bluuebunny/crossref_metadata_2025 huggingface dataset:
An artificial neural network to estimate soil temperature
Authors: Yang Chun-Chieh , Prasher Shiv O. , Mehuys Guy R.
Published: April 2011

This study was undertaken to develop an artificial neural network (ANN) model for transient simulation of soil temperature at different depths in the profile. The capability of ANN models to simulate the variation of temperature in soils was investigated by considering readily available meteorologic parameters. The ANN model was constructed by using five years of meteorologic data, measured at a weather station at the Central Experimental Farm in Ottawa, Ontario, Canada. The model inputs consisted of daily rainfall, potential evapotranspiration, and the day of the year. The model outputs were daily soil temperatures at the depths of 100, 500 and 1500 mm. The estimated values were found to be close to the measured values, as shown by a root-mean-square error ranging from 0.59 to 1.82 °C, a standard deviation of errors from 0.61 to 1.81 °C, and a coefficient of determination from 0.937 to 0.987. Therefore, it is concluded that ANN models can be used to estimate soil temperature by considering routinely measured meteorologic parameters. In addition, the ANN model executes faster than a comparable conceptual simulation model by several orders of magnitude.

Key words: Artificial neural networks, soil temperature, precipitation, potential evapotranspiration
Controlled release of phosphorus fertilizers by small, frequent additions in water solution
Authors: Nyborg M. , Solberg E. D. , Pauly D. G.
Published: April 2011

Controlled release of P was investigated with barley plants grown on two soils. Phosphorus fertilizers (monoammonium phosphate [MAP], diammonium phosphate [DAP] and ammonium polyphosphate [APP]) were dissolved in water and were applied full dose at sowing; 1/22 dose every 2nd day and 1/4 dose each 11th day. Uptake of fertilizer P in barley was much greater when the P was applied every 2nd and 11th day compared to only the day of sowing. Key words: Barley, diammonium phosphate, monoammonium phosphate, P uptake, P yield, release of P
Attenuation of cadmium, fluoride and uranium in phosphogypsum process water by calcareous soil
Authors: Poulsen L. , Dudas M. J.
Published: April 2011

Concerns about contaminant migration from phosphogypsum (PG) repositories prompted the present study. A sequential batch procedure, in which acidic process water (PW) from a phosphate fertilizer plant was reacted with samples of a calcareous till, was employed to determine the attenuation of environmentally sensitive elements by reaction with typical subsoils at PG waste repositories. PW leachates were monitored for total soluble fluoride (F) and pH during the experiment. Soil samples were analyzed for pH, F, cadmium (Cd), uranium (U), and calcium carbonate (CaCO3) equivalent at the end of the study. Leachate pH increased from <2 to 5.5 where it stabilized; soil pH stabilized at 6.5. Fluoride solution concentrations were reduced within regulatory limits. Soils accumulated Cd, F, and U in excess of background concentrations (up to 99 ×, 83 ×, and 12.5 ×, respectively). Soil carbonates persisted after leachate was buffered near pH 4.5, and played a major role in Cd attenuation. The results of this laboratory analog of a PW leaching gradient suggest contamination of groundwater is unlikely but accumulation of toxic elements in soil is an issue that may require consideration in the long-term decommissioning of PG waste repositories. Key words: Attenuation, cadmium, fluoride, leachate, phosphogypsum, uranium, waste management
In situ amelioration of sodic minespoil with chemical amendments and crop management. I. Soil chemical properties
Authors: Sansom J. J. , Naeth M. A. , Chanasyk D. S. , Bateman J. C.
Published: April 2011

Sodic minespoils, which often have undesirable properties that limit plant growth, may be ameliorated by chemical amendments. The objective of this study was to determine the effectiveness of sulfur and gypsum amendments in conjunction with crop management (summerfallow/barley rotation and continuous forage) in reducing the sodicity of a calcareous, sodic, sandy loam minespoil at the Highvale coal mine, west of Edmonton, Alberta. Amendments were added in chemically equivalent amounts to theoretically ameliorate the uppermost 35 cm of the spoil. Topsoil (20 cm) overlay both the amended and unamended spoil. Soil chemical parameters were measured to determine amendment effectiveness in an upper amended (20–35 cm depth interval from the surface), a lower amended (40–55 cm) and an upper unamended layer (55–70 cm), all within minespoil.Both sulfur and gypsum effectively reduced minespoil sodicity. The ameliorative effect on SAR occurred within 3 mo with gypsum amendment, but was slower with sulfur. Both amendments significantly lowered Sat% and pH but significantly elevated concentrations of Na+, Ca2+, Mg2+, K+and SO42− in the upper amended layer of the minespoil. Crop management had no significant effect on SAR; however, solute concentrations were lower at all depths under fallow/barley than under continuous forage treatments. Key words: Reclamation, sodicity, sulfur, gypsum, amelioration
Trace metals in Montreal urban soils and the leaves of Taraxacum officinale
Authors: Marr Kimberly , Fyles Helen , Hendershot William
Published: April 2011

Uptake of Cu, Zn, Mn, Pb, and Cd by Taraxacum officinale Weber (dandelion) growing on abandoned industrial sites, community gardens and parks in urban Montreal was measured to evaluate trace metal bioavailability. Total soil trace metal concentrations exceeded the Canadian remediation levels only in the industrial sites, but tissue concentrations at all land use types were normal. Multiple regression analysis suggests that available PO4 may reduce uptake of Cu and Zn. It is evident that sites classified as contaminated on the basis of total soil metal may have low levels of bioavailability. Key words: Trace metals, urban contaminated soils, dandelion
Effect of the structural organization of stagnic luvisols on drainage outflow
Authors: Bouzigues R. , Favrot J. C. , Chossat J. C. , Voltz M.
Published: April 2011

Drainflow and rainfall were recorded during a 10-yr period in 12 drainage plots, each 0.54 ha in area, that had been established on a stagnic luvisol (FAO soil classification) on the second terrace of the Garonne River in a 16-ha field cultivated with maize. Considerable variation in drainage efficiency and peak drainflow was noted between plots, unrelated to drain spacing (15, 20 and 30 m). This variability can be explained by the existence of two types of structure, prismatic and vertic, in the argic Btg horizon, with a gradual transition from one to the other as a function of the topographical undulations. Outflow is on average eight times greater in the vertic than in the prismatic facies. The drainflow data are in agreement with morphological observation of the soil structure and with the results of hydraulic conductivity measurements and piezometric and tensiometric monitoring. In practical terms, these results suggest that drain spacing should be closer in vertic than in prismatic facies. Key words: Stagnic luvisol, vertic structure, prismatic structure, argic B horizon, agricultural drainage, drainage outflow, soil water movements
Selenium concentration in plant material, drainage and surface water as influenced by Se applied to barley foliage in a barley – red clover – potato rotation
Authors: MacLeod J. A. , Gupta Umesh C. , Milburn P. , Sanderson J. B.
Published: April 2011

Foliar application to barley of 10 and 20 g Se ha−1, as sodium selenate, increased Se content of barley grain and straw and red clover forage. There was no significant effect of Se application on Se content of potato petioles or tubers in the third year of the rotation. The Se content of drainage water was increased during the fall and spring following Se application to barley. The highest Se concentration of 0.185 µg L−1 found in this study is well below the Canadian drinking water standard of 10 µg L−1.The Se concentrations of surface water bodies 0.5–1.0 km down slope from 10 pasture fields to which Se had been applied at 10 g ha−1 the year before, were not significantly different from surface water bodies 3–8 km from the treated fields. Selenium concentrations of all the surface water bodies ranged from 0.003 to 0.266 µg L−1, well below the maximum acceptable Se concentration for drinking water. Key words: Foliar-applied Se, plant Se, Podzol soil, Eastern Canada
Recovery of 15N-labelled fertilizers applied to barley on two artificially eroded soils in north-central Alberta
Authors: Pradhan R. , Izaurralde R. C. , Malhi S. S. , Nyborg M.
Published: April 2011

Soil erosion induces variability in soil properties which may influence nutrient use efficiency. A 2-yr field study was conducted with the following objectives: (1) to determine the recovery of 15N-labelled fertilizers applied to barley growing on artificially eroded soil, and (2) to compare N losses from nitrate- and ammonia-based N fertilizers. Field experiments were conducted in north-central Alberta in 1991 and 1992 on an Orthic Gray Luvisol (Site 1) and on an Eluviated Black Chernozem (Site 2) soil. At each site, a factorial experiment of three levels of artificial erosion (0, 10 and 20 cm) and three N sources (KNO3, urea, and control) was laid out as a split-plot design with four replications. The 15N-labelled fertilizers (5.63 atom % abundance) were banded in June 1991 at 150 kg N ha−1 within 46-cm by 46-cm steel frame microplots. The proportion of added N recovered by barley (Hordeum vulgare L.) was not affected by erosion level. Periodical water saturation and NO3− availability suggested denitrification as a major mechanism of N loss. The N losses ranged from 12 to 51 g N ha−1 in 1991 and 20 to 80 kg N ha−1 over the 2-yr period, but the N losses did not relate to erosion level. The N losses after 2 yr were greater from KNO3 than from urea at Site 1. Most of the added 15N was found in the surface 0- to 15-cm layer, but amounts of 15N were detected in the 15- to 30-cm or 30- to 45-cm layers. The results call for continued development of N management techniques geared to optimize crop growth and minimize losses from fields. Key words: Artificial erosion, barley, fate of applied N, 15N-labelled fertilizers, N immobilization, N loss
Seed germination and seedling dry matter production of canola, barley and wheat as affected by seed-placed KCl and polymer-coated KCl
Authors: Zhang Mingchu , Nyborg M. , Solberg E. D.
Published: April 2011

Seed-placed KCl often adversely affects seed germination and seedling growth because of the high salt index of the material. By coating KCl granules the adverse effect of the KCl can be reduced. Two greenhouse experiments with canola, barley and wheat, and one experiment in the field with barley were conducted to determine if normally adverse levels of seed-placed KCl fertilizer could be reduced when polymer-coated KCl is used. The results show that the number of germinated seeds and seedling dry matter were higher with the seed-placed coated KCl than the seed-placed regular non-coated KCl. Key words: KCl fertilizer, polymer-coated KCl, germination, seedling dry matter
Aspects of maize modelling in eastern Canada
Authors: Stewart D. W. , Dwyer L. M. , Reid L. M.
Published: April 2011

Maize (Zea mays L.) is a crop of growing importance in Eastern Canada. Modelling the temperature effects on phenological development, crop architecture and disease infection in maize contributes to the development of well-adapted, early-maturing varieties. Details of modelling these three aspects of maize growth were presented. The first focussed on quantifying the effect of air or soil temperature on maize phenological development. Crop growth was divided into two periods: vegetative (planting to silking) and grain filling (silking to maturity). A third period (planting to emergence) was separated within the vegetative period. Heat unit systems based on daily temperature response functions were developed to produce the most consistent heat unit sums for each period. The best fits of these functions were determined by minimizing standard deviations and coefficients of variation of these sums for each thermal period over locations and years. Calculated temperature response functions estimated thermal periods more consistently than growing degree days (GDD) for all three periods. The largest improvement was made in the silking to maturity period.The second aspect was a study of crop architecture. Methods were developed to mathematically characterize the structure of a canopy in terms of leaf area and leaf angle distributions with crop height and across the row. These calculations, in turn, were input to a soil–plant–atmosphere model to calculate interception of photosynthetically active radiation (PAR). Model calculations of PAR interception compared well with measurements for a range of plant types and plant population densities (R2 = 0.76).The third aspect was quantifying growth of Fusarium in maize. Differential equations were used to relate Fusarium rates of growth in maize ears to air temperature, relative humidity and precipitation. Integration of these equations over time produced quantitative estimates of fungal infection. Model calculations were compared to visual ratings of fungal infection for two Fusarium species over three years (R2 = 0.92).In each of the three aspects of this study, modelling tested our understanding of the processes involved and the dominant factors controlling these processes. Thus, modelling was an integral part of the scientific approach, synthesizing experimental data in a quantitative conceptual framework and identifying dominant factors and parameters which required additional focussed experimental evaluation. Key words: Phenological development, crop architecture, Fusarium infection
Characterization of nutrient regimes in some continental subalpine boreal forest soils
Authors: Chen H. Y. H. , Klinka K. , Fons J. , Krestov P. V.
Published: April 2011

To determine whether field-identified soil nutrient regimes (SNRs) can be characterized and segregated by direct soil nutrient measures, we collected samples of forest floor and mineral soil (0 to 30 cm) from a wide range of forest sites throughout the Engelmann Spruce — Subalpine Fir (ESSF) zone of British Columbia. The samples were analyzed for acidity, total C, total N, mineralizable N, and extractable Ca, Mg, K, P, and SO4-S. The study sites were stratified according to an a priori field classification (SNRs) and an a posteriori classification derived from quantitative classification (groups) using all direct measures of nutrients as discriminating variables. The two classification methods had 72% agreement. Regardless of the classification, nitrogen-related variables (C:N ratio, total N, and mineralizable N) in the mineral soil segregated best among SNRs or groups indicating the presence of a steep, N-driven regional soil nutrient gradient. Multiple regression models using SNRs, groups, or direct measures of nutrients together with surrogates of climate (elevation, latitude, and/or longitude) as predictors had the similar accountability for the variation in subalpine fir and Engelmann spruce site index (0.41 ≤ R2 ≤ 0.65). The similarity in the accountability for site index justifies the use of the a priori classification in estimating site quality. Comparison of mineralizable-N values for field-identified SNRs between different climatic regions showed similarities between boreal climates and discrepancies between boreal and cool mesothermal climates. The study gave further evidence that indices of plant-available nitrogen in the upper mineral soil provide useful measures for field-identified SNRs, but indicated that it may be necessary to expand the existing five-class a priori classification to accommodate differences in regional soil nutrient gradients. Key words: Classification, Engelmann spruce, subalpine fir, nitrogen, site index, soil nutrient regime
Crop residue and fertilizer management effects on some biological and chemical properties of a Dark Grey Solod
Authors: Soon Y. K.
Published: April 2011

A 10-yr experiment was initiated on a Dark Grey Solod near Beaverlodge, Alberta (55° 13′N, 119° 20′W) in 1985 to determine the effects of fertilizer management and barley (Hordeum vulgare L.) straw removal or incorporation on soil organic carbon (SOC) and related properties. Four crop residue treatments viz., (i) straw removed; (ii) straw ploughed in; (iii) straw disked in; (iv) straw disked in, plus a red clover (Trifolium pratense L.) green manure disked in every fifth year were superimposed on each of four fertilizer treatments. The fertilizer treatments were application of N and P: (i) banded at soil-test recommended rates (ST, b); (ii) broadcast-applied and incorporated at soil-test recommended rates (ST, bi); (iii) banded at soil-test rates of N + 25 kg ha−1 and of P + 10 kg ha−1 (ST +, b); (iv) as in (iii) but fertilizers broadcast-applied and incorporated (ST +, bi). Each treatment was replicated three times in a strip-plot design. Organic carbon, total nitrogen, total, organic and inorganic phosphorus, acid-hydrolysable carbohydrates, and microbial biomass C and N in the soil were not significantly influenced by crop residue treatments. The application of N and P fertilizers above soil-test recommended rates did not significantly affect any of the measured soil properties. Nitrogen application at the higher rate, irrespective of placement method, resulted in greater accumulation of nitrate, especially at 60–90 cm depth. It is concluded that barley straw removal over 10 yr from adequately fertilized continuous cropping systems in the Grey soil zone did not adversely affect SOC and some related nutrient pools and soil properties. Key words: Crop residue management, nitrogen, phosphorus, soil organic carbon, microbial biomass, soil carbohydrates
Crop residue and fertilizer management effects on nutrient use and barley production
Authors: Soon Y. K.
Published: April 2011

Cereal straw has many potential on-farm and off-farm uses. If straw is to be removed from land, the practice should not adversely impact long-term crop production and soil quality. A 10-yr experiment was conducted on a Dark Grey Solod near Beaverlodge, Alberta (55°13′N, 119°20′W) to determine the effects of fertilizer and straw management on the yield of, and nutrient (N and P) use by, continuous barley (Hordeum vulgare L.). Four straw management treatments: (i) straw removal; (ii) straw ploughed in; (iii) straw disked in; and (iv) straw disked in plus a red clover (Trifoleum pratense L.) green manure disked in every fifth year, were superimposed on four fertilizer treatments. The fertilizer treatments were application of N and P: (i) banded at soil-test recommended rates (ST,b); (ii) broadcast and incorporated at soil-test recommended rates (ST,bi); (iii) banded at soil-test rates of N+ 25 kg ha−1 and P+ 10 kg ha−1 (ST+,b); and (iv) as in (iii) but broadcast-applied and incorporated (ST+,bi). The straw ploughed-in treatment tended to produce lower annual barley yield and N uptake (by 9 and 13%, respectively) than the other three residue treatments. Barley yield and utilization of N and P were unaffected by straw removal as compared to disking-in straw. Barley yield and N uptake were higher (by 12 and 17%, respectively) with N and P application at the higher rate. At the recommended rate, broadcast-and-incorporated application of fertilizers resulted in lower yields and nutrient use than banded-in application. Treatment effects on P uptake tended to be small. The green-manured treatment used less fertilizer N, resulted in less total barley grain production, and did not increase the amount of crop residues incorporated. It is concluded that grain yield and nutrient (N and P) use of a continuous barley cropping system, fertilized at recommended rates of N and P, were unaffected by straw removal. Key words: Crop residue management, continuous barley production, fertilizer N and P
Monitoring soil acid-buffering capacity using a routine method for free lime
Authors: Ashworth John , Kirk Rhonda
Published: April 2011

A procedure involving equilibration of soil with 0.40 M acetic acid (normally used to estimate lime) was used instead to monitor changes in acid-buffering capacity of topsoil, in an area exposed to acid emissions. Samples taken from 15 sites in 1997 were analyzed together with matching samples taken in 1992. The procedure detected a smaller acid-buffering capacity in 1997 than in 1992 at two sites. Key words: Acid buffering capacity, acid emissions, lime
The influence of source on the sorption of dissolved organic carbon by soils
Authors: Moore T. R. , Matos L.
Published: April 2011

We examined the influence of dissolved organic carbon (DOC) source on the sorption of DOC by two clayey and two sandy soils using seven extracts from plant tissues and organic soil horizons. Sorption characteristics, such as null-point DOC concentration, partition coefficient and intercept, were determined over the initial solution concentration range of 0–50 mg DOC L−1. The clayey soils had larger partition coefficients and higher null points than the sandy soils. There was an average threefold variation in null-point DOC concentration and partition coefficient amongst the seven DOC extracts. Fractionation of the DOC samples into humic acid and hydrophobic and hydrophilic acids, bases and neutrals revealed weak relationships between the sorption characteristics and DOC chemistry. Key words: Dissolved organic carbon, sorption, fractionation, humic acid, fulvic acid
Effects of soil redistribution on soil properties in a cultivated Solonetzic-Chernozemic landscape of southwestern Saskatchewan
Authors: Pennock D. J. , McCann B. L. , Jong E. de , Lemmen D. S.
Published: April 2011

Although approximately 1.3 million ha of mixed Solonetzic – Chernozemic landscapes are cultivated in Saskatchewan, little information is available on the effects that agriculture has had on the quality of these soils. At our research site in southwestern Saskatchewan a clear landscape-scale pattern of soil distribution occurred. Regosolic and thin Chernozemic soils were associated with the long, gentle (2–5%) slopes and Solonetzic-influenced soils were associated with higher catchment area footslope and depressional positions. High rates of soil loss occurred throughout the landscape – overall a net soil loss of 31 Mg ha yr−1 was calculated using 137Cs redistribution techniques. No net depositional sites were observed in the 45 sampling points in the landscape, suggesting that the site was dominated by wind erosion. The high rates of loss were consistent with very low levels of soil organic carbon storage (37 to 46 Mg ha−1 to 45 cm) at all slope positions in the landscape and with the occurrence of sub-soil features in the plough layer. The Solonetzic-influenced soils occupy 38% of the site and have high sodium adsorption ratios (from 18 to 38 in the B horizon) and high soil resistance values as determined with a penetrometer. For the Solonetz and Solodized Solonetz soils these growth-limiting properties occur immediately below the 10-cm plough layer and may constitute a largely irreversible decrease in their productive capacity. Key words: Cesium-137, soil erosion, soil quality, landscape-scale, organic carbon
Impact de produits phytopharmaceutiques sur les microarthropodes du sol en culture de maïs irrigué: approche fonctionnelle par la méthode des sacs de litière
Authors: Cortet J. , Poinsot-Balaguer N.
Published: April 2011

The effects of two herbicides (atrazine and alachlore) and two insecticides (fipronil and carbofuran) were evaluated on soil mesofauna and organic matter decomposition, in a maize field with normal culture conditions, using the litter-bag method. The litter-bag method was discussed and considered to be adapted for this type of in situ study, especially under normal culture conditions, where it is difficult to find real control plots. However its adaptability is conditioned by some utilisation factors. The litter-bag colonization and modifications of this colonization by phytopharmaceuticals were interpreted using functional groups classification. Except for alachlore, herbicides appeared to have no differentiated effect on mesofauna. Accordingly, fipronil significantly affects the dynamics of bag colonization by selected groups belonging to soil mesofauna. Key words: Phytopharmaceuticals, maize, soil microarthropods, functional groups, trophic relationships, litter-bags
Chemical retardation of phosphate diffusion in simulated acid soil amended with lignosulfonate
Authors: Hao X. , Cho C. M. , Racz G. J.
Published: April 2011

The availability and movement of inorganic phosphate fertilizer is usually low due to precipitation and adsorption reactions in soil. Lignosulfonate (LS), which is produced from acid sulfite pulping processes, has similar characteristics to soil organic materials. An experiment was designed to study the effects of LS on P movement in a simulated acid soil containing aluminum-saturated cation exchange resin and acid-washed fine sand. The resulting simulated soil had a cation exchange capacity of 22 cmolc kg−1 and either no or 10 g kg−1 gibbsite. Movement of surface-applied monopotassium phosphate was studied in soil columns, either with 20 g kg−1 LS or without LS. Lignosulfonate reduced phosphate fixation and sustained a higher water extractable phosphate concentration near the surface of the columns, but had no effect on downward phosphate movement in the columns with gibbsite. Lignosulfonate reduced the solution concentration of P near the surface and reduced downward phosphate movement in the columns without gibbsite. The resin-sand column with gibbsite closely reflected an acid soil, and this research showed that adding LS would increase fertilizer P availability in a gibbsite-rich acid soil. Adding Ca-LS to Al-rich soil is beneficial for another reason, improving Ca nutrition, which is poor for these soils. Key words: Chemical retardation, phosphate diffusion, lignosulfonate amendment
Kinetics and equilibria of Metribuzin sorption on model soil components
Authors: Sha'ato R. , Buncel E. , Gamble D. G. , vanLoon G. W.
Published: April 2011

Sorption to solid phase materials is known to significantly affect the transport, bioavailability and ultimate fate of organic contaminants in soils and sediments. In order to develop a complete description of the fate of these compounds, it is necessary to understand both equilibrium interactions and rates and mechanisms of the sorption processes. The object of the present study was to investigate both these factors with respect to the sorption of metribuzin on model soil components, including the clay minerals kaolinite and montmorillonite, amorphous iron and aluminum hydrous oxides and humic acid. In all cases, uptake followed a similar course; there was a very rapid initial sorption process followed by continued uptake at a much slower rate. Rate constants for the slow sorption were smallest for the clay minerals, intermediate for the hydrous oxides and greatest for humic acid. Labile sorption capacities for metribuzin on the humic acid and clay minerals were also determined; the organic material had the largest capacity, and montmorillonite had a greater capacity than kaolinite. Key words: Metribuzin, sorption, clay minerals, humic material
Drip-fertigation of apple trees affects root distribution and development of K deficiency
Authors: Neilsen G.H. , Parchomchuk P. , Neilsen D. , Zebarth B. J.
Published: April 2011

The locations of root intersections were mapped relative to micro-emitters in spring, 1996 for Gala apple (Malus domestica Borkh) on M.26 rootstock, which were established and grown for 8 yr under micro-irrigation with fertigation. Root distribution was mapped for trees that had been irrigated daily between May and October using drip or microjet systems and fertigated each year during May. Drip-irrigated trees had nearly half of their total root intersections within 30 cm depth and lateral distance from the emitter. Roots of microjet-irrigated trees were more widely distributed over a soil volume extending to 60 cm depth and 90 cm lateral distance from the trees. Leaf K concentrations had decreased to near deficient concentrations for drip-irrigated trees after 5 yr.Root distribution mapping and soil sampling were undertaken in spring 1997 for N-fertigated Gala on M.9 apples, planted in 1992 on the same soil, with or without annual K applications during 1992–1996. Fertigation of 15 g K tree−1 each year in July–August did not affect root distribution, which remained laterally and vertically restricted but prevented the decline of exchangeable soil K below 50 mg kg−1, exchangeable K/Ca + Mg + K ratios below 0.04 and the appearance of K deficiency symptoms in the trees. There was no evidence of long-term soil-K enrichment after 5 yr of K fertigation. Key words: Leaf and soil K, micro-irrigation, Malus domestica Borkh, root restriction
Sewage water irrigation effects on some potentially toxic trace elements in soil and potato plants in northwestern India
Authors: Brar M. S. , Malhi S. S. , Singh A. P. , Arora C. L. , Gill K. S.
Published: April 2011

Sewage water is used for irrigation to improve crop yields, but it may affect the soil and crop quality. The effects of discharging the effluents of a leather complex on the concentrations of some potentially toxic elements (Cu, Fe, Mn, Zn, Al, As, Cr and Ni) in sewage water and the effects of irrigation with contaminated sewage water on the concentrations of these elements in soils and in potato (Solanum tuberosum L.) leaves and tubers were studied near Jalandhar city, Punjab, in northwestern India. Two treatments were 10 yr of irrigation with 300 mm of sewage water + 300 mm of ground water per annum (SW) and with 600 mm of ground water per annum (GW). Soils of the study fields were Typic Ustochripts with sandy to loamy sand texture. The concentrations of all elements except As increased following the addition of leather complex effluents in the sewage water, with the biggest increase in the concentration of Cr (from 2.7 mg to 14.0 mg Cr L−1). The SW treatment increased concentrations of all elements in soil except As, and the increase was significant to 60 cm depth for Fe, Mn, Zn, Al and Ni and to 30 cm depth for Cu and Cr. Irrigation with SW also increased the concentrations of these elements in potato leaves and tubers and the increase was generally higher in leaves than in tubers. The proportional increase of Cu, Fe, Zn and Al was less in plants than in soils, that of Mn and Cr was almost similar in plants and in soil, and that of Ni was more in plants than in soil. These elements, which accumulate in soils and crops, may become health hazards to humans and/or animals. Therefore, continued monitoring of the concentrations of potentially toxic elements in soil and plants and/or treatment of sewage water before using for irrigation is needed. Key words: Irrigation, leather industry effluent, Solanum tuberosum, potentially toxic elements, sewage water
Trophic structure of nematode communities, microbial biomass, and nitrogen mineralization in soils of forests and clearcuts in the southern interior of British Columbia
Authors: Forge T. A. , Simard S. W.
Published: April 2011

The trophic structure of nematode communities, lengths of fungal hyphae, and gross populations of protozoa and bacteria were compared between clearcuts and adjacent forests at three sites in the southern interior of British Columbia in 1996, 1997, and 1998. Total C and N, mineralizable N (anaerobic incubation), and N mineralised during aerobic incubations, were determined from the same soil samples used for biological assays. Net N mineralization did not differ between clearcuts and forests in 1997; in 1998 net N mineralization in the organic horizon was four times greater for forests than for clearcuts. Hyphal lengths and total microbial biomass were greater in forest soil than in clearcut soil. Bacterial abundance was greater in forest soil than in clearcut soil in 1996 only. The abundance of protozoa did not differ between clearcuts and forests. Fungivorous, omnivorous, and predacious nematodes were less abundant in clearcut soil than in forest soil. Bacterivorous nematodes were more abundant in the mineral soil of clearcuts than in forests in 1996, but did not differ between clearcuts and forests in any other combination of year and horizon. Net N mineralization was correlated with the ratio of bacterial biomass/fungal biomass (r = 0.72, 12 degrees of freedom), as well as the abundance of amoebae (r = 0.83), total nematodes (r = 0.80), bacterivorous nematodes (r = 0.74), and fungivorous nematodes (r = 0.83). Key words: Microfauna, nematode ecology, microbial biomass, clearcut harvesting, nitrogen mineralization
A precise method for the analysis of δ18O of dissolved inorganic phosphate in seawater
Authors: McLaughlin Karen , Silva Steven , Kendall Carol , Stuart‐Williams Hilary , Paytan Adina
Published: April 2011

A method for preparation and analysis of the oxygen isotope composition (δ18O) of dissolved inorganic phosphate (DIP) has been developed and preliminary results for water samples from various locations are reported. Phosphate is extracted from seawater samples by coprecipitation with magnesium hydroxide. Phosphate is further purified through a series of precipitations and resin separation and is ultimately converted to silver phosphate. Silver phosphate samples are pyrolitically decomposed to carbon monoxide and analyzed for δ18O. Silver phosphate samples weighing 0.7 mg (3.5 µmol oxygen) can be analyzed routinely with an average standard deviation of about 0.3‰. There is no isotope fractionation during extraction and blanks are negligible within analytical error. Reproducibility was determined for both laboratory standards and natural samples by multiple analyses. A comparison between filtered and unfiltered natural seawater samples was also conducted and no appreciable difference was observed for the samples tested. The δ18O values of DIP in seawater determined using this method range from 18.6‰ to 22.3‰, suggesting small but detectable natural variability in seawater. For the San Francisco Bay estuary DIP δ18O is more variable, ranging from 11.4‰ near the San Joaquin River to 20.1‰ near the Golden Gate Bridge, and was well correlated with salinity, phosphate concentration, and δ18O of water.
High‐frequency measurement of partial pressure and total concentration of carbon dioxide in seawater using microporous hydrophobic membrane contactors
Authors: Hales Burke , Chipman David , Takahashi Taro
Published: April 2011

To investigate CO2 chemistry in ocean water with greater time‐space resolutions, we developed measurement systems, which have state‐of‐the‐art precision but an order of magnitude or better increase in the frequency of analysis, for carbon dioxide partial pressures (PCO2) and total carbon dioxide concentrations (TCO2) in seawater. The PCO2 system was based on equilibration of a CO2‐free carrier gas stream with aqueous carbon dioxide in a flowing seawater sample stream using a commercially available membrane contactor unit normally employed in industrial applications followed by nondispersive infrared (NDIR) absorbance detection of the CO2 in the exit carrier gas. The TCO2 system was based on injection of a small‐volume seawater sample loop (~1 mL) into an acid (0.1 N HCl) liquid carrier stream to convert all carbonate and bicarbonate ions to aqueous carbon dioxide; this acidified sample was then passed through a custom‐made small‐volume membrane contactor unit where the sample's PCO2 was determined by equilibration of a CO2‐free carrier gas followed by NDIR detection. Results from lab tests and a field experiment in the Ross Sea polynya, Antarctica, are presented. The PCO2 system was determined to have a response time of about 3 s and precision of better than 1 µatm. The TCO2 system had a maximum analysis rate of one sample per 36 s, and reproducibility was determined to be better than 0.2% for a period of hours.
The use of oxygen microprobes to measure bacterial respiration for determining bacterioplankton growth efficiency
Authors: Briand Enora , Pringault Olivier , Jacquet Séverine , Torréton Jean Pascal
Published: April 2011

Heterotrophic bacterial growth efficiency (BGE), the ratio between the carbon consumed and the bacterial biomass produced, is a key factor in understanding flows of organic matter in aquatic ecosystems. Methods generally used to estimate bacterial respiration require long incubations (24 to 36 h) to measure significant rates during which nonlinear patterns of oxygen decrease may bias BGE computation. These respiration estimates are generally compared to bacterial production rates determined from radiotracer incorporation from much shorter incubations. The aim of this study was to improve the determination of bacterial respiration to better estimate BGE. For this purpose, we employed oxygen microprobes in predator free (0.6 µm filtered) seawater samples and determined in parallel bacterial abundance. The use of oxygen microprobes allowed us to continuously monitor oxygen concentration during the incubation. Hence, the length of incubation can be adjusted as soon as a significant decrease of oxygen is observed. At the most productive sites, respiration was measurable from the beginning of the incubation and varied with time. In contrast, at the oligotrophic sites, respiration was often detectable only after a lag‐phase of 5 to 10 h and remained constant thereafter. BGE was computed from the changes in bacterial abundance observed during the respiration measurements. This way, both processes were determined in similar incubation conditions. In comparison, the use of radiotracer derived bacterial production systematically resulted in an underestimation of BGE.
Quantification of sedimentary black carbon using the chemothermal oxidation method: an evaluation of ex situ pretreatments and standard additions approaches
Authors: Elmquist Marie , Gustafsson Örjan , Andersson Per
Published: April 2011

The highly condensed products and residues of incomplete combustion of biomass and fossil fuel termed black carbon (BC) partake in a multitude of important geochemical processes. However, ambiguity persists because different quantification methods give highly variable results, leaving it unclear whether this reflects method difficulties or that different methods simply mirror different parts of the BC spectrum. Introducing additional wet chemical ex situ pretreatment steps (Gélinas et al. 2001b), to a commonly applied chemothermal oxidation (CTO) method led to large handling and transfer losses of hydrophobic diesel‐soot BC (NIST SRM‐2975). The resulting yield of soot BC spiked to a coastal marine and a freshwater sediment was only 6 ± 1% and 70 ± 4%, respectively, for the entire ex situ procedure. Instead, a standard addition approach yielded statistically significant linear returns of incremental soot BC additions. The slopes suggested that 51 ± 6% and 78 ± 6% of the added soot BC was accounted for in the marine and freshwater sediment, respectively. The lower recovery of soot BC in the marine sediment is likely caused by chloride enhancing the contact between BC surfaces and mineral oxides, catalyzing the BC oxidation. A consequential lowering of the oxidation energy from 375°C to 360°C resulted in increased soot BC yields of 75 ± 7% and 97 ± 3% in the marine and freshwater sediments, respectively. The standard addition approach suggests a native “soot BC‐like” concentration of 0.48 mg BC/g dry weight (soot BC/total organic carbon = 0.03) in the bioturbated marine sediment from Kosterfjord, Skagerrak and 6.2 mg BC/g dry weight (soot BC/TOC = 0.10) in the heavily polluted Rhine River sediment.
Measuring surface complexity in ecological studies
Authors: Frost Natalie J. , Burrows Michael T. , Johnson Mark P. , Hanley Mick E. , Hawkins Stephen J.
Published: April 2011

Habitat complexity is a potential structuring force in benthic communities. Different studies often estimate complexity in different ways, and it is not always clear how precise the separate techniques are. Here we review three methods of estimating surface complexity: stereo photography, profile gauges, and lengths of chain contoured over the substratum. We derived fractal dimensions for the quadrats in the rocky intertidal zone using each technique. Complexity estimates from chains and profile gauges were related, but neither technique was correlated with the results from stereo photographs. Stereo photographs appeared to overestimate complexity on smooth surfaces. The variance of fractal dimension estimates increased nonlinearly with the mean fractal dimension in each quadrat. Recommendations for the number of replicates needed for a reliable estimate of fractal dimension from a quadrat, therefore, vary as a function of surface complexity. Within the range of complexities typically encountered on rocky shores, as few as three profiles or sets of chains can produce relatively reliable estimates of fractal dimension. The most robust and time effective method, however, would be to sample using as many chain profile sets per quadrat as is logistically feasible. Given the changes in precision with surface complexity, comparisons between studies need to take careful note of the number of replicates and the average level of surface complexity. A null result (no relationship between surface complexity and an ecological variable) could be produced by imprecise estimates of surface complexity based on too few replicate measurements per quadrat.
Correcting whole‐stream estimates of metabolism for groundwater input
Authors: Hall Robert O. , Tank Jennifer L.
Published: April 2011

Open‐channel metabolism is commonly measured in streams, but these measurements may be strongly biased by small inputs of low‐O2 groundwater seeping into the study reach that will appear to increase community respiration (CR), but decrease gross primary production (GPP). We developed a new equation that considers groundwater inputs when calculating metabolism. When streamwater O2 concentrations are much higher than groundwater O2 concentrations, a small amount of groundwater input can substantially bias CR. For example, a 200‐m, 100‐L s−1 stream reach that increases in discharge by only 5% may overestimate CR by two‐fold. Unlike CR, the degree of bias for GPP is unaffected by O2 concentration in groundwater, therefore it is easily calculated as a function of groundwater flux into the study reach. We applied this new correction for a cowpasture spring stream in Wyoming that increased in discharge by 50% over our study reach. Uncorrected CR was −18.8 g O2 m−2 d−1 and GPP was 11.6 g O2 m−2 d−1 in the spring stream; corrected CR was −11.4 g O2 m−2 d−1 and GPP was 16.2 g O2 m−2 d−1. Our modeling and data show that ecosystem metabolism estimates are extremely sensitive to groundwater inputs, even inputs that are difficult to measure by using mass‐balance of tracers. The largest unknown is the concentration of O2 in groundwater when correcting CR. We suggest that investigators attempt to correct for the impact of groundwater on any stream where the inflows are detectable.
Salvaging velocity measurements corrupted by nearby instruments
Authors: Pálmarsson Sveinn Ó. , Schladow S. Geoffrey , Fong Derek A.
Published: April 2011

A methodology is presented for salvaging velocity measurements that have been corrupted by the interference of nearby instruments. The method iteratively filters out spikes in the data that are not coherent with the median‐filtered velocity in spatial and temporal dimensions. An example is given for a data set from a benthic boundary layer, found to be corrupted by vortex shedding from nearby instruments co‐located for sampling of scalars with the velocity field. The effectiveness of the method is demonstrated by the reduction in energy at high frequencies and the reasonable flow velocities produced. This procedure provides realistic estimates of shear stress and other properties of the flow. Weaknesses of the method are the subjective determination of the size of the filter window, the criterion for sample deletion, and boundary conditions.
Analytical methods for the determination of sugars in marine samples: A historical perspective and future directions
Authors: Panagiotopoulos Christos , Sempéré Richard
Published: April 2011

Analytical techniques employed over the past three decades for sugar determination in marine samples are reviewed. This review first summarizes the different hydrolysis protocols used by marine biogeochemists to extract sugars from various marine matrices including sinking particulate organic matter (POM), dissolved organic matter (DOM), ultrafiltrated dissolved organic matter (UDOM), and sediments. The most commonly used methods for total sugar estimation are phenol sulfuric acid (PSA), 3‐methyl‐2‐benzo thiazoline hydrazone hydrochloride (MBTH), and 2,4,6‐tripyridyl‐s‐triazine (TPTZ). For individual sugars, gas chromatographyflame ionization detection (GC‐FID), liquid chromatography‐borate complexes (LC), high performance liquid chromatography‐ethylenediamine derivatives (HPLC‐EDA), high performance liquid chromatography‐p‐aminobenzoic acid derivatives (HPLC‐p‐AMBA), and high performance anion exchange chromatography‐pulsed amperometric detection (HPAEC‐PAD) have been employed, the last method being the most widely used. This study demonstrated that mild and strong hydrolysis give comparable results for open ocean samples, including POM, DOM, and UDOM (except for sediments) using chromatographic or colorimetric techniques. A survey of 130 sugar data sets revealed that more than half of the sugar‐C escapes analysis using chromatographic or colorimetric techniques compared to 1H and 13C NMR techniques. The reconciliation of the NMR and colorimetric or chromatographic measurements is likely to be the key to the understanding of the composition of DOM. This study also demonstrated that most of the published sugar data obtained by chromatographic techniques are related to suspended or sinking POM and sediments, and that there is a need for data on sugar composition in DOM and UDOM, which involve further analytical difficulties for chromatographic analysis.
Evaluating the suitability of coupled biophysical models for fishery management
Authors: Hinrichsen Hans-Harald , Dickey-Collas Mark , Huret Martin , Peck Myron A. , Vikebø Frode B.
Published: April 2011

Hinrichsen, H-H., Dickey-Collas, M., Huret, M., Peck, M. A., and Vikebø, F. B. 2011. Evaluating the suitability of coupled biophysical models for fishery management. – ICES Journal of Marine Science, 68: 1478–1487. The potential role of coupled biophysical models in enhancing the conservation, management, and recovery of fish stocks is assessed, with emphasis on anchovy, cod, herring, and sprat in European waters. The assessment indicates that coupled biophysical models are currently capable of simulating transport patterns, along with temperature and prey fields within marine ecosystems; they therefore provide insight into the variability of early-life-stage dynamics and connectivity within stocks. Moreover, the influence of environmental variability on potential recruitment success may be discerned from model hindcasts. Based on case studies, biophysical modelling results are shown to be capable of shedding light on whether stock management frameworks need re-evaluation. Hence, key modelling products were identified that will contribute to the development of viable stock recovery plans and management strategies. The study also suggests that approaches combining observation, process knowledge, and numerical modelling could be a promising way forward in understanding and simulating the dynamics of marine fish populations.