Thesis (M.S. - Plant Sciences)--University of Arizona. / Includes bibliographical references (leaves 90-92).

Drip irrigation lines placed 15 cm deep or 5 cm shallow below soil surface and furrow irrigation were compared on calcareous soils of southern Arizona. Crops grown were zucchini squash (Cucurbita pepo L.) 1982 and 1983 summers, and cabbage (Brassica oleracea var. capitata L.), 1982 fall. Furrows received a preplant application of phosphorus (P) at a rate of 100 kg P₂O₅/ha. Urea phosphate (UP) (17-44-0) solution was injected twice in drip lines during the growing season to give a total rate of 100 kg P₂O₅/ha on cabbage and 50 kg P₂O₅/ha on squash. Deep drip lines produced 52 and 34% higher yield than shallow drip in squash 1982 and 1983 experiments respectively. Deep drip yields were comparable to fertilized furrow yields with half the water and half the fertilizer rate of the furrow used by the deep drip. Unfertilized furrow yielded least. Application of UP in deep drip raised PO₄-P and NO₃-N concentration in squash leaves to comparable values in fertilized furrow plants. Shallow drip and unfertilized furrow plants had low nutrient concentrations. Soil analysis for NaHCO₃ extractable P and NO₃-N showed higher levels under drip than furrow treatments. Available P increased to 20 cm from emitters. EC was lower under drip than furrow. Soil pH was reduced by 0.5 units around emitters. Soil moisture in root zone was highest under furrows. Deep drip had more moisture than shallow drip. Injection of UP reduced water pH to 1.8 which prevented P precipitation. Cabbage yields were comparable under all fertilized treatments. Deep drip yielded 19% higher than shallow drip. Tissue analysis showed higher nutrient concentration under drip than furrow treatments. Soil analysis showed higher available P and NO₃-N and lower EC and pH under drip than furrow treatments. Mobility of PO₄ from UP was about 20 cm in soil columns. Rate of P fixation was high. Reduction in pH followed same pattern of P mobility. Root growth and distribution was more extensive under deep than shallow drip. Roots concentrated around deep UP zone in transparent cylinders.

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Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1981. / Includes bibliographical references.

Thesis (Ph. D. - Soils, Water, and Engineering)--University of Arizona. / Includes bibliographical references.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 48-54).

Made available in DSpace on 2014-06-11T19:26:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-23Bitstream added on 2014-06-13T18:30:32Z : No. of bitstreams: 1 ludwig_r_me_botfca.pdf: 320326 bytes, checksum: 0a09aded4c32fa5c59f0e31c7a4ba8dd (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / O bom desenvolvimento e a produtividade das culturas estão associados à disponibilidade de água em níveis ideais, que pode ocorrer de forma natural pelas chuvas ou por meio de irrigações. Nestes casos, a escolha do sistema de irrigação deve levar em consideração a sua eficiência, destacando-se a irrigação por gotejamento que é realizada diretamente na região radicular, em baixas vazões e alta frequência, mantendo o teor de água no solo em nível adequado. O uso de gotejadores não autocompensantes é significativo em cultivo protegido, áreas com hortaliças e em pomares, desde que o plantio seja em nível, uma vez que seu custo é menor. Entretanto, dada à ausência de mecanismos de autocompensação, as linhas laterais com gotejadores convencionais apresentam menor comprimento, o que implica em maior número de linhas de derivação. Desta forma, é oportuno avaliar procedimentos e técnicas que possam definir o comprimento máximo da linha lateral sem prejudicar a uniformidade de distribuição de água. Acredita-se que a utilização de dois espaçamentos em trechos distintos, e não um único como normalmente é realizado, seria uma alternativa para a obtenção de maiores comprimentos de linha lateral e, consequentemente, a redução nos custos de implantação. Isto também é alcançado com a utilização de maiores variações de vazão, podendo-se empregar um Δq de 30% que mesmo assim a uniformidade de emissão permanece acima de 80%, conforme preconizado por Wu (1997). As questões fundamentais são: a definição dos dois espaçamentos e a determinação do local de troca de espaçamento. Assim, foram desenvolvidos dois modelos matemáticos, um com programação não linear e outro de simulação elaborado com a linguagem de programação Pascal. Os resultados levaram ao entendimento de que a utilização da... / The crop development and productivity are associated with the water supply at optimal levels, which can occur naturally by rain fed or irrigation. In these cases, the choice of the irrigation system must consider the efficiency, which is especially drip irrigation which is carried out directly in the root region, with low flow and high frequency while maintaining water content in the soil at the appropriate level. The use of no pressure compensating emitters is significant in greenhouse cultivation and fruit orchard with trees planted on level, since its cost is low. Though, given the absence of pressure compensation mechanisms, the lateral lines are shorter, which implies in a greater number of manifold lines. Thus, it is appropriate to evaluate procedures and techniques that can increase the lateral line length without affecting the water distribution uniformity. It is believed that the use of two spacing in lateral line different sections, not one, as usually is done, would be an alternative to achieving greater lateral line lengths and hence reduction in initial costs. This can also be achieved with the use of higher flow variations, by applying a pressure variation of 30% and maintaining the emission uniformity over 80%, as proposed by Wu (1997). The fundamental questions are: defining the two spacing values and to find the ideal location for the exchange. Two mathematical models were developed, one with non-linear... (Complete abstract click electronic access below)

Orientador: Hélio Grassi Filho / Coorientador: Luiz Antonio de Andrade / Banca: Thomaz Figueiredo Lobo / Banca: Antonio Ribeiro da Cunha / Banca: Júlio César Thoaldo Romeiro / Banca: Rodrigo Domingues Barbosa / Resumo: O milho é considerado uma das principais culturas no Brasil. A irrigação por gotejamento vem ganhando espaço na cultura do milho, no intuito de aumentar a produtividade de maneira sustentável, porém, algumas limitações como tratos culturais que podem danificar os tubos emissores, como exemplo a capina. Dessa forma, uma alternativa interessante para suprir as necessidades hídricas das plantas de forma que não atrapalhe o manejo mecanizado de determinadas culturas, é o uso da irrigação por gotejamento subsuperficial (Subsurface Drip Irrigation - SDI. Este trabalho teve por objetivo analisar o desempenho da saída de água dos tipos fenda e cilíndrica na intrusão radicular de gotejadores em irrigação subsuperficial. A pesquisa foi realizada em estufa agrícola no departamento de Solos e Recursos Ambientais localizado na Faculdade de Ciências Agronômicas - Unesp/ Botucatu. O delineamento empregado foi em blocos casualizados (DBC) em esquema fatorial 2 x 2 com 5 repetições, sendo o primeiro fator, os diferentes tipos de saída de água (saída do tipo cilíndrica e do tipo fenda com o mesmo gotejador), e o segundo fator as diferentes formas de distribuição de água (fluxo contínuo e distribuição por pulsos). Foram analisados: altura de planta, altura de inserção da primeira espiga, número de folhas, massa de folhas fresca e seca, diâmetro de colmo, massa de colmo fresca e seca, massa de raiz fresca e seca, comprimento de espiga, número de fileiras da espiga, diâmetro da espiga e sabugo, m... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Corn is considered one of the main crops in Brazil. Drip irrigation has been gaining ground in the corn crop, without increasing the carrying capacity, however, some restrictions such as cultural treatments that can damage the emitting pipes, such as weeding. Thus, an interesting alternative to supply, such as the water needs of plants in a way that does not mechanically attract or manipulate crops, is the use of subsurface drip irrigation (Subsurface Drip Irrigation - SDI). The objective of this work was to analyze the performance of slit and cylindrical water outflow in the root intrusion of drippers in subsurface irrigation. The research was carried out in an agricultural greenhouse in the Department of Soils and Environmental Resources located at the Faculty of Agricultural Sciences - Unesp / Botucatu. The experimental design was a randomized block design in a 2 x 2 factorial scheme with 5 repetitions. The first factor is the different forms of water distribution (continuous flow and pulse distribution). Plant height, first ear insertion height, leaf number, fresh and dry leaf mass, stem diameter, fresh and dry stem mass, fresh and dry root mass, ear length, number of rows were analyzed. spike, spike and cob diameter, 100 grain weight, number of grains per spike, spike mass with straw and no fresh straw, spike mass without dry straw, productivity, irrigation water use efficiency and intrusion rate root. Data were submitted to analysis of variance complemented by Tukey test, being considered significant when P <0.05. The different water outlets of the emitters showed no statistical differences. It was concluded that the slit and cylindrical outlets presented good performance and did not present root intrusion for the cultivated corn ... / Doutor

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