Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 96-107). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

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Three drainage experiments were conducted on a newly developed organic soil where three cultural methods were superimposed. Measurements of carrot yields, subsidence, water table fluctuations, subsurface drain performance, hydraulic conductivity and soil bulk density were made. Rotovating the soil produced higher carrot yields than plowing or disking during the first year. The seven-year subsidence totalled 515 mm and depended mostly on organic soil depth. Hydraulic conductivity values did not change after five years of drainage. Bulk density of the top 0.20 m increased by 71% in 6 years, whereas the values down the profile increased between 3.3 and 16.2%. / The effect of two water table depths (WTD), 0.6 and 0.9 m, in an organic soil on soil water tension, subsidence swelling and carrot yields was studied in undisturbed cores in the greenhouse. Carrot yields were reduced by the 0.9 m WTD. Subsidence with the 0.9 m WTD was more than double that of the 0.6 m WTD. Raising the water table near the surface caused the soil to swell. / Hydraulic conductivity, bulk density, fiber content and drainable porosity were measured in undisturbed organic soil profiles. Values from all four properties decreased with increasing depth.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 122-143).

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 183-197). Also available on the World Wide Web.

Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2009. / Full text also available online. Scroll down for electronic link.

Plant roots are central to C- and N-cycling in soil. However, (i) plants differ strongly in tissue recalcitrance (e.g. lignin content) affecting their mineralization in soil, and (ii) rhizodeposits also vary strongly in terms of the metabolites that they contain. Therefore, (i) we used 13C labelled ryegrass root and shoot residues as substrates to investigate the impact of tissue recalcitrance on soil processes through controlled incubation of soil, (ii) we assessed variations in root C-deposition between barley genotypes and their respective impacts on soil processes using 13CO2 labelled plants, (iii) using 13C/15N enriched ryegrass root residues as tracer material, we investigated the impacts of barley genotypes on mineralization of recently incorporated plant residues in soil and plant uptake of the residue-derived N, and (iv) we applied a quantitative trait loci analysis approach to identify barley chromosome regions affecting soil microbial biomass and other soil and root related traits. In the first study, addition of root residues resulted in reduced C-mineralization rates, soil microbial activity and soil organic matter (SOM) priming relative to shoot residues. Planted experiments revealed (i) genotype effects on plant-, SOM- and residuederived surface soil CO2-C efflux and showed that incorporation of plant derived-C to the silt-and-clay soil fraction varied between genotypes, indicating relative stabilization of root derived-C as a result of barley genotype, (ii) that plant uptake of residue released N between genotypes was linked to genotype impacts on residue mineralization, and (iii) barley chromosome regions that influence plant-derived microbial biomass C. These results (i) suggest that greater plant tissue recalcitrance can lower soil C-emissions and increase C-storage in soil, and (ii) demonstrate the barley genetic influence on soil microbial communities and C- and N-cycling, which could be useful in crop breeding to improve soil microbial interactions, and thus promote sustainable crop production systems.

Made available in DSpace on 2014-06-11T19:35:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-29Bitstream added on 2014-06-13T18:46:45Z : No. of bitstreams: 1 silva_mp_dr_ilha.pdf: 1046855 bytes, checksum: ed7d2f423c1e4d7223ecfca99890e8fd (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A utilização de resíduos vegetais no solo é uma prática cultural antiga. No entanto, com o passar dos anos, em função da utilização de fertilizantes químicos, esta prática foi perdendo interesse, porém recentemente tem despertado novamente a atenção por parte dos produtores e pesquisadores. O trabalho teve como objetivo analisar o crescimento, produtividade e qualidade fisiológica do feijoeiro de inverno irrigado cultivado após diferentes plantas de cobertura, bem como as possíveis interações dessa pratica com diferentes doses de P 2O5 em semeadura, e a influência das plantas de cobertura sobre as características químicas e físicas do solo. A pesquisa foi conduzida no período de inverno de 2010 e 2011, na Fazenda de Ensino, Pesquisa e Extensão da Faculdade de Engenharia do Campus de Ilha Solteira – UNESP, localizada no Município de Selvíria/MS. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas com 4 repetições. Constituídos pela combinação de plantas de cobertura (milheto, Crotalaria juncea, mucuna-preta, guandu, milheto + Crotalaria juncea, milheto + guandu e milheto + mucuna-preta), além de ser também utilizada uma área em pousio, e níveis P2O5 em semeadura, constituídos por ausência de adubação fosfatada e doses de P2O5 (60, 90 e 120 kg ha-1). Foram avaliados: porcentagem de recobrimento, produção e teor de nutrientes na matéria seca das culturas de cobertura; teor de nutrientes nas folhas de feijoeiro; matéria seca das plantas; componentes de produção, produtividade e qualidade fisiológica das sementes. Foram realizadas avaliações físicas e químicas do solo. De acordo com os resultados, pode se concluir que: o uso de palhada de Crotalaria juncea, milheto + Crotalaria juncea e milheto + mucuna-preta proporcionaram melhores condições... / The use of plant residues in soil is an ancient cultural practice. However, over the years, depending on the use of chemical fertilizers, this practice was losing interest, but recently has attracted renewed attention from producers and researchers. The study aimed to analyze the growth, yield and physiological quality of irrigated winter common bean cultivated after different cover crops, as well as possible interactions of practice with different doses of P2O5 at sowing, and the influence of cover crops on the chemical characteristics and physical soil. The survey was conducted during winter 2010 and 2011, at the Unesp experimental farm, Ilha Solteira campus, in Selviria, Mato Grosso do Sul state, Brazil. The experimental design was a randomized block in split plot with four replications. Constituted by the combination of cover crops (millet, sunn hemp, velvet bean, pigeon pea, pearl millet + sunn hemp, pearl millet + millet + pigeon pea and velvet bean), and is also used in a fallow field, and P 2O5 levels in seeding consisting of the absence of phosphate and levels of P2O5 (60, 90 and 120 kg ha-1). Were evaluated: percentage of coverage, production and nutrient content in dry matter of cover crops, nutrient content in bean leaves, plant dry matter, yield components, yield and physiological quality of seeds. Evaluations were carried out physical and chemical soil in relation to the use of cover crops. According to the results, it can be concluded that the use of straw sunn hemp, consortia millet + sunn hemp and millet + black velvet bean provided better conditions for the production of beans and economy in the application of phosphorus in no- tillage system, the species used as cover caused changes in soil chemical properties, the highest values of macroporosity and lower bulk density occurring in layer 0-0,20... (Complete abstract click electronic access below)