Title: Surface chemistry of calcium and phosphorus retention in selected acid tropical soils from the Republic of Vietnam
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00098359/00001
 Material Information
Title: Surface chemistry of calcium and phosphorus retention in selected acid tropical soils from the Republic of Vietnam
Physical Description: xiii, 160 leaves : ill. ; 28 cm.
Language: English
Creator: Tinsley, Richard Lee, 1943- ( Dissertant )
Popenoe, Hugh ( Thesis advisor )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1974
Copyright Date: 1974
Subjects / Keywords: Soil acidity ( lcsh )   ( lcsh )
Soil Science thesis Ph. D
Soils -- Vietnam   ( lcsh )
Dissertations, Academic -- Soil Science -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Abstract: Soil colloids from six acid tropical pedons were identified and grouped as either predominately constant-charge or predominately constantpotential type colloids. The surface chemistry of Ca and P retention of the two colloidal types was contrasted and related to crop response to Ca amendments applied to the different pedons. The two Ultisol pedons contained predominately constant-charge phyllosilicate colloids similar to the colloids of most temperate soils. With this type of colloid, the surface charge results from ion substitution in the silicate minerals which provides a permanent negative charge on the colloidal surface. In this system, acidity results from H and Al3+ ions satisfying the negative charges, and inorganic P exists as Fe and Al phosphates. Liming the two soils that had constant-charge colloids neutralized the acidity, increased the base saturation, and increased the P availability by raising the solubility of the Fe and Al phosphates. These reactions provided a more favorable plant environment. The four Oxisol pedons contained predominately constant-potential colloids in the form of Fe and Al sesquioxides, non-crystalline material, and organic matter. In this system, the colloidal charge results from the adsorption of' potential-determining Jr and 0H~ ions. Since these soils are highly weathered, the soil reaction approaches that of maximum colloidal stability which is the zero point of charge. These soils, therefore, have a low surface charge for H and Al3+ td satisfy. Thus, these soils are low in exchangeable acidity even at low pH values. Also, in this colloidal system, P is tenaciously adsorbed directly to the colloidal surface by ligand exchange. The availability of adsorbed P is more dependent on competitive anions than pH. Thus, liming the pedons containing predominantly constant-potential colloids neither neutralized appreciable exchangeable acidity nor increased the availability of P. Instead, liming rapidly increased the surface charge density by adsorbing 0H~ ions, and this charge was satisfied by adsorbing Ca. The Ca so adsorbed was retained with greater tenacity than that on the exchange complex of pedons with predominantly constant-charge colloids. Greater crop response on the pedons dominated by constant-potential colloids occurred when competitive anions were added to reduce the P adsorption energy and increase the P desorption rate than when the acidity was neutralized with lime.
Statement of Responsibility: by Richard Lee Tinsley.
Thesis: Thesis (Ph. D.)--University of Florida, 1974.
Bibliography: Includes bibliographical references (leaves 154-159).
General Note: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00098359
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000566499
oclc - 37900555
notis - ACZ2931


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