Graduation date: 1997

The onsite costs and benefits of conservation tillage in the Camas Prairie Region of Northern Idaho were estimated. The evaluation of these costs and benefits included a measurement of the long-term effects of soil erosion on cropland productivity. A model developed by Daniel Taylor (1982) was used as a base for estimating the onsite costs and benefits of conservation tillage. Although the agronomic relationships of this model were theoretically and empirically consistent, the variable and depreciation cost trends were not. Therefore, this model was revised. A technique for generating site-specific variable and depreciation costs was developed and incorporated into the original Taylor model. The depreciation cost calculation was modified to include Salvage value and modified to correspond with the crop yields used in this analysis. An algorithm to model changes in output prices was added to the model. Heavy tillage, reduced tillage, and no-till were simulated. Reduced tillage was projected to be the most profitable tillage system for farmers with planning horizons of 75 years or longer and personal discount rates of under 7%. Heavy tillage was projected to be the -most profitable tillage system for farmers with planning horizons shorter than 75 years. No-till was always the least profitable tillage system, although the highest yield projections were produced under no-till. A summer fallow crop rotation was simulated and the results were compared with the results of an annual cropping rotation. The summer fallow rotation was projected to be less profitable than the annual cropping rotation. No-till and reduced tillage subsidization and cross compliance pricing were examined as two potential policies which could be used to induce farmers to adopt conservation tillage. Subsidies ranged from zero to $22.97 per acre annually, depending on the planning horizon and personal discount rate of the farmer. Cross compliance prices 11% higher than the normalized prices used in this analysis were needed to induce farmers to adopt no-till practices. / Graduation date: 1984

Field plots under organic and conventional management system were investigated to detect the effects of soil management practices on their soil physical, chemical and microbiological properties. The 16 farms studied, located in France, were arranged into eight matched pairs (organic/conventional). / The study revealed that in comparison with the conventionally managed soils, the organically managed soils tended to have equal to higher pH, buffering capacity, Ca, organic matter and moisture contents, and lower potential acidity values, as well as higher numbers of aerobic mesophyle and lactobacilli, and more intense alkaline phosphatase activity. The differences in soil properties between the members of matched pairs, in general were relatively small. / Soil organic matter content and nutrient availability (Ca, P), the use of lime and/or soil CaCO$ sb3$ concentrations, and use of chemical fertilizers and pesticides were found to have an influence on soil microbial activity. Soil and crop type were also found to influence some of the chemical and biological properties.

Bibliography: p. 291-301. / xxxii, 301 p. : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Basic hypothesis is that improved water use efficiency of rainfed crops can be achieved by adoption of tillage and sowing practices and crop rotation systems which improve surface and subsurface soil structure to increase the accession of rainfall and availability of soil water. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1997?

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

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

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Feb. 25, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:24:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-12-06Bitstream added on 2014-06-13T20:52:16Z : No. of bitstreams: 1 cominetti_fr_me_botfca.pdf: 308890 bytes, checksum: 60027f68184d35e1ec358949e3137922 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / A cultura da soja é um dos mais importantes produtos agrícolas do país. O sistema de produção de soja predominante utiliza como forma de preparo do solo o uso de arados e grades, caracterizado pela intensa mobilização do solo podendo causar danos ambientais e degradação do solo. Como alternativa para solucionar esses problemas, indica-se a mínima mobilização do solo, mantendo resíduos vegetais na superfície do solo, favorecendo sua conservação. Com o objetivo de avaliar o desempenho agronômico de cultivares de soja recomendadas para o Estado de São Paulo em diferentes sistemas de preparo do solo, desenvolveu-se o presente trabalho,instalado e conduzido em campo experimental na Fazenda Experimental Lageado da Faculdade de Ciências Agronômicas da UNESP, Campus de Botucatu. O delineamento experimental foi em blocos ao acaso com parcelas subdivididas com quatro repetições. Os tratamentos resultaram da combinação de três sistemas de preparo do solo e dez cultivares de soja totalizando trinta tratamentos. Os três sistemas de preparo do solo foram: PR- preparo reduzido com escarificador, PC- preparo convencional com grade aradora e niveladora e PD- plantio direto sob vegetação de triticale dessecada com herbicida, foram instalados nas parcelas e as variedades de soja nas subparcelas. Os cultivares de soja foram: C1- IAC 18, C2- FT Abyara, C3- IAS 5, C4- Embrapa 45, C5- IAC 8.2, C6- FT Cometa, C7- Embrapa 133, C8- M.Soy 7501, C9- IAC 22 e C10- Engopa 315. Os resultados demonstram que os sistemas de preparo do solo não influenciaram: altura de inserção da primeira vagem, número de vagens, população inicial e final de plantas, número de grãos por vagem e peso de mil grãos e produtividade, influenciando apenas a altura de plantas. / The soybean is the most important agricultural product of the country. The tillage system that predominates in this crop is the conventional tillage with plowing or heavy harrowing and the leveling harrowing characterized by intense mobilization of the soil causing damages to the environment and soil degradation. As an alternative to solve these problems a minimum or no soil mobilization is suggested maintaining vegetable residues in the surface on behalf of the soil conservation. In the seeds market there are lots of soybean cultivares regarding morphologic, physiologic and productivity characteristics. The present work was carried out with the purpose of evaluating the behavior of the soybean cultivares in different soil management systems recommended to the state of São Paulo. The experiment was installed and conducted in the Experimental Farm Lageado in the College of Agricultural Sciences, UNESP, Botucatu Campus. The experimental delineation utilized was the random block with subdivided plots in four replicates. The treatments were combination of three soil management systems and ten cultivares of soybean. The three management systems were: PC- conventional tillage with heavy harrowing and leveling; PR- reduce tillage with moulboard and PD- no tillage in the vegetation dried with herbicid were installed in the plots, the ten cultivares of the soybean were: C1- IAC 18, C2- FT Abyara, C3- IAS 5, C4- Embrapa 45, C5- IAC 8.2, C6- FT Cometa, C7- Embrapa 133, C8- M.Soy 7501, C9- IAC 22 e C10- Engopa 315 were installed in the subplots. The results demonstrated that the soil management practies did not influence the productivity, height of insert of the first shell, number of shells, initial and final population of plants, number of grain by shell and weight of one thousand grains, influenced only by the height of the plants.

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