Determination of the Charge Character of Selected Acid Soils1

Grove, John H.; Fowler, Corinne; Sumner, M. E.

doi:10.2136/sssaj1982.03615995004600010006x

Cited by 44 publications

(19 citation statements)

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“…Briefly, 3% hexametaphosphate was added to air-dried soils (2-mm sieved) and used as a dispersal agent, followed by fractionation and quantification of each particle size by sieving. CEC was measured using a modified, unbuffered salt extraction method 37 , and exchanged NH 4 þ was analysed colorimetrically (Alpkem RFA-303) 38 . WHC was measured by applying the appropriate pressure for field capacity (0.1 bar) and wilting point (15 bar) for sandy soil textures 39 .…”

Section: Methodsmentioning

confidence: 99%

Emerging land use practices rapidly increase soil organic matter

et al. 2015

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Section: Methodsmentioning

confidence: 99%

Emerging land use practices rapidly increase soil organic matter

et al. 2015

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“…Soil pH in water was determined using a 1:1 soil/deionized water ratio. The cation exchange capacity (CEC) was determined with an extraction method using unbuffered salt (Grove et al, 1982). To assess the agronomic soil P values in acidic, low-CEC South Carolina soils, the Mehlich-1 extraction was used (Mehlich, 1978).…”

Section: Materialsand Methods Soil Descriptions and Characterizationmentioning

confidence: 99%

Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Rick

Arai

2011

Soil Science Soc of Amer J

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Labile P is a well-recognized nonpoint sourec pollutant in agroecosystems. Predicting the fate and transport of P in watershed systems is critical in protecting water quality. In this case study, we investigated the role of soil nanoparticles in P release in South Carolina agricultural soils. Batch desorption experiments were coupled with scanning and transmission electron microscopy (EM) and x-ray absorption spectroscopy (XAS) to better assess the reactivity of soil nanoparticles. The surface soils contained a total P concentration of 260 to 940 mg kg" ', approximately 40 to 60% of which was ammonium oxalate extractable R The 30-d desorption experiments showed that P desorption was initially rapid, followed by a slow continuous release at pH 5.5 and 7. It was generally not correlated with the release of soil nanoparticles (operationally defined as 10-200 nm). Phosphorus was not readily retained on these nanoparticles at pH 4 to 7. These nanoparticles were rich in Si and S, and coated with Fe and C and trace amounts of P, Ca, Na, Mg, and Al. The EM images of nanoparticle morphology showed C-associated globular formations as well as assembled platelets and spherical nanoparticles. The colloid-and nanoparticlefaeilitated P release has often been suggested as one of the important pathways for P transport in the soil-water environment. This study presents a new aspect of nanoparticle reactivity in the soil environment, however: nanoparticles do not always contribute to P transport processes.

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“…Several problems have been associated with the CEC and ESP determinations Oster, 2001a). These include: (1) in addition to removing exchangeable Ca 2 þ and Mg 2þ , the extractants may dissolve some CaCO 3 and MgCO 3 in calcareous soils, thereby erroneously increasing the values of CEC (Thomas, 1982;Amrhein and Suarez, 1990), particularly when it is calculated as the sum of exchangeable cations as given in Equation 3 ; (2) the value of CEC obtained in variable charge soils is crucially dependent on pH, concentration, and buffering capacity of the extractant used (Grove et al, 1982;Sumner et al, 1998); and (3) removal of Na þ by extractants from sources such as sodium zeolites that do not contain a true form of exchangeable Na þ (Babcock, 1960;Bower and Hatcher, 1962;Oster, 2001a). In addition, laborious analytical procedures are used that involve several lengthy determinations for the parameters such as exchangeable cations and CEC, which are used in the calculation of ESP.…”

Section: Esp ¼ 100ðe Na þ=Cec ð2þmentioning

confidence: 99%

Degradation processes and nutrient constraints in sodic soils

Qadir¹,

Schubert²

2002

Land Degrad Dev

373

186

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Accumulation of excess sodium (Na þ ) in a soil causes numerous adverse phenomena, such as changes in exchangeable and soil solution ions and soil pH, destabilization of soil structure, deterioration of soil hydraulic properties, and increased susceptibility to crusting, runoff, erosion and aeration, and osmotic and specific ion effects on plants. In addition, serious imbalances in plant nutrition usually occur in sodic soils, which may range from deficiencies of several nutrients to high levels of Na þ . The structural changes and nutrient constraints in such soils ultimately affect crop growth and yield. The principal factor that determines the extent of adverse effects of Na þ on soil properties is the accompanying electrolyte concentration in the soil solution, with low concentration promoting the deleterious effects of exchangeable Na þ even at exchangeable sodium percentage (ESP) levels less than 5. Consequent to an increase in the use of poor quality waters and soils for crop production, the problems of sodic soils can be expected to increase in future. The mechanisms that explain sodic behaviour can provide a framework in which slaking, swelling and dispersion of clay together with nutrient constraints in sodic soils may be assessed so that the practices to manage such soils can be refined for long-term sustainable agriculture.

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Determination of the Charge Character of Selected Acid Soils1

Cited by 44 publications

References 0 publications

Emerging land use practices rapidly increase soil organic matter

Emerging land use practices rapidly increase soil organic matter

Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Degradation processes and nutrient constraints in sodic soils

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