Dissertations / Theses on the topic 'Sprinkler irrigation. Irrigation efficiency'

Thesis (MBA)--Stellenbosch University, 2012.<br>This research study analyses the market potential for the Floppy Sprinkler irrigation system in the global market. It explores the global irrigation market and its environment to identify the driving forces that influence the industry as well as the potential that Floppy Sprinkler could unleash as a competitor. The researcher assesses the industry value chain to determine the fit and alliance opportunities for Floppy Sprinkler in the value chain. The study further analyses the competitive pressures influencing the competitive environment. Applied research is used in this study to gain a comprehensive understanding of the market. Acknowledged diagnostic models in the field of strategic management were used to guide the study. These included the PESTLE analysis to evaluate the macro-environment of the agriculture sector; the value chain analysis to assess the agricultural industry value chain; Porter’s Five Forces Model to analyse the competitive pressures for Floppy Sprinkler; and the SWOT analysis to identify the strengths, weaknesses, opportunities and threats. The relevant data were collected through both primary and secondary sources. Two questionnaires were designed, the first to industry specialists in the agriculture sector with the purpose to gain insight of the irrigation and agriculture environment; and the second to Floppy Sprinkler irrigation system users, with the purpose to obtain a rating, opinion and relevance of the product in the market. The research disclosed that forces within the macro environment influence the industry significantly. These specifically revolved around climate change, water scarcity, land availability, soil degradation, population growth and changing lifestyles. The value chain analysis revealed that opportunities exist in the agriculture industry to create horizontal and vertical alliances to strengthen Floppy Sprinkler’s position in the market. Competitive pressures in the market include direct competitors of Floppy Sprinkler, as well as the bargaining power of suppliers and buyers. Threat of new entrants and substitute products are not perceived to be immediate competitive pressures for Floppy Sprinkler owing to its cutting-edge technology, which offers a distinctive competitive advantage. Finally, opportunities were identified, which served as recommendations for Floppy Sprinkler in developing its strategy.

Com a necessidade de se promover o uso eficiente da água na agricultura, aprimoramentos e novos desenvolvimentos em equipamentos de irrigação são sempre bem-vindos. Um sistema de irrigação por gotejamento móvel (IRGMO), trata-se da união entre a irrigação por pivô central (irrigação por aspersão) e a irrigação por gotejamento (irrigação localizada). O sistema é constituído por tubos de descida que unem a linha principal do pivô central (aço zincado) com as linhas gotejadoras (polietileno). A vazão em cada ponto de derivação do pivô é calculada em função da vazão dos gotejadores e do número de emissores por metro linear de mangueira. A área é irrigada através do movimento circular do equipamento no campo, que arrasta sobre o terreno e sobre o dossel das plantas as linhas gotejadoras. As vantagens deste sistema híbrido de irrigação é poder utilizar gotejadores de vazão elevada (2 - 12 litros/ hora), o que reduz o risco de entupimento do sistema, assim como, requerer somente 1 a 2 % da quantidade equivalente de metros lineares de tubogotejadores da irrigação localizada fixa sobre o terreno. Este trabalho teve como objetivo apresentar uma metodologia de cálculo para o dimensionamento deste novo sistema de irrigação por gotejamento móvel, assim como, desenvolver um software livre de dimensionamento deste sistema. O software foi desenvolvido em Visual Basic 2015, utilizando a interface do Microsoft Visual Studio Community 2015 (Windows). A linguagem de programação segue a metodologia baseada em um conjunto de 44 equações, as quais por meio parâmetros fornecidos pelo usuário possibilitam o dimensionamento do sistema. O resultado foi um software leve, capaz de realizar os cálculos necessários rapidamente, apresentando ao final dimensionamento uma janela com resumo do sistema IRGMO e uma tabela contendo as informações para cada linha de derivação. Os resultados podem ser salvos em um arquivo de texto ou podem ser enviados diretamente ao Microsoft Excel, os parâmetros utilizados pelo usuário podem ser salvos também, dessa forma permitindo que um mesmo dimensionamento possa ser feito várias vezes. Além de apresentar o software desenvolvido, este trabalho apresenta também alguns cenários de dimensionamento.<br>With the need to promote the efficient use of water in agriculture, enhancements, and new developments in irrigation equipments are always welcome. A mobile drip irrigation system (IRGMO), is the union of center-pivot irrigation (sprinkler irrigation) and drip irrigation (localized irrigation). The system consists of lowering pipes connecting the main line of the central pivot (galvanized steel) with driplines (polyethylene). The flow at each point deriving from the pivot is calculated in function of the flow rate drippers and a number of transmitters per linear meter of hose. The area is irrigated through the circular motion of the equipment in the field which drags on the ground and on the canopy of plants driplines. The advantages of this hybrid system of irrigation is the use of high flow drippers (2-12 liters/hour), which reduces the risk of clogging the system, as well as it requires only 1 to 2% of the equivalent amount of linear meters of irrigation driptubes fixed on the ground. This work aimed to introduce a calculation methodology for the sizing of this new mobile drip irrigation system, as well as, to develop a free software system sizing. The software was developed in Visual Basic 2015, using the interface of Microsoft Visual Studio Community 2015 (Windows). The programming language follows the methodology based on a set of 44 equations, which through user-supplied parameters allows the sizing system. The result was a lightweight application, able to perform the necessary calculations quickly, showing the end sizing a window with a summary of the IRGMO system and a table containing the information for each line. The results can be saved in a text file or sent directly to Microsoft Excel, the parameters used by the user can be saved as well, and thus allowing that an even sizing can be done several times. In addition to introducing the application development, this paper presents also some sizing scenarios.

A água é um recurso cada vez mais escasso, em quantidade e em qualidade, cujo consumo crescente aumenta a necessidade de melhorar constantemente a concepção e o dimensionamento dos sistemas de rega. No presente trabalho caracterizou-se e avaliou-se o desempenho de um equipamento de rega automotor com canhão e com barra, esta trabalhando com aspersores de impacto de média pressão, observando-se a capacidade de ajustamento destes equipamentos às condições particularmente difícies de um solo Mediterrâneo. Os ensaios de campo consistiram na avaliação dos referidos sistemas mediante uma rede de pluviómetros colocados na área dominada pelos aspersores. Os valores de Uniformidade de Distribuição e do Coeficiente de Uniformidade de Christiansen obtidos nas diferentes avaliações foram muito variáveis, dependendo fundamentalmente da velocidade do vento durante o ensaio e da pressão de funcionamento dos aspersores. Só se alcançaram níveis aceitáveis quando se considerou 35% de sobreposição entre faixas adjacentes, obtendo-se os melhores resultados nos equipamentos funcionando com menor pressão de serviço. As perdas por evaporação e arrastamento pelo vento foram consideráveis, o que originou Eficiências Potenciais de Aplicação baixas. Estas perdas foram superiores no equipamento canhão. Verifica-se a existência potencial de escorrimento superficial, junto da linha de passagem do aspersor, uma vez que a intensidade de precipitação excede a infiltrabilidade do solo. Este escorrimento verificou-se unicamente para uma velocidade de deslocação do equipamento de 10 mlh. ### Abstract - As water availability continuously decreases, irrigation systems must be carefully designed and used. In the present work a hose-drawn travelling sprinkler system was evaluated with two travelling sub-systems: a gun sprinkler and a lateral bar equipped with medium pressure sprinklers. Field experiments consisted on the evaluation of the refered systems, using a set of catch cans conveniently placed on the area irrigated by the sprinklers. The values of the Distribution Uniformity (UD) and Coefficient of Uniformity of Christiansen (UC) observed in the different evaluations were quiet variable, depending on the wind speed during the evaluation and the sprinkler operational pressure. Acceptable values of UD and UC were obtained only when a 35% overlapping between two paths were considered. Wind drift and evaporation tosses were significant. Thus, low values of Potential Application Efficiency were observed. Such tosses were greater with the travelling gun system. Excess water above soil infiltrability, therefore with a potential for runoff and erosion, was observed only for 10 m/h speed of travelling.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-05-24T19:31:37Z No. of bitstreams: 1 JONAS CARLOS SANTINO - DISSERTAÇÃO PPGEA 2002..pdf: 8664728 bytes, checksum: 1073738dd910a18404b200d943f370f2 (MD5)<br>Made available in DSpace on 2018-05-24T19:31:37Z (GMT). No. of bitstreams: 1 JONAS CARLOS SANTINO - DISSERTAÇÃO PPGEA 2002..pdf: 8664728 bytes, checksum: 1073738dd910a18404b200d943f370f2 (MD5) Previous issue date: 2002-08<br>O objetivo deste trabalho foi avaliar a performance de um pivô central rebocável em nível de campo, na Fazenda Capim, localizada no município de Capim-PB. Os resultados da avaliação do equipamento nas três bases estudada levaram a concluir que: o equipamento apresentou bons resultados quando analisado como um todo para as base, constatou-se problemas de uniformidade e de eficiência em alguns setores quando a análise foi feita por raio individualmente, indicando setores com déficit e outros com excesso de água, o equipamento apresentou seus piores resultados quando foi avaliado na base 5, verificou-se que existe uma dispersão das lâminas de água aplicadas em relação ao valor médio, em todas as bases estudadas, as pressões de entrada do pivô nas bases, 4 e 5 estão muito abaixo da pressão recomendada o que resultou numa baixa vazão nestas bases.<br>The objective of this work was to evaluate the performance of a towable pivot center in thefield on Fazenda Capim in the municipal district of Capim-PB. The results of the equipment evaluation of the three studied bases showed that the equipment presented goodresults when analyzed as a whole for them. Uniformity and efficiency problems in some sections were analyzed when the analysis was individually made by ratio, indicating sections with deficit and other with excess of water. The equipment presented their worst results when it was evaluated in base 5. It was verified a dispersion of the applied water sheets in relation to the mean value, in ali studied bases. The pressures on pivot in bases 4 and 5 are a lot below the recommended pressure and resulted in low flow in these bases.

Three tests were conducted to compare delayed applications of Kerb applied by air with those applied through the sprinklers. Early (6-5-02) season and mid (10-20-02) applications made through the sprinklers were significantly more effective than those applied by air. The late season (11-17-02) application was made too early and the weed control was poor demonstrating the need for proper timing regardless of the application technique. It was concluded that chemigation can be an effective technique for making delayed applications of Kerb to lettuce in the low deserts.

In the Canterbury region, New Zealand, water is a contentious issue when irrigation and dairy farming are involved. The Canterbury region accounts for 70% of the total irrigated land area in New Zealand and is one of the most productive agricultural regions. Traditionally, water has been seen as an abundant resource, but growing water demands are now outstripping the supply of water, hence threatening the sustainability of agricultural productivity. In the long term, this problem may worsen as a result of climate change, which is predicted to increase water demands and reduce supply in many parts of Canterbury. In the recent and on-going expansion of irrigation systems, modern sprinkler irrigation methods, namely centre pivot and lateral spray irrigation technology, have replaced the old border-dyke systems. This has been due to the need to increase irrigation flexibility and efficiency to guarantee pasture growth for dairy production in dry periods. This conversion has resulted in a reduction of windbreaks to 2 m heights or sometimes led to 100% removal of windbreaks so as to accommodate centre pivot or linear move irrigation systems. Removal of windbreaks or reduction of windbreak height may increase wind speed across a field. Both spray evaporation loss and evapotranspiration are a function of wind speed. Hence, any increase in wind speed may lead to an increase in irrigation requirements. There is little information currently available on outlining how reduction of windbreak height or the complete removal of windbreaks affects efficiency in water application. Thus, this research was done to quantify the effects of windbreaks on water savings under sprinkler irrigation systems in the Canterbury region under various climatic conditions. The research was done in three major steps: (1) spray evaporation loss (SEL)was measured under various climatic conditions for two typical spray nozzles(Nelson Irrigation Corporation Rotator R3000 and Spinner S3000 nozzles) to develop SEL prediction models; (2) wind speed reduction behind windbreaks was quantified for fields under various wind conditions; and (3) the effects of wind speed reduction by windbreaks was modelled for evapotranspiration, spray evaporation loss and irrigation. The results showed that an increase of wind speed, due to the removal of windbreaks or a reduction of height of windbreaks, leads to an increase in evapotranspiration and spray evaporation losses in irrigated agriculture. For the size of the fields considered in this study which are 80 m by 80 m (Site 1 with medium porosity windbreaks) and 120 m by 120 m (Site 2 with low porosity windbreaks), extra irrigation water of up to 14% is needed in one growing season when windbreaks are reduced to 2 m in height. When windbreaks are completely removed from the field, extra irrigation water of up to 38% and 64% is needed when irrigating using the Rotator R3000 nozzle and the Spinner S3000 nozzle, respectively. Thus, reduction of water resource use can be achieved in irrigated agriculture if irrigation systems can be designed to operate under existing windbreaks. Other savings can follow, from reduced requirements for pumping, fuel and labour costs. Lastly, with future climate change projections showing that the Canterbury region will get windier and hotter, windbreaks can help mitigate water losses associated with sprinkler irrigation

Improving water efficiency is and will continue to be a top concern to meet the world food production demands for a growing population. By having a clear understanding of water efficiencies, communities will be able to address these concerns from an economic standpoint and use more productive methods to grow food and limit water consumption. This study examines the water efficiencies of three irrigation methods over a single growing season in southeastern Oklahoma. Two crops, tomatoes and cucumbers, were grown using drip irrigation, a self-wicking container, and a non-circulating hydroponics barrel. Results at the end of the season showed the drip irrigation method had the highest water efficiency in terms of yield of product over water applied for both crops. The drip irrigation method also had the lowest associated set up costs and second lowest time requirements after the hydroponics method. These results were found to be consistent with other studies that compared drip irrigation to other irrigation methods and showed drip to have the highest water efficiencies.

A two year study was conducted from 2000-2002 to evaluate the use of overhead sprinkler irrigation for suppressing thrips populations in romaine lettuce. Specifically we looked at how the duration and frequency of sprinkler irrigation use reduced adult and larval populations following various irrigation applications employed specifically for thrips suppression. We also evaluated combinations of insecticide spray regimes, used in association with sprinkler irrigation runs, for suppressing thrips populations in both fall and spring seasons. The results of the study demonstrated that overhead sprinkler irrigation has the ability to suppress thrips populations in romaine lettuce. At best, we experienced about 50% population reduction using only sprinkler irrigation compared with the untreated control during these trials. Sprinkler ruins of durations of > 4 hrs and more than 4 cm of water appeared to provide the minimal necessary for suppression. Furthermore, sprinkle runs of 2 or 3 times weekly appeared to provide the most consistent suppression. In contrast, insecticide sprays consistently provided >80% suppression and provided higher yielding and better quality lettuce than sprinklers. The use of sprinkler irrigation, in addition to insecticide sprays did not significantly improve thrips suppression or yields. However, sprinkler irrigation is being used season long in some romaine fields and in organic production and should be of benefit for thrips suppression, particularly in organic systems where effective insecticide alternatives are not currently available.

Orientador: Ricardo Antonio Ferreira Rodrigues<br>Banca: Orivaldo Arf<br>Banca: Rita de Cássia Félix Alvarez<br>Resumo: Os manejos de água e de nitrogênio são importantes para atender adequadamente as necessidades da planta de arroz. Em região com verão chuvoso, o manejo de água é função do regime das precipitações e das irrigações, as quais são realizadas para suprir os períodos de deficiência hídrica. Em relação à necessidade por nitrogênio, o mesmo pode ser suprido com aplicação no solo na forma mineral e, também pela utilização de bactérias capazes de fixar o nitrogênio atmosférico ou a combinação dos dois métodos. Por isso, o objetivo deste trabalho foi avaliar o efeito de lâminas de água, inoculação de sementes com Azospirillum brasilense e doses de nitrogênio em cobertura, utilizando como fonte nitrogenada o sulfato de amônio, no desenvolvimento, componentes de produção, produtividade e qualidade industrial de grãos de arroz de terras altas. O delineamento experimental utilizado foi o de blocos casualizados, em esquema fatorial 2 x 2 x 5, com quatro repetições. Os tratamentos consistiram na combinação de lâminas de água (irrigado + precipitação pluvial e não irrigado + precipitação pluvial), da inoculação das sementes (não inoculado e inoculado) e da adubação nitrogenada em cobertura (0, 25, 50, 75 e 100 kg ha-1 de N). A altura de plantas foi influenciada pelo manejo de água e pelas doses de nitrogênio testadas, mas não ocorreu acamamento de plantas. O manejo de água também influenciou o número de panículas m-2, a fertilidade dos colmos e das espiguetas, teor de nitrogênio na planta, nos grãos e na folha, massa de 100 grãos, massa hectolítrica e produtividade de grãos, além de reduzir o número de dias para o florescimento e a duração do ciclo da cultura. A inoculação das sementes com A. brasilense aumentou o número de colmos e número de panículas por metro quadrado. As doses de N testadas não interferiram na produtividade do arroz de terras altas<br>Abstract: The water and nitrogen management are important to adequately meet the needs of the rice plant. In the region with a rainy summer, the water management is a function of rainfall and irrigation which are made to meet periods of water stress. The nitrogen can be supplied with application to soil in mineral form and the use of bacteria capable of fixing atmospheric nitrogen or combination of two methods. Therefore, the objective of this study was to evaluate the water levels, seed inoculation with Azospirillum brasilense and nitrogen doses, in cover, in the development, production components, productivity and quality of grain of upland rice. A randomized block design was used in a 2 x 2 x 5 factorial scheme, with four repetitions. The treatments consisted in water levels (irrigation + rainfall and no irrigation + rainfall), seeds inoculation (uninoculated and inoculated) and nitrogen fertilization in cover (0, 25, 50, 75 and 100 kg ha-1 N). The high plants was influenced by water management and nitrogen doses tested, but there was no bedding plants. The water management also influenced number of panicles per square meter, the fertility of stems and spikelets, nitrogen content in plant, grains and leaf, mass of 100 grains, hectoliter weight and grain yield, and reduce the number of the days to flowering and duration of the crop cycle. The seeds inoculation with A. brasilense increased the number of stems and number of panicles per square meter. The nitrogen doses were tested did not interfere in yield of upland rice<br>Mestre

In der Wintersaison 2005-2006 wurde ein Split-Split Plot-Design Feldversuch mit drei Wiederholungen für jede Behandlung von Kartoffeln, als Indikatorpflanze, unter den ariden Bedingungen der Kharga Oasis in der Westlichen Wüste von Ägypten durchgeführt. Drei Bewässerungslevel (100 %, 80 %, und 60 % of ETc) mit Tröpfchenbewässerung, zwei Mulchvarianten (Zuckerrübenabfall ohne und mit 24 ton ha-1) und 4 Kompostraten (0, 12, 24, und 36 ton ha-1) wurden getestet. Generell und als Ergebnis einer Regressionsanalyse der Versuchsvarianten ohne Kompost war die beste Variante die Tröpfchenbewässerung bei 80% ETc unabhängig ob gemulcht oder nicht gemulcht wurde. Andererseits die Variante mit 36 t Kompost und mit 24 t Mulch ergab die besten Ergebnisse bei 60% of ETc sowohl beim Ertrag und den Ertragskomponenten, bei den hydrophysikalischen Eigenschaften, bei der Bodenwasserretention, beim Wasserverbrauch, bei den Pflanzenkoeffizienten, der Wassernutzungseffizienz, der Düngernutzungseffizienz sowie beim Nettogewinn. Wird die Rate der Kompostgabe aber auf 24 ton ha-1 reduziert, die höchsten Nettogewinne bei der lokalen Vermarktung als auch signifikant beim Kartoffelexport werden erreicht.<br>Under the arid condition of Kharga Oasis in the Western Desert of Egypt, split-split plot design field experiment with three replications for each treatment using potato as an indicator plant was carried out during the winter season 2005-2006. Three irrigation levels of water regime (100 %, 80 %, and 60 % of ETc) using drip irrigation system, two treatments of soil covering (sugar cane wastes at the rate of 0 and 24 ton /ha) and compost rates (0, 12, 24, and 36 ton ha-1) were tested. In general and as a result of the triple interaction among the studied treatments, using drip irrigation either with soil mulching or not, 80 % of ETc as a water regime was the best. On the other hand, reducing drip irrigation water level at 60% of ETc in mulched soil that was treated with 36 ton ha-1 of compost recorded the highest values yield and yield components, soil hydrophysical properties, soil water retention, water consumption, crop coefficients, water economy water use efficiency, fertilizer use efficiency, net profit. But reducing the compost rate to 24 ton ha-1 attained the highest net profit for local potato consumption and achieved the best significant net profit for exportation.

The overall objective of this study was to determine the influence of intermittent water application via overhead irrigation on water and N leaching, substrate water distribution, and plant growth in a pine bark substrate. Intermittent irrigation was defined as the application of a plants' daily water allotment in multiple applications with prescribed intervals between applications. Specifically, experiments were conducted to determine: 1) the influence of water application rate and pre-irrigation substrate moisture content on water application efficiency, 2) the influence of the number of intermittent applications and interval duration between applications on application efficiency, 3) substrate water distribution after intermittent irrigation, 4) efficiency of intermittent irrigation in unamended and sand-amended pine bark, and 5) influence of intermittent irrigation on plant growth. In all experiments, Marigold (<u>Tagetes erecta</u> L. 'Apollo') was grown in unamended or sand-amended pine bark in 3.8-liter containers. After saturation, bark was allowed to dry via evapotranspiration to targeted moisture deficits after which irrigation treatments were applied via a simulated overhead irrigation system. In experiments evaluating intermittent irrigation, water was applied intermittently (multiple applications with intervals between applications) or continuously (single application). After 1 h drainage, collected leachate was measured and analyzed (in two experiments) for electrical conductivity, N0₃-N and NH₄-N and water application efficiency (percentage of applied water that is retained in the substrate) determined. There was an inverse linear relationship between water application rate and efficiency. Leachate N (total) increased linearly as application rate increased. Efficiency increased curvilinearly and leachate N (total and concentration) increased linearly as pre-irrigation substrate moisture content decreased. Efficiency of intermittent irrigation was greater than continuous irrigation over a range of pre-irrigation substrate moisture contents, and in both unamended and sand-amended pine bark. Intermittent efficiency increased linearly as interval duration between applications increased. Efficiency of five 60 ml applications was greater than three 100 ml applications. Gravimetric moisture content of the bottom third of the substrate was greater with intermittent than continuous irrigation. Intermittent efficiency was greater in pine bark than in sand-amended pine bark when the water deficit from container capacity was the same for both substrates. Repeated intermittent irrigations resulted in less water and N leaching compared to continuous irrigation. Intermittent irrigation did not result in substrate nutrient accumulation and had no adverse effect on plant growth. Fresh and dry root weights and shoot and root N concentrations were greater with intermittent irrigation than continuous irrigation.<br>Ph. D.

Suitable areas for subirrigation and sprinkler irrigation were identified in Richelieu and St-Hyacinthe counties.<br>Land suitable for subirrigation includes uniform sandy textured profiles deeper than 1 m, with hydraulic conductivities greater than 0.5 m/d and lying on a clay layer at approximately 2 m from the surface, and with slopes less than 0.5% and little or no microrelief.<br>Soils that failed to satisfy the subirrigation criteria and that would most benefit from sprinkler irrigation were identified. These soils had available water holding capacities of less than 7.5 cm per 100 cm of soil. Most of the soils suitable for sprinkler irrigation were shallow sand (50 cm) over clay.<br>Both the Richelieu and St-Lawrence Rivers could meet the flow demand for the total irrigated area. However, 57% of the subirrigable land is located at more than 20 km from the Richelieu and St-Lawrence and could be more economically supplied by the Yamaska River. The Yamaska River could supply all the subirrigated land in its vicinity (4 900 ha) and part of the land suited for sprinkler irrigation (1 000 ha) 4 out of 5 years. (Abstract shortened by UMI.)

Thesis (MScAgric)--University of Stellenbosch, 2003.<br>ENGLISH ABSTRACT: Poor water management and poor water use efficiency (WUE) have been identified as one of the major problems experienced by vegetable growers in most of the developing countries, including South Africa. This poor management and poor utilization of water have led to a drastic decline in the quality and quantity of available water. In South Africa agriculture uses about 50% of available water. Increasing water demand for domestic, industrial and mining uses, may decrease agriculture's share to less than the current 50%, henceforth, better utilization of this resource is imperative. Selection of a good irrigation system can limit water loss considerably. Some irrigation systems have a potential to save more water than others do. Since irrigation systems affect the WUE of crops, care should be taken when selecting an irrigation system under conditions of limited water quantity. Ebb-and- Flood watering systems have been introduced for effective sub-irrigation and nutrient delivery within closed systems. Such a system was adapted in South Africa, to develop a vegetable production unit for use by families in rural communities, while saving substantial amounts of water. A need to further improve the WUE of this system was subsequently identified. Two studies were conducted at the experimental farm of the University of Stellenbosch (Department of Agronomy). The first trial was conducted under controlled conditions in a glasshouse, and the second under open field conditions. In the first trial, Beta vulgaris (Swiss chard) and Amaranthus spp. ('Imbuya') were grown in two root media; gravel and pumice. In addition, an 'Ebb-and-Flood' and a 'Constant level' system were used with nutrient solutions at two electrical (EC) conductivity levels 1.80 and 3.60 mS cm-I. The results of this (2x2x2x2) factorial experiment indicated that a combination of the 'Ebb-and-Flood' system with gravel as a root medium produced the best results at a low EC, when 'imbuya' was used. A high total WUE was found with 'imbuya', (7.35 g L-I) at EC 1.80 mS cmicompared to a relatively low WUE of 5. 90 g L-I when the 3.60 mS cm-I nutrient solution was used. In the second trial, 'Imbuya's' foliage dry mass, leaf area and WUE was evaluated under field conditions at the Stellenbosch University experimental farm, during the summer of2002. The experimental farm (33°55'S, 18°52'E) is situated in the cooler coastal wine grape-producing region of South Africa with a relatively high annual winter rainfall. This trial was conducted on an alluvial soil, with clay content of 25% and a pH of 5.9 (KC!). A closed 'Ebb-and-Flood' system was compared with two open field irrigation systems ('Drip' and 'Flood') using nutrient solutions at two electrical conductivity levels (1.80 and 3.60 mS cm-i) in all three cases. Foliage dry mass, leaf area as well as WUE was best with 'Drip' irrigation, when a nutrient solution with an electrical conductivity of 3.60 mS cm-i was used. In spite of the fact that additional ground water was available for the soil grown 'Drip' and 'Flood' treatments, the 'Ebb-and-Flood' system outperformed the 'Flood' treatment, especially when the nutrient solution with an EC of 3.6 mS cm-i was used. Insufficient root aeration in the flooded soil could have been a contributing factor. The fact that the 'Ebb-and-Flood' and 'Drip' systems gave the best results when the high EC solution was used to fertigate the plants, may indicate that the plants could have hardened due to the mild EC stress, better preparing them to adapt to the extreme heat that was experienced in the field.<br>AFRIKAANSE OPSOMMING: Swak: bestuur van water en 'n swak: water-gebruik-doeltreffendheid (WOD) is as een van die belangrikste probleme geïdentifiseer wat deur groente produsente in die meeste ontwikkelende lande, insluitend Suid-Afrika, ervaar word. Hierdie swak bestuur en benutting van water het daartoe bygedra dat 'n drastiese afname in die kwaliteit asook in die kwantiteit van beskikbare water ervaar word. In Suid-Afrika gebruik die landbou-sektor ongeveer 50% van die beskikbare water. Toenemende water behoeftes vir huisgebruik, industrieë en die mynbou mag hierdie 50% aandeel van die landbou sektor laat krimp. Beter benutting van hierdie skaars hulpbron is dus noodsaaklik. Die keuse van goeie besproeiingsisteme mag waterverliese merkbaar beperk aangesien sekere sisteme se water-besparingspotensiaal beter as ander is. Aangesien besproeiingstelsels die WOD van gewasse beïnvloed, is spesiale sorg nodig waar 'n besproeiingstelsel onder hierdie toestande van beperkte waterbronne gekies moet word. 'Ebb-en-Vloed' sisteme kan aangewend word om water en voedingselemente van onder in 'n wortelmedium te laat opstoot en in 'n geslote sisteem te laat terugdreineer. So 'n sisteem is in Suid-Afrika ontwikkel waarmee groente vir families in landelike gebiede geproduseer kan word terwyl water bespaar word. 'n Behoefte om die WOD van hierdie produksiesisteem verder te verbeter is egter geïdentifiseer. Twee ondersoeke is by die Universiteit van Stellenbosch se proefplaas (Departement Agronomie) gedoen. Die eerste proef is onder beheerde omgewingstoestande in 'n glashuis uitgevoer en die tweede onder veld toestande. In die eerste proef is Beta vulgaris (Snybeet) en Amaranthus spp. ('Imbuya') in twee tipes wortelmedia; gruis en puimsteen verbou. 'n 'Ebb-en-Vloed' asoook 'n 'Konstante vlak' besproeiingsisteem is gebruik terwyl voedingsoplossings ook by twee peile van elektriese geleiding (EC) teen 1.80 en 3.60 mS cm-I toegedien is. Die resultate van hierdie (2x2x2x2) fakroriaal eksperiment het aangetoon dat 'n kombinasie van die 'Ebb-en-Vloed' sisteem met gruis as 'n wortelmedium die beste resultate teen 'n lae EC lewer waar 'imbuya' gebruik is. Die WOD met 'imbuya' was hoog (7.35 g L-1) by 'n EC van 1.80 mS cm-I, vergeleke met 'n relatief lae WOD van 5. 90 g L-1 waar die 3.60 mS cm-I voedingsoplossing gebruik is. In die tweede proef is 'Imbuya' se droë blaarmassa, blaar oppervlakte en WOD onder veldtoestande op die Universiteit van Stellenbsoch se proefplaas in die somer van 2002 ge-evalueer. Die proefplaas (33°55'S, 18°52'E) is in die koeler kusstreke van die wyndruif produksiegebied in die winterreëngebied van Suid-Afrika geleë. Hierdie proef is op alluviale grond met 25% klei en 'n pH van 5.9 (KCi) uitgevoer. 'n Geslote 'Ebb-en-Vloed' sisteem is met twee veld-besproeiingsisteme vergelyk ('Drup' en 'Vloed') terwyl voedingsoplossings teen twee peile van elektriese geleiding (1.80 en 3.60 mS cm-I) in al drie gevalle gebruik is. Blaar droëmassa, blaaroppervlakte asook die WGD was die beste met 'Drup' besproeiing waar die EC van die voedingsoplossing 3.60 mS cm-I was. Ten spyte van die feit dat ekstra grondwater vir die 'Drup' and 'Vloed' behandelings beskikbaar was, het die 'Ebben- Vloed' stelsel beter as die 'Vloed' behandeling gedoen veral waar die voedingsoplossing se EC 3.6 mS cm-I was. Swak wortelbelugting was waarskynlik die rede waarom vloedbesproeiing swak produksie gelewer het. Die feit dat die 'Drup' en die 'Ebb-en-Vloed' behandelings in die veldproef die beste gedoen het waar die EC hoog was, mag moontlik met die gehardheid van die plante verband hou wat aan ekstreem warm en dor toestande blootgestel was.

Made available in DSpace on 2014-06-11T19:23:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-05Bitstream added on 2014-06-13T18:50:26Z : No. of bitstreams: 1 guirra_appm_me_jabo.pdf: 278924 bytes, checksum: 904126f5d8e8dc9fa0c2d2c6db8f43da (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>A maioria dos catálogos técnicos dos fabricantes não especifica, para as diferentes posições do defletor e pressões de serviço, o perfil radial de distribuição de água de seus aspersores, limitando-se à apresentação de valores de vazão e raio de alcance. Devido a ausência das informações (posição do defletor x pressão de serviço x espaçamento), neste trabalho teve-se como objetivo avaliar o desempenho do aspersor NaanDanJain, com bocal de 3,5 mm de diâmetro (cor azul), modelo 435 ½” M, operando com as pressões de 100, 200, 300 e 400 kPa, em cinco posições do defletor de ajuste (30º; 21,4º; 12,8º; 4,2º e 0º). Para a determinação dos parâmetros avaliados utilizou-se o método da malha, e com o auxílio do aplicativo computacional CATCH 3D calculou-se a sobreposição das lâminas de água com oito espaçamentos. A simulação da uniformidade de aplicação de água (CUC e CUD) apresentou melhores resultados para o espaçamento 6 x 6 m nas pressões de 200, 300 e 400 kPa. A utilização da pressão de 100 kPa resultou em menor uniformidade de aplicação para todos os espaçamentos ensaiados, sendo recomendadas pressões superiores a 100 kPa. As diferentes pressões e ângulos do defletor influenciaram o raio de alcance, o perfil de distribuição e a uniformidade de distribuição de água. As diversas combinações de ângulo do defletor e pressão de serviço possibilitaram a utilização do aspersor em diferentes condições operacionais<br>The most of manufacturer technical catalogs do not specify, to the different deflector position and work pressure, the water distribution radial profile of its sprinklers, limiting only the flow values and reach ray values presentation. Due to the lack of information (deflector position vs. work pressure vs. spacing) in this work it was evaluated the performance of the sprinkler NaanDanJain, nozzle with diameter 3.5 mm (blue), model 435 ½” M, working under pressure of 100, 200, 300, and 400 kPa in five deflector adjustment positions (30°, 21.4°, 21.8°, 4.2°, and 0°). To determine the evaluated parameters the mesh method was used, and with the computational application CATCH 3D the water depht overlap was calculated with eight replications. The water application uniformity simulation (CUC and CUD) presented better results to the 6 x 6 m spacing in the 200, 300, and 400 kPa pressures. The 100 kPa pressure use resulted in a lower spraying uniformity to all the evaluated spacing, being, this way, recommended pressures higher than 100 kPa. The different pressures and deflector angles influenced the operation range, the distribution profile, and the water distribution uniformity. The several deflector angle and work pressure combinations allowed use the sprinkle in different operational conditions

Made available in DSpace on 2014-06-11T19:29:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-14Bitstream added on 2014-06-13T18:39:38Z : No. of bitstreams: 1 moura_rs_me_ilha.pdf: 363425 bytes, checksum: 48c43d19cdd6885b5be63fdcc650f9fb (MD5)<br>Universidade Estadual Paulista (UNESP)<br>Os manejos de água e de nitrogênio são importantes para atender adequadamente as necessidades da planta de arroz. Em região com verão chuvoso, o manejo de água é função do regime das precipitações e das irrigações, as quais são realizadas para suprir os períodos de deficiência hídrica. Em relação à necessidade por nitrogênio, o mesmo pode ser suprido com aplicação no solo na forma mineral e, também pela utilização de bactérias capazes de fixar o nitrogênio atmosférico ou a combinação dos dois métodos. Por isso, o objetivo deste trabalho foi avaliar o efeito de lâminas de água, inoculação de sementes com Azospirillum brasilense e doses de nitrogênio em cobertura, utilizando como fonte nitrogenada o sulfato de amônio, no desenvolvimento, componentes de produção, produtividade e qualidade industrial de grãos de arroz de terras altas. O delineamento experimental utilizado foi o de blocos casualizados, em esquema fatorial 2 x 2 x 5, com quatro repetições. Os tratamentos consistiram na combinação de lâminas de água (irrigado + precipitação pluvial e não irrigado + precipitação pluvial), da inoculação das sementes (não inoculado e inoculado) e da adubação nitrogenada em cobertura (0, 25, 50, 75 e 100 kg ha-1 de N). A altura de plantas foi influenciada pelo manejo de água e pelas doses de nitrogênio testadas, mas não ocorreu acamamento de plantas. O manejo de água também influenciou o número de panículas m-2, a fertilidade dos colmos e das espiguetas, teor de nitrogênio na planta, nos grãos e na folha, massa de 100 grãos, massa hectolítrica e produtividade de grãos, além de reduzir o número de dias para o florescimento e a duração do ciclo da cultura. A inoculação das sementes com A. brasilense aumentou o número de colmos e número de panículas por metro quadrado. As doses de N testadas não interferiram na produtividade do arroz de terras altas<br>The water and nitrogen management are important to adequately meet the needs of the rice plant. In the region with a rainy summer, the water management is a function of rainfall and irrigation which are made to meet periods of water stress. The nitrogen can be supplied with application to soil in mineral form and the use of bacteria capable of fixing atmospheric nitrogen or combination of two methods. Therefore, the objective of this study was to evaluate the water levels, seed inoculation with Azospirillum brasilense and nitrogen doses, in cover, in the development, production components, productivity and quality of grain of upland rice. A randomized block design was used in a 2 x 2 x 5 factorial scheme, with four repetitions. The treatments consisted in water levels (irrigation + rainfall and no irrigation + rainfall), seeds inoculation (uninoculated and inoculated) and nitrogen fertilization in cover (0, 25, 50, 75 and 100 kg ha-1 N). The high plants was influenced by water management and nitrogen doses tested, but there was no bedding plants. The water management also influenced number of panicles per square meter, the fertility of stems and spikelets, nitrogen content in plant, grains and leaf, mass of 100 grains, hectoliter weight and grain yield, and reduce the number of the days to flowering and duration of the crop cycle. The seeds inoculation with A. brasilense increased the number of stems and number of panicles per square meter. The nitrogen doses were tested did not interfere in yield of upland rice

The objective of this study was to determine how border irrigation performance is affected by inflow hydrograph shape. Sloping borders with open end boundary condition were selected for the study. A computer program called SRFR was used for simulations with the choice of zero inertia model as the mathematical model describing the movement of water along the border run. Five inflow hydrograph shapes were chosen from over fifteen shapes for evaluation. They are named as follows: constant (CON), cutback (CB), cablegation (CG), modified cutback (MCB), and modified cablegation (MCG). Different ranges of the input parameters were used to cover a wide spectrum of field conditions. Input parameters ranges and values are four infiltration families, 0.25, 0.5, 1.0, and 2.0; three slopes, 0.001, 0.0025, and 0.005; two field lengths, 650 ft and 1300 ft; three Manning's roughnesses, 0.04, 0.15, and 0.25; and three volumes, low, med., and high, which reflect 2, 4, and 6 inches of required depth. It has been found that the inflow hydrograph shape has a substantial influence on the maximum application efficiency, maximum Eₐ. Values of maximum Eₐ range from 61 percent to 80 percent. While CG gives the lowest average value of maximum Eₐ, 61 percent, CB and MCB give the highest average maximum Eₐ at 80 percent. CON gives an average value equal to 71 percent. MCG has an average value close to those given by CB and MCB and equal to 78 percent. The maximum Eₐ values range from low of zero to as high as 95 percent. Fortunately, more than 90 percent of the 216 values for each inflow hydrograph are above 70 percent for all shapes except CG. Most values fall between 70 to 80 percent for CON, 75 to 90 percent for CB, 80 to 95 for MCB, and 75 to 85 for MCG. CG has a much wider range with most maximum Eₐ values falling between 40 and 85 percent. CB and MCB are more sensitive to changes in the input parameters than CON and MCC, but far less than CG, which is the most sensitive.

Residential irrigation efficiency is a long-term concern for any community that faces water supply stress. When ability to raise water prices is constrained, public education and conservation programs can produce reduced water usage. Understanding the factors behind residential irrigation efficiency allows the design of more effective conservation campaigns. Combining site-specific water budgets with usage data for four hundred homes in North Texas enables quantifying efficient irrigation behavior. A survey of homeowners tests for the presence of conservation-positive attitudes and the knowledge required to implement those attitudes. The influence of neighbors’ watering habits is investigated using spatial clustering tools. Findings are analyzed in the context of an attitude, knowledge, and habit model of conservation behavior. The presence of automatic irrigation systems, small irrigated areas, and having knowledge of the amount that one waters one’s lawn are found to contribute to more intensive irrigation. Mixed evidence for small-scale clustering in irrigation intensity is presented.

In England and Wales, rising demands on water resources and competition between sectors is leading to increased pressure on field vegetable growers to irrigate more efficiently. Approximately 40,000ha of field scale vegetables are irrigated in England and Wales in a dry year. Between 60% and 90% of this area is estimated to be irrigated using hose-reels fitted with rainguns. However, despite their popularity, these systems are inherently non-uniform in water distribution, particularly in windy conditions. Improving their application uniformity has therefore been identified as one of the most practical solutions to increasing irrigation efficiency for field vegetable growers. This thesis develops an integrated approach to model the spatial and temporal impacts of irrigation non-uniformity on the yield and quality of a vegetable crop grown in the UK. The research used carrots as a representative crop because of their sensitivity to irrigation and high importance within the field vegetable sector. The impacts of a range of raingun equipment and management strategies (field orientation, lane spacing, sector angle, night versus day irrigation) have been evaluated. Two models were used to simulate raingun irrigation. TRAVGUN was first used to generate a database of wind affected wetted pattems for a typical raingun system. 'TRAVELLER' then simulated raingun movement down and across a field, applying these pattems according to ambient wind conditions and a pre-defined range of equipment and management strategies. Carrot yield response to spatially variable irrigation was simulated using the model Carrot Calculator". A spreadsheet model was also developed to quantify the impacts of irrigation non-uniformity on carrot quality. The models were calibrated and validated using data collected during 2003 and 2004 from field sites on commercial farms in East Anglia. The outputs from the research include new information, datasets and detailed maps showing the spatial and temporal pattems of irrigation application and their consequent impacts on crop yield and quality. The findings demonstrated that the raingun equipment and management strategies employed by growers can have a considerable impact on application uniformity, and hence on crop production. Of particular importance were the closely linked variables of lane spacing and sector angle. The I analyses suggested that the highest application uniformity occurred using a lane spacing of 70 m and a sector angle of 210° where wind speeds were < 2 m s". At higher wind speeds, narrowing the lane spacing to 60 m and using a sector angle of 180° (or 210Â ° where the wind speed was greater than 3 m s`l) provided maximum uniformity. If the lane spacing cannot be altered from 70 m, increasing the sector angle to 240° at higher wind speeds improved uniformity. The industry recommended lane spacing of 72 m may therefore be marginally too wide, particularly under windy conditions. The research also confirms that orientating fields/travel lanes perpendicularly to the prevailing wind direction and irrigating at night when wind speeds are typically lower can help reduce application non-uniformity. These findings have helped to substantiate many of the measures being widely discussed for improving irrigation efficiency. The integrated approach has also enabled the combination of various equipment and management strategies to be more thoroughly evaluated than was previously possible. Irrigation uniformity was found to have a considerable impact on carrot crop yield and, in particular, quality. For example, in a typical dry year, simulated non-uniform irrigation resulted in a total yield loss of 4%, a marketable yield loss of 8% and a premium root yield loss of 11%. This could have resulted in an income loss of approximately .E288-585 ha" (4-8%). Importantly, and contrary to grower perceptions, this research demonstrated that a small but appreciable crop loss (up to 1%) may occur due to just a single non-uniform irrigation during critical crop growth periods. This research has provided useful insight and new information in support of developing recommendations to assist growers not only in improving their crop production but also in demonstrating efficient irrigation both for meeting grower protocol requirements and at abstraction licence renewal. I addition, the findings will help inform the regulatory authorities on the complexities and difficulties of achieving efficient irrigation. The research approach could also be readily utilised by manufacturers to assist in designing and improving raingun equipment. Although the modelling approach was developed for raingun irrigated carrots, the methodology could be readily extended to other crops and overhead irrigation systems to provide tools for growers and the crop services industry to evaluate system performance and the impacts for crop production.

Successful establishment of shrub and tree legumes in the southwestern United States is dependent on rainfall amount, frequency and distribution, seedbed temperatures and available water conditions affecting seed germination and seedling establishment. The line source sprinkler irrigation gradient system (LSSIGS) was used to test effects of different seedbed available water and temperature conditions on seedling emergence and establishment, and morphological and physiological characteristics of catclaw (Acacia greggii), jojoba (Simmondsia chinensis), velvet mesquite (Prosopis juliflora var. velutina) and blue paloverde (Cercidium floridum) during the summers of 1992 and 1993 at the Tucson Plant Materials Center. Irrigation plus precipitation in July and August added 356.7, 344.6, 265.1, 209.8, 106.9 and 76.2 mm of water in 1992 and 285.2, 252.6, 207.7, 186.6, 106.6 and 68.1 mm in 1993 for distances of 1.5, 4.5, 7.5, 10.5, 13.5 (lowest irrigation) and 16.5 (no irrigation) respectively, from the line-source sprinkler. Irrigation created available soil moisture differences between irrigated and unirrigated soils during rainless periods in July but generally created little difference in soil water availability within the irrigation system different distances from the line-source sprinkler. Lack of large soil water availability differences resulted from an initially wet soil profile and natural rainfall in August of both years. Jojoba seedling emergence lagged about 2-3 weeks behind that of the other species which emerged within a week of irrigation. Seedlings emerged on unirrigated soils after August rains on both years. Although seedling establishment and plant growth was generally highest for the highest levels of irrigation, establishment was acceptable (at least 2 plants per meter of row) at all irrigation levels and on unirrigated soils for all species for both years, except for unirrigated jojoba in 1992. Lack of large differences in available soil water precluded precise determination of the significance of physiological and morphological characteristics for drought tolerance during seedling establishment of these species. However, rapid and high seedling emergence and root growth of paloverde, mesquite, and acacia make these species good selections for abandoned farmland revegetation. A possible establishment strategy for these 3 species on similar soils in the Sonoran desert would be to irrigate either pre or post-sowing in July to bring the upper 40-60 cm of soil profile to field capacity, then irrigate daily for about a week until seedlings emerge. Irrigation could then be discontinued and seedlings should survive on subsurface soil moisture. Establishment of jojoba might require longer irrigation periods. A more rigorous comparison of the drought tolerance of these species with the LSSIGS would be to sow and irrigate them on an initially dry soil profile.

Orientador: José Renato Zanini<br>Banca: Marconi Batista Teixeira<br>Banca: Othon Carlos da Cruz<br>Resumo: A maioria dos catálogos técnicos dos fabricantes não especifica, para as diferentes posições do defletor e pressões de serviço, o perfil radial de distribuição de água de seus aspersores, limitando-se à apresentação de valores de vazão e raio de alcance. Devido a ausência das informações (posição do defletor x pressão de serviço x espaçamento), neste trabalho teve-se como objetivo avaliar o desempenho do aspersor NaanDanJain, com bocal de 3,5 mm de diâmetro (cor azul), modelo 435 ½" M, operando com as pressões de 100, 200, 300 e 400 kPa, em cinco posições do defletor de ajuste (30º; 21,4º; 12,8º; 4,2º e 0º). Para a determinação dos parâmetros avaliados utilizou-se o método da malha, e com o auxílio do aplicativo computacional CATCH 3D calculou-se a sobreposição das lâminas de água com oito espaçamentos. A simulação da uniformidade de aplicação de água (CUC e CUD) apresentou melhores resultados para o espaçamento 6 x 6 m nas pressões de 200, 300 e 400 kPa. A utilização da pressão de 100 kPa resultou em menor uniformidade de aplicação para todos os espaçamentos ensaiados, sendo recomendadas pressões superiores a 100 kPa. As diferentes pressões e ângulos do defletor influenciaram o raio de alcance, o perfil de distribuição e a uniformidade de distribuição de água. As diversas combinações de ângulo do defletor e pressão de serviço possibilitaram a utilização do aspersor em diferentes condições operacionais<br>Abstract: The most of manufacturer technical catalogs do not specify, to the different deflector position and work pressure, the water distribution radial profile of its sprinklers, limiting only the flow values and reach ray values presentation. Due to the lack of information (deflector position vs. work pressure vs. spacing) in this work it was evaluated the performance of the sprinkler NaanDanJain, nozzle with diameter 3.5 mm (blue), model 435 ½" M, working under pressure of 100, 200, 300, and 400 kPa in five deflector adjustment positions (30°, 21.4°, 21.8°, 4.2°, and 0°). To determine the evaluated parameters the mesh method was used, and with the computational application CATCH 3D the water depht overlap was calculated with eight replications. The water application uniformity simulation (CUC and CUD) presented better results to the 6 x 6 m spacing in the 200, 300, and 400 kPa pressures. The 100 kPa pressure use resulted in a lower spraying uniformity to all the evaluated spacing, being, this way, recommended pressures higher than 100 kPa. The different pressures and deflector angles influenced the operation range, the distribution profile, and the water distribution uniformity. The several deflector angle and work pressure combinations allowed use the sprinkle in different operational conditions<br>Mestre

<p>Studies were conducted to evaluate the effect of pre-irrigation media moisture deficit, irrigation application rate, and intermittent irrigation on irrigation efficiency [(amount applied - amount leached) amount applied' 100] of spray stake-irrigated, container-grown plants. In the first experiment, pine bark-filled containers were irrigated to replace moisture deficits of 600, 1200, or 1800 ml. Deficits were returned in single, continuous applications at application rates of 148, 220, and 270 ml/min. Application rate did not affect irrigation efficiency. Efficiency decreased with increased medium moisture deficit. In the second experiment, containers, at 600 ml media moisture deficits, were irrigated with 400 or 600 ml (65% and 100% water replacement, respectively). Irrigation volumes were returned in a single, continuous application or in 100ml applications with 30 min intervals between irrigations (intermittent). Irrigation efficiency was greater with intermittent irrigation, 95 % and 84 % for 400 and 600 ml replacement, respectively, than with continuous irrigation, 84% and 67% for 400 and 600 ml replacement, respectively. When applied intermittently, most water loss from containers occurred after 400 ml were applied. In the third experiment, containers were irrigated with 600 ml (100% water replacement) in 50, 100, or 150 ml applications with 20, 40, or 60 min intelVals between applications. A control was included in which 600 ml was applied in a single, continuous application. Irrigation efficiency increased with decreasing application volume and increasing length of interval between applications. The greatest efficiency (86%) was produced with an irrigation regimen of 50 ml applications with at least 40 min between applications. The control treatment (continuous) produced an irrigation efficiency of 62%. When applied intermittently, most water loss from containers occurred after a total of 300 ml were applied.</p><br>Master of Science

Atriplex canescens (Pursh) Nutt., Atriplex polycarpa (Torr.) Wats., and Atriplex lentiformis (Torr). Wats. have been considered candidate perennial shrubs for revegetation of abandoned farmlands in southern Arizona. Objectives of the 1992-1994 field studies were to investigate the establishment characteristics of populations of these species and to estimate water requirements for establishing transplants and/or seedlings under a line-source sprinkler irrigation system. During the summer on a sandy loam soil, seedling establishment occurred at total water amounts greater than 200 mm but was absent at amounts less than 150 mm The poor stand establishment was attributed to high soil temperatures at 1 to 3-cm depth which were not optimum for seed germination. Transplant survival percentages were greater than 89% except for accessions of A. canescens var. linearis (S. Wats.) Munz, which were affected by rabbit herbivory. Transplants were successfully established by planting into a wet soil profile followed by cumulative precipitation amounts of 60 to 70-mm. Establishing Atriplex taxa during the summer using transplants was more promising than direct-seeding. On a silt loam soil during the 1993 winter, stand establishment was not increased under cumulative precipitation and irrigation amounts greater than 100 mm compared to 66 mm of precipitation. On a clay loam soil during the 1994 winter, supplemental irrigations increased the probability of seedling emergence and stand establishment was higher under total water amounts greater than 100 mm. Differences between years in response to the line-source irrigation gradient were attributed to the number of consecutive days when soil moisture at 1 to 3-m depth was high for optimal seedling emergence. During the winter, plant heights were not affected by total water amounts between 182 to 248-mm (1993) and between 119 to 150-mm (1994), whereas heights were reduced at total water amounts less than 100 nun in 1993, and less than 90 mm for all species in 1994 except A. polycarpa. In southern Arizona where precipitation is erratic in amount and timing, supplemental irrigations may increase the probability of successful seedling establishment of Atriplex shrubs.

Maximum wheat (Triticum aestivum L.) yields in Zambia were obtained with weekly irrigation at 85% of class A pan evaporation during the whole irrigation interval and split application of urea N of which the initial portion of the fertilizer was either broadcast and incorporated or broadcast after the crop had established itself. This corresponded with maximum utilization of fertilizer N. The proportion of N derived from fertilizer was independent of fertilizer placement at various water regimes and N utilization was primarily a function of water availability.<br>Two nonnodulating soybean (Glycine max L.) cultivars, Clark RJ1 and N77, or in their absence Pearl millet (Panicum glaucum L.) were judged to be appropriate reference crops for estimating N$ sb2$ fixation by soybeans using $ sp{15}{ rm N}$ isotope dilution techniques. A local soybean cultivar, Magoye, was rated highest among three cultivars tested for its ability to support N$ sb2$ fixation by Bradyrhizobium japonicum and contributed biologically fixed N$ sb2$ to a subsequent wheat crop.

The overall objective of this study was to evaluate the performance of selected furrow irrigation models for field conditions in south-east Australia. The other important aspects which were examined during this study include: developing a methodology for estimating of infiltrating characteristics, assessing the applicability of the Manning and other similar equations for flows in furrow irrigation, investigating the variation of shape factor during irrigation developing methodology for estimation of recession time and exploring the sensitivity of the models to the input parameters. Field experiments were conducted at Walla Park in northern N.S.W. and on two selected paddocks at the University Farm, Richmond, in western Sydney,Australia, over a period of three years. The validity of the assumption that the shape factor of advancing water front during furrow irrigation varies between 0.7 and 0.8 was investigated using field data collected from irrigation events monitored in the study. It was found that the average values of the shape factor varied from 0.96 to 1.80 at Walla Park site, from 0.56 to 0.80 at Field Services unit paddock site and from 0.78 to 0.84 at Horticulture Farm paddock site. The value of shape factor was affected by uniformity of furrow cross section along the length, the value and uniformity of furrow slope, furrow length and infiltration characteristics of soil. This means it is difficult to recommend a typical value for the shape factor for a given field situation.The performance of the models for prediction of advance and recession characteristics and runoff were evaluated using different indices of performance. In general, it was found that the Walker-HD and ZI model was the most satisfactory for the field conditions encountered in this study. This finding can provide a basis for initiating work on developing design criteria and management strategies for furrow irrigation in south-east Australia.<br>Doctor of Philosophy (PhD)

A forage sorghum irrigation study was conducted at Maricopa, AZ to determine water use and if sub-optimal irrigation increases water use efficiency and profitability. Sorghum was planted on July 10 with a row spacing of 40 inches and irrigated three times with a total of 8.7 inches of water to establish the crop. Variable amounts of irrigation water were applied commencing on Aug 12 based on 25, 50, 75, and 100% of estimated crop water use (evapotranspiration, ET). The plots were 53.3 ft wide (16 rows) and 40 ft long. ET was estimated from soil water measurements using a neutron probe. The total amount of water applied was 15.5, 19.8, 23.7, and 27.8 inches for the 25, 50, 75, and 100% ET treatments, respectively. The forage was harvested on Oct 28 near the soft dough stage. Forage yields adjusted to 70% moisture were 11.3, 16.4, 21.5, and 23.1 tons/acre for the 25, 50, 75, and 100% ET treatments, respectively. Yield produced per inch of water used by the crop (WUEET, water use efficiency of water used in ET) increased with water application. Yield produced per inch of water applied to the crop (WUEirr, water use efficiency of irrigation water applied plus rainfall) also increased with water application, but then decreased from the 75 to 100% ET treatments. Nevertheless, sub-optimal irrigation strategies are not economical using the results from this study assuming a water cost of $45 per acre-foot and a sorghum silage value of $20 per ton. For sub-optimal irrigation strategies to be economical, water costs would have to increase, sorghum silage value would have to decrease, or the differences in the irrigation efficiencies of the strategies being compared would have to be greater than measured in the present study.

Irrigation water use efficiencies were studied for the State of Arizona in terms of nutritive values such as calories and proteins. The major crops and crop groups, 15 counties, 6 water planning districts, and four irrigation systems were evaluated. Cotton accounted for more than 40 percent of the Statewide total protein production. The most efficient calorie producing crop was potatoe. The feed crops produced the highest percentage of protein. On yield per acre basis, the leading counties were La Paz and Yuma. District IV produced the highest calorie and protein both per acre and acre-foot basis. The overall output/input ratio for the state's irrigated agriculture was found to be 1.79. This ratio was based on 450 feet of pumping lift and considering energy used to deliver and distribute water as the only direct energy input.

Analyses of possible synergies between energy recovery and water management are essential for achieving sustainable improvements in the performance of pressurized irrigation networks. Improving the energy efficiency of water systems by hydraulic energy recovery is becoming an inevitable trend for energy conservation, emissions reduction, and increases in profit margins. This Ph.D. research is focused on the proposal and development of an optimization methodology that improves energy efficiency in pressurized irrigation networks. To develop this methodology, the main objective of this Ph.D. thesis, the research is supported by secondary objectives. The first secondary objective overviews the state-of-the-art for different hydropower systems, paying attention to those systems in which residual energy can be considered for energy improvement. Furthermore, the need to analyze this energy improvement in pressurized irrigation networks is justified through enumerating the main advantages and disadvantages of these energy recoveries. This first objective establishes the contextualization stage of the thesis. The second part of this Ph.D. research, which develops the rest of the objectives, is called the procedural stage. This phase contains the analytical and experimental development of this research. The analytical phase develops the main steps of the optimization strategy. Each step comprises one methodology or method that is focused on the following objectives: ¿ To propose a methodology to determine the circulating flow over time in pressurized irrigation networks in any line depending on the agronomist intrinsic parameters of the established crops ¿ To develop a calibration strategy for the flow assignment in lines, which indicates the success of the proposed methodology ¿ To establish the energy balance as well as the involved energy terms to quantify the theoretical recoverable energy in pressurized water networks, particularly in irrigation networks ¿ To present a new methodology to maximize the recovered energy considering the actual feasibility to allocate pumps working as turbines (PATs) within pressurized water networks by using simulated annealing as a water management tool. The analytical phase is complemented with an intensive experimental campaign in two different PATs (radial and axial) in steady and unsteady flow conditions. The campaign regarding steady flow conditions enables the study of the efficiency variations in the machine as a function of the flow and rotational speed. The experimental analysis as well as the modification of the classical affinity laws allows one to determine the best efficiency line (BEL) and the best efficiency head (BEH) based on Suter parameters. Both lines enable modelers to establish the optimal rotational speed as a function of the flow during each instant to maximize the recovered energy. These new lines (BEL and BEH) should be incorporated within the optimization strategy, developing a procedure to recover energy as a function of the number of installed machines. Finally, to complement the developed analysis for the installation of the recovery systems in pressurized water systems, the unsteady flow in these facilities is also analyzed.<br>El desarrollo de los análisis de las posibles sinergias entre los sistemas de recuperación de energía y la gestión del agua es esencial, para poder lograr mejoras en la eficiencia energética de las redes de riego presurizadas a través de medidas sostenibles. La mejora de la eficiencia energética, mediante la recuperación de la energía hidráulica, se está convirtiendo en una tendencia inevitable para la conservación de la energía, la reducción de las emisiones de gases efecto invernadero y el aumento de los márgenes de beneficio en los sistemas de distribución de agua presurizados. Esta tesis doctoral está centrada en la propuesta y desarrollo de una metodología de optimización, la cual, mejore la eficiencia energética en redes de riego presurizadas. Para desarrollar esta metodología, objetivo principal de esta tesis, la investigación está basada en diferentes objetivos secundarios. El primer objetivo secundario, estudia el estado del arte en los diferentes sistemas hidroeléctricos, prestando atención a aquellos sistemas en los que, la energía residual puede ser tenida en cuenta para mejorar la eficiencia energética. La necesidad de analizar esta mejora energética en las redes de riego presurizadas, se justifica mediante la enumeración de las principales ventajas y desventajas de estos sistemas de recuperación tienen sobre los sistemas de distribución. Este primer objetivo, establece la etapa de contextualización de la tesis. La segunda parte de la tesis, denominada fase procedimental o de procedimiento, desarrolla el resto de los objetivos y contiene, el desarrollo analítico y experimental de esta investigación. La fase analítica desarrolla los principales bloques que forman la estrategia de optimización. Estos bloques de contenido están constituidos, cada uno de ellos, por una metodología desarrollada o método aplicado, cubriendo los siguientes objetivos: ¿ Proponer una metodología que determine el caudal circulante a lo largo del tiempo, en cualquier línea, en función de los parámetros intrínsecos agronómicos. ¿ Desarrollar una estrategia de calibración para la asignación de caudales en líneas, que demuestre la bondad de la metodología propuesta. ¿ Establecer el balance energético, así como los términos energéticos involucrados, para cuantificar la energía recuperable teórica en redes presurizadas, particularmente en redes de riego. ¿ Presentar una nueva metodología de maximización de energía recuperada donde la viabilidad de asignar bombas trabajando como turbinas (PATs) dentro de redes de distribución sea considerada, mediante el uso de la herramienta 'simulated annealing' en la gestión del agua. La fase analítica se complementa con el desarrollo de una campaña experimental en dos PATs diferentes (una de tipo radial y otra de tipo axial). Ambas máquinas han sido ensayadas en condiciones de flujo permanente y transitorio. El análisis experimental en condiciones de flujo permanente ha permitido estudiar la variación de la eficiencia de la máquina en función del caudal y de la velocidad de rotación de la misma. Este análisis experimental, así como la modificación de las leyes clásicas de semejanza, han hecho posible la definición de la mejor línea de eficiencia (best efficiency line (BEL)) y la mejor eficiencia de altura recuperada (best efficiency head (BEH)). Ambas líneas están basadas en los parámetros de Suter, y permiten a los modeladores el establecimiento de la velocidad de giro óptima en función del caudal circulante en cada instante, maximizando la energía recuperada. Estas nuevas líneas (BEL y BEH) deben incorporarse a la estrategia de optimización, teniéndolas en cuenta a lo largo del proceso para recuperar energía en función del número de máquinas instaladas en el sistema. Finalmente, para complementar el análisis desarrollado de la instalación de sistemas de recuperación energética en redes de distribución, se ha anali<br>El desenvolupament de les anàlisis de les possibles sinergies entre els sistemes de recuperació d'energia i la gestió de l'aigua són essencials per a aconseguir millores en l'eficiència energètica de les xarxes de reg pressuritzades a través de mesures sostenibles. La millora de l'eficiència energètica, mitjançant la recuperació de l'energia hidràulica, s'està convertint en una tendència inevitable per a la conservació de l'energia, la reducció de les emissions de gasos efecte hivernacle i l'augment dels marges de benefici en els sistemes de distribució d'aigua pressuritzada. Aquesta tesi doctoral està centrada en la proposta i desenvolupament d'una metodologia d'optimització, la qual millore l'eficiència energètica en xarxes de reg pressuritzades. Per a desenvolupar aquesta metodologia, objectiu principal d'aquesta tesi, la recerca ha estat basada en diferents objectius secundaris. El primer objectiu secundari estudia l'estat de l'art en els diferents sistemes hidroelèctrics, centrant-se en aquells sistemes en els quals l'energia residual pot ser tinguda en compte per a millorar l'eficiència energètica. La necessitat d'analitzar aquesta millora energètica en les xarxes de reg pressuritzades es justifica mitjançant l'enumeració dels principals avantatges i desavantatges que aquests sistemes de recuperació tenen sobre els sistemes de distribució. Aquest primer objectiu estableix l'etapa de contextualització de la tesi. La segona part de la tesi, denominada fase procedimental o de procediment, desenvolupa la resta dels objectius i conté(, )el desenvolupament analític i experimental d'aquesta recerca. La fase analítica desenvolupa els principals blocs que formen l'estratègia d'optimització. Aquests blocs de contingut estan constituïts cadascun d'ells per una metodologia desenvolupada o mètode aplicat, els quals cobreixen els següents objectius: ¿ Proposar una metodologia que determine el cabal circulant al llarg del temps, en qualsevol línia, en funció dels paràmetres intrínsecs agronòmics. ¿ Desenvolupar una estratègia de calibratge per a l'assignació de cabals en línies, que demostre la bondat de la metodologia proposada. ¿ Establir el balanç energètic, així com els termes energètics involucrats, per a quantificar l'energia recuperable teòrica en xarxes pressuritzades, particularment en xarxes de reg. ¿ Presentar una nova metodologia de maximització d'energia recuperada, on la viabilitat d'assignar bombes treballant com a turbines (PATs) dins de xarxes de distribució siga considerada, mitjançant l'ús de l'eina "simulated annealing" en la gestió de l'aigua. La fase analítica es complementa amb el desenvolupament d'una campanya experimental en dues PATs diferents (una de tipus radial i una altra de tipus axial), les quals han sigut assajades en condicions de flux permanent i transitori. L'anàlisi experimental, en condicions de flux permanent, ha permès estudiar la variació de l'eficiència de la màquina en funció del cabal i de la velocitat de rotació de la mateixa. Aquesta anàlisi experimental, així com la modificació de les lleis clàssiques de semblança, han fet possible la definició de la millor línia d'eficiència (best efficiency line (BEL)) i la millor eficiència d'altura recuperada (best efficiency head (BEH)). Ambdues línies estan basades en els paràmetres de Suter i permeten als modeladors l'establiment de la velocitat de gir òptima, en funció del cabal circulant en cada instant, maximitzant l'energia recuperada. Aquestes noves línies (BEL i BEH) han d'incorporar-se a l'estratègia d'optimització, tenint-les en compte al llarg del procés per a recuperar energia en funció del nombre de màquines instal·lades en el sistema. Finalment, per a complementar l'anàlisi desenvolupada de la instal·lació de sistemes de recuperació energètica en xarxes de distribució, s'ha analitzat el règim transitori en aquests sistemes quan es produeix<br>Pérez Sánchez, M. (2017). METHODOLOGY FOR ENERGY EFFICIENCY IMPROVEMENT ANALYSIS IN PRESSURIZED IRRIGATION NETWORKS. PRACTICAL APPLICATION [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84012<br>TESIS<br>Premiado

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 81-86).<br>This thesis presents a mathematical model investigating the physics behind pressure compensating (PC) drip irrigation emitters and a design of a highly efficient solar powered centrifugal pump for small-acreage farmers drawing from shallow groundwater. The global community is facing a worsening crisis with regards to the water-energy agriculture nexus. Irrigation is a proven way to increase the agricultural productivity of a plot of land; however, with a growing population, it will be necessary to invest in methods of irrigation that are both energy- and water-efficient, and intensify the agricultural output per unit of land. Drip irrigation, a method of irrigation where water is delivered directly to the plant roots through a network of tubes and valves, is a highly water-efficient method that gives high yield per unit area. The current challenge to adoption facing drip irrigation is the high capital and operating costs. It is possible to cut these costs by developing a valve, called an emitter, that gives the desired flow rate at a lower pressure. This lower pressure in turn requires less energy from the pump, allowing for a smaller and less expensive pump, and even making a solar-powered system affordable for small-acreage farmers. In coming decades, it will become increasingly necessary to switch from fossil-fuel based energy to renewables, such as solar. For small acreage farmers in the developing world, this switch will not only alleviate the pains of paying the recurring and volatile costs for diesel fuel, it will also help to lighten the load on the electrical grid by those using electric pumps.<br>by Katherine Anne Taylor.<br>S.M.

Orientador: Edson Eiji Matsura<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola<br>Made available in DSpace on 2018-08-09T10:08:00Z (GMT). No. of bitstreams: 1 Bizari_DouglasRoberto_M.pdf: 2631930 bytes, checksum: 700468abc20c4dc5eeb63fae0866a7d0 (MD5) Previous issue date: 2007<br>Resumo: A intensificação do uso da terra pelo emprego de técnicas como a irrigação tem proporcionado aumento anual do número de safras e redução dos riscos do empreendimento. Porém, a agricultura irrigada precisa ganhar mais eficiência por meio da utilização do sistema plantio direto, que promove de forma sustentada, o aumento da produtividade e a redução da lâmina de água aplicada. O presente trabalho teve por objetivo demonstrar que o manejo da irrigação em condições de Plantio Direto na cultura do feijoeiro (cultivar Carioca precoce) contribui para a preservação dos recursos hídricos pela redução do número de irrigações em função da cobertura morta e das características físico-hídricas apresentadas por este sistema de manejo. O experimento foi conduzido no Campo Experimental da Faculdade de Engenharia Agrícola da UNICAMP, em Campinas, SP, no período de junho a setembro de 2006, em Latossolo Vermelho distroférrico, submetidos aos seguintes tratamentos: sistema plantio direto 1 (SPD 1), sistema plantio direto 2 (SPD 2), plantio convencional 1 (PC 1) e plantio convencional 2 (PC 2), irrigados por aspersão convencional, sendo que o manejo da irrigação foi realizado pelo método tensiométrico. Os resultados mostraram que os tratamentos com SPD apresentaram menores valores de evapotranspiração da cultura praticamente durante todo o seu ciclo, sendo esta diferença mais acentuada na fase de florescimento, mostrando a importância da manutenção da cobertura morta em sua superfície. Os tratamentos com SPD foram mais eficientes no uso da água, apresentando maiores valores de produção com menor quantidade de água aplicada quando comparado aos tratamentos com PC<br>Abstract: The intensification of soil use by the techniques as the irrigation has providing annual increase crops number and reduction of the enterprise risks. However, the irrigated agriculture needs to be more efficiency, through use the no tillage system that promote increases the productivity e reduction of the applied water. The aim this research was to demonstrate that irrigation management in no tillage system with bean crop (cultivar Carioca precoce) contributes whit the preservation of water resources once the mulching and others characteristics presented by this soil tillage promotes the reduction of the numbers of irrigations. This experiment was carried in the Experimental Field of University of Agricultural Engineering of UNICAMP, in Campinas, SP, in the period of June to September of 2006, in a Latossolo Vermelho distroférrico, submitted to the following treatments: no tillage system 1 (SPD 1), no tillage system 2 (SPD 2), tillage system 1 (PC 1) and tillage system 2 (PC 2), using a sprinkle irrigation system managed with tensiometers. The results showed that the SPD treatments presented smaller evapotranspiration values during practically all the crops cycle. This difference was more accentuated in the flowering phase, showing the importance of the maintenance of the mulching. The SPD treatments also presented the largest values of production associated with a smaller quantity of applied water. These results evidenciated that, in this study, the SPD treatment presents a higher water use efficiency than PC treatments<br>Mestrado<br>Agua e Solo<br>Mestre em Engenharia Agrícola

Rice (Oryza sativa L.) crop has an important role to attend the food demand of a growing world population, and the production increment will come not just from increasing efficiency in the current cropland, but also from expansion to new areas. The tropical lowland plains of northern Brazil are already being converted to rice production, although the lack of scientific knowledge and agricultural practices suited local conditions. This region presents soils with weathered clays with distinct properties from those grown in traditional rice regions, and deploying agricultural practices developed to others agroecosystem lead to instable crop yield inadequate uses of agricultural inputs. Water is the greatest resource that rice crop relies on, and worldwide continuous flooding is broadly used. Alternative irrigations regimes with purpose to save water have been proposed due the threatens of water scarcity, and promising results stimulate this approach, despite grain yield penalties due drought stress and/or decrease of soil N availability. The soil moisture and oxygen amount interfere on nitrogen dynamics, thus can enhance loss process and change crop response to N fertilizer. In tropical lowland region of Brazil water and nitrogen are limited and continuous flooding irrigation is not sustainable due huge water amount used associated to low grain yields. Therefore, this research was performed aiming an integrated assessment of irrigation regimes, nitrogen use and crop performance in rice crop in Brazilian tropical lowland. The field experiment was done during three years in a Plinthaquults soil at Tocantins. The first stage was aimed to identify the irrigation regime which provides the best water use efficiency (WUE), nitrogen use efficiency (NUE) and crop performance with indigenous N soil supply and nitrogen fertilizer. The second stage compared the best observed irrigation regime to continuous flooding, and the nitrogen relationship to crop components along their development and harvest. The first experiment was a split-plot design with 5 irrigation regime (IR) in main plot: alternate wet and dry in short cycle (AWDS); alternate wet and dry in long cycle (AWDL); Continuous flooding (CF); Non-flooding aerobic (NF); saturated soil without ponding water (SS). And subplot was N fertilizer rate: 0 and 150 kg ha-1 of N. Crop performance was affected by IR and N level. In the average of three years nitrogen uptake (NU) was 32% higher in NF than any other irrigation regime. Grain yield across N level was 7.2, 8.8 and 7.5 Mg ha-1 in NF and in CF were 5.6, 8.2 and 6.9 Mg ha-1, respectively in 2014, 2015 and 2016. The isotopic NUE showed total recovery of 81.5 % of 15N in NF and 62, 61, 56, 56% in SS, AWDS, AWDL, CF respectively. The average WUE of delivered water was 0.7 kg grain m-3 in NF, and 0.47, 0.40, 0.35, 0.32 kg grain m-3 water in SS, AWDS, AWDL and CF, respectively. The second experiment was a split-plot design with: continuous flooding (CF) and non- flooding aerobic (NF) in the main plot and fertilizer nitrogen (0, 50, 150 and 250 kg ha-1) in the subplot during the 2014, 2015 and 2016. Biomass (AGB) nitrogen uptake (NU) and leaf area index (LAI) were observed along crop development in the 0 and 150 subplots in 2015 and 2016 growing seasons. As was the relationship between AGB, NU, panicle density (PD), spikelet number (NS) and grain yield (GY) at physiological maturity. The aerobic rice provided higher NU throughout rice development and LAI equal or superior to CF. At harvesting, NU and PD had different relationships to N rates among CF and NF, with NF showing 18% higher NU as 27% PD higher than CF across years and N rate. The grain GY relationship to N rates was also distinct in 2014 and 2015, and GY across N rates in NF was 20% and 12% higher than CF for 2014 and 2015, respectively. This research concludes for such agroecosystem, as long there is no drought stress, rice crop in non-flooding aerobic irrigation regime performs higher efficiency of water and N use, and moreover presents better overall crop performance with less need to nitrogen fertilizer than traditional continuous flooding or any other water saving irrigation regime.<br>A cultura do arroz (Oryza sativa L.) tem importante papel em fornecer alimento à crescente população mundial, e o incremento da produção virá não só do ganho de eficiência de áreas em uso, mas também da incorporação de novas áreas. As planícies tropicais do norte do Brasil já estão sendo convertidas para cultivo de arroz, apesar da falta de conhecimento científico e práticas agrícolas apropriadas às condições locais. Essa região apresenta solos com minerais de argila intemperizados e propriedades distintas daqueles de regiões tradicionais de cultivo, e a transferência das práticas agrícolas desenvolvidas para outros agroecossistemas têm resultado em produtividades variáveis e uso inadequado de insumos. A água é principal recurso no cultivo do arroz, e a irrigação com inundação constante é largamente disseminada pelo mundo. Regimes alternativos de irrigação a fim de economizar agua tem sido propostos em razão da ameaça de escassez de água, e resultados promissores estimulam a disseminação dessa técnica, apesar de prejuízos à produtividade em razão do estresse por seca e/ou menor disponibilidade de nitrogênio (N) do solo. A umidade do solo e a quantidade de oxigênio interferem na dinâmica de N e podem favorecer processos de perdas e alterar a resposta do cultivo à adubação nitrogenada. Nas planícies tropicais do Brasil a disponibilidade de água e N são limitadas, e a inundação contínua não é sustentável em razão da quantidade de agua requerida associada a baixa produtividade da cultura. Portanto, esta pesquisa foi realizada com o objetivo de estudar de forma integrada o regime de irrigação e o uso de N, e performance da cultura em várzea tropical. O experimento foi realizado durante três anos em Plintossolo no estado do Tocantins. Na primeira etapa da pesquisa procurou-se identificar o regime de irrigação que proporciona maior eficiência de uso da água (WUE), eficiência de uso de nitrogênio (NUE) e performance de cultivo com N nativo do solo e quando aplicado N fertilizante. Na segunda fase comparou-se o regime de irrigação que proporcionou melhores índices de eficiência de água e N ao regime de lâmina contínua com a hipótese que a relação entre aplicação de fertilizante N e componentes de produção seriam diferentes entre os regimes. Na primeira fase adotou-se delineamento de parcela subdividida com 5 regimes de irrigação (IR): lâmina alternada de inundação e drenagem em ciclo curto (AWDS); lâmina alternada de inundação e drenagem em ciclo longo (AWDL); lâmina contínua (CF); sem formação de lâmina e solo aeróbico (NF); e sem formação de lâmina e solo saturado (SS). Nas subparcelas avaliou-se as doses de N fertilizante: 0 e 150 kg ha-1. A performance de cultivo foi afetada pelo IR e dose de N. Na média dos 3 anos, o acúmulo de nitrogênio na parte aérea (NU) foi 32% maior em NF do que em todos os outros regimes de irrigação. A produtividade de grãos média entre as duas doses de N foi 7,2, 8,8 e 7,5 Mg ha-1 em NF e 5,6, 8,2, 6,9 Mg ha-1 in CF, respectivamente em 2014, 2015 e 2016. A NUE foi de 81,5% de recuperação de 15N em NF e 62, 61, 56 e 26% em SS, AWDS, AWDL e CF, respectivamente. A média de WUE em relação a água aplicada foi 0,7 kg grão m-3 em NF e 0,47, 0,40, 0,35, 0,32 kg grão m-3 água em SS, AWDS, AWDL e CF, respectivamente. Na segunda fase adotou-se o delineamento experimental de parcelas subdivididas com inundação contínua (CF) e sem formação de lâmina e solo aeróbico (NF) na parcela principal e aplicação de N fertilizante (0, 50, 150, 250 kg ha-1) nas safras 2014, 2015, 2016. Biomassa (AGB) acúmulo de nitrogênio (NU) e índice de área foliar (LAI) foram avaliados ao longo do desenvolvimento da cultura nas doses de 0 e 150 kg ha-1 nas safras de 2015 e 2016. Assim como a relação entre AGB, NU densidade de panícula (PD), número de espiguetas (NS) e produtividade de grãos (GY) na maturidade fisiológica A condição aeróbica proporcionou maior NU ao longo do desenvolvimento e LAI maior ou igual a CF. Na colheita, NU e PD tiveram diferentes repostas ao nitrogênio fertilizante quando em NF ou CF, mostrando NU 18% maior em NF assim como PD 27%maior em NF do que em CF na média de anos e dose de N. A resposta da GY ao nitrogênio fertilizante também foi diferente quando em NF ou CF, e na médias de dose de N fertilizante, NF proporcionou produtividade 20% e 12% maior do que CF em 2014 e 2015, respectivamente. Conclui-se nessa pesquisa que nesse agroecossistema, desde de que que não ocorra estresse por seca, o arroz cultivado em sistema de irrigação sem formação de lâmina e solo aeróbico é mais eficiente no uso de água e nitrogênio. E ainda, com melhor desempenho de produtividade e menor dependência de N fertilizante em comparação ao cultivado em lâmina contínua ou qualquer outro regime alternativo que economize água.

How can we explain the paradoxical outcomes of resource efficiency? As a key pillar of worldwide sustainable development policies, the concept of resource efficiency has become increasingly important to scrutinize. The overreliance on efficiency coupled with the intention of conserving scarce resources can sometimes backfire. Understanding the intermediate process that leads to the negative, paradoxical outcome is imperative for a sustainable future, especially for societies that risks resource degradation. This study takes the explanatory route and aims to problematize the usage of efficient technology in a resource scarce developing country, namely, Morocco. It is argued that the causal mechanism which links the independent variable (drip irrigation technology) to the observed outcome (total increased resource consumption) has to do with production and consumption processes, which is theorized to be spurred by efficiency. These mechanisms have been derived from the theory of Jevons Paradox and juxtaposed with empirical findings from the Guerdane irrigation scheme, a scheme which sought to increase productivity and simultaneously reduce water scarcity. The study makes use of the case-study approach and the process-tracing method. The chosen method provides a means for establishing a timeline of events, alternative explanations, as well as providing grounds for a primary explanation for the observed outcome. The findings point to reduced labour costs and initial water savings as the empirically derived causal mechanisms. These mechanisms, spurred by the implementation of drip irrigation technology, consequently gave rise to the expansion of irrigated land which in turn increased water withdrawals and eventually resulted in a paradoxical, negative outcome where the total consumption of water resources increased. Taken together, these results deepen our understanding of the problematic usage of efficient technology when different types of social processes are not accounted for.

Doctor of Philosophy<br>Department of Agricultural Economics<br>Jeffrey M. Peterson<br>Nathan P. Hendricks<br>The two studies presented in this dissertation examine incentives for groundwater extraction and their resulting effect on aquifer depletion. Both studies apply dynamic optimization methods in a context of irrigated agriculture in arid and semi-arid regions such as in western Kansas. The first study examines the effects of capital subsidies aimed at increasing irrigation application efficiency. The second study examines the effects of changing incentives posed by changes in climatic patterns and by technical progress in the form of increasing crop water productivity. Both studies have significant policy and groundwater management implications. Subsidies for the adoption of (more) efficient irrigation technologies are commonly proposed and enacted with the goal of achieving water conservation. These subsidies are more politically feasible than water taxes or water use restrictions. The reasoning behind this type of policy is that increased application efficiency makes it possible to sustain a given level of crop production per acre with lower levels of groundwater pumping, all else equal. Previous literature argues that adoption of more efficient irrigation systems may not reduce groundwater extraction. Rewarding the acquisition of more efficient --and capital intensive-- irrigation equipment affects the incentives farmers have to pump groundwater. For instance, the farmer may choose to produce more valuable and water intensive crops or to expand the irrigated acreage after adopting the more efficient irrigation system. Hence, the actual impact of the policy on overall groundwater extraction and related aquifer depletion is unclear. The first chapter examines the effects of such irrigation technology subsidies using a model of inter-temporal common pool groundwater use with substitutable technology and declining well-yields from groundwater stocks, where pumping cost and stock externalities arise from the common property problem. An optimal control analytical model is developed and simulated with parameters from Sheridan County, Kansas-- a representative region overlying the Ogallala aquifer. The study contrasts competitive and optimal allocations and accounts for endogenous and time-varying irrigation capital on water use and groundwater stock. The analysis is the first to account for the labor savings from improved irrigation technologies. The results show that in the absence of policy intervention, the competitive solution yields an early period with underinvestment in efficiency-improving irrigation technology relative to the socially efficient solution, followed by a period of over-investment. This suggests a potential role for irrigation capital subsidies to improve welfare over certain ranges of the state variables. In contrast to previous work, the findings are evidence that significant returns may be achieved from irrigation capital subsidies. Finally, a policy scenario is simulated where an irrigation technology subsidy is implemented to explore whether such a program can capture significant portions of the potential welfare gain. Results indicate that the technology subsidy can improve welfare, but it captures a relatively small portion of the potential gains in welfare. The second chapter presents a dynamic model of groundwater extraction for irrigation where climate change and technical progress are included as exogenous state variables-- in addition to the usual state variable of the stock of groundwater. The key contributions of this study are (i) an intuitive description of the conditions under which groundwater extraction can be non-monotonic, (ii) a numerical demonstration that extraction is non-monotonic in an important region overlying the Ogallala Aquifer, and (iii) the predicted gains from management are substantially larger after accounting for climate and technical change. Intuitively, optimal extraction is increasing in early periods when the marginal benefits of extraction are increasing sufficiently fast due to climate and technical change compared to the increase in the marginal cost of extraction. In contrast, most previous studies include the stock of groundwater as the only state variable and, consequently, recommend a monotonically decreasing extraction path. In this study, the numerical simulations for a region in Kansas overlying the Ogallala Aquifer indicate that optimal groundwater extraction peaks 23 years in the future and the gains from management are large (29.5%). Consistent with previous literature, the predicted gains from management are relatively small (6.1%) when ignoring climate and technical change. The realized gains from management are not substantially impacted by incorrect assumptions of climate and technical change when formulating the optimal plan.

Partial rootzone drying (PRD) is an irrigation management technique designed to reduce water use in grapevines without a decline in yield, thereby increasing water–use efficiency (measured as t/ML) (WUE). The principle of PRD is to keep part of the root system at a constant drying rate to produce soil-derived signals to above–ground plant organs to induce a physiological response. Major PRD effects include a reduced canopy size and greatly increased WUE with possible improvements in fruit quality. Although we have a good understanding of the hormonal physiology of PRD, little is known on the effect of PRD on partitioning of C, N and inorganic ions such as K. This thesis broadens our knowledge on the effects of PRD on grapevine field performance, growth and dry matter accumulation as well as its effects on physiology and biochemistry. In field experiments over 3 seasons, PRD reduced water use in grapevines without a significant decline in yield. PRD effects included reduced shoot growth and greatly increased WUE. Field–grown Cabernet Sauvignon, where the PRD grapevines were irrigated at half the control rate, and Shiraz where the PRD grapevines were irrigated at same rate as controls, confirmed that PRD is not simply an irrigation strategy that applies less water, rather it alters the way in which the plant responds to its environment, e.g. PRD alters the sensitivity of the stomatal response to atmospheric conditions and significantly influence enzymes that regulate nutrient accumulation and partitioning. PRD did not change the total amount of carbon and nitrogen on a whole plant basis. However, it caused a significant partitioning of carbon and nitrogen towards trunk, roots and fruit at the expense of shoot growth. This change in partitioning occurred as a result of altered activity of the enzymes controlling the assimilation of carbon and nitrogen. PRD significantly reduced nitrate reductase (NR) activity in grapevine leaves, which catalyses the first step in the assimilation of nitrate irrespective of the amount of water applied. The reduction in NR activity is correlated with the development of the PRD cycle and the associated reduction in stomatal conductance. PRD also significantly altered grapevine sucrolytic enzyme activity that regulate source:sink relationships. PRD showed transient increases in leaf sucrose phosphate synthase (SPS) activity (formation of sucrose) compared to control, but significantly reduced leaf neutral invertase (sucrose cleavage) and leaf starch content in both field and potted experiments. This may indicate an increased photosynthetic capacity and a reduction in its sink strength for sucrose in favor of organs such as fruit and roots. This hypothesis was reinforced by the fact that berries showed significantly higher levels in glucose and fructose early in the season. Berry sugar content and Brix at harvest however was unaffected. Although PRD had no significant effect on berry characteristics at harvest such as Brix and pH, it occasionally reduced per berry K+ content and increased total amino acid concentration that may lead to positive outcomes for wine quality. PRD–treated grapevine roots on the 'wet'– and 'drying'–sides differed greatly in enzyme activity and osmolality. PRD significantly increased osmolality in both wet and drying roots by increasing total osmolyte concentration that may facilitate the movement of water from wet to dry roots. The increases in osmolality were also associated with increased free polyamine production (spermidine and spermine) in PRD roots that may be related to increased root growth and density.<br>Thesis (Ph.D.)--School of Agriculture and Wine, 2005.

Knowledge of water use, through water foot printing (WF) in smallholder agriculture crop production is the key to the global fight against poverty, achievement of food security and sustainability within the world’s rural community. Water footprint of a crop can be defined as the volume of fresh water used to produce a certain crop in all the steps in the production line. This study, therefore aimed at contributing towards improvements in rural livelihoods by raising awareness of the increased productive use of green, blue and grey water in smallholder agriculture in South Africa. This was done through determination of water footprints of five vegetable crops, i.e. potatoes (Solanum tuberosum), tomatoes (Solanum lycopersicum), dry beans (Phaseolus vulgaris), cabbage (Brassica oleracea spp) and spinach (Spinacia oleracea) in the 2000-2013 period. Quantification of water footprints has been done worldwide but, in South Africa (SA) focus has mostly been on the industrial and domestic sector. Water footprint assessment framework, was used to estimate the full impact of vegetable production on water resources at Zanyokwe, Thabina and Tugela Ferry irrigation schemes as case studies. The CROPWAT@ model was used to calculate crop evapotranspiration, differentiating green and blue water. Local climatic data were obtained from SA weather services, while the crop and soil parameters were obtained from the FAO data base. Nitrogen was considered the main pollutant hence its use in the grey water footprint calculation. Generally, Thabina irrigation scheme had the highest water footprint, followed by Tugela Ferry irrigation scheme whilst Zanyokwe irrigation scheme had the lowest. Green beans had the highest water footprint at all the three irrigation schemes with Thabina irrigation scheme having the highest (3535.1 m3/ton). For Tugela Ferry irrigation scheme, the calculated WF was 2753 m3/ton whilst the lowest was observed at ZIS i.e. 2407.6 m3/ton. Cabbage had the lowest water footprint. The highest water footprint for growing cabbage was 254.5 m3/ton in TFIS, 223.1 m3/ton in TIS and the lowest was 217.8 m3/ton in ZIS. The differences observed in the WF of a crop at each scheme maybe attributed to the differences management, weather and environmental characteristics, in the three locations. Moreover, the needs for ET are related to soil type and plant growth, and primarily depend on crop development and climatic factors which are closely related to climatic demands. The grey water footprint was calculated using the recommended fertilizer application rates for all the three sites. Green beans had the highest WFgrey i.e. 373 m3/ton and the lowest was cabbage with 37 m3/ton. Potato, spinach and tomatoes had 156 m3/ton, 214 m3/ton and 132 m3/ton, respectively. Grey water footprint in this study was higher as compared to other studies, possibly because of the high rates of nitrogen fertilizers used in the calculations and the low yields farmers get. Compared with estimates from other studies, the water footprints of vegetable production within smallholder irrigation schemes was relatively high. There is therefore, a need to focus on crop management and tillage practices that will help in increasing yield while minimizing water usage.

Increased water- and fertilizer-use-efficiency in containerized crop production, via reduced water loss, enhances crop-available nutrients while reducing non-point source agrichemical contributions in accordance with regulatory standards. Previous studies detailed nutrient leaching patterns throughout crop production seasons, leaving little known about water and dissolved nutrient (solute) movement through soilless substrates during irrigation. The following experiments evaluated fundamental water and solute transport principles through pine-bark based substrates. 1) Ilex crenata Thunb. 'Bennett's Compactum' were grown in 2.7 L containers. Tensiometers detected wetting front (WF) movement throughout the substrate during irrigation. 2) Tracer solution (containing NO3-, PO43- and K+) and deionized water (DI) were applied to substrate-filled columns to characterize tracer breakthrough under saturated and unsaturated conditions. 3) Controlled-release fertilizer (CRF) was topdressed (surface-applied), incorporated (throughout substrate), dibbled (center of substrate) or not applied to fallow substrate, irrigated with DI and leachate analyzed to determine nutrient concentrations throughout irrigation. Tensiometers revealed that seasonal root growth affected substrate pre-irrigation moisture distribution. Wetting fronts channeled through the substrate before becoming thoroughly wetted. Tracer breakthrough occurred with less effluent volume under unsaturated conditions. Breakthrough of NO3- and PO43- was relatively conservative, though 37% of K+ was retained by the substrate. Leachate concentrations for topdressed and incorporated CRF peaked early (first 50mL effluent) before diminishing with continued leaching. Leachate concentrations for dibbled CRF initially increased (first 150mL leachate), plateaued and then diminished. These results show the relative rapidity which water and solutes move through pine-bark during irrigation and demonstrate methods for future research on within-irrigation solute transport.<br>Master of Science

La maîtrise du transfert de nitrates sous les systèmes irrigués est un objectif primordial dans l’agriculture moderne. Celle-ci exige la recherche, surtout en plein champ, de conduire une stratégie optimale de fertigation. Dans ce but, un protocole expérimental sur une parcelle de 2 ha a été mis en oeuvre pour analyser le devenir de l’’azote sous différents scénarios d’irrigation et de fertilisation d’une culture de maïs. Dans l’articulation de ce travail, et pour pouvoir étudier la dynamique de l’azote en systèmes irrigués, nous avons tout d’abord réussi à définir et clarifier la relation ambigüe entre la méthode d’irrigation (irrigation gravitaire, par aspersion ASP, en goutte à goutte de surface GGS ou enterré GGE) et les différentes transformations de l’azote (Fixation, Minéralisation, Immobilisation, Nitrification, Dénitrification et Volatilisation). Cette relation, peu claire et non traitée dans d’autres études similaires, a été étudiée en mettant l’accent sur l’effet de certains facteurs, comme par exemple, l’humidité de sol et sa température, sur l’activité microbienne et donc sur les différentes transformations de l’azote (comme la minéralisation) et ce en mettant en avant la relation directe ou indirecte avec les méthodes d’irrigation. Une différence significative a été observée pour la minéralisation in situ entre les traitements sans aucun apport d’engrais menés sous les deux méthodes d’irrigation GGE et ASP. Une méthode manuelle d’analyse a été ensuite mise au point et validée pour déterminer la concentration en azote dans les échantillons de sol prélevés dans le cadre de ce travail. Cette méthode peu onéreuse pourrait être profitable aux agriculteurs. Les données issues de l’ensemble des traitements ont été utilisées pour modéliser les flux hydriques et azotés à l’aide de modèle HYDRUS-2D pour les systèmes par aspersion et en goutte à goutte enterré. L’analyse de sensibilité aux paramètres liés au transfert de nitrates du modèle de transfert a permis d’estimer la dynamique azotée pour d’autres contextes hydro-pédo-climatiques plus complexes. En conclusion, la présente thèse a permis d’améliorer la connaissance du fonctionnement de la fertigation en irrigation goutte à goutte enterré par comparaison avec l’aspersion, en milieu méditerranéen, en vue d’une diminution des entrants agrochimiques dans un contexte d’économie de la ressource en eau<br>The main goal in modern agriculture is the control of nitrogen fluxes in agricultural soils under the irrigation techniques. This objective requires a lot of research, especially in the field, to escort an optimal strategy of fertigation. For this purpose, an experimental protocol has been applied to follow the soil nitrogen fate for various irrigation and fertilization scenarios, during two intensive field campaigns in maize plots. In the articulation of our work, and to be able to examine the nitrogen dynamics in unsaturated agricultural soils under irrigated systems, we succeeded firstly to determine and clarify the ambiguous relation between the irrigation techniques (flood irrigation, sprinkler irrigation, surface and subsurface drip irrigation) and the different nitrogen transformations (Fixation, Mineralization, Immobilization, Nitrification, Denitrification and Volatilization) in agricultural contexts. This relationship, which is unclear and untreated in other similar studies, has been reviewed by studying the impact of certain factors, such as soil moisture and soil temperature under different irrigation techniques, on microbial soil activity and therefore on the nitrogen transformations (such as mineralization). A significant difference of mineralization was observed in maize plots with no fertilizer application treatment between sprinkler irrigation and subsurface drip irrigation. The experimental data collected have been used to analyze the water and nitrogen fluxes for various initial conditions and fertilisation strategies under sprinkler and subsurface drip irrigation by using the HYDRUS-2D model. Analyzing the sensitivity of nitrogen fluxes parameters using HYDRUS-2D allowed to estimate the nitrogen dynamics under more complex agro-pedoclimatic contexts. In conclusion, the present study allowed to improve the fertilization knowledge under both the sprinkler and subsurface drip irrigation in a Mediterranean environment