No description available.

Under intensive farming, soil structure degradation and soil erosion are primarily associated with losses of organic matter. Restoration of soil structure may depend on the amount and nature of the organic amendment added. The effect of the addition of humic and fibric materials, and beeswax, a naturally occurring source of long-chain aliphatics comparable to those present in humic materials, on microbial activity and the structural properties of a waterlogged silty clay low in organic carbon was investigated. The incorporation of the fibric material increased the microbial activity in proportion to the amount of material added, whereas the humic and beeswax materials had the opposite effect. All organic materials added increased the cohesion of aggregates due to non water-dispersible cements. The fibric material was predominantly composed of polysaccharides and large quantities were required to produce a positive effect. The humic material was mainly lipids and the effect was associated with the time of incubation rather than the amount of material added. Principal-component analysis showed that the humic material was more effective at stabilizing soil aggregates than the fibric material, although the fibric material had a greater effect on the resistance of aggregates to slaking forces. Further testing with beeswax showed that the clay-associated lipids increased by 3.5-4.0 times the resistance of soil aggregates to the slaking forces, whereas the effect of hydrophobic "free" lipids was transient and accessory by coating and embedding soil aggregates.

Bibliography: leaves 147-170. / x, 170 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Aims to determine the influence of sodicity on the nature and decomposition of organic matter; and the influence of organic matter and its components on the structural stability of sodic soils. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1998?

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

Techn. Universiẗat, Diss., 2006--München.

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1998? / Includes bibliographical references (leaves 147-170).

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1997. / Includes bibliographical references (leaves 164-193).

Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy & Farming Systems, 1997? / Bibliography: leaves 155-169.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. William T. Cooper, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 1, 2005). Document formatted into pages; contains xiii, 91 pages. Includes bibliographical references.

Universiẗat, Diss., 2003--Bayreuth. / Erscheinungsjahr an der Haupttitelstelle: 2003.