activity (qCO2, and Cmic:Corg), organic C contents, and organic C mineralization rates were compared between the Ah and Bw horizons of the soils in the two stands. The microbial biomass activity in A-horizons differed appreciably. The metabolic quotient was higher under Pinushalepensis while the Cmic to Corg ratio was higher under Cedrus atlantica, which indicated a possible stressed condition for soil microbial biomass in the Pinus halepensisstand The turnover of decomposable C did not differ significantly between the two soils, but the A-horizons of the Cedrus atlantica site appeared poorer in total organic C content. Key Words: Forest soil, soil chemistry, soil fertility, soil-vegetation relationship, organic matter dynamics, soil microbial biomass
Soil-available phosphorus as evaluated by desorption techniques and chemical extractions
Authors: Ziadi N. , Simard R R , Tran T S , Allard G.
Published: April 2011

The P-supplying power of the fine-textured soils from Abitibi-Temiscaming (Quebec, Canada) has never been investigated. Anion exchange membranes (AEM), the electro-ultrafiltration (EUF) technique and chemical extractions were used to describe their P status. Phosphorus was desorbed from four soils that had received 52.4 kg P ha–1 yr–1 from 1994 to 1996 and from unfertilized soils. The cumulative amount of P desorbed in 75 min by EUF from unfertilized soils varied from 10 to 69 mg P kg–1. Averaged over all sites and treatments, the amount of soil P extracted by different methods ranged from 1.0 to 18.9 mg P kg–1. The cumulative grass P uptake was significantly related to P desorbed by all methods (0.39 < r < 0.84). A close relationship between grass P uptake and PAEMs indicated the adequacy of the AEMs to determine plant-available P in Abitibi-Temiscaming soils. A high degree of linearity (0.97 < R2 < 0.99) of the EUF-P desorption curves at 200 V and 20°C with time was obtained. This indicates that soils have a high capacity to buffer removal of P from soil solution with reserve P. The EUF technique has shown that these soils hold very large inorganic P reserves and this may explain the lack of grass response to P fertilizers. Key words: Anion exchange membranes, grass-P uptake, P-desorption, Mehlich3-P, Olsen-P.
Soil moisture and nutrient variation within an undulating Manitoba landscape
Authors: Manning G. , Fuller L G , Eilers R G , Florinsky I.
Published: April 2011

The use of discrete management units for variable-rate N fertilization requires that factors influencing grain yield response to N fertilizer are adequately characterized by delineating landscapes into such management units. The objective of this study was to compare the use of topographically derived landform element complexes (LEC) and the use of individual soil series as management units. Soil volumetric moisture content, nitrate-N, exchangeable ammonium-N, extractable phosphorus, exchangeable potassium, and sulphate-sulphur were studied in 10 intensively sampled transects in an undulating glacial till landscape near Miniota, Manitoba. The study site was delineated into upper, mid and lower LEC using a digital elevation model derived from relative elevation data. The LEC were useful in capturing gross variability at a manageable landscape scale. Among LEC there was a general trend of lower > mid > upper for median values of soil moisture, nitrate, phosphate, potassium and sulphate, as these attributes generally increased with convergent landscape character. Differences among LEC were often statistically significant, and relative distributions exhibited temporal persistence. The site was also stratified by soil series, including Newdale, Varcoe and Angusville soils (Black Chernozems), which were identified by examination of individual soil cores at each sample point. Stratifying the site into management units using soil genetic information, which is reflective of historical moisture conditions and biomass production, was expected to be superior. There was little advantage, however, in using soil series rather than LEC. Spatial distributions of the most agronomically relevant attributes (soil moisture and nitrate) were expressed at a landscape scale broader than that at which soil series occurred within the site. While there were important differences among soil series with respect to nutrients such as phosphate and sulphate, the site was better stratified by LEC with respect to soil moisture and nitrate. Key words: Soil-landscape, soil series, soil moisture, soil residual nitrate, extractable phosphorus
Wheat yield and grain protein variation within an undulating soil landscape
Authors: Manning G. , Fuller L G , Flaten D N , Eilers R G
Published: April 2011

The objective of this study was to compare landform element complexes (LEC) and soil series as discrete management units for variable rate N fertilizer application. Crop response attributes including grain yield, and grain protein concentration were studied in ten intensively sampled transects in an undulating glacial till soil-landscape near Miniota, Manitoba. In 1997, a year with growing season precipitation 37% below average, median grain yield tended to increase with both N fertilizer and with convergent character in the landscape (upper < mid < lower). Varcoe soils, located predominantly within the lower LEC, were generally more productive than Newdale soils. Grain protein concentration increased with N fertilizer, but tended to decrease with convergent character in the landscape (upper > mid > lower), and was lowest in the Varcoe series. In 1998, growing season precipitation was 62% above average. Grain yield responses to N fertilizer were greater, due in part to declining N fertility in the check and 45 kg ha–1 treatments. Trends among LEC were opposite to those in 1997, as median grain yield estimates tended to decrease with convergent character in the landscape (upper > mid > lower). Grain yield was modeled as a function of estimated plant-available N supply within each LEC and soil series. Modeled 1997 grain yield maxima were 2077, 2261 and 2485 kg ha–1 in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 89, 130 and 130 kg N ha–1, respectively. In 1998, the relative order of modeled maxima among LEC was reversed. Grain yield of 2501, 2355 and 2227 kg ha–1 were predicted in the upper, mid and lower LEC. Estimated plant-available N supply at the yield maxima were 146, 142 and 154 kg N ha–1, correspondingly. In 1997, plateau yields were 2379, 2495 and 2325 kg ha–1 for Newdale, Varcoe and Angusville series, respectively, where the Varcoe series responded most strongly to estimated plant-available N supply. The corresponding estimated plant-available N supply values at the modeled maxima were 195, 139 and 110 kg ha–1. In 1998, plateau yields were 2343, 2253 and 2285 kg ha–1 for Newdale, Varcoe and Angusville series, respectively. The corresponding estimated plant-available N supply values at the modeled maxima were 136, 148 and 155 kg ha–1. Successful variable-rate fertilization by LEC or soil series will require long-term empirical study to establish risk-based grain yield-N relationships, and to determine if an economic advantage over conventional fertilization practices exists. Key words: Variable-rate fertilization, nitrogen, wheat yield, grain protein concentration, soil-landscape
Sorption of anthropogenic organic compounds by soil organic matter: a mechanistic consideration
Authors: Xing Baoshan
Published: April 2011

Sorption experiments with apolar organic compounds (naphthalene and 1,2-dichorobenzene) were conducted to evaluate sorption mechanisms in soil organic matter (SOM). All isotherms were nonlinear and competition between solutes was observed. Nonlinearity and competition increased in an order of peat humic acid (HA) < peat < peat humin. Isotherms of Al-saturated HA (Al-HA) were more nonlinear than untreated HA and Ca-HA, and sorption/desorption hysteresis occurred only in Al-HA. These results are not consistent with partitioning theory or the presence of high-surface-area carbonaceous materials (HSACM) in soil. But the results are consistent with dual-mode sorption, where SOM is postulated to have both condensed (rigid) and expanded (flexible) domains, and adsorption takes place only in the condensed domains and partitioning in both domains. These non-ideal sorptive behaviors need to be incorporated into predictive models to more accurately describe the fate and transport of organics in soil and subsurface environments. Key words: sorption, organic compounds, organic matter, dual-mode, partition, mechanisms
Sorption of cadmium on humic acid: Mechanistic and kinetic studies with atomic force microscopy and X-ray absorption fine structure spectroscopy
Authors: Liu C. , Frenkel A I , Vairavamurthy A. , Huang P M
Published: April 2011

Humic acids (HA) constitute a major fraction of the organic matter in soils and sediments. Little is known about the kinetics and mechanisms of Cd sorption by HAs, especially those pertaining to the surface features and structure of the Cd-humate complexes. We investigated Cd sorption by HA using the conventional batch method, N2-BET method, atomic force microscopy (AFM), and extended X-ray absorption fine structure (EXAFS) spectroscopy to gain a better understanding of the kinetics and mechanisms. Cadmium sorption by HA can be described by the parabolic diffusion equation. The increase in the apparent diffusion coefficient with an increase in the initial Cd concentration was less pronounced at higher initial Cd concentrations, apparently due to an enhancement in aggregation of the Cd-humate complexes. The HA before and after Cd sorption at Cd concentrations ≤ 10–6 M in different reaction times was spheroidal in shape. The Cd-humate complexes formed at 10–4 and 10–3 M Cd gradually changed to resemble the shape of a bean with increasing reaction time, thereby substantially decreasing their specific surface. Cadmium ions raveled the spheroidal HA particles into a bean-like structure by coordinating to six O atoms from the functional groups of HA, with a Cd-O distance of 2.297(2) Å. The Cd-O bond strength decreased with increasing initial Cd concentration. Key words: Cadmium, humate complexes, conformation, atomic force microscopy, EXAFS
Effect of light on birnessite catalysis of the Maillard reaction and its implication in humification
Authors: Jokic A. , Frenkel A I , Huang P M
Published: April 2011

The Maillard reaction between carbohydrates and nitrogenous compounds originally investigated in 1912 has subsequently been proposed as a possible pathway for the formation of humic substances in natural environments. However, the role of mineral catalysis of the Maillard reaction is little understood and the promoting effect of light on such catalysis is not known. Birnessite (δ-MnO2), which is commonly present in soil environments, was investigated for its activity in promoting the Maillard reaction between glucose and glycine at a light intensity of 168 µE s–1 m–2 or in the dark. The presence of substantial quantities of Mn(II) was detected in both the supernatant and solid phase of the glucose-glycine-birnessite systems. The spectroscopic evidence indicates that birnessite, in the presence of light, is a very effective catalyst in abiotic browning of solutions of glucose and glycine. Furthermore, birnessite significantly promoted the reaction even in the absence of light. Therefore, the abiotic heterogeneous catalytic role of soil minerals such as birnessite in polycondensation of simple sugars and amino acids merits close attention in the formation of humic substances in natural environments. Key words: Maillard reaction, heterogeneous catalysis, light, birnessite, humic substance formation, XANES