Re-examining the flocculating power of sodium, potassium, magnesium and calcium for a broad range of soils

Zhu, Yingcan; Ali, Aram; Dang, Aaditi; Wandel, Andrew P.; Bennett, John McLean

doi:10.1016/j.geoderma.2019.05.041

Cited by 32 publications

(18 citation statements)

References 34 publications

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“…These observations support the findings of Fajardo et al (2016) that SI was positively correlated with pH, clay content, and exchangeable Na + and Mg +2 , and (r = 0.90). This is in contrast to a recent study that demonstrated exchangeable Mg +2 played a negligible role in flocculation of soil particles and aggregate stability (Zhu et al, 2019). It is believed that the observed correlation in our study is due to the dependence of exchangeable Mg +2 on clay content, CEC, and shrink-swell minerals, such as smectite, rather than a direct causal effect.…”

Section: Slaking Index and Soil Propertiescontrasting

confidence: 99%

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Jones

Filippi

Wittig

et al. 2021

SOIL

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Abstract. Soil aggregate stability is a useful indicator of soil physical health and can be used to monitor condition through time. A novel method of quantifying soil aggregate stability, based on the relative increase in the footprint area of aggregates as they disintegrate when immersed in water, has been developed and can be performed using a smartphone application – SLAKES. In this study the SLAKES application was used to obtain slaking index (SI) values of topsoil samples (0 to 10 cm) at 158 sites to assess aggregate stability in a mixed agricultural landscape. A large range in SI values of 0 to 7.3 was observed. Soil properties and land use were found to be correlated with observed SI values. Soils with clay content >25 % and cation exchange capacity (CEC) : clay ratio >0.5 had the highest observed SI values. Variation in SI for these soils was driven by organic carbon (OC) content which fit a segmented exponential decay function. An OC threshold of 1.1 % was observed, below which the most extreme SI values were observed. Soils under dryland and irrigated cropping had lower OC content and higher observed SI values compared to soils under perennial cover. These results suggest that farm managers can mitigate the effects of extreme slaking by implementing management practices to increase OC content, such as minimum tillage or cover cropping. A regression-kriging method utilising a Cubist model with a suite of spatial covariates was used to map SI across the study area. Accurate predictions were produced with leave-one-out cross-validation, giving a Lin's concordance correlation coefficient (LCCC) of 0.85 and a root-mean-square error (RMSE) of 1.1. Similar validation metrics were observed in an independent test set of samples consisting of 50 observations (LCCC = 0.82; RMSE = 1.1). The potential impact of implementing management practices that promote soil OC sequestration on SI values in the study area was explored by simulating how a 0.5 and 1.0 % increase in OC would impact SI values at observation points and then mapping this across the study area. Overall, the maps produced in this study have the potential to guide management decisions by identifying areas that currently experience extreme slaking and highlighting areas that are expected to have a significant reduction in slaking by increasing OC content.

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Section: Slaking Index and Soil Propertiescontrasting

confidence: 99%

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Jones

Filippi

Wittig

et al. 2021

SOIL

View full text Add to dashboard Cite

show abstract

“…The strongest correlation with SI in this study was observed with exchangeable Mg +2 (r = 0.90). This is in contrast to a recent study that demonstrated exchangeable Mg +2 played a negligible role in flocculation of soil particles and aggregate stability (Zhu et al, 2019). It is believed that the observed correlation in our study is due to the dependence of exchangeable Mg +2 on clay content, CEC and shrink-swell minerals, such as smectite, rather than a direct causal effect.…”

Section: Slaking Index and Soil Propertiescontrasting

confidence: 99%

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Jones¹,

Filippi²,

Wittig³

et al. 2020

Preprint

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Abstract. Soil aggregate stability is a useful indicator of soil physical health and can be used to monitor condition through time. A novel method to quantify soil aggregate stability, based on the relative increase in the footprint area of aggregates as they disintegrate when immersed in water, has been developed and can be performed using a smartphone application – SLAKES. In this study the SLAKES application was used to obtain slaking index (SI) values of topsoil samples (0 to 10 cm) at 158 sites to assess aggregate stability in a mixed agricultural landscape. A large range in SI values of 0 to 7.3 was observed. Soil properties and land use were found to be correlated with observed SI values. Soils with clay content > 25 % and CEC : clay ratio > 0.5 had the highest observed SI values. Variation in SI for these soils was driven by OC content which fit a segmented exponential decay function. An OC threshold of 1.1 % was observed below which the most extreme SI values were observed. Soils under dryland and irrigated cropping had lower OC content and higher observed SI values compared to soils under perennial cover. These results suggest that farm managers can mitigate the effects of extreme slaking by implementing management practices to increase OC content, such as minimum tillage or cover-cropping. A regression-kriging method utilising a Cubist model with a suite of spatial covariates was used to map SI across the study area. Accurate predictions were produced with leave-one-out cross-validation (LOOCV) giving an LCCC of 0.85 and an RMSE of 1.1. Similar validation metrics were observed in an independent test set of samples consisting of 50 observations (LCCC = 0.82; RMSE = 1.1). The potential impact of implementing management practices that promote soil OC sequestration on SI values in the study area was explored by simulating how a 1 % increase in OC would impact SI values at observation points, and then mapping this across the study area. Overall, the maps produced in this study have the potential to guide management decisions by identifying areas that currently experience extreme slaking, and those areas that are expected to have a significant reduction in slaking by increasing OC content.

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“…Con respecto al PSI, de acuerdo a Richards (1990), un suelo se considera sódico cuando tiene un PSI ≥ 15%, sin embargo, Zhu et al (2019) mencionan que desde un PSI > 5% existen efectos negativos sobre las propiedades físicas de los suelos ocasionando defloculación de las arcillas y colapso de los agregados. Castellanos et al (2000) mencionan que, en suelos de textura f ina, a valores de PSI > 5% la conductividad hidráulica desciende signif icativamente, llegando a niveles muy bajos a PSI = 10%.…”

Section: Resultados Y Discusiónunclassified

“…El 73% de los sitios fueron de textura gruesa a media, el 22% moderadamente f ina y solo el 5% f ina. Si se consideran los contenidos bajos de MO y K, el 29% de los sitios que obtuvieron un PSI entre 5-15% podrían tener problemas del orden físico, como la dispersión de las arcillas que propiciará la degradación de la estructura de los suelos, como mencionan Zhu et al (2019); el impacto de este problema será mayor en los suelos de textura moderadamente f ina que corresponden a los sitios con textura franco limoso arcilloso y franco arcilloso, y en los de textura f ina que son los sitios arcilloso limoso y arcilloso (Cuadro 2 y 3).…”

Section: Resultados Y Discusiónunclassified

Fertilidad e índice de calidad del suelo de la cuenca del río San Pedro en Nayarit

Martínez-Rodríguez

Can-Chulim

Ortega-Escobar

et al. 2021

Terra

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El área agrícola de la cuenca del río San Pedro en Nayarit es una llanura costera con suelos de origen aluvial, sometidos a inundación, deposición y a diferentes procesos que controlan el aporte de nutrientes y la fertilidad del suelo. El objetivo de esta investigación fue evaluar las propiedades de los suelos para diagnosticar la fertilidad y determinar el índice de calidad del suelo, tomando como parámetros pH, MO, N, P, K, CIC, Ca y Mg. Se realizaron muestreos a 30 cm de profundidad en 38 sitios en junio de 2017 y en 45 en 2018. Se midió pH, CE, textura, Da, CO, MO, N inorgánico, P, CIC y bases intercambiables. Los valores promedio, máximo y mínimo fueron pH 5.78, 8.15 y 3.28; MO 1.58, 3.02 y 0.65%; N inorgánico 22.5, 43.6 y 3.5 mg kg-1; P Olsen 32.5, 67.4 y 1.4 mg kg‑1; K 0.45, 0.80 y 0.10 cmolc kg-1, respectivamente. La CE promedio fue 1.39 dS m-1 e indica que no existen problemas de salinidad. El 73% de los sitios fueron de textura arenosa a franco. El índice de calidad del suelo (SQI por su nombre en inglés) indica que la cuenca tiene un nivel de fertilidad medio, SQI promedio de 0.64; el 17% de los sitios tuvieron una fertilidad baja con pH entre 3.28-5.40, MO 0.81-1.20%, N 10-20 y P 5-10 mg kg-1; 42% media, pH 6.41-7.30, MO 2.01‑2.50, N 40-60 y P 15-20 mg kg-1; 36% moderadamente alta, y 5% alta con pH 8.20-8.80, MO 3.01-4.00, N 100-150 y P 25-35 mg kg-1. La distribución del SQI demuestra que en la llanura superior los suelos son de fertilidad baja a media, en la llanura intermedia y baja son de fertilidad media a alta, y en las partes de menor altura, la fertilidad está limitada por la interacción entre el sistema continental y el marino que salinizan los suelos.

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Re-examining the flocculating power of sodium, potassium, magnesium and calcium for a broad range of soils

Cited by 32 publications

References 34 publications

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Mapping soil slaking index and assessing the impact of management in a mixed agricultural landscape

Fertilidad e índice de calidad del suelo de la cuenca del río San Pedro en Nayarit

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