Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 88-90). Also available on the World Wide Web.

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 8, 2007) Includes bibliographical references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 39-41).

Thesis (M.A.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 72-87).

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

A soil surface under production gives a certain yield of a certain crop. In our modern society, any kind of industry must be efficient and has to give profits to its owner. Efficiency of the plant production industry varies greatly from year to year and from place to place. [...]

This study aims: 1) To quantify the factors affecting the changes of site water status of the high sand tailings, 2) To investigate the growth and physiological responses of <I>Acacia mangium </I>and <I>A. auriculiformis </I>to the fluctuations of site water status on high sand dunes, and 3) To identify characteristics which may allow the trees to adapt to and survive on high sand tailings. In both shade and open plots on sand tailings, diurnal air water deficits would be anticipated particularly in sunny days and late afternoon in cloudy days. The results from dipwell showed that the main source of soil water supply to the sand tailings is solely dependent on the rainfall and not from surrounding mining pools. Furthermore, at 6 d after rainfall <37 mm, sand tailings at 0-15 cm depth had low sand suction showing soil water deficit to plant uptake. Hence, the rainfall distribution would determine the growth of acacias in sand tailings. Dry periods significantly reduced (P<0.05) the shoot length and stem diameter growth rates and leaf area of both acacias. Dry periods also significantly increased leaf and branch number shedding rates of both acacias. Generally, shading did not improve the growth rates of both acacias in dry periods but significantly delayed leaf shedding of the two acacias in dry periods. <I>A. auriculiformis </I>had significantly higher shoot length and stem diameter growth rates as the result of higher leaf and shoot numbers. The superiority of <I>A. auriculiformis</I> compared to <I>A. mangium </I>in adapting to high sand tailings was explained by its growth patterns that had characteristics of drought avoidance, and/or tolerance. Greater vegetative growth was observed in <I>A. auriculiformis </I>than <I>A. mangium </I>in wet periods. The effects of atmospheric and soil water fluctuations on some physiological responses of the two species were also examined.

This thesis examines the potential of nine break crops (bean, carrot, swede, hemp, sugar beet, potato, lupin, oilseed rape and linola), against an oat control crop.  Seven rotational field trails were carried out at five sites across the UK. The most profitable break crops in this study were carrot and potato in terms of direct economic return to the farmer.  Mean annual returns were £5175 and £3668 respectively.  Cereal yields following break crops were found to be more affected by the soil fertility before the break crops were planted, than the actual break crop.  Studies on the nutrient concentration of break crops showed that by the second year of the experiment, over 50% of the break crops were deficient in either N, P or K, with N deficiency being most common.  Subsequent cereal crops mostly had adequate nutrient concentrations. Break crop and cereal yields were more strongly correlated with soil nutrient concentrations at the start of the experiment that previous crop.  Root crops showed a strong N response, sugar beet had a strong Mg response, linola, oilseed rape and oat had strong K responses, and wheat and barley yields were strongly influenced by soil N, P and Cu.  In general soil nutrients decreased over the experiment as did pH and soil organic matter. In general there was an inverse relationship between the crops yield and the crop’s nutrient concentration, so as the yield of a crop increases, the concentration of nutrients in the plant matter, or quality, decrease. The break crops, hemp, linola and carrot generally had positive effects on reducing weed populations during growth and in the subsequent cereal crop compared with the control crop.  In additional these break crops were pest- and disease-free during growth.  Other break crops, such as bean, swede and oilseed rape were shown to suffer from many weed, pest or disease problems, which may limit their potential for inclusion in an organic rotation.

Agroforestry offers a land-use management methodology that may provide solutions to environmental degradation in the tropics. However, practitioners of agroforestry are faced with the dilemma of clearing more forest cover in order to increase crop size and sustain their income. The aim of this study is to understand the agroforester’s dilemma and to measure the value of the agroforestry ecosystem stewardship in yerba maté (Ilex paraguariensis A. St. Hil.) agroforestry parcels of the South American Atlantic forest eco-region. Biodiversity, carbon sequestration and vegetation cover were measured to be considerably higher in yerba maté (Ilex paraguariensis A. St. Hil.) agroforestry plantations than in neighboring monoculture crops. Agroforestry vegetation cover values were measured to have between 65-89% cover while monocultures had roughly 25% cover. Agroforestry stored carbon values ranged between 154.7-172.7 Mg C ha-1, compared to monoculture plantation values of 81.3 Mg C ha-1. Finally, as measured using the Shannon index, values of species richness ranged from 2.7-3.5 in agroforestry parcels and between 0.9-1.3 in monocultures, and values of evenness ranged between 0.6 and 0.8 in agroforestry parcels, and 0.2 in monocultures. These findings illustrate that yerba maté agroforestry can potentially contribute as a regional climate change mitigation strategy. Valuating and monetizing ecosystem services and engaging smaller farmers with worldwide ecosystem marketplaces offer the potential to expand the dialogue around payments for the valuable ecosystem services that agroforesters are providing. An analysis of market prices available within the ecosystem marketplace for total ecosystem services being conserved on agroforestry parcels amounted to a range in value between $16 – $160 ha-1 yr-1. To address environmental degradation in the Atlantic Forest region, in South America, governments should motivate environmental conservation to support a shift towards sustainable yerba maté production which supports livelihoods of small-scale farmers, economic justice and environmental sustainability. / Graduate

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