bluuebunny/crossref_metadata_2025 huggingface dataset:
Fate of 15N-labelled fertilizer applied to corn grown on different soil types
Authors: Tran Thi Sen , Giroux Marcel
Published: April 2011

From an environmental standpoint, it is important to follow the fate of applied fertilizer N in soil–plant system. In this study, field experiments were conducted at two sites (Du Contour and Sainte-Rosalie series) in the Saint-Hyacinthe region in 1989 and 1990, and at four sites (Le Bras-I, -II, -III and Fourchette series) at Saint-Lambert-de-Lauzon in 1989, 1990 and 1991. The site and year combinations represented a range of different climatic conditions. The 15N-labelled fertilizer as 15NH415NO3 was spread on microplot at 180 kg N ha−1 rate, just before corn seeding. The recovery of fertilizer N (NREC) of grain and silage corn (Zea may L.) varied from 47 to 51%. At harvest, the amount of residual mineral N (soil and fertilizer) in soil profile (0–90 cm) ranged from 55 kg N ha−1 in a wet growing season to 176 kg N ha−1 in a dry growing season. The NREC in the mineral pool varied from 1.4% in wet growing season, especially on sandy soil, to 20.6% under dry conditions. The NREC recovered in the organic and fixed pools was 16.3, 24.6 and 38.9% of applied rate on the sandy soil, silt loam soil and clay loam soil, respectively. This pool was immobilized in soil profile and less subjected to significant loss overwinter than the mineral pool. The annual loss of fertilizer N varied from 13.6% on Sainte-Rosalie soil, having high N immobilization capacity, to 44.1% on Le Bras-II. These results shown that under the humid conditions found in Quebec, application of fertilizer N exceeding the optimum N rate will contribute to environmental pollution risk especially on permeable soils or soils having low N fixation and immobilization capacity. Key words: Fertilizer N loss, 15N-fertilizer, corn, mineral N, organic N
Field evaluation of a water use model for potatoes
Authors: Shaykewich C. F. , Ash G. H. B. , Raddatz R. L. , Tomasiewicz D. J.
Published: April 2011

A water use model for potatoes (Solanum tuberosum L.) was calibrated and tested. The model requires phenological relationships for estimating emergence, degree of crop cover and rooting depth. These weather-driven crop growth functions were previously calibrated using field data from 1994 and 1995. In this paper, the model was tested using field data from the 1996 growing season at two locations. The 1996 crop growth parameters were estimated fairly accurately. This contributed to reasonably accurate (average bias <3 mm, root mean square error <15 mm) root zone available soil water estimates by the model. Thus, the model could be used in irrigation scheduling. Key words: Evapotranspiration, rooting depth, ground cover
Plant uptake and DTPA-extractability of Cd, Cu, Ni and Zn in a Norwegian alum shale soil as affected by previous addition of dairy and pig manures and peat
Authors: Arnesen A. K. M. , Singh B. R.
Published: April 2011

Residual effects of cow manure, pig manure and peat soil on the DTPA-extractability and plant uptake of cadmium, copper, nickel and zinc were investigated in the second and third years after application to an alum shale soil. Wheat and barley were grown in alternate years. The effects of the organic matter applied differed among metals, sources of organic matter and time after application. The Cd concentrations in grain was reduced by the rates of peat soil, whereas the manures had no significant effect. Copper concentrations in grain and Zn concentrations in both grain and straw generally increased with rates of organic matter. Nickel concentration in grain tended to decrease with increasing rates of cow and pig manure applied, whereas it tended to increase with the addition of peat soil.The concentrations of DTPA-extractable metals in the soil were generally higher in the second and third years than in the first year after application of organic matter. Some of the metals bound by organic matter in the first year were probably released as the organic matter was decomposed. Decreases in DTPA-extractable Cd and Ni were found by the addition of pig and cow manure, whereas these manures resulted in increased DTPA-extractable Zn. The application of peat soil, on the other hand, resulted in increased amounts of DTPA-extractable Cu, Zn and Ni, probably due to decreased soil pH. Key words: Heavy metals, solubility, plant uptake, organic matter
Microbial biomass respiration response to added carbon and nitrogen as an indicator of nitrogen availability in forest soils
Authors: Au William , Fyles James W. , Côté B.
Published: April 2011

The relationship between a microbial biomass respiration response to added C and N (NIR) and N mineralized in buried-bags in the field was examined. Significant negative correlations were found between organic horizon NIR values and the amount of mineralized N measured at various times, however no significant correlations were found in the mineral horizon. These results suggest that NIR has potential for use as a physiological indicator of forest floor N availability. Key words: Microbial biomass, respiration, SIR, N mineralization
Microbial biomass C and alkaline phosphatase activity in two compost amended soils
Authors: Lalande Roger , Gagnon Bernard , Simard Régis R.
Published: April 2011

Addition of compost from various sources and of different maturity may affect the soil biochemical properties. A field study was conducted to evaluate the effect of different composts, spring-applied alone or in combination with ammonium nitrate (AN), on microbial biomass C (MBC) and alkaline phosphatase activity (APA) in two soils cropped with spring wheat (Triticum aestivum L. 'Messier') in eastern Quebec, Canada. The experiment was conducted in 1994 and 1995 at different sites on a Kamouraska clay (Orthic Humic Gleysol) and a Saint-André sandy loam (Fragic Humo-Ferric Podzol). Treatments included composts at 180 kg N ha−1, composts at 90 kg N ha−1 supplemented with AN, AN at 90 kg N ha−1, and an unfertilized control. Soil MBC and APA were measured 30 d after compost application and at wheat harvest. Additional sampling was made the following spring. Generally, larger MBC and APA values were found at wheat harvest in soils treated with composts alone than with AN alone or unfertilized. These effects were related to soil C content and climatic conditions. Compost type affected soil biochemical properties which could be attributed to the total C supply and material maturation state. Compost addition constitutes an efficient short-term way to promote soil microbial biomass and enzyme activity in cold climates. Key words: Compost, fertilizer, microbial biomass, soil enzyme, wheat
Soil organic matter quality and aggregate stability under eight potato cropping sequences in a fine sandy loam of Prince Edward Island
Authors: Angers Denis A. , Edwards Linnell M. , Sanderson J. Brian , Bissonnette Nicole
Published: April 2011

Soil degradation and soil organic matter (SOM) reduction have long been suspected to occur under intensive potato (Solanum tuberosum L.) production in Prince Edward Island. Thus, this study was conducted to evaluate the effect of eight potato cropping sequences involving barley (Hordeum vulgare L.), ryegrass (Lolium multiflorum L.), red clover (Trifolium pratense L.) and barley under-seeded with red clover on aggregate stability and SOM properties of a Charlottetown fine sandy loam (Orthic Humo-Ferric Podzol). Total C and N, light-fraction (density < 1.7 g cm−3) C (LF-C) and light-fraction N (LF-N), microbial biomass C (MBC), carbohydrate content, alkaline phosphatase activity (APA) and aggregate stability were determined in the 0- to 15-cm soil layer in the 6th and 10th years of the trial. Average C and N contents were 20 to 27% greater in sequences that included 3 or 4 yr of potatoes and a high frequency of red clover than in a 9-yr potato sequence; and were attributed to the less frequent tillage and higher organic matter inputs associated with the forage component. The response for MBC, LF-C, LF-N and APA was greater than those for total C and N suggesting that the former parameters may better reveal SOM changes caused by variations in potato management than the latter. Light-fraction N was particularly sensitive to the inclusion of perennial legumes in the cropping sequence. Wet-aggregate stability was 33% higher after 6 yr in the sequence with 50% frequency of red clover than in the continuous potato system, but no effect was noted after 10 yr. The results of this study indicate that sequences which are limited to 30 to 40% of potatoes and have a high frequency of perennial forage such as red clover, lead to greater SOM content and quality of a Charlottetown fine sandy loam compared to continuous potatoes. Trends in aggregate stability generally followed those of SOM fractions but the effects were relatively smaller and varied with time. Key words: Potato, Solanum tuberosum L., soil aggregation, organic matter, carbon, nitrogen, light fraction, microbial biomass
Relationships between biological and chemical measures of N supplying power and total soil N at field scale
Authors: Selles F. , Campbell C. A. , McConkey B. G. , Brandt S. A. , Messer D.
Published: April 2011

Producers and scientists are seeking more accurate methods for estimating the N-supplying power of soil at the field level. This has become more urgent as new management technologies, such as precision farming, gain popularity on the Canadian Prairies. We characterized the N status of the soil on an 18-ha site on which a new long-term alternative farming experiment was being initiated at Scott, Saskatchewan, by taking 160 cores in a systematic manner in June 1994. In these cores we determined: i) total soil N; and ii) the N-supplying power of the soil by determining mineralizable N by aerobic incubation at optimum temperature and moisture, and by extracting NH4–N with 2 M KCl at 100°C. Because the field had been fertilized shortly before sampling, residual fertilizer N severely affected the quality of determinations of N supplying power at the 0- to 7.5-cm depth. Consequently, we limited our investigation to the 7.5- to 15-cm depth. We also determined pH, bulk density, and particle size distribution. Using geostatistics, simple correlations, and multiple regression analyses, we demonstrated a close association between the biological and chemical measures of N-supplying power of the soil. Semivariograms revealed that the spatial structure of the variance of both variables was similar, with about 70% of the variance resulting from unidentified processes, and the rest explained by spatial structure. Field maps prepared with block-kriged estimates, revealed that these two measures of N-supplying power were similarly distributed throughout the landscape, and followed closely the spatial distribution of total soil N throughout most of the field. However, we identified two areas of the field where the two estimators of N-supplying power had a weak association with total soil N. Multiple regression and cluster analysis indicated that this disparity was a function of differences in soil pH, bulk density, and geometric mean diameter of soil particles, suggesting that soil erosion-transport processes may have altered the nature of organic N in areas of the field. The relationship between N mineralized during a 24-wk incubation and NH4–N extracted with hot KCl was not affected by these differences, suggesting that the biological and chemical procedures tested were accessing similar pools of soil N. We concluded that hot KCl NH4–N should prove useful for quantifying the N supplying power of soils. Key words: Geostatistics, estimation, kriging, spatial variability, mineralizable N
Vegetation, soil hydrophysical properties, and grazing relationships in saline-sodic soils of Central Argentina
Authors: Cisneros J. M. , Cantero J. J. , Cantero A.
Published: April 2011

Land use and grazing regime can influence the dynamic of soil water and salt in humid areas. In Central Argentina, more than 2 ×106 ha are subjected to either permanent or cyclical processes of land salinization, alkalinization, flooding and sedimentation. In this region, the natural vegetation is the principal resource on which most systems of animal production are based. The objective of this study was to evaluate the effects of plant cover and grazing over some hydrophysical properties of three saline-sodic soils (two Gleic Solonetz in duripan phase and one Mollic Solonetz in fragipan phase), within a catena sequence. The effects on bulk density, saturated hydraulic conductivity, infiltration runoff, superficial salt accumulation and soil salinity distribution were determined in both bare and covered soil conditions, inside and outside of grazing exclosures. The results showed increased bulk density of topsoil for bare conditions, while saturated hydraulic conductivity did not show significant differences. In soils without any cover, the infiltration decreased significantly. Consequently, the runoff coefficient and salinity were greater, as indicated by significant salt accumulation in the topsoil. The soil profile salinity was reduced as a function of exclosure time, showing a trend toward desalinization resulting from a combined effect of soil cover and changes in intensity of land use. A conceptual model of salt and water dynamics in the soil profile for the landscape scale is postulated. The role of vegetation in regulating water and salt movement in poorly drained areas is emphasised as a basis for the development of management strategies. Key words: Saline and sodic soils, infiltration, runoff, grazing, exclosure, model
Comparison of three methods of measuring surface area of soils
Authors: Jong E. de
Published: April 2011

Surface area (SA) is an important property of soils, but different methods can give widely different estimates of SA, and of the contribution of organic matter to SA. This study was undertaken to compare two common methods of measuring SA (EGME [ethylene glycol monoethyl ether] and N2 sorption) with SA estimates using H2O sorption on selected Saskatchewan soils; some soils from Kenya were included to show the impact of clay mineralogy. For the Saskatchewan soils, the three estimates of SA were highly correlated to each other and to clay content, but SA EGME was 2 to 3 times SA H2O and 7 to 52 times SA N2. Organic matter did not appear to contribute to SA EGME, increased SA H2O and decreased SA N2. Clearly the three methods differ in their access to internal and external surface area and this should affect their utility as indices of the sorptive capacity of field soils. Key words: Surface area, EGME, N2 sorption, water sorption
Influence of organic waste amendments on selected soil physical and chemical properties
Authors: Zebarth B. J. , Neilsen G. H. , Hogue E. , Neilsen D.
Published: April 2011

Sandy, infertile soils can benefit from the addition of organic waste amendments. Annual applications of organic wastes for as long as 4 yr increased soil organic matter content, decreased soil bulk density, and increased soil water retention of a coarse-textured soil. However, soil water-holding capacity was not necessarily increased, and there was a limited effect on soil cation exchange capacity. Key words: Cation exchange capacity, water retention, soil pH, soil organic matter, soil bulk density
Nitrogen and phosphorus release from on-farm and industrial composts
Authors: Gagnon Bernard , Simard Régis R.
Published: April 2011

Source materials and manure management may affect compost nutrient availability to plants. A laboratory experiment was conducted to determine the impact of these factors on the N and P release from 23 on-farm and 6 industrial composts. Composts were mixed with the Ap horizon of an Arago sandy loam (Humo-Ferric Podzol), at 200 mg N kg−1, and incubated for 13 wk in glass jars at 35 °C. The soil mineral N content at the end of incubation was the highest from poultry litter, sheep manure, horse manure and vegetable residue sources whereas the fresh solid, beef and young dairy manure composts resulted in high N immobilization. The release of N from the compost organic N fraction was in most cases negative. The soil Mehlich-3 P content at the end of the incubation period was higher from the poultry litter than from any other sources, whereas P was strongly immobilized from week 1 to week 13 in the fresh solid, beef and young dairy manure compost amended soils. Septic tank sludge compost was the least efficient N and P source among industrial products whereas the others showed N and/or P release comparable to most on-farm composts. In dairy manure compost, use of wood in bedding, turning compost windrow, increasing composting duration and sheltering material against precipitation all reduced P immobilization during incubation. Organic N mineralization in soil was only significantly increased by composting duration. This study indicated that the short-term N and P potential nutrient value of composts are dependent upon compost source materials and manure management, and should be based on their inorganic N and P content. Key words: Composting, farm manure management, N and P mineralization
Carbon and nitrogen mineralization in soil treated with chloride and phosphate salts
Authors: Curtin D. , Steppuhn H. , Campbell C. A. , Biederbeck V. O.
Published: April 2011

This study was undertaken to characterize the response of organic matter mineralization to soluble electrolyte concentration. We added salts (either KCl or KH2PO4) to a non-saline Black Chernozem at rates of 0 to 64 mmol kg−1 and measured the amounts of C and N mineralized in a 40 d incubation (21 °C and field capacity). Precipitation of calcium phosphate in KH2PO4-treated soil resulted in electrical conductivity (EC), measured in a 1:2 soil:water extract, being lower than in KCl-treated soil. Dissolved organic C (DOC) was increased (up to twofold) by KH2PO4 addition but KCl had little effect. The relationship between C mineralization and EC appeared to be independent of salt type. Mineralization decreased sharply (by 50%) when EC increased from 0.5 dS m−1 (check value) to 1.3 dS m−1. Inhibition of nitrification was not detected until EC increased to about 2 dS m–1. Key words: Mineralization, organic matter, salinity, chloride, sulfate
Uptake of fertilizer sulfur by maize from soils of low sulfur status as affected by vesicular-arbuscular mycorrhizae
Authors: Banerjee M. R. , Chapman S. J. , Killham K.
Published: April 2011

Vesicular-arbuscular mycorrhizae (VAM) generally enhances uptake and translocation of P and encourages plant growth and development in nutrient-deficient soils. Contradictory reports about the role of VAM in S uptake and translocation may result from insufficient consideration of soil S status. In this study, using soils of low S status, VAM inoculation increased the content of radioactively labelled S (35S) in shoots of maize plants. Key words: Maize plant, S-uptake, Vesicular-arbuscular mycorrhizae fungi
Assessing biological soil quality with chloroform fumigation-incubation: Why subtract a control?
Authors: Franzluebbers A. J. , Haney R. L. , Hons F. M. , Zuberer D. A.
Published: April 2011

Microbial biomass, as part of the active pool of soil organic matter, is critical in decomposition of organic materials, nutrient cycling, and formation of soil structure. We evaluated chloroform fumigation-incubation with subtraction of a control (CFI/F–C) and without subtraction of a control (CFI/F) as methods to assess biological soil quality. Relationships between CFI/F and potential C mineralization, particulate organic C, and soil organic C were stronger (r2 = 0.86 ± 0.07, n = 232) than those between CFI/F–C and the same soil C pools (r2 = 0.25 ± 0.09) in soils from Georgia. From published data, relationships of CFI/F with potential C mineralization and soil organic C were stronger than those of chloroform fumigation-extraction and substrate-induced respiration with these soil C pools. Effects of land management on biological soil quality using CFI/F were consistent with those determined using other soil C pools as response variables. However, land management effects on biological soil quality using CFI/F–C were either contrary to those using other soil C pools or not detectable because of greater inherent variability in CFI/F–C. Chloroform fumigation-incubation without subtraction of a control is a robust and reliable method to assess biological soil quality under a wide range of soil conditions. Key words: Active soil carbon, chloroform fumigation-extraction, microbial biomass, soil organic matter, soil quality, substrate-induced respiration
Interpretation of microbial biomass measurements for soil quality assessment in humid temperate regions
Authors: Carter M. R. , Gregorich E. G. , Angers D. A. , Beare M. H. , Sparling G. P. , Wardle D. A. , Voroney R. P.
Published: April 2011

Soil microbial biomass (SMB) measurements are often used in soil biological analysis; however, their interpretation can be problematic. In this review, both the limitations and benefits of indirect (both CHCl3 fumigation incubation and fumigation extraction, and substrate-induced respiration) SMB measurements are outlined, along with their value and interpretation as attributes or indicators to assess some soil quality (SQ) functions (e.g., enhance plant growth, maintain aggregation, regulate energy) for mainly humid, temperate soils, with specific emphasis on research conducted in eastern Canada and New Zealand. Indirect SMB methods are subject to limitations analogous to "soil test" procedures (e.g., soil sampling and handling, water content, storage prior to treatment), and also the difficulties with establishing an acceptable "control" and fraction (i.e., k value) of SMB mineralized or extracted. In many cases, such limitations present a need for some degree of standardization (e.g., pre-conditions of 7- to 10-d incubation at 25°C and −0.001 MPa water potential) prior to SMB measurement. However, for SQ assessment, where "comparative" rather than "absolute" values of SMB are often of interest, use of commonly derived k values seem appropriate for surface soils.Soil ecological factors govern SMB and often underlie much of the spatial and temporal variation in SMB. Plant species composition, mainly through net primary productivity and litter quality, can affect SMB measurements along with trophic cascades in soil, where interactions among soil organisms can influence microbial activity. Benefits of SMB measurements relate mainly to the assessment of both soil C turnover and management induced changes in organic matter. The combination of SMB and δ13C to elucidate the transformations and fate of organic C in cropping and soil management systems has also shown that both temporal and spatial redistribution of C inputs, and soil type (i.e., particle size distribution) are dominant factors in turnover and nutrient flow through the SMB.For SQ assessment, SMB is not a useful indicator for the function of soil as a "medium for plant growth" in regard to plant productivity for intensively farmed temperate soils. For the function of soil to "maintain aggregation", where SMB is one agent only of a multi-faceted process, the relationship between SMB and soil aggregation is not always present and tends to be site-specific. In regard to the "regulate energy" soil function, SMB is related to some degree with decomposition and mineralization processes. The main role of SMB for SQ assessment is to serve within a minimum data set of other indicators (e.g., macroorganic C) to monitor soil organic C storage and change. Key words: Soil microbial biomass, humid climate, soil quality
Tillage and cover crop impacts on aggregation of a sandy soil
Authors: Ball-Coelho B. R. , Roy R. C. , Swanton C. J.
Published: April 2011

In corn (Zea mays L.) – soybean [Glycine max (L.) Merr.] – winter wheat (Triticum aestivum L.) rotations cultivated in sandy soil under three tillage systems, with and without cover cropping, the soil wind-erodible fraction (<0.85 mm) ranged from 78 to 96%. Proportion and wet-aggregate stability (WAS) of the 0.85- to 5.7-mm fraction both ranked no-till (8.1% of total soil weight and 49% water-stable) > chisel plow (6.7 and 39%) > conventional plow (5.3 and 35%). Cover cropping had little effect on dry aggregate size distribution or WAS. Key words: Zea mays, Secalecereale, soil structure, aggregate stability, cover crop, tillage
Phytoavailability of Cu and Zn to lettuce (Lactuca sativa) in contaminated urban soils
Authors: Tambasco G. , Sauvé S. , Cook N. , McBride M. , Hendershot W.
Published: April 2011

This study compares the effectiveness of several chemical evaluation procedures to predict Cu, and Zn concentrkjghgfsdations in lettuce (Lactuca sativa 'Buttercrunch') grown on contaminated soils from the Montreal urban area. The plant growth assays were performed in the greenhouse using field-collected, non-spiked soils. The soils were characterized using several chemical extraction reagents, as well as electrochemical speciation of the soil solution free metal species. The chemical characterization was supplemented with labile metal pool determinations using anion exchange membranes treated with DTPA or EDTA. The results show that the more sophisticated electrochemical speciation and exchange resins procedures did not consistently improve predictions of metal uptake. We believe this is due to the minimization of metal solubility caused by the circumneutral or alkaline pH values and the relative homogeneity of the relatively small urban soil sample set that we used. The metal solubility and bioavailability in the soils tested were minimized by the particular chemical properties of the soils, obscuring any potential advantages from more discriminate soil chemical evaluation procedures. Nevertheless, the reported regressions (for 10 different methods) are valid estimates of Cu and Zn phytoavailability in contaminated urban soils. Key words: Lettuce, trace metals, bioavailability, chemical speciation, ion exchange membranes, contaminated soils, free ion
Pedogenic carbonate in Chernozemic soils and landscapes of southeastern Saskatchewan
Authors: Wang Dunling , Anderson Darwin W.
Published: April 2011

The objective of this study was to characterize soil carbonates and estimate their accumulation by using a method based on δ13C values of soil carbonate in pedons and landscapes. Dark Brown Chernozem soils of the Amulet Association (with mixed C3 and C4 plants) and native Black Chernozem soils of the Oxbow Association (with a pure C3 plants) were included. Six soil samples representing the Cca and Ck horizons of the Oxbow and Amulet Associations were chosen for detailed pedogenic carbonate studies, which include particle size fractionation, mineralogical identification, surface morphology examination, and stable carbon isotopic compositions analysis on the particle size fractions.X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses of the fractionated particle sizes indicated that dolomite dominates the carbonate occurring in the Ck horizons, and is mainly in medium and coarse silt fractions. In the Cca horizons, carbonate in clay and fine silt fractions is mostly calcite, whereas dolomite dominates the carbonates in medium and coarse silt fractions. Calcitic coatings on the surfaces of both silt and sand particles were observed. Stable carbon isotope ratio (δ13Cvalue) of carbonate was −8‰ in the clay fraction of Cca horizons in which carbonate is dominated by calcite. Carbonate in the fine particle size fractions of the Cca horizons is dominated by calcite and has the most depleted δ13C values, indicating that pedogenic carbonate occurs as calcite and mainly in the fine particle size fractions. In contrast, carbonates from coarse silts of Ck horizons were composed solely of dolomite and had the most enriched δ13C values (−1.1 to −1.4‰), a character of lithogenic carbonate. On a landscape basis, carbonate occurs mainly in the Cca horizons in mid- and upper slope soils as a result of moisture movement and ground water fluxes. Soils in the depressions were more leached and contained small amounts of carbonate, mostly in the 60- to 90-cm depth. Calculations from the δ13C values of soil carbonates indicate that about 50–68% of the carbonate in the Cca horizons of middle slope soils is of pedogenic origin, which is equivalent to a CaCO3 storage of 136–188 kg m−2. In contrast, 5 to 39% (0–36 kg m−2 CaCO3) of carbonate stored in the lower slope soils is of pedogenic origin. Thirty-one to fifty percent of the carbonate (equivalent to 100–134 kg m CaCO3) in upper slope soils is of pedogenic origin. Key words: Carbonate, pedogenic, calcite, dolomite, δ13C value, XRD, SEM, landscape
Soil sampling size estimates for soils under teak (Tectona grandis Linn. F) plantations and natural forests in Ashanti Region, Ghana
Authors: Amponsah G. I. , Meyer W. L. , Murchison H. G.
Published: April 2011

The variability of forest soil properties and the number of samples required to achieve desired levels of precision for estimation of property means have received little attention in the tropics. Highly variable forest soil properties require more intensive sampling and often have less predictive value for site assessment purposes. Sites at Offinso and Juaso Forest Districts in the Ashanti region, Ghana, were used to study the variability patterns for selected physical and chemical properties. Sites selected for this study were in the moist semi-deciduous forest zone and had nearly identical physiographic characteristics. A simple random sampling procedure was used to obtain soil samples at each site. In each of three natural forest stands and three teak plantations, 16 soil pits were examined and soil samples from the 0- to 20-cm (major rooting depth) and 20- to 40-cm depths were analyzed for selected chemical and physical properties. In the 0- to 20-cm depth, coefficients of variation varied from 8% (pH) to 72% (available P), and in the 20- to 40 cm depth from 16% (pH) to 116% (available P) under teak plantations. Similarly, in the 0- to 20-cm depth coefficients of variation varied from 11% (pH) to 40% (exchangeable K) and in the 20- to 40-cm depth from 10% (bulk density) to 86% (available P) under natural forests. Under both cover types, more samples were required to estimate means at ±10% allowable error with a confidence level of 95% for chemical properties than for physical properties. Key words: Tectona grandis plantations, moist semi-deciduous forest zone, Ghana, soil physico-chemical properties, forest ochrosol
Distribution of mercury in soils at a decommissioned gas plant
Authors: Ohut Connie K , Dudas M. J. , Nason G. E.
Published: April 2011

The range and distribution of mercury in soils at a decommissioned gas plant near Turner Valley, Alberta were investigated in order to facilitate risk assessment and the remediation and development of the site into a tourism area. Although high levels of Hg were thought to be present in some areas on the site, it was unclear whether the source of the Hg was industrial processes or from river deposition of HgS impurities after erosion of upstream sulfide deposits. Background Hg concentrations in undisturbed soils and surficial bedrock near the gas plant were also unknown. Mercury concentrations in surface soil material on the gas plant site were found to range up to 230 mg Hg kg−1 soil, with the highest concentrations found next to process building doorways. Investigation of Hg distribution with soil depth showed that levels were generally highest at the surface, dropping rapidly with depth to near background levels of 0.07 mg Hg kg−1 soil or lower. The highest Hg concentrations were associated with the clay fraction, which contained up to 2300 mg Hg kg−1 soil. The results are consistent with an anthropogenic source from spillage of elemental Hg contained in manometers and pressure monitoring devices used in plant buildings. Mercury concentrations at depth and in uncontaminated surface soils were similar to those reported by Dudas and Pawluk (1976) for surface soils formed in glacial and fluvial deposits elsewhere in Alberta. Key words: Mercury, contamination, soils, Turner Valley
Characterization of soil P in coastal forest chronosequences of southern Vancouver Island: effects of climate and harvesting disturbance
Authors: Preston C. M. , Trofymow J. A.
Published: April 2011

Limitation of tree growth due to inadequate P supply has been found for young plantations following harvesting of old-growth in high rainfall areas of coastal British Columbia. To understand the reasons for P limitation, we investigated P chemistry in mineral soil to 50 cm depth in sites from the Coastal Forest Chronosequence project on Vancouver Island. This allowed comparison of biogeoclimatic subzone (higher rainfall on west than east coast sites) and of time from harvesting disturbance (seral stage). Available (Bray 1) P was significantly higher (P < 0.001) on the drier east side (up to 50 mg kg−1), than on the west side (<5 mg kg−1), although total P values were less divergent (694 mg kg−1, east and 534 mg kg−1, west). There were no significant seral stage effects on total and available P. Extraction with 0.5 M NaOH recovered 50–60% of total P, except for samples from 10–30 cm depth on the west side, for which only 20% was recovered, an effect not found for C. Analysis of the NaOH extracts by 31P nuclear magnetic resonance (NMR) spectroscopy showed much higher proportions of orthophosphate P on the east side. West side extracts were higher in organic P forms, especially diesters, typical of forest ecosystems with restricted nutrient cycling and high precipitation. On the west side, low concentrations of available P, higher proportions of organic P in NaOH extracts, and depression of NaOH extractability at 10–30 cm are consistent with P being a limiting nutrient for tree growth, a problem that may be exacerbated by harvesting disturbance. Key words: Forest chronosequences, harvesting disturbance, 31P NMR, P cycling, organic P
Investigation into mechanisms leading to the development, spread and persistence of soil water repellency following contamination by crude oil
Authors: Roy J. L. , McGill W. B.
Published: April 2011

We investigated mechanisms by which soil water repellency may develop, spread and persist at old crude oil spill sites. We tested if its development may be due to soil sorption of vapour-phase petroleum compounds, its spread due to mechanical dispersal and mixing, and its persistence due to association of causative agents with humin and soil mineral surfaces. Development. Readily wettable soils acquired water repellency following 60 d of storage in the presence of oil-contaminated subsoil material. Change in soil wettability was attributed to soil sorption of vapour-phase petroleum compounds emanating from the contaminated material. We cite literature reports indicating that liquid-phase petroleum compounds can also cause soil water repellency. To that effect, we report how we tested and finally rejected the hypothesis that sorption of petroleum asphaltenes might be the sole cause of soil water repellency. Spread. We describe how mixing one mass unit of water-repellent soil with two to four mass units of wettable adjacent soil is sufficient to impart severe water repellency to soil mixes from three sites. Persistence. The water-repellent condition found at old crude oil spill sites is highly resistant to natural weathering and nondestructive extraction procedures. We show here that it also resists exhaustive extraction with 0.1 M NaOH and conclude that causative agents of soil water repellency are at least not solely associated with humic and fulvic acid fractions. Key words: Soil water repellency, asphaltenes, cultivation, humic acids, sorption, crude oil
Recovery of chemical and physical properties of boreal plain soils impacted by pipeline burial
Authors: Soon Y. K. , Arshad M. A. , Rice W. A. , Mills P.
Published: April 2011

Pipeline construction on the Canadian boreal plain occurs on woodland and/or agricultural fields, but soil recovery from its impact is not well documented. Therefore, we quantified changes over 3 yr (1992 to 1994) in the chemical properties of two Grey soils and the physical properties of a Grey soil that were subjected to pipeline burial and cropped to barley. The pipeline right-of-way (RoW) was divided into three zones: a road (or work) area used for vehicular traffic, a trench area for burying pipeline, and a pile (or spoil) area where soil was stockpiled during excavation. Pipeline construction resulted in mixing of subsoil material with topsoil, and the chemical properties most affected were those that varied most with depth. The pH, electrical conductivity, soluble sulphate, and exchangeable Ca and Na were increased in the surface 20 cm of soil, particularly the road and trench areas. The affected properties moderated 2 or 3 yr after pipeline construction as soluble components were dissolved or dispersed and translocated back to lower soil depths. The RoW zones had increased soil strength and compaction, and reduced water retention and infiltration rates. However, the deterioration in soil physical condition was similar across the RoW zones, indicating that it was due mainly to land clearing, a requirement to convert woodland to agricultural land. Improvement in bulk density, and water infiltration and retention in 1993 and 1994 indicated that the RoW was undergoing rehabilitation with time as a result of natural processes and annual cropping. Key words: Chemical properties, exchangeable cations, sulphate, physical properties, soil-water, pipelines
Recovery of 15N-labeled fertilizer by spring bread wheat at different N rates and application times
Authors: Tran Thi Sen , Tremblay Gilles
Published: April 2011

Optimal N fertilization can improve the yield and quality of spring bread wheat in eastern Canada. This study aimed to determine the economical N rate for the production of spring bread wheat (Triticum aestivum L. 'AC Pollet') and to compare the effect of application times on the efficiency of fertilizer N use. The experiment was conducted during 2 yr on two sites of Sainte-Rosalie clay loam. The experimental treatments were arranged in a split-plot design with N rates (0, 30, 60, 90, 120, 180 kg ha−1) as the main plots and the application times of fertilizer N (15NH415NO3 applied at seeding and booting stages) as the subplots. Grain yield, grain protein concentration and straw N content of wheat were increased significantly with N application rates. The economic N rates were 90 and 120 kg ha−1 for 1993 and 1994, respectively. The recovery of 15N-labeled fertilizer (%FNR) in grain and straw was higher when applied at booting stage than at seeding in both years. In 1993, FNR varied from 37.8 to 45.7% for seeding and from 62.1 to 68.4% for booting stage treatments. The respective values were 23.1 to 30.4% and 41.3 to 50.7% in 1994. At each N rate, the proportion of N derived from fertilizer (Ndff) was higher in grain than that in straw when 15N fertilizer was applied at booting stage. The combined recovery of 15N fertilizer (% total FNR) applied at seeding and booting, as determined by the isotopic and the difference method, was in the same range, with a mean of 49.8% and 36.2% for 1993 and 1994, respectively. Soil N supplies for wheat during the growing season were 54 and 61 kg N ha−1 in 1993 and 1994, respectively. No priming effect of added fertilizer N on the mineralization of soil N was observed. Key words: Spring bread wheat, 15N-labeled fertilizer, split N application, fertilizer N recovery
Tillage for soil fertility before fertilizers
Authors: Warkentin B. P.
Published: April 2011

The present concern for decreased tillage in crop production systems makes it interesting to look back 300 years to when Jethro Tull introduced his system of intensive tillage for cereals and fodder crops. His experiments in England, at a time when landowners started paying more attention to farming, established that frequent tillage with plows could substitute for manure or fallow in continuous cropping of wheat. The general understanding was that exposed soil absorbed plant nutrients from the atmosphere; therefore, it was important to turn over lower layers and to leave the soil in a loose condition where more surfaces were exposed. In addition to controlling weeds, a probably equally important factor was speeding up mineralization of organic matter through increased aeration. This would account for the increased yields even where weeds were not present, and the ability to substitute tillage for fallow. Tull's system of cultivating wheat grown in rows, sometimes on ridges, was vehemently debated in the 18th century and was not widely accepted. The benefits would have diminished as organic matter content of soils decreased, and was probably not effective on all soils. Key words: Horse-hoeing husbandry, mineralization, ploughing, Jethro Tull
Continuous chemical monitoring with osmotically pumped water samplers: OsmoSampler design and applications
Authors: Jannasch Hans W. , Wheat C. Geoff , Plant Josh N. , Kastner Miriam , Stakes Debra S.
Published: April 2011

Long‐term osmotically pumped fluid samplers, or OsmoSamplers, were developed to reliably and autonomously collect continuous small‐volume water samples for monitoring aqueous environments in remote locations for up to several years. OsmoSamplers provide sequential milliliter‐size samples that, when analyzed, yield high‐resolution time‐series for a wide range of dissolved components. These instruments fill an important niche that has not been addressed by automated samplers or in situ analyzers. OsmoSamplers can be customized for flow rate and duration for addressing numerous scientific questions. The samplers consist of an osmotic pump that continuously pulls fluid sample into a long small‐bore tube. They are thus extremely simple, reliable, and require neither electrical power nor moving parts. Upon recovery, fluid samples are extracted from subsections of the sample tubing, where each subsection integrates a discrete time interval. The time‐stamped subsamples are then analyzed for chemical species of interest. Sample smearing due to static and dynamic diffusion and mixing is kept to a minimum by the use of small‐bore tubing (0.5 to 1.2 mm inside diameter) and low flow rates (0.1 to 12 mL d−1). Theory and laboratory experiments show that sample smearing is not significantly greater than that calculated from static diffusion alone. OsmoSamplers have been tested in the laboratory and deployed at sea. Results from laboratory tests and field deployments illustrate initial results and potential applications.
A cold chromium distillation procedure for radiolabeled sulfide applied to sulfate reduction measurements
Authors: Kallmeyer Jens , Ferdelman Timothy G. , Weber Andreas , Fossing Henrik , Jørgensen Bo Barker
Published: April 2011

The separation and detection of extremely small amounts of radiolabeled reduced sulfur species for the determination of very low sulfate reduction rates (SRR) with the 35SO42− radiotracer was improved by optimization of the entire distillation and detection process. By reducing the amount of background radioactivity, the threshold from which turnover of radiotracer can be detected was lowered considerably. Reduction of the background radioactivity was achieved by (1) reducing cross‐contamination between distillations by modifying the distillation setup, and (2) preventing an unidentified 35S‐containing compound that greatly contributes to the background from reaching the final trap by lowering the distillation temperature. These improvements allow the measurement of low SRR, shorter incubation times, and the use of less radiotracer. Experiments with pure sulfur minerals and a variety of sediments verified that the efficiency of the new method is equal to the hot single‐step chromium reduction method, but with a greatly improved reproducibility.
Discriminating between intra‐ and extracellular metals using chemical extractions
Authors: Hassler Christel S. , Slaveykova Vera I. , Wilkinson Kevin J.
Published: April 2011

Several washing agents (EDTA, CDTA, NTA, 8 HQS, Ti‐EDTA‐citrate, Ca2+, and H+) were tested for their ability to extract adsorbed metal from biological surfaces to distinguish between internalized and total cellular metal (Pb, Ni, Cd, Zn, and Cu) for a green alga, Chlorella kesslerii. Although a single extraction protocol cannot be provided that would be acceptable for all biological species and metals, several guidelines are proposed that should facilitate the interpretation of metal bioaccumulation data. It was shown that for the studied metals, a thermodynamic explanation was generally sufficient to explain the metal extraction results. At pH 6.0, a solution of 5 × 10−3 M ethylenediaminetetraacetic acid (EDTA) was an acceptable washing agent in most cases, whereas Ca or proton exchange solutions did not appear to quantitatively remove adsorbed metals. Conditions of ligand excess could be attained with relatively small concentrations of added ligand, effectively minimizing potential damage to the organism, including modifications in membrane permeability. Potential deleterious effects of the wash agents were verified. For example, a Ti‐EDTA‐citrate or an EDTA wash at high concentrations resulted in perturbations of algal membrane permeability. In spite of potential difficulties interpreting extraction data, the usefulness of the extraction protocols was clearly demonstrated for several organisms.
A technique for establishing reference nutrient concentrations across watersheds affected by humans
Authors: Dodds Walter K. , Oakes Robert M.
Published: April 2011

Establishing reference nutrient conditions for rivers and streams is necessary to assess human impact on aquatic ecosystems and protect water quality and biotic integrity. Several methods have been proposed: (1) percentiles from statistical distributions of all rivers and streams in a region or dataset, (2) reference stream approaches, and (3) modeling river networks from existing reference streams. We propose an additional statistical method to estimate the influence of anthropogenic land uses on lotic nutrient concentrations. First, we quantify regional variation by using analysis of covariance, where total nitrogen or total phosphorus is the dependent variable, region is the categorical predictor, and percentage of anthropogenic land use (e.g., cropland, urban land) is the covariate. This allows for the aggregation of regions if there is not a significant regional effect, or if there is a significant regional effect, identifies the need to analyze regions separately. Second, we develop multiple linear regression models with best‐model techniques in which anthropogenic land‐use classifications are the independent variables, and the logarithms of in‐stream nutrient concentrations are the dependent variables. The intercept of these regression models (i.e., expected nutrient concentration in the absence of human activities assuming linear extrapolation to the origin) represents the reference nutrient concentrations. This analysis suggests that larger percentages of cropland and urban land have strong positive influences on in‐stream nutrient concentrations, both in eastern Kansas and across the conterminous United States. The most appropriate method for regions may depend on the relative availability of reference sites and other data sources. The covariance/reference approach offers a potential method for regions with limited numbers of reference sites.