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. / Thesis (Ph.D.)--School of Agriculture and Wine, 2005.

Thesis (M.S.)--University of Wisconsin, 1967. / Extension Repository Collection. Typescript (carbon copy). Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 84-85).

OLIVEIRA, Antônio Dimas Simão de. Avaliação do sensor de umidade TOPDEA no manejo da irrigação. 2008. 71 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Progarma de Pós-Graduação em Engenharia de Agrícola, Fortaleza-CE, 2008. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-06-14T12:51:05Z No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-06-14T12:51:34Z (GMT) No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) / Made available in DSpace on 2016-06-14T12:51:34Z (GMT). No. of bitstreams: 1 2008_dis_adsoliveira.pdf: 13748562 bytes, checksum: 57833bde003cd50858fd12de77a6e763 (MD5) Previous issue date: 2008 / The scientific community, in recent years, has intensified studies to measure the impacts to the environment caused by pollution, mainly the adverse effects to air and water. The fact that less than 1% of the global water resources is comprised of drinking water and available at the surface of the earth makes it a commodity of conflict. According to the FAO by 2030 to meet the demand caused by the growth of the world population a 14% increase in available drinking water will be required for irrigation. To meet that expectation, the classical questions of when and how much to irrigate needs to be assessed. Thus, professionals in the fields of engineering have especially focused on practices to increase the efficiency of irrigation. This study aimed at evaluating a moisture sensor, a capacitive type, called TOPDEA, in irrigation management. The soil moisture is the most basic index to quantify water in a soil, expressed in units of mass or volume. The monitoring of the soil moisture is one of the most important factors for proper irrigation management. The experiment was carried out in the Irrigated Perimeter of the Lower Acaraú Basin – Ceará, in two different fields: The first one cultivated with bananas where preliminary tests were conducted to evaluate the sensor calibration, and the second one with watermelon for irrigation scheduling. The sensors were calibrated by means of the regression analysis between moisture and frequency output of the sensors from saturation to approximately 4% moisture content. The calibration was validated by comparing resulting irrigation timing produced by scheduling the irrigation with sensors and with a weather station. The number of sensors per hactare was analyzed by analyzing the timing of irrigation for each additional sensor in the field. The effect of the placement of the sensors (position in relation to the dripper and plant) was evaluated. The calibration equation for the sensor was found to be potential ( 1778371018 −2,3894213 q = f ). The highest readings occurred with frequency of the sensor installed 25.3 cm from the emitter, while the lowest occurred at 19.85 cm. The largest irrigation time was found when two sensors were used for each hectare, while the lowest was found using five sensors per hectare. The total irrigation depth with the scheduling conducted with capacitive sensors was 377.96 mm, which resulted in a total volume of 532.17 m³ of water in the entire cycle of watermelon. Crop yield was 36.0 t ha-1 and the water efficiency of 0.068 kg L-1. Water productivity was 16.18 to 26.47% higher compared to the irrigation management commonly practiced in the irrigation district for watermelon. Given the characteristic of soil physics with low water storage capacity, the daily irrigation requirement must be fractioned into several irrigation pulses starting early morning and the application of the total daily requirement in one irrigation event during the night (practice commonly conduction in the district to reduce the electricity bill) should be avoided leading to inefficient of irrigation. The distance between the sensor and the emitter has direct influence on its output. The TOPDEA sensor has proven to be accurate and efficient in the management of irrigation. / A comunidade científica mundial, nos últimos anos, tem intensificado os estudos para mensurar os impactos causados ao ambiente pela poluição, principalmente os efeitos adversos ao ar e água. O fato de menos de 1% da água ser potável e estar disponível à superfície da terra torna a mesma um bem de conflito. Segundo a FAO até 2030 será necessário um incremento de 14% da água potável, na irrigação, a fim de suprir a demanda provocada pelo crescimento da população mundial. Um dos problemas clássicos, no manejo da irrigação, é determinar quando e quanto irrigar e no intuito de sanar tal problema, profissionais da área de engenharia buscam cada vez mais, através de pesquisas, aumentar a eficiência de irrigação. O presente trabalho teve como objetivo avaliar um sensor de umidade, do tipo capacitivo, denominado TOPDEA, no manejo da irrigação. A umidade do solo é o indicador mais básico da água em uma amostra de solo. O monitoramento da umidade do solo é um dos fatores mais importantes para manejo correto da irrigação, contribuindo de forma direta para a determinação de quando e quanto irrigar. O experimento foi realizado no Perímetro Irrigado do Baixo Acaraú – Ceará, em duas áreas distintas: A primeira com banana para ensaios preliminares de campo e avaliação da equação de calibração do sensor e a segunda com melancia para o manejo da irrigação propriamente dito. Os sensores foram calibrados através de análise de regressão entre umidade e freqüência produzida pelos mesmos, partindo do ponto de saturação até aproximadamente 4% de umidade. A avaliação da equação de calibração ocorreu através da comparação entre os dados dos sensores e os dados da estação meteorológica, para tempo de irrigação. O número de sensores por hectare foi analisado pela comparação entre o número de sensores por hectare e seus respectivos tempos de irrigação. O efeito geométrico da distância de instalação dos sensores, em relação aos emissores, foi analisado através do teste de médias das leituras com as respectivas distâncias de instalação. A equação de calibração para a umidade foi do tipo potencial ( 1778371018 −2,3894213 q = f ). As maiores leituras de frequência ocorreram com o sensor instalado a 25,3 cm do emissor, enquanto que as menores ocorreram a 19,85 cm. Os maiores tempos de funcionamento do sistema de irrigação ocorreram utilizando-se dois sensores por hectares, enquanto os menores tempos ocorreram utilizando-se cinco sensores por hectare. A lâmina total de irrigação utilizando-se sensores foi de 377,96 mm, o que resultou em um volume total de água igual a 532,17 m³ para todo o ciclo da cultura. A produtividade foi de 36,0 t ha-1 e a eficiência do uso da água foi de 0,068 kg L-1. A produtividade da água foi de 16,18 a 26,47% superior àquela obtida com o manejo da irrigação local praticado no perímetro para a cultura da melancia. Dada a característica de armazenamento do solo, deve-se fracionar a irrigação com a primeira ocorrendo nas primeiras horas da manhã. Assim, a irrigação noturna de uma grande lâmina (prática comum do Perímetro) conduz à ineficiência da irrigação. A distância entre o sensor e o emissor tem influência direta da resposta do mesmo. O sensor TOPDEA mostrou-se preciso e eficiente no manejo da irrigação.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A comunidade cientÃfica mundial, nos Ãltimos anos, tem intensificado os estudos para mensurar os impactos causados ao ambiente pela poluiÃÃo, principalmente os efeitos adversos ao ar e Ãgua. O fato de menos de 1% da Ãgua ser potÃvel e estar disponÃvel à superfÃcie da terra torna a mesma um bem de conflito. Segundo a FAO atà 2030 serà necessÃrio um incremento de 14% da Ãgua potÃvel, na irrigaÃÃo, a fim de suprir a demanda provocada pelo crescimento da populaÃÃo mundial. Um dos problemas clÃssicos, no manejo da irrigaÃÃo, à determinar quando e quanto irrigar e no intuito de sanar tal problema, profissionais da Ãrea de engenharia buscam cada vez mais, atravÃs de pesquisas, aumentar a eficiÃncia de irrigaÃÃo. O presente trabalho teve como objetivo avaliar um sensor de umidade, do tipo capacitivo, denominado TOPDEA, no manejo da irrigaÃÃo. A umidade do solo à o indicador mais bÃsico da Ãgua em uma amostra de solo. O monitoramento da umidade do solo à um dos fatores mais importantes para manejo correto da irrigaÃÃo, contribuindo de forma direta para a determinaÃÃo de quando e quanto irrigar. O experimento foi realizado no PerÃmetro Irrigado do Baixo Acaraà â CearÃ, em duas Ãreas distintas: A primeira com banana para ensaios preliminares de campo e avaliaÃÃo da equaÃÃo de calibraÃÃo do sensor e a segunda com melancia para o manejo da irrigaÃÃo propriamente dito. Os sensores foram calibrados atravÃs de anÃlise de regressÃo entre umidade e freqÃÃncia produzida pelos mesmos, partindo do ponto de saturaÃÃo atà aproximadamente 4% de umidade. A avaliaÃÃo da equaÃÃo de calibraÃÃo ocorreu atravÃs da comparaÃÃo entre os dados dos sensores e os dados da estaÃÃo meteorolÃgica, para tempo de irrigaÃÃo. O nÃmero de sensores por hectare foi analisado pela comparaÃÃo entre o nÃmero de sensores por hectare e seus respectivos tempos de irrigaÃÃo. O efeito geomÃtrico da distÃncia de instalaÃÃo dos sensores, em relaÃÃo aos emissores, foi analisado atravÃs do teste de mÃdias das leituras com as respectivas distÃncias de instalaÃÃo. A equaÃÃo de calibraÃÃo para a umidade foi do tipo potencial ( 1778371018 −2,3894213 q = f ). As maiores leituras de frequÃncia ocorreram com o sensor instalado a 25,3 cm do emissor, enquanto que as menores ocorreram a 19,85 cm. Os maiores tempos de funcionamento do sistema de irrigaÃÃo ocorreram utilizando-se dois sensores por hectares, enquanto os menores tempos ocorreram utilizando-se cinco sensores por hectare. A lÃmina total de irrigaÃÃo utilizando-se sensores foi de 377,96 mm, o que resultou em um volume total de Ãgua igual a 532,17 m para todo o ciclo da cultura. A produtividade foi de 36,0 t ha-1 e a eficiÃncia do uso da Ãgua foi de 0,068 kg L-1. A produtividade da Ãgua foi de 16,18 a 26,47% superior Ãquela obtida com o manejo da irrigaÃÃo local praticado no perÃmetro para a cultura da melancia. Dada a caracterÃstica de armazenamento do solo, deve-se fracionar a irrigaÃÃo com a primeira ocorrendo nas primeiras horas da manhÃ. Assim, a irrigaÃÃo noturna de uma grande lÃmina (prÃtica comum do PerÃmetro) conduz à ineficiÃncia da irrigaÃÃo. A distÃncia entre o sensor e o emissor tem influÃncia direta da resposta do mesmo. O sensor TOPDEA mostrou-se preciso e eficiente no manejo da irrigaÃÃo. / The scientific community, in recent years, has intensified studies to measure the impacts to the environment caused by pollution, mainly the adverse effects to air and water. The fact that less than 1% of the global water resources is comprised of drinking water and available at the surface of the earth makes it a commodity of conflict. According to the FAO by 2030 to meet the demand caused by the growth of the world population a 14% increase in available drinking water will be required for irrigation. To meet that expectation, the classical questions of when and how much to irrigate needs to be assessed. Thus, professionals in the fields of engineering have especially focused on practices to increase the efficiency of irrigation. This study aimed at evaluating a moisture sensor, a capacitive type, called TOPDEA, in irrigation management. The soil moisture is the most basic index to quantify water in a soil, expressed in units of mass or volume. The monitoring of the soil moisture is one of the most important factors for proper irrigation management. The experiment was carried out in the Irrigated Perimeter of the Lower Acaraà Basin â CearÃ, in two different fields: The first one cultivated with bananas where preliminary tests were conducted to evaluate the sensor calibration, and the second one with watermelon for irrigation scheduling. The sensors were calibrated by means of the regression analysis between moisture and frequency output of the sensors from saturation to approximately 4% moisture content. The calibration was validated by comparing resulting irrigation timing produced by scheduling the irrigation with sensors and with a weather station. The number of sensors per hactare was analyzed by analyzing the timing of irrigation for each additional sensor in the field. The effect of the placement of the sensors (position in relation to the dripper and plant) was evaluated. The calibration equation for the sensor was found to be potential ( 1778371018 −2,3894213 q = f ). The highest readings occurred with frequency of the sensor installed 25.3 cm from the emitter, while the lowest occurred at 19.85 cm. The largest irrigation time was found when two sensors were used for each hectare, while the lowest was found using five sensors per hectare. The total irrigation depth with the scheduling conducted with capacitive sensors was 377.96 mm, which resulted in a total volume of 532.17 m of water in the entire cycle of watermelon. Crop yield was 36.0 t ha-1 and the water efficiency of 0.068 kg L-1. Water productivity was 16.18 to 26.47% higher compared to the irrigation management commonly practiced in the irrigation district for watermelon. Given the characteristic of soil physics with low water storage capacity, the daily irrigation requirement must be fractioned into several irrigation pulses starting early morning and the application of the total daily requirement in one irrigation event during the night (practice commonly conduction in the district to reduce the electricity bill) should be avoided leading to inefficient of irrigation. The distance between the sensor and the emitter has direct influence on its output. The TOPDEA sensor has proven to be accurate and efficient in the management of irrigation.

Doctor of Philosophy / Department of Agricultural Economics / Jeffrey M. Peterson / Nathan P. Hendricks / 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.

This dissertation endeavours to provide a practicable method to evaluate any existing or proposed irrigation water use against the purpose of the National Water Act (Act 36 of 1998) (NWA) as described in section 2. It firstly focuses on section 2(d) of the NWA, which requires the promotion of efficient, sustainable and beneficial use of water in the public interest. Although the evaluation of the degree to which this purpose is being achieved by a specific irrigation water use is the topic of this dissertation, it is further argued that by viewing this aspect comprehensively enough, it actually covers five other requirements of section 2, concerning irrigation water use. The efficiency and effectiveness of the irrigation operation is evaluated. It includes irrigation technology aspects, the efficiency of the relevant irrigation systems and water supply infrastructure, irrigation management skills and the proper application of best management practices by the irrigator that determines the overall efficiency and effectiveness of the irrigation operation. Aspects that determine sustainability of the particular water use that are included in the evaluation, entail among others the protection of the water resource (surface and groundwater) and other natural resources, the riparian habitats and all relevant aquatic ecosystems. Other aspects concerning sustainability are the prevention and control of the chemical pollution of the water and soils resources through the irrigation process, as well as salination and water-logging of land through wrong agricultural and irrigation practices. A further aspect is investigated here for a particular water use namely whether it really represents beneficial use in the public interest, by analysing the socio-economical and political considerations unique to every particular situation. This also requires the consideration of intangible benefits and costs, which are by nature subjective and for which the specific requirements will differ from the one situation to the other. In order to provide a procedure that is transparent and consistent enough to withstand any challenge from users or proposed users in this regard, it has been decided to utilise amongst others the BBBEE scorecard, which has been developed and is presently being implemented by government, also in terms of section 27(1)(b) of the NWA. / Dissertation (MEng)--University of Pretoria, 2008. / Civil Engineering / unrestricted

In South Africa, the limited extent of indigenous forests accelerated the development of fast-growing introduced species plantations, on which the country is now heavily reliant for its fibre and timber products. However, the plantation forestry industry is challenged with limited freshwater resources, the need for sustainable management of introduced tree species in commercial forest production systems, and a diversity of plant ecological production factors such as soils that have to be manipulated for the purposes of increasing production capacities. Additionally, plantations are established in the limited high rainfall regions of the country and the industry’s water use has been regulated since 1972. Conversely, natural forests also provide valuable goods, however, their slow growth rates have restricted their development as commercial tree production systems. In this regard the forestry industry is continuously seeking to provide for the country’s timber and fibre needs while ensuring the provision of other ecosystem services from tree production systems. Recent developments in the forestry industry have therefore been focused on water use efficiency in current and alternative tree production systems. There is also widespread unsubstantiated belief that indigenous tree species are efficient users of water. Against this background this study sought to explore the single tree water use and water use efficiencies of introduced commercial plantation species (Pinus radiata) and that of important indigenous species (Ilex mitis, Ocotea bullata and Podocarpus latifolius) for timber and fibre production in the southern Cape region of South Africa. Single tree water use measurements were carried out for a year using the heat pulse velocity method. Growth measurements for utilisable stem wood were done on a quarterly basis for the specimen trees and growth increments over the year were determined. Single tree water use efficiency was a calculated as a function of grams of stem wood gained per litre of water transpired. Measurements of daily weather conditions and soil water content were concurrently taken during the year. The relationships between the variables that express daily climatic conditions, soil water content and daily volumes of transpired water were explored. Empirical models for the prediction of daily transpiration as a function of climate and soil water content were then developed using multiple linear regression analysis. Pinus radiata trees exhibited higher totals of volumetric transpiration than the indigenous species. The water use patterns of Pinus radiata showed higher peaks of maximum and minimum daily and seasonal water use while the indigenous species showed temperate patterns of water use throughout the year. Podocarpus latifolius attained the lowest water use efficiency in the year (0.49g/L) while Pinus radiata, Ocotea bullata and Ilex mitis had comparable water use efficiency values ranging between 1g/L to 2.50g/L. Significant positive correlations existed between climatic variables and daily sapflow volumes of the tree specimens. Daily total solar radiation showed the highest positive correlation with daily transpiration and the average value of the correlation coefficient for solar radiation and water use for all tree species was 0.70 (p < 0.001). Empirical models for predicting daily water use integrated the variables expressing plant available moisture and energy. The study enhances our understanding of single tree water use, water use efficiency, the drivers of transpiration and the applicability of such studies in developing rapid estimation techniques for water use in current and alternative South African tree production systems.

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. / Master of Science

Call number: LD2668 .T4 1985 M49 / Master of Science

O Projeto de Irrigação Genil-Cabra (PIGC), Coletividade Santaella, está localizado na província de Córdoba-Espanha. Nesse Distrito avaliou-se a irrigação das campanhas de 2004/2005 e 2005/2006. Como complementações, foram realizadas entrevistas com os agricultores, objetivando determinar os custos de produção da área, a adoção das novas tecnologias, por parte da comunidade, a orientação do Sistema de Assessoramento ao Irrigante SAR , a produtividade e o consumo da água em cada parcela. Após a coleta dos dados, foram determinados indicadores, como a eficiência da irrigação, a produtividade da água e a relação benefício-custo do investimento. Para determinar a eficiência da irrigação, a pesquisa seguiu a metodologia utilizada por Mateos (2007). Como complementação a essa metodologia, foram introduzidas outras ferramentas, como DEM, SIG e entrevistas com os agricultores. No trabalho realizado por Fernandez et al. (2007), essa área estava dividida em 17 parcelas, denominadas recintos. Definiu-se uma nova delimitação da área, por meio de um DEM mais preciso e, após a nova delimitação e a realização da entrevista, identificou-se a necessidade de dividi-la em áreas de cadastro ou parcelas, com informações do produtor e do site oficial de cadastro. Dessa forma, a área passou a ter 33 parcelas, dando maior amplitude à pesquisa. Depois de entrevistar os agricultores e de comparar as informações com as ortofotos obtidas pelo site de cadastro, pôde-se identificar cultivos diferenciados dos citados por Fernandez et al. (2007). Esse fato foi importante para definir a eficiência do uso da água, visto que as áreas globais foram alteradas e, como exemplo, observou-se que o cultivo com oliveira foi menor do que o citado por Fernandez et al. (2007). Na campanha de 2005, tal cultivo ocupou uma extensão de 105,61 ha; já na de 2006, com o cultivo de novas áreas com oliveiras, esse valor passa para 112 ha, que contrastam com os 169,25 ha, calculados anteriormente. A eficiência da irrigação do ano da campanha de 2005 foi 81,99% e no de 2006, 90%, o mesmo encontrado por Fernandez et al. (2007), o que se justifica pela irrigação deficitária realizada no PIGC. Em relação à produtividade da água (PW), observa-se que os maiores valores foram detectados pela análise por recinto, tanto em 2005 quanto em 2006, justificadas pelo baixo volume de água demandado, observado nos sensores. No cálculo para a PW na parcela, usa-se, como denominador, a evapotranspiração da cultura, enquanto, no cálculo da PW do recinto, usa-se o volume de água que entra na área, ou seja, a água aplicada. Visto que a irrigação foi deficitária, então certamente haverá uma maior produtividade da água no nível do recinto. Os valores obtidos foram 4,06;0,37 m-3 para recintos e parcelas (2005) e 6,60;0,27 m-3 (2006). Esses valores são similares aos encontrados por Garcia-Vila et al. (2008) e Lorite et al. (2004b). Em relação à avaliação socioeconômica, pôde-se concluir que os irrigantes possuem plena consciência do uso correto da irrigação, porém não confiam nos dados do SAR, já que praticamente nenhum deles aceita a recomendação diária ofertada por esse serviço. / The Genil-Cabra irrigation scheme (GCIS), Coletividade Santaella, is located in Andalusia, southern Spain. This irrigation district has a strong run-government performance helping the private sector to do applied researches, whose investments brings good results to the farmers. It was evaluated the irrigation in 2004/2005 season and 2005/2006 season. To complement the work, it was done interviews with the farmers in the studied area to determine: production cost of the area, the technologies adoption, the orientation of farmer helping system (Servicio de Asesoramiento al Regante; SAR), the yield and water consumption in each parcel. After collecting all data it was made a study to determine indicators, such as irrigation efficiency, water productivity and cost/benefit relationship of the investments. To determine irrigation efficiency was followed the methodology used by Mateos (2007) complemented with the SIG and farmer interviews. In work made by Fernandez et al. (2007), this area was divided in 17 parcels called recintos. It was defined a new area delimitation through a land digital model more precise, and after the new delimitation and the interviews, it was realized a necessity to divide them in record areas or parcels, it identified by the farmers and by the record official web. In this way, the area became has to 33 parcels, and it gives bigger range to research. After the farmer interviews and compared the information with the orthophotos obtained from the record web it was identified crops differentiated from Fernandez et al. (2007). This fact was important to define the water use efficiency, due the global areas were altered, for example, it was observed that olive cultivation was smaller than cited by Fernandez et al. (2007). In the 2005 season occupied an area of 105.61 ha, however in the 2006 season it was 112 ha due the increase in olive area, that contrasted with 169.5 ha calculated previously by Fernandez et al. (2007). The irrigation efficiency in the 2005 season was 81.99% and in 2006 was 90%, same values encountered by Fernandez et al. (2007), that is due the deficit irrigation realized in the GCIS. In relation to water productivity (WP), it was observed that the biggest values were detected by recinto analyze, both in 2005 and 2006 season, due to low water volume demanded, observed in the sensors. In the parcel WP calculation, it was used the crop evapotranspiration as denominator; however in the recinto WP calculation it was used the applied water. Since the irrigation was deficiency, then likely will have a bigger WP in the recinto level. The values obtained were 4.06;0.37( m-3) to recintos and parcels (2005) and 6.60;0.27( m-3) to recintos and parcels (2006). These results are similar to encountered by Garcia-Vila et al. (2008) and Lorite et al. (2004b). In the socio-economic evaluation from the area could be concluded that irrigators have a full conscience of irrigation correct use, however they dont trust in the SAR database, since most of them don´t accepted the diary recommendation offer by this service.