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No. of bitstreams: 1 Dissertação - Mozar Alves Gondim Neto.pdf: 14312351 bytes, checksum: a7f1fe152f71b60e0b419de9b300950d (MD5) Previous issue date: 2012-02-15 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / In the Amazon, corn is grown mainly by small producers who have small areas for cultivation and apply low level of technology in agriculture. Considering the importance of maize for subsistence farming in the Amazon region, this research was conducted to evaluate the performance of three maize cultivars (Saracura, BRS1030 and Sol da Manhã) submitted by two different forms of management (preparation and conventional tillage) in lowland areas in the state of Amazonas. The research was developed by Embrapa Western Amazon, at the experimental station of the Cauldron, in the city of Iranduba - AM, in the season of 2010/2011, The soil is classified as Haplic Gleysoil (Embrapa 1999), considered a high natural fertility. The experimental design was a randomized block, split plot with four replications. The plots were defined by two management systems (System Conventional Tillage - Tillage System and SPC - SPD) and the subplots characterized by the use of three maize cultivars (Saracura, BRS 1030 and Sol da Manhã). Were evaluated: plant height, height of ear insertion, stem diameter, ear diameter, ear length, ear weight with straw, cob without straw weight, number of ears / ha, yield, grain moisture, number kernels per row and number of kernels per row. In general, all the evaluated statistically influenced by tillage systems studied. Observing the isolated cultivars, it was found that there were significant effects for Saracura among the management systems for the characteristics spike length, spike weight with and without straw yield, grain moisture and grain number per row. For BRS1030 (plant height, ear weight with and without straw, number of ears / ha and productivity) and the Sol da Manhã (plant height, height of ear height, weight of ears with husk, weight of spikes without straw and productivity). Regarding cultivars, all traits were statistically significant, except for the determination of grain moisture. The Saracura was superior to the others in the following characteristics (plant height, height of ear height, weight of ears without straw, grain moisture, grain number per row and number of kernels per row). The BRS1030 was superior to the other characteristics (stem diameter, ear diameter, ear length, weight of ears with husk, weight of ears without straw, number of ears / ha and productivity). Cultivar Sol da Manhã was lower than all genotypes for all traits. / No Amazonas, o milho é cultivado, principalmente, por pequenos produtores que dispõem de pequenas áreas para cultivo e aplicam baixo nível de tecnologia na lavoura. Considerando a importância da cultura do milho para a agricultura de subsistência da região Amazônica, esta pesquisa foi conduzida com o objetivo de avaliar o desempenho de três cultivares de milho (Saracura, BRS1030 e Sol da Manhã) submetida a duas diferentes formas de manejo (Preparo Convencional e Plantio Direto) em áreas de várzea no Estado do Amazonas. A pesquisa foi desenvolvida em área da Embrapa Amazônia Ocidental, na estação experimental do Caldeirão, no município de Iranduba – AM, na safra agrícola de 2010/2011, em solo classificado como Gleissolo Háplico (Embrapa 1999), considerado de alta fertilidade natural. O delineamento experimental utilizado foi em blocos ao acaso, com parcelas subdivididas e quatro repetições. As parcelas foram definidas por dois sistemas de manejos (Sistema de Preparo Convencional - SPC e Sistema Plantio Direto – SPD) e as subparcelas caracterizadas pelo uso de três cultivares de milho (BRS Saracura, BRS 1030 e BRS Sol da Manhã). Foram avaliados: altura das plantas, altura da inserção da espiga, diâmetro do colmo, diâmetro da espiga, comprimento da espiga, peso da espiga com palha, peso da espiga sem palha, número de espigas/ha, produtividade, umidade dos grãos, número de grãos por fileira e número de grãos por carreira. De forma geral, nenhuma das características avaliadas foi estatisticamente influenciada pelos sistemas de manejo estudado. Observando-se as cultivares isoladas, verificou-se que houve efeito significativo para a Saracura entre os sistemas de manejo para as características comprimento da espiga, peso da espiga com e sem palha, produtividade, umidade dos grãos e número de grãos por fileira. Para a BRS1030 (altura de plantas, peso da espiga com e sem palha, número de espigas/ha e produtividade) e para o Sol da Manhã (altura das plantas, altura da inserção da espiga, peso das espigas com palha, peso das espigas sem palha e produtividade). Quanto às cultivares, todas as características estudadas foram estatisticamente significativas, exceto para a determinação da umidade dos grãos. A Saracura foi superior às demais nas seguintes características (altura de plantas, altura da inserção da espiga, peso das espigas sem palha, umidade dos grãos, número de grãos por fileira e número de grãos por carreira). O BRS1030 foi superior às demais nas características (diâmetro do colmo, diâmetro da espiga, comprimento da espiga, peso das espigas com palha, peso das espigas sem palha, número de espigas/ha e produtividade). A cultivar Sol da manhã foi inferior às demais cultivares para todas as características avaliadas.

A produção de algodão (Gossypium hirsutum L.) em sistema adensado iniciou no Brasil na safra 2008/09 com objetivo de aumentar a lucratividade da propriedade, por meio da intensificação de uso do solo e redução de custos. Este sistema é, substancialmente, alterado em relação ao convencional, pelo aumento da população de plantas, semeadura tardia (segunda safra) e em relação a dose do nitrogênio. O objetivo desta pesquisa consiste em conhecer o comportamento do algodoeiro adensado ao fornecimento de nitrogênio, em razão da cultura antecessora. O algodoeiro foi semeado em quatro tipos de sucessão: (i) sobre soja (Glycine max L.) sucedida de milheto (Pennisetum glaucum L.); (ii) sobre resíduo da soja; (iii) sobre resíduo do milheto; e (iv) em pousio, na ausência de cultura antecessora e controle de plantas daninhas. Em cada situação o algodoeiro foi conduzido sem nitrogênio e nas doses de 50 kg ha-1; 100 kg ha-1; e 200 kg ha-1 de N. A dose de nitrogênio para a máxima produtividade do algodoeiro adensado variou com a presença do resíduo, 88 kg ha-1 na sucessão milheto com soja, 127 kg ha-1 na sucessão a soja e na sucessão ao milheto ou ao pousio a produtividade foi inferior, com resposta linear até a dose 200 kg ha-1. O crescimento vegetativo foi maior com a aplicação do nitrogênio, mas a produtividade teve resposta quadrática ao fornecimento do nutriente. A produtividade foi maior quando cultivado sobre palha de milheto com soja (maior quantidade e relação C/N de 26), mesmo em menor doses de N do que nas outras palhas. A presença de palha, independentemente da relação C/N, contribui para o ganho em qualidade da fibra. / In Brazil, the narrow row cotton (Gossypium hirsutum L.) system started in the 2008/09 crop season aiming to increase farms profit, by intensive land use and lower productions costs. This system is substantially altered from the conventional (wide row), due high plant population, late sowing (second crop) and nitrogen management. With a target to know the nitrogen response of narrow row cotton in succession, the cotton was sowed in four situations: (i) after a succession of millet (Pennisetum glaucum L.) and soybeans (Glycine max L); (ii) after soybeans; (iii) after millet; and (iv) without previous culture and with weeds control. In each situation the cotton was farmed without nitrogen application and with rates of 50 kg ha-1; 100 kg ha-1; and 200 kg ha-1 of nitrogen. The nitrogen rate of maximum productivity was dependent on the preceding crop, 88 kg ha-1 after succession of millet and soybeans, 127 kg ha-1 after soybeans and in succession of millet or without previous culture the productivity was lower, with linear response until 200 kg ha-1. The vegetative growth was higher with nitrogen application, but the productivity had quadratic response to nitrogen fertilization. The higher productivity was on cotton sowed upon the millet with soybeans straw (more quantity of straw and relation C/N 26), even with less nitrogen than in the other straws. On the presence of straw, independent of C/N relation, the fiber quality was better.

Made available in DSpace on 2014-08-20T14:33:03Z (GMT). No. of bitstreams: 1 dissertacao_giusepe_stefanello.pdf: 2272777 bytes, checksum: 97c1ff8637ae6d298ecef527b42a16bb (MD5) Previous issue date: 2013-01-21 / The crops of corn and beans are sown on a large number of small farms where conventional tillage is commonly used. The farmers are interested in adopting no tillage farming. However, small planters suited for this purpose are not available in the market. The portable hand seeder (jab-type) was found to be used for more than half of these farmers, including direct seeding, in southern Brazil. Despite the positive factors of their use, there are field capacity and operating performance constraints as well as ergonomic problems. Companies are not interested in designing equipment better suited for this segment, continuing to produce old-fashioned planters. It is urgent to develop equipment of this size in order to enhance the sowing quality of these crops and to reduce the difficulty of the work of these farmers. The aim of this work was to conduct informational and conceptual design phases of a human-powered planter for direct seeding of corn and beans employing a design methodology. Drill concepts capable of performing tillage and no-tillage seeding have been developed, focusing on real technological needs related to the cultivation of these crops. One was chosen, among the concepts of the planters, which evolved into a final design, using currently existing principles of solution, obtaining the design of a push punch planter with superior characteristics when compared with the planters currently available. The concept is formed by a tubular steel frame, a ring-type vertical seed meter, nine punchers, depth gauge wheels and closure and firming wheel, enabling sowing quality, minimum soil disturbance and hence minimum energy demand / O milho e o feijão são semeados em grande número de pequenas propriedades agrícolas e geralmente em sistema convencional de cultivo. Há interesse dos agricultores familiares em migrar para o sistema de semeadura direta, porém não estão disponíveis no mercado semeadoras de pequeno porte adequadas para esse fim. Na região sul do Brasil foi constatada a utilização de semeadoras manuais portáteis (saraquá) por mais da metade desses agricultores, inclusive para semeadura direta. Apesar dos fatores positivos da sua utilização, há restrições de capacidade e desempenho operacional, além de problemas ergonômicos. As empresas não se interessam em projetar equipamentos mais adequados para esse segmento, continuando a produzir semeadoras antiquadas. É urgente o desenvolvimento de equipamentos desse porte, que confiram maior qualidade na semeadura dessas culturas e reduzam a dificuldade de trabalho desses agricultores. O objetivo do presente trabalho foi, através de metodologia de projeto, realizar as fases de projeto informacional e projeto conceitual de uma semeadora de tração humana para semeadura direta de milho e feijão. Foram desenvolvidas concepções capazes de realizar semeadura direta e convencional, focando nas reais necessidades tecnológicas relativas ao cultivo dessas culturas. Foi escolhida uma, dentre as concepções da semeadora, a qual evoluiu para a concepção final, utilizando princípios de solução existentes e atualmente empregados, obtendo-se a concepção de uma semeadora puncionadora de empurrar com características superiores em relação às semeadoras atualmente disponíveis. A mesma é constituída de estrutura tubular de aço, um dosador tipo anel vertical, nove puncionadores, rodas limitadoras de profundidade e roda cobridora compactadora, que permitem a semeadura com qualidade, mínimo revolvimento do solo e, consequentemente, mínima demanda energética.

Orientador: Claudio Bianor Sverzut / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-04T01:35:06Z (GMT). No. of bitstreams: 1 WeirichNeto_PedroHenrique_D.pdf: 810392 bytes, checksum: 192714e40250366271122cb286585056 (MD5) Previous issue date: 2004 / Resumo: Na atual conjuntura, em tempos de globalização e auto sustentabilidade, a agricultura brasileira é obrigada a rever conceitos. Nesta revisão novas técnicas são agregadas ao processo produtivo agrícola. Exemplos clássicos são as ¿técnicas¿ de semeadura sob a palha (Plantio Direto) e o manejo localizado de insumos (Agricultura de Precisão). A região dos Campos Gerais, Paraná, não foge a regra, região altamente tecnificada onde a semeadura sob a palha é uma realidade, começa a transformar conhecimento relativo ao manejo localizado de insumos. Mesmo, temporalmente, em estágios diferentes estas técnicas trazem ainda muitas dúvidas. Com vistas a contribuir nesta discussão realizou-se trabalho cujo objetivo foi qualificar o processo de semeadura junto ao sistema produtivo do milho no sistema de semeadura sob a palha. Escolheu-se o milho por este ocupar aproximadamente 1/3 da área agrícola de verão da região, e ser cultura de suma importância da rotação de culturas, um dos pilares do sistema de semeadura sob a palha. Utilizou-se análise de regressão linear múltipla, pelos métodos passo a passo (¿stepwise¿) e melhor regressão possível (¿bestsubset¿). Como variáveis representativas do processo de semeadura, independentes, analisou-se em duas linhas de semeadura, a distribuição de plantas através das variáveis; população de plantas e pressão de população de plantas (variável que considera o espaçamento individualmente) e a profundidade de deposição da semente. Em uma área agrícola, com doze anos de semeadura sob a palha, demarcaram-se 60 pontos eqüidistantes de 40 m. Em cada ponto mensurou-se como variáveis independentes; pH, Al, H+Al, Ca, Ca+Mg, P, K, CTC, V%, relaçãoCa/Mg, relaçãoCa/K, argila, areia, silte, profundidade do Horizonte A, profundidade do Horizonte A+transição, cota, resíduo, foram atribuídas notas para problemas na planta, problemas na espiga e quantificação de plantas espontâneas. Como variáveis representativas de rendimento do milho, dependentes, mensurou-se a massa de grãos por planta, a altura e o diâmetro de colmo da planta. Das duas linhas de semeadura acompanhadas, a linha dois sempre mostrou os melhores indicadores de ajuste. Este fato talvez pode ser explicado pelo estresse inicial sofrido pelas plantas da linha três, devido ao tempo de emergência de plântulas, ocasionando pela profundidade de deposição da semente. Os coeficientes de determinação (R2) variaram de 33,4% para o diâmetro da linha três, a 74,7% para a altura de planta da linha dois. As variáveis; população de plantas e pressão de população sempre se mostraram presentes nos conjuntos regressores que melhor explicaram os fenômenos de rendimento do milho / Abstract: In the actual time of globalization and self sustainability, Brazilian agriculture needs to review its paradigms. In this review new techniques are incorporated in the agriculture production process; classical examples are the no tillage system and the localized management of fertilizers (Precision Farming). The region of Campos Gerais, in the state of Paraná, is not an exception of this rule; a very high level of technology is employed, the no till system is a reality and knowledge about precision farming is being employed. As a brand new technology at the regional context, precision farming is subject to several uncertainties. Hence, this research was developed in order to make a contribution on this subject; the main goal was to qualify the seeding process of the corn production system in the no tillage system. This culture was chosen because about one third of the region cultivated area in the summer season is planted with it, and its importance in crop rotation, one of the pillars of the no till system. Linear multiple regression was used in order to analyze data using both, stepwise and best subset techniques. To represent the seeding process (independent variable), plant distribution in two seeding rows was analyzed through the variation in plant population, plant population pressure (a variable that considers spacing individually), and depth of seeding. In a cultivated field with 12 years of no tillage, 60 equidistant points (40 m.) were defined. At each point the following variables (independent) were measured: pH, Al, H+Al, Ca, Ca+Mg, P, K, CTC, V%, Ca/Mg index, CA/K index, clay content, sand content, silt content, depth of A horizon, depth of A horizon + transition A/B, relative altitude and amount of harvest residue. A scoring system was defined to include in the analysis problems in the plants, problems in the cobs and amount of weed infestation. The weight of grain by plant, plant height and the stem diameter were chosen as representative of corn production (dependent variable). The comparison of the two observed seeding lines showed that the line two always had a better correlation. This fact can be explained by the initial stress in the other line (line three) induced by the time of emergence of plants related to the depth of seeding. Coefficient of determination (R2) varied from 33,4% related to the stem diameter to the line three, to 74,4% to plant height in the line two. The variables plant population and plant population pressure were always present in the regressions equations with a better explanation of corn yield / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

Orientador: Bastiaan Philip Reydon / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Economia / Made available in DSpace on 2018-08-27T05:27:00Z (GMT). No. of bitstreams: 1 Telles_TiagoSantos_D.pdf: 2532419 bytes, checksum: 074d49e9f68a6dcd4d343ff801020e43 (MD5) Previous issue date: 2015 / Resumo: Os preços de terras agrícolas podem ser determinados tanto pelos fatores produtivos quanto pelos fatores especulativos. Entre os fatores produtivos, é reconhecido que investimentos na conservação dos solos em áreas destinadas às atividades agropecuárias podem valorizar as terras agrícolas. O plantio direto na palha é uma tecnologia que integra diretrizes da agricultura conservacionista e que garante uma série de vantagens à produção agropecuária, com possíveis impactos no preço das terras, o que contribui para que a adoção desse tipo de preparo do solo esteja crescendo no Brasil. Essa expansão foi de tal grandeza que no Censo Agropecuário 2006, realizado pelo Instituto Brasileiro de Geografia e Estatística (IBGE), foi dedicada uma seção específica para o levantamento de informações sobre os tipos de preparo do solo. Esse levantamento possibilitou o cruzamento de informações sobre os tipos de preparo do solo com o preço das terras agrícolas, oferecendo a possibilidade de verificar se as terras utilizadas com o plantio direto na palha são mais valorizadas do que aquelas utilizadas com outros tipos de preparo, ou seja, cultivo convencional ou cultivo mínimo. Os resultados indicaram que no Estado do Paraná as terras agrícolas em áreas de lavouras temporárias com plantio direto na palha, quando comparadas aos demais tipos de preparo, são mais valorizadas. Essa valorização das terras associada ao plantio direto na palha também pode ser observada em outras Unidades da Federação, tais como Bahia, São Paulo, Rio Grande do Sul, Mato Grosso do Sul, Mato Grosso e Goiás. Mas o fenômeno da expansão do plantio direto na palha e aumento do valor das terras que utilizam a tecnologia pode estar relacionado a outros aspectos técnicos e econômicos inerentes a esta tecnologia, dentre os quais: a redução de risco de perdas de produção associados às questões climáticas e de custos, redução no número de operações agrícolas em comparação aos outros tipos de preparo e simplificação na gestão da propriedade agrícola. Adicionalmente, outro fator que pode ter influenciado essa relação entre plantio direto e valorização das terras agrícolas foram ações governamentais, por meio de programas e políticas públicas com foco na conservação e recuperação dos solos. Isso suscita a questão de que é válido investigar com mais profundidade a repercussão do programas dessa natureza na valorização do ativo terra enquanto fator para a tomada de decisão dos agricultores na adoção de práticas propostas pela agricultura conservacionista / Abstract: The cost of farm lands is determined by both productive and speculative factors. Soil conservation is one such factor that might result in the appreciation of areas dedicated to agriculture. The no-tillage (NT) is a technology integrating the guidelines of conservation agriculture and ensures several advantages to agricultural productions. It also impacts land prices and, in turn, favors the adoption of this type of soil preparation in Brazil. The expansion of the use of the NT was so significant that the 2006 Agricultural Census, carried out by the Brazilian Institute of Geography and Statistics (IBGE), dedicated one specific section for the acquisition of information about the types of soil preparation. The collected data allowed the study of the correlation between the type of soil preparation and the cost of farm lands. In particular, it enabled the comparison between the direct prices of lands using NT or other soil preparation, that are conventional tillage and minimum tillage. The results indicate that, in Parana State, farm lands in large areas of annual crops using NT are negotiated at higher prices comparison with land using other forms of soil preparation. This Brazilian farm land appreciation in association with the NT was also observed in other Federation units, such as Bahia, São Paulo, Rio Grande do Sul, Mato Grosso do Sul, Mato Grosso and Goias. The observed higher prices might also be associated with other technical and economical aspects, inherent to the NT, such as the reduction of risk of yield loss due to climate issues and decreased costs, diminished number of agriculture operations, in comparison with the other types of soil preparation and simplified management of the property. Additionally, another factor that might have influence on this relationship between the NT and the appreciation of the farm lands were governmental actions, represented by public programs and policies focusing on the conservation and restoration of soils. It raises the question that it is important to investigate more deeply the repercussion of such policies in the appreciation of land as an asset in the farmer's decision to adopt practices of the tillage conservation agriculture / Doutorado / Desenvolvimento Economico, Espaço e Meio Ambiente / Doutor em Desenvolvimento Economico

No description available.

Conventional farming systems create socio-economic problems through increased production costs and loss of the soil and chemicals that are washed from the farmlands. Even though no-till farming systems can increase farm profit and reduce environmental degradation, soil compaction can negate the advantages of no-till farming when no-till systems are used continuously under certain soil and climatic conditions. One objective of this study was to evaluate the long-term effects of the no-till method on bulk density, capillary porosity, noncapillary porosity, void ratio, and cone index of the soil. Although tillage affected cone index significantly, moisture variations caused difficulty in interpreting the results. No statistically significant differences in other parameters were found among no-till, conventional till, and control fallow treatments within each of three cropping seasons. However, within each tillage treatment these parameters showed significant variations between test seasons. When the soil bulk density data is required at close depth intervals, the core sample method becomes laborious while its use is limited by soil type and moisture conditions. The neutron probe densitometer is difficult to use in tillage studies due to practical problems. Among the predictive models for bulk density, some require parameters determined through expensive laboratory procedures while others have not been proven to work in field conditions. Therefore, the second objective was to develop a model to predict soil bulk density using cone index and moisture content data for a Virginia soil. Two separate models have been developed for top and subsoil layers using remolded natural soil samples. The topsoil model predicted bulk density close to the actual data taken in recently disturbed soils. One cropping season after plowing, predicted values were about 10% higher than the actual, a result which could be due to the aging effect. The subsoil model, on the other hand, under-predicted soil bulk density by about I5% After the model coefficients for a particular soil are determined through laboratory tests, cone index and moisture data can be used to predict bulk density in that soil. This procedure may save time and expense in future research on soil compaction. / Ph. D.

Experiments were conducted with 'BigSur' broccoli (<i>Brassica oleracea</i> var. <i>italica</i> Plenck) at two sites in fall of 1993 and at two sites in the spring of 1994 on a Hayter loam in southwestern Virginia. Objectives were to determine the tillage main-plot (CT = conventional tillage, and NT = no-tillage) and weed-control subplot (C = no overseeding or preemergent herbicide; HB = oxyfluorfen; RC = red clover (<i>Trifolium pratense</i> L.); WC = Dutch white clover (<i>Trifolium repens</i> L.); and HV = hairy vetch (<i>Vicia villosa</i> Roth) effects on broccoli yield and weed suppression. At all sites, marketable broccoli yield was equal or higher in NT than CT and was unaffected by overseeded legume living mulches. Overseeded legumes suppressed weeds as well as the HB in three of the four sites. These data show that the NT systems used in these experiments can suppress weeds and produce high broccoli yields and that overseeded legume living mulches can be effectively established after transplanting to suppress weeds without reducing broccoli yield. / Master of Science

Field experiments were conducted in 1983 and 1984 to compare conventional tillage (CT) versus no-tillage (NT) production of broccoli and cabbage. The tillage treatments were applied in combination with four rates of applied nitrogen fertilizer and three cover crops: hairy vetch (<u>Vigia villosa</u> Roth), Austrian winter pea (<u>Fisum arvenu</u> L.), and cereal rye (<u>Secale cereale</u> L.). Transplants of 'Premium Crop' broccoli (<u>Brassica oleracea</u> var. <u>italica</u> Plenck) and 'Market Prize' cabbage (<u>Brassica oleracea</u> var. <u>capitata</u> L.) were set with a locally adapted NT vegetable planter. None of the variables studied affected the final plant stand. Yield and head size with NT were equal to or greater than CT. Soil moisture was higher under NT plots throughout the growing season. Yield and head size with the two legume covers were equal to or greater than those with the rye cover. Yield and head size tended to increase as applied N was increased, although differences were not always significant. The data, although not conclusive, indicate that the legume cover crops provided additional nitrogen for the cole crops. / Master of Science

Field experiments were conducted at three Virginia locations in 1990 and 1991 to evaluate the effects of cover crop suppression method, nonselective herbicide, no-till cultivation, and herbicide banding on weed control, corn vigor, and corn yield. These factors were evaluated in experimental areas containing either a rye (Secale cereale) cover crop or in areas with no cover crop. In areas with a rye cover crop, the cover crop suppression methods evaluated were paraquat or mechanical suppression via mowing. In areas without a cover crop, paraquat was compared to a treatment without paraquat. Five selective herbicide treatments were evaluated within each level of the variable described above. These treatments included a control or no selective herbicides, a preemergence herbicide combination of atrazine plus metolachlor, and a postemergence herbicide combination of dicamba plus nicosulfuron. The preemergence and postemergence herbicides were applied either broadcast or banded over the crop row. The use of no-till, interrow cultivation was evaluated for each combination of the cover crop suppression method or nonselective herbicide and selective herbicide variables. Where a rye cover crop was present, paraquat significantly improved control of this species relative to mowing, and it provided significantly better control of most weed species and increased corn vigor and yield. In the absence of a cover crop, paraquat significantly improved weed control, but its effect on corn vigor and yield was dependent on weed pressure. Where weed pressure was moderate to heavy, paraquat significantly improved corn vigor and yield, whereas, it did not have a significant effect on these variables if weed pressure was low. In some situations, paraquat did not significantly improve late season weed control with broadcast selective herbicides, however, it provided quicker control of established weeds which significantly improved corn growth, especially in dry soil conditions. With or without a rye cover crop, cultivation did not significantly improve weed control, corn vigor, or corn yield when used with broadcast selective herbicides. Banded selective herbicides with cultivation provided weed control and corn vigor and growth equivalent to broadcast selective herbicides without cultivation if weed pressure was low. Where weed pressure is moderate to heavy, banded herbicides with cultivation did not perform as well as broadcast treatments without cultivation. Postemergence herbicides provided weed control and corn growth equivalent to preemergence herbicides, but use of effective nonselective herbicides at planting to control established weeds was critical. / Master of Science