Diffusion of Aqueous Solutions of Phosphoric Acid at 25°(

Edwards, O. W.; Huffman, E. O.

doi:10.1021/j150581a011

Cited by 64 publications

(32 citation statements)

References 4 publications

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“…For concentrations higher than 5 mol/L, the diffusion coefficient decreases appreciably (Figure 1). In a previous article, Edwards and Huffman (1959) obtained the diffusion coefficient of aqueous solutions of phosphoric acid using a two-lens Gouy diffusiometer over the concentration range 0.036 to 16 mol/L. Their results are also plotted in Figure 1, the shape of the plot being similar to that obtained in this work.…”

Section: Discussionsupporting

confidence: 73%

Variation of phosphoric acid diffusion coefficient with concentration

1995

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Section: Discussionsupporting

confidence: 73%

Variation of phosphoric acid diffusion coefficient with concentration

1995

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“…Loblolly pine ) Red maple ) 0.75 0.74 † parameters used by NST 3.0 ‡ parameters used by SSAND and PCATS § The values of D L for nitrate and potassium were taken from Parsons (1959), and that of phosphorus from Edwards and Huffman (1959). Table 7.…”

Section: Parameters Unitsmentioning

confidence: 99%

“…Units No fertilizer addition 75kg ha -1 of fertilizer addition 150kg ha -1 of fertilizer addition 1.4 1.41 1.4 † parameters used by NST 3.0 ‡ parameters used by SSAND and PCATS § The values of D L for nitrate and potassium were taken from Parsons (1959), and that of phosphorus from Edwards and Huffman (1959). a and c were set as 1 and 0 for every run.…”

Section: Parametersmentioning

confidence: 99%

Nutrient uptake estimates for woody species as described by the NST 3.0, SSAND, and PCATS mechanistic nutrient uptake models

Lin

Kelly

2010

Plant Soil

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With the advent of the personal computer, mechanistic nutrient uptake models have become widely used as research and teaching tools in plant and soil science. Three models NST 3.0, SSAND, and PCATS have evolved to represent the current state of the art. There are two major categories of mechanistic models, transient state models with numerical solutions and steady state models. NST 3.0 belongs to the former model type, while SSAND and PCATS belong to the latter. NST 3.0 has been used extensively in crop research but has not been used with woody species. Only a few studies using SSAND and PCATS are available. To better understand the similarities and differences of these three models, it would be useful to compare model predictions with experimental observations using multiple datasets from the literature to represent various situations for woody species. Therefore, the objectives of this study are to: (i) compare the predictions of uptake by the NST 3.0, SSAND, and PCATS models for a suite of nutrients against experimentally measured values, (ii) compare the behavior of the three models using a one dimensional sensitivity analysis; and (iii) compare and contrast the behavior of NST 3.0 and SSAND using a multiple dimensional sensitivity analysis approach. Predictions of nutrient uptake by the three models when run with a common data set were diverse, indicating a need for a reexamination of model structure. The failure of many of the predictions to match observations indicates the need for further studies which produce representative datasets so that the predictive accuracy of each model can be evaluated. Both types of sensitivity analyses suggest that the effect of soil moisture on simulation can be influential when nutrient concentration in the soil solution (C Li ) is low. One dimensional sensitivity analysis also revealed that I max negatively influenced the uptake estimates from the SSAND and PCATS models.Further analysis indicates that this counter intuitive response of I max is probably related to low soil nutrient supply. The predictions of SSAND under low-nutrient-supply scenarios are generally lower than those of NST 3.0. We suspect that both of these results are artifacts of the steady state models and further studies to improve them, such as incorporating important rhizospheric effects, are needed if they are to be used successfully for the longer growth periods and lower soil nutrient supply situations more typical of woody species.iii Acknowledgements

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“…1. For the calculations, the following values were used: diffusion coefficient of solute in water (D) 8.9 × 10 -6 cm 2 s -1 at 25°C (Edwards and Huffman, 1959), volumetric water content (h) 0.5 cm 3 cm -3 , impedance factor (f) 0.083 and 0.09 for 100% black peat and 80% black peat + 20% mineral component, respectively.…”

Section: Buffer Power (B)mentioning

confidence: 99%

Phosphorus dynamics in peat‐based substrates

Khandan‐Mirkohi

2008

Z. Pflanzenernähr. Bodenk.

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The mobility of nutrients in soils is well characterized, whereas little information is available for common horticultural substrates based on peat. Aim of the current study was to investigate the mobility and dynamics of phosphorus (P) as well as the parameters involved in P transport to plant roots in peat-based substrates. A series of experiments was run to determine the impedance factor (f) and the buffer power (b). The impedance factor was determined for black peat and black peat mixed with 20% and 40% (v/v) of mineral component at volumetric water content (h) of 40%, 50%, 60%, and 70% and at different diffusion time. Buffer power was calculated for black peat and black peat mixed with 20% (v/v) of seven different mineral components. Phosphorus was applied at rates of 0, 35, and 100 mg (L substrate -1 ), respectively. The impedance factor was not affected by addition of the mineral component to peat. However, f increased from 0.03 to 0.2, by increasing h from 40% to 60%, indicating that water content has a significant effect on this parameter. Substrate-solution P ranged from 0.3 to 27 and from 1 to 95 mg P (L solution) -1 for the P-application rate of 35 and 100 mg P (L substrate) -1 , respectively. Buffer power of the substrates ranged from 1 to 17.25 depending on the mineral component, and it was positively correlated with oxalate-soluble Fe and Al in the substrate. The calculated effective diffusion coefficient for P in the substrate was in the range of 10 -7 to 10 -8 cm 2 s -1 . This high value could be attributed mostly to the low buffer power rather than to the high impedance factor.

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Diffusion of Aqueous Solutions of Phosphoric Acid at 25°(

Cited by 64 publications

References 4 publications

Variation of phosphoric acid diffusion coefficient with concentration

Variation of phosphoric acid diffusion coefficient with concentration

Nutrient uptake estimates for woody species as described by the NST 3.0, SSAND, and PCATS mechanistic nutrient uptake models

Phosphorus dynamics in peat‐based substrates

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