Thesis (Ph. D., Plant Science)--University of Idaho, December 2007. / Major professor: John E. Lloyd. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Orientador: Edivaldo Domingues Velini / Banca: Silvio José Bicudo / Banca: Julio Cezar Durigan / Resumo: O presente trabalho teve como objetivos a quantificação da produção de biomassa seca das principais palhadas utilizadas como cobertura morta em sistemas de plantio direto, nos Estados do Paraná e Mato Grosso do Sul, bem como a avaliação das dinâmicas de molhamento e o comportamento de um traçante (simulando herbicidas), em diferentes coberturas mortas. No levantamento de biomassa foram amostrados os resíduos culturais de cevada (Hordeum vulgare L.), azevém (Lolium multiflorum), trigo (Triticum aestivum), aveias colhida e rolada (A. strigosa Schieb), milho (Zea mays), milheto (Penisetum americanum) e capim-braquiária (Brachiaria decumbens Stapf). As frequências acumuladas dos dados originais forma adequadamente ajustados segundo modelo de Gompertz, apresentando elevada precisão (Rø > 0,9873). Os restos culturais de milho e trigo apresentaram a maior e menor uniformidades de distribuição do peso de matéria seca, respectivamente. Os estudos de dinâmica de molhamento e recuperação do corante FDC-1 foram desenvolvidos através de simulação de chuva artificial sobre 3000, 6000 e 9000 Kg de matéria seca ha elevado a -1, utilizando sete tipos de palhas. Destacam-se em, ambos os casos, o ajuste adequado dos dados originais ao modelo de Mitscherlich (Rø > 0,9064 e > 0,9758). Os resultados indicam uma tendência de uniformização na retenção da água das chuva entre os diferentes tipos de palhadas, com o aumento da quantidade de cobertura utilizada. A formação de "pontos secos" associados a "canais preferenciais de escorrimento", induzem a menor capacidade de embebição e retenção da água das chuvas pelas palhadas. As quantidades totais do corante FDC-1 que atingiram o solo foram relativamente uniformes, após precipitações entre 10 e 20 mm, independente do tipo e quantidade de palha, indicando que ambas características pouco interferem na capacidade do traçante em transpor a cobertura morta. / Abstract: The presente work had as objectives to quantify the production of dry cultural residues of the man straws used as mulches in no-till systems, in the State of Paraná and Mato Grosso do Sul, as well as, to evaluate the wetting dynamic and the behavior of a dye (simulating herbicides), in different cultural residues. In the biomass survey it were evaluated the cultural residues (Kg of dry matter ha raised -1) of barley (Hordeum vulgare L.), perennial ryegrass (Lolium multiflorum), wheat (Triticum aestivum), harvested oat (Avena strigosa Schieb), rolled oat (Avena strigosa Schieb), corn (Zea mays), millet (Penisetum americanum) and braquiária grass (Brachiaria decumbens Stapf). The acumullated frequencies of the original data fitted well to the Gompertz model (Rø > 0,9064 e > 0,9758). The most and least uniform distribution of the cultural residues in the field were observed for corn and wheat respectivelly. The studies of the wetting dynamic and recovery of the dye FDC-1 were developed through simulation of artificial rain on 3000, 6000 and 9000 Kg of dry matter ha raised -1 of seven types of straws. The data fitted well to the Mitscherlich (Rø > 0,9064 and > 0,9758). The results indicated an uniformity tendency in the retention of the rain water among the different types of straws, with the increase of th amont of mulch. The formation fo "dry points" associated to "preferential channels of running off", reduces the capacity of absorption and retention of the rain water by the straws. The total amounts of the dye FDC-1 that reached the soil were relatively uniform, after precipitations between 10 and 20 mm, independt of the type and amount of straw, indicating that both characteristics have minimum efects in the capacity of the dye in transporting the straw. / Mestre

Made available in DSpace on 2014-06-11T19:28:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-03Bitstream added on 2014-06-13T20:58:20Z : No. of bitstreams: 1 rosa_cs_me_jabo.pdf: 131509 bytes, checksum: bc16df4958bfbe25ec06eb32b88f84cd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho foi estudar a veiculação do oxyfluorfen à palha de arroz e a seletividade de Salvia splendens ao herbicida. Para tal, um ensaio de campo foi instalado, no delinamento de blocos casualisados, no esquema fatorial 4 x 3, com quatro repetições. Os tratamentos experimentais constaram de quatro quantidades de palha de arroz (0, 4, 6 e 8 t/ha) e três doses do herbicida oxyfluorfen (0, 1 e 2 L/ha). Os parâmetros avaliados foram altura de plantas, número de inflorescências e fitoxicidade de sálvia e a densidade da comunidade infestante. Concluiu-se que os tratamentos que levaram a veiculação do herbicida (nas duas doses testadas e nas três quantidades de palha) apresentaram bom controle de plantas daninhas sem que efeitos fitotóxicos severos fossem observados nas plantas de sálvia. A pulverização direta do herbicida sobre o solo e as plantas de sálvia não se mostrou viável para esta ornamental, visto que foram observados sintomas severos de fitointoxicação. O tratamento que obteve os resultados mais satisfatórios e por isso pode ser recomendado foi o que recebeu o herbicida na dose de 2 L/ha veiculado à 4 t/ha de palha de arroz. / The objective of this work was to study the possibility of oxyfluorfen herbicide translocation the straw rice and the selectivity Salvia splendens for the product. The randomized block design was used, in the factorial scheme 4 x 3, with four repetitions. The main factor was corporate for four amount straw rice (0, 4, 6 and 8 t/ha) and three doses of the oxyfluorfen herbicide (0, 1 and 2 L/ha). The results showed that traits which the herbicide was used with straw rice, showed great results to weeds control, with out occurrence of high phytotoxicity in the salvia plants.

Please read the abstract in the section 00front of this document / Dissertation (M Inst Agrar (Pasture Science))--University of Pretoria, 2001. / Plant Production and Soil Science / unrestricted

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En la agricultura moderna se usan diferentes tipos de plásticos sintéticos para mejorar las condiciones de cultivo y favorecer el desarrollo, la productividad y el manejo de las plantas. Además, permiten incrementar la conservación y comercialización de productos frutihortícolas. Particularmente, la técnica de mulching es una práctica agrícola que consiste en colocar una protección/cobertura plástica sobre el suelo para mejorar el desarrollo de cultivos dado que cambia el microclima y el balance energético del suelo. En tal sentido, deben controlarse principalmente dos aspectos como la incidencia de la radiación solar y las condiciones del suelo que influyen directamente sobre el crecimiento de los cultivos. El primer aspecto se regula teniendo en cuenta que, la incidencia de la radiación solar depende del color del mulch. Asimismo, el color influye sobre la estabilidad térmica de la película plástica. El segundo aspecto depende principalmente del contenido de micro y macronutrientes en el suelo de modo tal que estén disponibles para el crecimiento y desarrollo del cultivo y, de esta manera, alcanzar rendimientos elevados. La deficiencia de estos nutrientes se debe a varios factores, siendo el principal la continua remoción debido al cultivo intensivo, alcanzando, en algunos casos, concentraciones inferiores a las requeridas para un crecimiento normal. Particularmente, los micronutrientes como hierro, cobre, manganeso, etc. son los que están en pequeñas cantidades y se agotan más rápidamente. Por esta razón, es de vital importancia incluirlos en los planes de fertilización de los cultivos que comúnmente se utilizan para incorporar macronutrientes. Estas problemáticas conducen a la necesidad de desarrollar materiales plásticos para mulching que presenten un comportamiento activo, con un costo competitivo y conservando las propiedades mecánicas de las películas plásticas que actualmente se usan para tal fin. En tal sentido, el objetivo general de esta tesis es desarrollar películas plásticas para mulching que permitan la liberación controlada de micronutrientes a partir de películas de polietileno/negro de humo. Para tal fin, se planteó que, mediante una modificación superficial con partículas minerales con capacidad de sorción, las películas plásticas podrían retener micronutrientes en superficie que posteriormente, durante ciclos de riego-evaporación-condensación, puedan ser aportados al suelo. De esta manera, el mulch activo proveerá micronutrientes en función de los requerimientos nutricionales específicos de las plantas (actividad a medida) y contribuirá a mantener/incrementar la concentración de estos elementos en el suelo aún en cultivos intensivos. Asimismo, estas películas activas deberán conservar sus propiedades al ser expuestas a las condiciones ambientales severas y ser durables durante el tiempo de cultivo para luego poder retirarlas y disponerlas en forma sostenible, por ejemplo, reciclándolas. Para el desarrollo de este mulch activo se tuvieron en cuenta aspectos económicos y sostenibles tanto en el diseño de la formulación como en las propiedades finales de la película y el proceso de obtención propuesto. Inicialmente, se dimensionó el mercado actual de agroplásticos a nivel nacional y global. Por otra parte, a partir de la interacción con productores del sector agrícola, empresas fabricantes de mulch plástico e investigadores y profesionales de agronomía se analizó el proceso de producción actual con sus ventajas y desventajas, los costos, los sistemas de colocación y recolección de mulch plástico y las tendencias actuales de uso. Asimismo, se identificó que, una de las problemáticas asociada al uso del mulch, es la deficiencia de micronutrientes en el suelo luego de la postcosecha como consecuencia del cultivo intensivo. Para desarrollar el mulch activo se propone una metodología que incluye dos etapas. Inicialmente, se llevará a cabo una modificación superficial de películas plásticas incluyendo partículas minerales con capacidad de sorción. Posteriormente, los micronutrientes se incorporarán sobre las películas modificadas superficialmente mediante atomizado de soluciones de sales solubles para obtener las películas activas. El sistema de modificación superficial a emplearse es factible de ser escalado, pudiendo adaptarse a sistemas continuos de producción de películas plásticas o ser aplicado en línea en el procesamiento industrial convencional. En el marco de esta tesis doctoral se prepararon películas con y sin la inclusión de micronutrientes. Estas películas se caracterizaron morfológica, fisicoquímica, térmica y mecánicamente con múltiples técnicas analíticas complementarias. Además, se estudió la capacidad de liberación de micronutrientes y el comportamiento de degradación de las películas por exposición directa a la intemperie y por envejecimiento acelerado según norma. Para ello, películas de polietileno/negro de humo fueron modificadas superficialmente con distintas partículas minerales: talco, zeolita y carbonato de calcio. Se utilizó un tipo de partícula para cada película modificada. Como micronutrientes se usaron hierro, cobre y manganeso que son fundamentales para el crecimiento de lechuga, cultivo utilizado como testigo debido a su rápido crecimiento y mostrar síntomas visibles frente a la deficiencia de los micronutrientes. Se verificó que las partículas minerales se adhirieron correctamente a la superficie de las películas y que los micronutrientes se sorbieron sobre las tres partículas. Asimismo, se probó que los micronutrientes se liberan en forma controlada con distintos experimentos que dan conclusiones complementarias. En todos los casos, las películas presentan propiedades mecánicas adecuadas para la colocación manual y automática del mulch en campo. Además, sus propiedades térmicas les permiten soportar las temperaturas a las que estará expuesto el mulch. Por otra parte, se demostró que resisten el envejecimiento acelerado y la exposición directa a la intemperie durante al menos 6 meses, tiempo de cultivo promedio para la mayoría de los productos frutihortícolas. Para demostrar la eficacia del sistema propuesto como mulch activo, se llevó a cabo un estudio de campo durante 50 días, utilizando cultivo de lechuga y películas modificadas con talco porque, a nivel laboratorio, tienen el mejor comportamiento de retención/liberación de micronutrientes. Se tomaron muestras de hojas, raíces y sustrato para determinar parámetros tales como peso fresco y seco de hojas y raíces, área foliar, número de hojas desplegadas, tasa de crecimiento de cultivo, índice de clorofila y concentración de nutrientes en hoja y sustrato. Estos parámetros permiten evaluar el efecto del sistema propuesto sobre el crecimiento de las plantas y sobre la retención de micronutrientes en el suelo. En todos los casos se realizó un análisis comparativo con un sistema testigo que comprende el uso de mulch comercial con una fertilización conteniendo macronutrientes, nutrientes secundarios y micronutrientes. Los resultados de este estudio son muy promisorios dado que se observó que las plantas donde el sustrato se cubrió con las películas activas presentaron un muy buen desarrollo, sin señales de deficiencia de micronutrientes. Se evidenció también que los micronutrientes retenidos en la superficie de las películas activas pueden liberarse y migrar hacia el suelo de manera tal que el cultivo pueda absorberlos y desarrollarse adecuadamente. Asimismo, se consiguió conservar y/o aumentar el contenido de micronutrientes en el suelo, que era uno de los objetivos prioritarios del desarrollo dado que lo habilita para el cultivo intensivo, paliando el problema de remoción de micronutrientes en suelo. / In modern agriculture, different kinds of synthetic plastics are used to improve growing conditions and favor the development, productivity and management of plants. In addition, they allow an increase in the conservation and commercialization of fruit and vegetable products. The mulching technique is an agricultural practice that consists of placing a protection/plastic cover on the soil to improve the development of crops since it changes the microclimate and the energy balance of the soil. In this sense, two aspects such as the incidence of solar radiation and soil conditions that directly influence crop growth must be controlled. The first aspect is regulated considering that the incidence of solar radiation depends on the color of the mulch. Likewise, the color influences the thermal stability of the plastic film. The second aspect depends mainly on the content of micro and macronutrients in the soil. They should be available for the growth and development of the crop and, thus, achieve high yields. The deficiency of these nutrients is due to several factors, being the main one, their continuous removal. It is caused by intensive farming reaching, in some cases, concentrations lower than those required for normal plant growth. This problem is more remarkable with micronutrients such as iron, copper and manganese that are in small quantities and run out more quickly. For this reason, it is of vital importance to include them in fertilization plans that are commonly used to incorporate macronutrients. These problems lead to the need to develop plastic materials for mulching that present an active behavior, with a competitive cost and conserving the mechanical properties of the plastic films that are currently used for this application. In this sense, the general objective of this thesis is to develop plastic films for mulching that allow controlled release of micronutrients from polyethylene/carbon black films. To this end, it was suggested that, through a superficial modification with mineral particles with sorption capacity, plastic films could retain micronutrients on the surface that later, during irrigation-evaporation-condensation cycles, could be released to the soil. In this way, the active mulch will provide micronutrients based on the specific nutritional requirements of the plants (tailored activity) and will contribute to maintain/increase the concentration of these elements in the soil even in intensive farming. Likewise, these active films should retain their properties when exposed to environmental conditions and be durable during cultivation time so that they can be sustainably removed and disposed, for example, by recycling them. For the development of this active mulch, economic and sustainable aspects were considered both in the formulation design and film final properties, and the proposed production process. Initially, the current agro-plastics market was seized at a national and global level. Moreover, from the interaction with producers of the agricultural sector, companies that manufacture plastic mulch and agronomy professionals, the mulching system was analyzed with its advantages and disadvantages, costs, plastic mulch placement and collection systems and current usage trends. Likewise, it was identified that one of the main problems associated with the use of mulch is the micronutrients deficiency in soil after post-harvest because of intensive farming. A two stages methodology is proposed to develop the active mulch. Initially, surface modification of plastic films will be carried out using mineral particles with sorption capacity. Subsequently, the micronutrients will be incorporated on the superficially modified films by spraying soluble salt solutions to obtain the active films. The surface modification system should be feasible to be scaled, being able to adapt to continuous plastic film production systems or to be applied online in conventional industrial processing. Within the framework of this doctoral thesis, films were prepared with and without the inclusion of micronutrients. These films were subjected to morphological, physicochemical, thermal and mechanical characterization through multiple complementary analytical techniques. In addition, the ability to release micronutrients and the degradation behavior of the films under direct exposure to the environment and accelerated aging were studied. For this purpose, polyethylene/carbon black films were surface modified with different mineral particles such as talc, zeolite and calcium carbonate. One type of particle was used for each modified film. Iron, copper and manganese were used as micronutrients, since they are essential for the growth of lettuce, crop used as a control plant due to its rapid growth and for showing visible symptoms of micronutrient deficiency. It is verified that mineral particles are correctly adhered to the film surface and micronutrients were sorbed on the particles. Likewise, it was proven that the micronutrients are released in a controlled way. In all cases, films have adequate mechanical properties for the manual and automatic placement of mulch in the field. In addition, their thermal properties allow them to withstand the temperatures to which mulch will be exposed. On the other hand, it was shown that they resist accelerated aging and direct exposure to the environment for at least 6 months, which is the average cultivation time for most fruit and vegetable products. To demonstrate the effectiveness of the proposed system as active mulch, a field study was carried out for 50 days, using lettuce crops and talc-modified films since they have the best micronutrient retention/release behavior. Leaf, root and substrate samples were used to determine parameters such as fresh and dry weight of leaves and roots, leaf area, number of unfolded leaves, crop growth rate, chlorophyll index and concentration of nutrients in leaf and substrate. These parameters allow the evaluation of the effect of the proposed system on plant growth and on the retention of micronutrients in soil. In all cases, a comparative analysis was carried out with respect to a control system that includes the use of commercial mulch with a fertilization containing macronutrients, secondary nutrients and micronutrients. The results of this study are very promising since plants grown with the active films presented a very good development without signs of micronutrient deficiency. It was also evidenced that the micronutrients retained on the active film surface can be released and migrate to the soil being available for proper crop development. Likewise, it was possible to preserve and/or increase the micronutrient content in the soil, which is one of the main objectives of this thesis since it enables minimizing the problem of soil micronutrient removal due to intensive farming.

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Successive cropping of two vegetable crops grown on the same site in one season utilizing trickle irrigation, plastic mulch, and soil fumigation was performed in two separate experiments. In 1980, cabbage (Brassicae olericea L. var capitata cv. Market Prize) was followed by tomato (Lycopersicon esculentum Mill cv. Pik Red). In 1981, cabbage was followed by broccoli (Brassicae oleracea L. var italica cv. Green Duke). Double cropping increased the annual productivity of the research plots both years and decreased production costs by 35% compared to conventional single cropping systems. Early spring planting of the first crop was essential for economic production of the second crop. Trickle irrigation increased yields of all crops grown and was the factor most responsible for yield response both years. Black plastic mulch increased yields of tomato and total yields in 1980 but cole crops showed no significant yield response to mulch either year. No difference in crop yield resulted from soil fumigation either year. Increased production costs have caused growers to seek improved methods to offset risks and costs involved. Trickle irrigation can reduce the risks involved in producing vegetables and is particularly suited to multiple cropping on plastic mulch. / Master of Science