The relationship between water-soluble P and modified Morgan P: results based on data and chemical modelling

DG Lumsdon, CA Shand, R Wendler, AC Edwards, MI Stutter, S Richards, AH Sinclair

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

An improved understanding of potential soluble phosphorus (P) loss in run-off and leachate from agriculturally managed soils presents practical and theoretical challenges. Our study aimed to discover whether modified Morgan extractable P (MMP) can be used to predict water-soluble P (WSP). We first addressed the relationship between MMP and WSP, and whether MMP is useful for predicting the WSP concentrations demanded by water quality regulations. Secondly, we applied novel soil chemical models to explain why the relationship between MMP and WSP depends upon soil properties. Thirdly, we explain how soil properties relate to potential soluble P loss in situations in which soil is subjected to a wide liquid-to-soil ratio (e.g. run-off and rivers) compared with those with a narrow ratio (e.g. soil porewater). To address these P loss scenarios, 60 agricultural topsoils (0–10 cm) were collected from a mixed-farming catchment (Lunan catchment, northeast Scotland) and chemically characterized. Theoretical understanding of P solubility was obtained with a P sorption model. The data showed variability in the relationship between MMP and WSP. Modelling shows the MMP versus WSP relationship is nonlinear, depending on several confounding factors (P sorption capacity (PSC), Ca, pH) and the liquid-to-soil ratio (L:S) employed for WSP determination. Consequently, the slope of the relationship is not unique but depends subjectively on the set of soils surveyed. MMP versus WSP at large L:S (e.g. in run-off or rivers) is positively correlated to PSC, whereas at narrow L:S (e.g. porewater) there is a negative correlation with PSC. The study provides new ideas for the interpretation and extrapolation of agronomic soil test data for soils of varied properties and highlights the need to utilize insights from soil chemistry.
Original languageEnglish
Pages (from-to)162 - 171
Number of pages10
JournalSoil Use and Management
Volume32
Issue number2
DOIs
Publication statusFirst published - 17 May 2016

Fingerprint

modeling
water
soil
runoff
porewater
catchment
mixed farming
liquid
chemical
soil chemistry
soil test
river
topsoil
leachate
soil property
solubility
phosphorus
water quality
loss

Bibliographical note

1030789

Keywords

  • Extractable phosphorus
  • Geochemical modelling
  • Modified Morgan method
  • Soil phosphorus
  • Water-soluble phosphorus

Cite this

Lumsdon, DG ; Shand, CA ; Wendler, R ; Edwards, AC ; Stutter, MI ; Richards, S ; Sinclair, AH. / The relationship between water-soluble P and modified Morgan P: results based on data and chemical modelling. In: Soil Use and Management. 2016 ; Vol. 32, No. 2. pp. 162 - 171.
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abstract = "An improved understanding of potential soluble phosphorus (P) loss in run-off and leachate from agriculturally managed soils presents practical and theoretical challenges. Our study aimed to discover whether modified Morgan extractable P (MMP) can be used to predict water-soluble P (WSP). We first addressed the relationship between MMP and WSP, and whether MMP is useful for predicting the WSP concentrations demanded by water quality regulations. Secondly, we applied novel soil chemical models to explain why the relationship between MMP and WSP depends upon soil properties. Thirdly, we explain how soil properties relate to potential soluble P loss in situations in which soil is subjected to a wide liquid-to-soil ratio (e.g. run-off and rivers) compared with those with a narrow ratio (e.g. soil porewater). To address these P loss scenarios, 60 agricultural topsoils (0–10 cm) were collected from a mixed-farming catchment (Lunan catchment, northeast Scotland) and chemically characterized. Theoretical understanding of P solubility was obtained with a P sorption model. The data showed variability in the relationship between MMP and WSP. Modelling shows the MMP versus WSP relationship is nonlinear, depending on several confounding factors (P sorption capacity (PSC), Ca, pH) and the liquid-to-soil ratio (L:S) employed for WSP determination. Consequently, the slope of the relationship is not unique but depends subjectively on the set of soils surveyed. MMP versus WSP at large L:S (e.g. in run-off or rivers) is positively correlated to PSC, whereas at narrow L:S (e.g. porewater) there is a negative correlation with PSC. The study provides new ideas for the interpretation and extrapolation of agronomic soil test data for soils of varied properties and highlights the need to utilize insights from soil chemistry.",
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The relationship between water-soluble P and modified Morgan P: results based on data and chemical modelling. / Lumsdon, DG; Shand, CA; Wendler, R; Edwards, AC; Stutter, MI; Richards, S; Sinclair, AH.

In: Soil Use and Management, Vol. 32, No. 2, 17.05.2016, p. 162 - 171.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The relationship between water-soluble P and modified Morgan P: results based on data and chemical modelling

AU - Lumsdon, DG

AU - Shand, CA

AU - Wendler, R

AU - Edwards, AC

AU - Stutter, MI

AU - Richards, S

AU - Sinclair, AH

N1 - 1030789

PY - 2016/5/17

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N2 - An improved understanding of potential soluble phosphorus (P) loss in run-off and leachate from agriculturally managed soils presents practical and theoretical challenges. Our study aimed to discover whether modified Morgan extractable P (MMP) can be used to predict water-soluble P (WSP). We first addressed the relationship between MMP and WSP, and whether MMP is useful for predicting the WSP concentrations demanded by water quality regulations. Secondly, we applied novel soil chemical models to explain why the relationship between MMP and WSP depends upon soil properties. Thirdly, we explain how soil properties relate to potential soluble P loss in situations in which soil is subjected to a wide liquid-to-soil ratio (e.g. run-off and rivers) compared with those with a narrow ratio (e.g. soil porewater). To address these P loss scenarios, 60 agricultural topsoils (0–10 cm) were collected from a mixed-farming catchment (Lunan catchment, northeast Scotland) and chemically characterized. Theoretical understanding of P solubility was obtained with a P sorption model. The data showed variability in the relationship between MMP and WSP. Modelling shows the MMP versus WSP relationship is nonlinear, depending on several confounding factors (P sorption capacity (PSC), Ca, pH) and the liquid-to-soil ratio (L:S) employed for WSP determination. Consequently, the slope of the relationship is not unique but depends subjectively on the set of soils surveyed. MMP versus WSP at large L:S (e.g. in run-off or rivers) is positively correlated to PSC, whereas at narrow L:S (e.g. porewater) there is a negative correlation with PSC. The study provides new ideas for the interpretation and extrapolation of agronomic soil test data for soils of varied properties and highlights the need to utilize insights from soil chemistry.

AB - An improved understanding of potential soluble phosphorus (P) loss in run-off and leachate from agriculturally managed soils presents practical and theoretical challenges. Our study aimed to discover whether modified Morgan extractable P (MMP) can be used to predict water-soluble P (WSP). We first addressed the relationship between MMP and WSP, and whether MMP is useful for predicting the WSP concentrations demanded by water quality regulations. Secondly, we applied novel soil chemical models to explain why the relationship between MMP and WSP depends upon soil properties. Thirdly, we explain how soil properties relate to potential soluble P loss in situations in which soil is subjected to a wide liquid-to-soil ratio (e.g. run-off and rivers) compared with those with a narrow ratio (e.g. soil porewater). To address these P loss scenarios, 60 agricultural topsoils (0–10 cm) were collected from a mixed-farming catchment (Lunan catchment, northeast Scotland) and chemically characterized. Theoretical understanding of P solubility was obtained with a P sorption model. The data showed variability in the relationship between MMP and WSP. Modelling shows the MMP versus WSP relationship is nonlinear, depending on several confounding factors (P sorption capacity (PSC), Ca, pH) and the liquid-to-soil ratio (L:S) employed for WSP determination. Consequently, the slope of the relationship is not unique but depends subjectively on the set of soils surveyed. MMP versus WSP at large L:S (e.g. in run-off or rivers) is positively correlated to PSC, whereas at narrow L:S (e.g. porewater) there is a negative correlation with PSC. The study provides new ideas for the interpretation and extrapolation of agronomic soil test data for soils of varied properties and highlights the need to utilize insights from soil chemistry.

KW - Extractable phosphorus

KW - Geochemical modelling

KW - Modified Morgan method

KW - Soil phosphorus

KW - Water-soluble phosphorus

U2 - 10.1111/sum.12265

DO - 10.1111/sum.12265

M3 - Article

VL - 32

SP - 162

EP - 171

JO - Soil Use and Management

JF - Soil Use and Management

SN - 0266-0032

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