MONOSACCHARIDES IN HYDROLYSATES OF WATER-STABLE AGGREGATES AFTER 67 YEARS OF CROPPING TO SPRING WHEAT AS DETERMINED BY CAPILLARY GAS CHROMATOGRAPHY

1984 ◽  
Vol 64 (4) ◽  
pp. 647-656 ◽  
Author(s):  
J. F. DORMAAR
Keyword(s):  
Gas Chromatography ◽  
Spring Wheat ◽  
Capillary Gas Chromatography ◽  
Detector Response ◽  
Organic C ◽  
Native Prairie ◽  
Water Stable Aggregates ◽  
Southern Alberta ◽  
Aggregate Fractions

Two non-replicated, unfertilized, dryland grain rotations—continuous wheat and wheat-fallow — were established in 1912 on a Dark Brown Chernozemic soil in southern Alberta. The effect of long-term cropping on the monosaccharide distribution in the hydrolysates of the water-stable aggregates was assessed. Although all the hydrolysates of the aggregates had the same suite of monosaccharides, the relative proportions changed with cultivation. The eight monosaccharides identified represented between 92 and 96% of the total GC detector response. The monosaccharide C of aggregate organic C for the native prairie varied from 6.9 to 7.6%, while for the continuous wheat and the wheat and fallow of the wheat-fallow rotation it varied from 3.6 to 5.5%, from 1.8 to 5.1%, and from 1.6 to 6.7%, respectively; the higher percentages were associated with the larger aggregate fractions. Except for galactose, the average relative proportions of the monosaccharides identified in the hydrolysates of the water-stable aggregates were not much different from those reported in the literature for the hydrolysates of whole soils. Key words: Monosaccharides, aggregate fractions, water-stable aggregates, capillary gas chromatography, long-term rotation

BURNING CROP RESIDUES: EFFECT ON SELECTED SOIL CHARACTERISTICS AND LONG-TERM WHEAT YIELDS

1979 ◽  
Vol 59 (2) ◽  
pp. 79-86 ◽  
Author(s):  
J. F. DORMAAR ◽  
U. J. PITTMAN ◽  
E. D. SPRATT
Keyword(s):  
Spring Wheat ◽  
Crop Residues ◽  
Soil Characteristics ◽  
Chelating Resin ◽  
Available P ◽  
Total N ◽  
Organic C ◽  
Water Stable Aggregates ◽  
Straw Burning

Soils from a long-term spring wheat — spring wheat — fallow crop rotation study at Lethbridge, Alberta, and two similar crop rotations at Indian Head, Saskatchewan, were analyzed for pH, organic C, total N, chelating resin-extractable C, polysaccharides, water-stable aggregates, NH4-N, NO3-N, and available P. Several agronomic practices, including straw burning, have been tested in the rotations. At Lethbridge, soil samples from the straw-burning treatment showed a decrease (P < 0.05) in soil polysaccharides and in the percentage of water-stable aggregates. At Indian Head, where straw was burned, organic C and polysaccharide content of all soils were decreased (P < 0.05), and NH4-N and available P were decreased (P < 0.05) in some soils. The other soil characteristics examined were not affected by burning of the previous crop residue or, as with available P, reacted differently at different sites. Long-term wheat yields tended to be greater in all experiments when straw was not burned. On the basis of the results obtained, burning of crop residues on a long-term basis must be discouraged.

Screening and quantification of hypnotic sedatives in serum by capillary gas chromatography with a nitrogen-phosphorus detector, and confirmation by capillary gas chromatography-mass spectrometry.

1986 ◽  
Vol 32 (2) ◽  
pp. 325-328 ◽  
Author(s):  
V A Soo ◽  
R J Bergert ◽  
D G Deutsch
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Capillary Gas Chromatography ◽  
Gas Chromatography Mass Spectrometry ◽  
Detector Response ◽  
Capillary Gc ◽  
Chromatography Mass Spectrometry ◽  
Nitrogen Phosphorus Detector ◽  
Sedative Drugs ◽  
Nitrogen Phosphorus

Abstract We describe a quantitative screen for hypnotic-sedative drugs in which we use capillary gas chromatography with a nitrogen-phosphorus detector (GC/NPD) as the primary method and capillary gas chromatography-mass spectrometry (GC-MS) for confirmation. GC retention times of the acid-extracted underivatized drugs were stable (CVs less than 1%), and the detector response varied linearly over a 20-fold concentration range with a mean correlation coefficient for 11 drugs of 0.989. The limits of detection were satisfactory (0.5 mg/L in a 0.5-mL serum sample and 1-microL injection volume), as were precision (average CV 5.2% within day, 6.4% between day). The complementary use of capillary GC-MS not only unambiguously confirms presumptive peaks identified by GC, but also prevents reports of false positives and identifies compounds not included in the quantitative GC screen that may be listed in the GC-MS library.

Long-term aspects of phospholipidic analysis of fatty acid methyl esthers by use of nonpolar capillary gas chromatography

1993 ◽  
Vol 57 (5) ◽  
pp. 813S-813S ◽  
Author(s):  
André EP de Jong ◽  
Taco S van den Berg ◽  
Annemieke Nijmeijer-Couprie ◽  
Jan P Goedhart ◽  
Ep Oosting
Keyword(s):  
Gas Chromatography ◽  
Fatty Acid ◽  
Capillary Gas Chromatography ◽  
Acid Methyl

Cultivation effects on dispersible clay of soil aggregates

1995 ◽  
Vol 75 (1) ◽  
pp. 101-107 ◽  
Author(s):  
L. G. Fuller ◽  
Tee Boon Goh ◽  
D. W. Oscarson
Keyword(s):  
Soil Aggregates ◽  
Aggregate Size ◽  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Organic C ◽  
Size Fractions ◽  
Clay Dispersion ◽  
Native Prairie ◽  
Exchangeable Ca

The objective of this study was to examine the effect of long-term cultivation on clay dispersibility of four aggregate size fractions (2.0–9.5 mm, 0.85–2.0 mm, 0.25–0.85 mm, and < 0.25 mm) obtained from a Chernozemic soil by comparing two cultivated sites with an adjacent native prairie site. Aggregate size fractions (ASF) were subjected to increasing levels of ultrasonic energy and the amount of clay dispersed at each energy level was determined. Organic carbon, hexose carbon, soluble hexose C, total clay, cation exchange capacity (CEC), and exchangeable cations were measured for each ASF. Clay contained within prairie aggregates was held much more strongly within the aggregate and therefore showed greater stability towards dispersion by ultrasonic vibration. More energy was required to disperse one-half of the ASF clay under prairie than under cultivated soils (228–425, and 95–229 kJ L−1 for prairie and cultivated macroaggregates, respectively; 370–433, and 249–334 kJ L−1 for prairie and cultivated microaggregates, respectively). Clay dispersibility was significantly correlated with organic C, hexose C, soluble hexose C, non-hexose C, CEC, and exchangeable Ca and Mg but was not correlated with total ASF clay. Long-term cultivation of this soil resulted in a decrease in the energy required to disperse an equivalent proportion of clay from aggregates relative to that of the grassland soil. Thus, cultivation of these soils has resulted in aggregates which are more susceptible to clay dispersion and therefore prone to water erosion and surface crusting. Key words: Clay dispersion, aggregation, carbohydrate

EPIC estimates of soil water, nitrogen and carbon under semiarid temperate conditions

1998 ◽  
Vol 78 (3) ◽  
pp. 551-562 ◽  
Author(s):  
G. Roloff ◽  
R. de jong ◽  
C. A. Campbell ◽  
R. P. Zentner ◽  
V. M. Benson
Keyword(s):  
Soil Water ◽  
Environmental Quality ◽  
Spring Wheat ◽  
Potential Evapotranspiration ◽  
Soil Layer ◽  
Triticum Aestivum L ◽  
Total N ◽  
Organic C ◽  
Support Tool

The Environmental Policy Integrated Climate (EPIC) model is an important support tool for environmental management. Previous tests of the model have determined that it is suitable for long-term yield estimation, but it is less precise in assessing annual yield variability. To determine the reasons for the discrepancies between estimated and measured yields, we tested the ability of EPIC version 5300 to predict soil water and soil nitrogen dynamics, using data from a long-term spring wheat (Triticum aestivum L.) rotation experiment in the semiarid prairie region of Canada. Potential evapotranspiration (PET) estimates varied among methods tested: Priestley-Taylor and Penman-Monteith methods resulted in PET means that were about twice those obtained with the Hargreaves and Baier-Robertson methods. The higher PET means were associated with an excessive estimation of net radiation. We used the Baier-Robertson method to generate the other estimates reported herein. EPIC generally overestimated total soil water, but it still allowed clear differentiation among rotation phases and times of the year, and provided adequate estimates of water during the critical shot-blade stage. Water estimates by soil layer were also generally overpredicted, especially at depths from 0.15 to 0.60 m, but we were able to differentiate among rotation phases and times of the year. Precision of these latter estimates was generally low, accounting at most for 27% of the variability, and varied by soil layer, rotation phase and time of the year. Nitrate-N estimates tended to be lower than measured values, especially at depths below 0.3 m and during vegetative growth phases. However, the estimates also allowed us to distinguish among the rotation phases and times of the year. Total N and organic C were satisfactorily estimated by EPIC. In general, EPIC provided adequate long-term estimates of the environmental quality indicators tested. Key words: Environmental quality, environmental modelling, sustainability, spring wheat, fallow, potential evapotranspiration methods

LONG-TERM WEATHERING OF AMOCO CADIZ OIL IN SOFT INTERTIDAL SEDIMENTS

1989 ◽  
Vol 1989 (1) ◽  
pp. 401-405 ◽  
Author(s):  
David S. Page ◽  
Judith C. Foster ◽  
Paulette M. Fickett ◽  
Edward S. Gilfillan
Keyword(s):  
Gas Chromatography ◽  
Oil Spill ◽  
Capillary Gas Chromatography ◽  
Reference Site ◽  
Aliphatic Hydrocarbons ◽  
Soft Sediment ◽  
Biogenic Hydrocarbons ◽  
Intertidal Sediments

ABSTRACT Samples of sediment were taken at intervals between 1979 and 1986 from soft sediment locations in the Aber Benoit, an estuary heavily impacted by the Amoco Cadiz oil spill of 1978, and from a comparable reference site outside the spill zone. Each sample was analyzed for aliphatic hydrocarbons by capillary gas chromatography. The data demonstrate the progressive weathering of the Amoco Cadiz oil resulting in an assemblage of biogenic hydrocarbons similar to the reference site by 1986 at all but the most heavily impacted locations. The data indicate that any residues of weathered Amoco Cadiz oil present in 1985-86 were in the final stages of degradation.

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