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Registro Completo
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Biblioteca(s): |
Embrapa Trigo. |
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Data corrente: |
29/05/1992 |
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Data da última atualização: |
02/11/2019 |
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Autoria: |
WIETHÖLTER, S. |
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Título: |
Predicting potassium uptake by corn in the field using the strontium nitrate soil testing method and a diffusion-controlled uptake model. |
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Ano de publicação: |
1983 |
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Fonte/Imprenta: |
Madison: University of Wisconsin, 1983. |
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Páginas: |
244 p. |
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Idioma: |
Inglês |
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Notas: |
Thesis PhD. |
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Conteúdo: |
The rate of potassium uptake by plants grown in soil is limited by the rate of diffusion to the roots. Calculation of diffusion rates requires a knowledge of the soil solution concentration (C[indice]1i), buffer power (b) and diffusion coefficiente (D). The Gapon equation was used to calculate selectivity coefficients for K+, Na+, Ca2+, Mg2+, Mn2+ and Al3+ from concentrations in 0.004M Sr(NO3)2 extracts and from amounts exchangeable in M NH4Cl. For a proposed routine method, C[indice]1i, b and D were calculated from the Sr(NO3)2 equilibration. This required the use of estimated selectivity coefficients obtained from regression of pH, OM, clay and cation ratios on determined selectivity coefficients. A constant-root-absorbing-power (constant-[alfa]) diffusion equation was applied to a root model that assumed an effective radius (a[indice]e) of 0.07 cm (root radius + root-radius + root-hair length). A root length:plant dry matter ratio of 1000 cm g[elevado a]-1 dry matter was used, and each root segment was assumed to effective in K+ uptake for the same time period. Initially, uptake was assumed to occur only within the root-hair cylinder, the time of effective depletion being estimated with a steady- state, interacting-root model. After depletion of the root-hair cylinder, diffusion from outside was assumed to start, with radius equal to a[indice]e and [alfa] estimated from the Michaelis-Menten equation. Root hairs had to be effective for 4-5 days to satisfy the total K+ uptake estimated from K+ content of the ear leaf. Uptake of K+ by corn at 51 field sites throughout Wisconsin was best predicted by the diffusion model (r[elevado]2=0.58 with determined selectivity coefficients and 0.51 with estimated coefficients). The K+ concentration in Sr(NO3)2 also correlated well (r[elevado]2=0.49). Exchangeable K+ was a por predictor (r[elevado]2=0.13). The diffusion model applied to data from Sr(NO3)2 equilibration appears promising as a routine soil testing method for K+. With this approach, fertilizer recommendations could be based on on theoretically-derived estimates of K+ uptake rather than on empirically-derived relationships. MenosThe rate of potassium uptake by plants grown in soil is limited by the rate of diffusion to the roots. Calculation of diffusion rates requires a knowledge of the soil solution concentration (C[indice]1i), buffer power (b) and diffusion coefficiente (D). The Gapon equation was used to calculate selectivity coefficients for K+, Na+, Ca2+, Mg2+, Mn2+ and Al3+ from concentrations in 0.004M Sr(NO3)2 extracts and from amounts exchangeable in M NH4Cl. For a proposed routine method, C[indice]1i, b and D were calculated from the Sr(NO3)2 equilibration. This required the use of estimated selectivity coefficients obtained from regression of pH, OM, clay and cation ratios on determined selectivity coefficients. A constant-root-absorbing-power (constant-[alfa]) diffusion equation was applied to a root model that assumed an effective radius (a[indice]e) of 0.07 cm (root radius + root-radius + root-hair length). A root length:plant dry matter ratio of 1000 cm g[elevado a]-1 dry matter was used, and each root segment was assumed to effective in K+ uptake for the same time period. Initially, uptake was assumed to occur only within the root-hair cylinder, the time of effective depletion being estimated with a steady- state, interacting-root model. After depletion of the root-hair cylinder, diffusion from outside was assumed to start, with radius equal to a[indice]e and [alfa] estimated from the Michaelis-Menten equation. Root hairs had to be effective for 4-5 days to satisfy the total K+ upta... Mostrar Tudo |
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Palavras-Chave: |
Applied Statistics; Estatistica aplicada; Maize; Mathematical model; Modelos matematicos. |
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Thesagro: |
Absorção; Milho; Potássio; Solo; Zea Mays. |
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Thesaurus NAL: |
absorption; corn; potassium; soil. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 02972nam a2200301 a 4500
001 1841891
005 2019-11-02
008 1983 bl uuuu m 00u1 u #d
100 1 $aWIETHÖLTER, S.
245 $aPredicting potassium uptake by corn in the field using the strontium nitrate soil testing method and a diffusion-controlled uptake model.
260 $aMadison: University of Wisconsin$c1983
300 $a244 p.
500 $aThesis PhD.
520 $aThe rate of potassium uptake by plants grown in soil is limited by the rate of diffusion to the roots. Calculation of diffusion rates requires a knowledge of the soil solution concentration (C[indice]1i), buffer power (b) and diffusion coefficiente (D). The Gapon equation was used to calculate selectivity coefficients for K+, Na+, Ca2+, Mg2+, Mn2+ and Al3+ from concentrations in 0.004M Sr(NO3)2 extracts and from amounts exchangeable in M NH4Cl. For a proposed routine method, C[indice]1i, b and D were calculated from the Sr(NO3)2 equilibration. This required the use of estimated selectivity coefficients obtained from regression of pH, OM, clay and cation ratios on determined selectivity coefficients. A constant-root-absorbing-power (constant-[alfa]) diffusion equation was applied to a root model that assumed an effective radius (a[indice]e) of 0.07 cm (root radius + root-radius + root-hair length). A root length:plant dry matter ratio of 1000 cm g[elevado a]-1 dry matter was used, and each root segment was assumed to effective in K+ uptake for the same time period. Initially, uptake was assumed to occur only within the root-hair cylinder, the time of effective depletion being estimated with a steady- state, interacting-root model. After depletion of the root-hair cylinder, diffusion from outside was assumed to start, with radius equal to a[indice]e and [alfa] estimated from the Michaelis-Menten equation. Root hairs had to be effective for 4-5 days to satisfy the total K+ uptake estimated from K+ content of the ear leaf. Uptake of K+ by corn at 51 field sites throughout Wisconsin was best predicted by the diffusion model (r[elevado]2=0.58 with determined selectivity coefficients and 0.51 with estimated coefficients). The K+ concentration in Sr(NO3)2 also correlated well (r[elevado]2=0.49). Exchangeable K+ was a por predictor (r[elevado]2=0.13). The diffusion model applied to data from Sr(NO3)2 equilibration appears promising as a routine soil testing method for K+. With this approach, fertilizer recommendations could be based on on theoretically-derived estimates of K+ uptake rather than on empirically-derived relationships.
650 $aabsorption
650 $acorn
650 $apotassium
650 $asoil
650 $aAbsorção
650 $aMilho
650 $aPotássio
650 $aSolo
650 $aZea Mays
653 $aApplied Statistics
653 $aEstatistica aplicada
653 $aMaize
653 $aMathematical model
653 $aModelos matematicos
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