Comparing simple methods for measuring phosphate sorption by soils

Soil Research ◽  
2001 ◽  
Vol 39 (6) ◽  
pp. 1433 ◽  
Author(s):  
D. G. Allen ◽  
N. J. Barrow ◽  
M. D. A. Bolland
Keyword(s):  
Single Point ◽  
Phosphate Sorption ◽  
Indirect Measures ◽  
Oxalate Solution ◽  
Western Australian ◽  
Sorption Curve

Phosphate sorption curves were measured for 103 Western Australian soils sampled from farmers’ fields. A measure of phosphate buffering obtained from a fitted curve was compared with indexes obtained from single-point measurements of phosphate sorption. The single-point indexes were adjusted for the phosphate present in the sampled soils by adding the phosphate extracted by the bicarbonate reagent to the measured sorption. Iron and aluminium extracted by an oxalate solution were measured as indirect indexes. The single-point indexes were closely correlated with the values obtained from the sorption curve. Their correlation was much larger than that of indirect measures.

Towards a single-point method for measuring phosphate sorption by soils

Soil Research ◽  
2000 ◽  
Vol 38 (6) ◽  
pp. 1099 ◽  
Author(s):  
N. J. Barrow
Keyword(s):  
Single Point ◽  
Solution Concentration ◽  
Point Method ◽  
High Rate ◽  
Point Estimate ◽  
Single Pair ◽  
Single Application ◽  
Phosphate Sorption ◽  
Point Estimates ◽  
Sorption Curve

Data from 4 separate studies using widely differing soils were used to assesswhether single-point estimates of the relative buffering could be used asestimates of buffering derived from fitted curves. The relative bufferingcapacity of soils for P was summarized using the ‘O&Svalue’. This is the increase in P sorption between concentrations of 0.25 and 0.35 mg P/L.Phosphate sorption curves were described by the modified Freundlich equation:S = acb – q, whereS ( g/g) is the measured sorption,c ( g/mL) the solution concentration, anda, b, and qare parameters. The fitted O&S value is given by:a (0.35 b – 0.25b ). If a single pair of values for sorption andconcentration is measured, rather than a sorption curve, thea value can be estimated from (S+ q)/cb . An estimate of the O&S value can beobtained from (S + q) (0.35b – 0.25 b)/c b .Because the b parameter occurs in both the numerator andthe denominator, the single-point estimate of the O&S value was notvery sensitive to the value allocated to b provided thevalue of c was in the range 2–5 mg P/L. Formost of the soils of low to moderate buffering, the P extracted by the Colwellreagent was a useful estimate of q. For these soils, thesingle-point estimates using this value of q weresimilar to the values found from the fitted curves. One group of exceptionswere some soils of low buffering which had received a single application ofphosphate at a high rate. For these soils, the Colwell reagent extracted largeamounts of phosphate. Another group of exceptions were soils of highbuffering. For these the Colwell reagent gave values much lower than thefitted value of q and was of little value in improvingthe calculation of single-point estimates. The single point estimates forthese soils were about 20% too low but nevertheless well correlatedwith the values from the fitted curves.

The Moving-IAT

2017 ◽  
Vol 33 (6) ◽  
pp. 445-452
Author(s):  
Monika Fleischhauer
Keyword(s):  
Internal Consistency ◽  
Personality Assessment ◽  
Block Structure ◽  
Mental Representations ◽  
Indirect Measures ◽  
Attitude Research ◽  
Self Reports ◽  
Implicit Personality ◽  
Single Block ◽  
Psychometric Quality

Abstract. Accumulated evidence suggests that indirect measures such as the Implicit Association Test (IAT) provide an increment in personality assessment explaining behavioral variance over and above self-reports. Likewise, it has been shown that there are several unwanted sources of variance in personality IATs potentially reducing their psychometric quality. For example, there is evidence that individuals use imagery-based facilitation strategies while performing the IAT. That is, individuals actively create mental representations of their person that fit to the category combination in the respective block, but do not necessarily fit to their implicit personality self-concept. A single-block IAT variant proposed by attitude research, where compatible and incompatible trials are presented in one and the same block, may prevent individuals from using such facilitation strategies. Consequently, for the trait need for cognition (NFC), a new single-block IAT version was developed (called Moving-IAT) and tested against the standard IAT for differences in internal consistency and predictive validity in a sample of 126 participants. Although the Moving-IAT showed lower internal consistency, its predictive value for NFC-typical behavior was higher than that of the standard IAT. Given individual’s strategy reports, the single-block structure of the Moving-IAT indeed reduces the likelihood of imagery-based strategies.

On the Stability of Evaluative Conditioning Effects

2013 ◽  
Vol 44 (6) ◽  
pp. 380-389 ◽  
Author(s):  
Sabine Förderer ◽  
Christian Unkelbach
Keyword(s):  
Evaluative Conditioning ◽  
Indirect Measures ◽  
The Stability ◽  
Over Time

Evaluative conditioning (EC) refers to valence changes in neutral stimuli (CSs) through repeated pairing with liked or disliked stimuli (USs). The present study examined the stability of EC effects in the course of 1 week. We investigated how this stability depends on memory for US valence and US identity. We also investigated whether CSs evaluations occurring immediately after conditioning (i.e., evaluative consolidation) are necessary for stable EC effects. Participants showed stable EC effects on direct and indirect measures, independent of evaluations immediately after conditioning. EC effects depended on memory for US valence but not for US identity. And although memory decreased significantly over time, EC effects remained stable. These data suggest that evaluative consolidation is not necessary, and that conditioned preferences and attitudes might persist even when people do not remember the concrete source anymore.

Exploring the suitability of indirect measures of aggression

2010 ◽  
Author(s):  
Sarah Teige-Mocigemba ◽  
K. C. Klauer
Keyword(s):  
Indirect Measures

The Western Australian Goldfields

1914 ◽  
Vol 111 (25) ◽  
pp. 508-509
Author(s):  
L. E. Shapcott
Keyword(s):  
Western Australian

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

Mill Experiences with Single Point Kappa Analysers

2017 ◽  
Vol 71 (3) ◽  
pp. 289-293
Author(s):  
Yusuke Ishimoto
Keyword(s):  
Single Point

DAYTON v. THE WESTERN AUSTRALIAN INSURANCE COMPANY LIMITED

1924 ◽  
Vol [1924] VLR ◽  
pp. 153-166 ◽  
Keyword(s):  
Insurance Company ◽  
Company Limited ◽  
Western Australian
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