Masters Theses

Date of Award

3-1970

Degree Type

Thesis

Degree Name

Master of Science

Major

Agronomy

Major Professor

F. F. Bell

Committee Members

G. J. Buntley, H. A. Fribourg, K. B. Sanders

Abstract

Tennessee soils are many and varied. They vary widely in both texture and fertility. Therefore, each soil needs to be characterized in detail for crop suitability. Some chemical properties of twelve soil profiles were investigated. The chemical properties selected for study were those that were believed to most strongly influence the classification and fertility status of the soils. The main objective of this study was to determine some selected chemical characteristics of several representative soils in Tennessee. A second objective was to compare the chemical characteristics within and among the soils studied. Twelve soil series located on six Agricultural Experiment Stations of The University of Tennessee in East, Middle, and West Tennessee were investigated. The following properties were studied: pH by five different methods, cation exchange capacity by two different methods, exchangeable bases, percent base saturation, exchange acidity, available P and K, and particle size distribution. Most soils studied were low in pH, percent base saturation, Ca/Mg ratios and available P and K in the subsoils, but these values were relatively high in the surface horizons. Cation exchange capacity of most soils was rather low except in Sequoia and Maury soils. Exchangeable Ca was rather high, while exchangeable Mg was relatively low in most of the soil profiles. Exchangeable K and Na were very low throughout the soil profiles. Exchange acidity showed considerable fluctuation, as did the soil reaction among horizons of each soil profile. In all soil profiles, cation exchange capacity varied with ex change acidity and with clay content. Exchange acidity also varied with clay content, with the exception of the Dickson and Sequatchie profiles. The pH values varied with the sum of exchangeable bases and percent base saturation in all soils studied. Two cycles of profile development were noted in the Dickson, Huntington, Sequoia, Collins, Grenada, Emory, Tilsit, Loring, and Dexter profiles, but there was only one developmental sequence in the Sequatchie, Maury, and Hartsells profiles. The laboratory data appeared to support the field observations in this regard. The ammonium acetate and the sum of cations methods were used in determining cation exchange capacity and in calculating percent base saturation. In certain soils, great differences between the two cation exchange capacity methods were noted as regards the magnitude of the cation exchange capacity and the percent base saturation, whereas, with other soils, little difference between the two cation exchange capacity methods was noted in the magnitude of these two properties. The younger soils appeared to have greater differences in percent base saturation, calculated by the ammonium acetate cation exchange capacity method versus by the sum of cation cation exchange capacity method, than did the older soils. Emory and Collins profiles showed the greatest differences in percent base saturation, due to cation exchange capacity method, whereas Sequoia and Tilsit both had the smallest differences in this value between the cation exchange capacity methods. In the cases of the other eight soils, the effect of the cation exchange capacity method on the magnitude of the percent base saturation was variable. The cation exchange capacity values determined by the two methods showed similar trends.

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