Dissertations / Theses on the topic 'Irrigation efficiency'

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.

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.

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.

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

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.

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.

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.

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.

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)

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.

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.

<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

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

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.

Philosophiae Doctor - PhD<br>Nigeria, like many African countries is caught up in the uncertainty of the effectiveness of agricultural intervention in achieving food security, poverty reduction and improved quality of life. This ambiguity is more pronounced especially in rural areas where majority of the poor and those involved in agriculture reside. Indeed, issues relating to resource utilization and productivity in the agricultural sector and how they affect livelihoods and food security of smallholder households remain underexplored. The study examines the contribution of small-scale irrigation agriculture towards ensuring food security and poverty alleviation among smallholder households. It assesses the productivity, food security and livelihoods status of smallholder households in the Middle Rima Valley Irrigation Project, North West Nigeria, the relationship that exist between the phenomena, as well as factors influencing them. It also explores smallholder households’ differentials on the basis of their efficiency, food security and income status, and what other factors determine the smallholder typologies. The research was situated within three bodies of theoretical work; political ecology, political economy of food and agriculture, and sustainable livelihoods. This was done with a view to providing a nuanced understanding of both the micro and macro processes and factors influencing agricultural production, food security and livelihoods of smallholder households. A concurrent triangulation mixed methods research design was adopted for the study. This involves the use of both quantitative and qualitative methods of research to drive the research agenda. Systematic random sampling technique was used to collect data for the quantitative aspect and purposive sampling was used to select participants for semi-structured interviews for the qualitative research. A total of 370 questionnaires were administered but 306 questionnaires were successfully completed and returned, representing an 83% response rate. Also eight respondents were interviewed for the study. While thematic content analysis was used to analyse the qualitative data, quantitative data was analysed using both descriptive and inferential statistics.

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.

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.

Application of anaerobic swine (Sus scrofa domesticus) lagoon liquid onto cropland by irrigation is a common method of waste disposal and treatment. Currently, the application rate of swine lagoon liquid is based on the N concentration of the lagoon liqu id and the N required by the receiver crop to obtain a realistic yield. In North Carolina, only 50% of the total N in the swine lagoon liquid applied by irrigation is considered available for plant use during the first year after application. Uncertaint y exists as to whether this coefficient accurately predicts the amount of plant-available N. Therefore, research was conducted in the Coastal Plain of North Carolina to determine the efficiency of N uptake by corn (Zea mays L.) and soybean (Glycine max M errill) receiving swine lagoon liquid through irrigation. The line-source sprinkler irrigation method was used to provide a continuous variable N rate, ranging from 0 to 290 kg N/ha, across the field during 1999 and 2000. Ammonia volatilization losses r anged from 6 to 22% during irrigation. Crop yield and grain N recovered were affected more by the amount of liquid than N applied in 1999. Nitrogen recovered in grain in 1999 was <15% for both corn and soybean at 168 kg N/ha of either swine lagoon liqui d or ammonium nitrate. In 2000 at the 168 kg N/ha rate, grain N removal by corn, nonnodulating soybean, and nodulating soybean was 28, 25, and 39% from swine lagoon liquid and 45, 31, and 56% from ammonium nitrate. Based on yields and grain N removed by corn and nonnodulating soybean in 2000, N from applied swine lagoon liquid, accounting for N losses during irrigation, was about 70% as effective as ammonium nitrate. Symbiotic N2 fixation by the soybean was reduced by 60% when applied N reached 175 kg N/ha for both ammonium nitrate and swine lagoon liquid. While nodulating soybean removed more grain N than did either corn or nonnodulating soybean in 2000, soil inorganic N concentrations at the end of the growing season were higher for the nodulating s oybean. Therefore, it is not conclusive if soybean would be a better receiver crop than corn for swine lagoon liquid. Based on the results of this study, using the 50% available N coefficient of the lagoon liquid comes close to predicting plant-availabl e N when N losses during irrigation are around 25%. Nitrogen losses during irrigation can significantly affect plant-available N when applied N is based on the N concentrations of the lagoon liquid.

This project assessed the contribution of Vertosols to the nitrogen supply of cotton in Darling Downs region, Australia. Two years of nitrogen dynamics measurements throughout the soil profile under field and laboratory conditions demonstrated that, on average, 87 per cent of nitrogen was supplied by the soil to the cotton crop. This research provides a practical framework for establishing a sustainable nitrogen management strategy to enable efficient use of nitrogen in irrigated cotton production. The results of this research are potentially applicable to similarly managed cropping systems in vertosols.

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.

14 pp.<br>This publication summarizes the results of a three year research study that evaluated whether the turf water duties mandated by the Arizona Department of Water Resources provide adequate water to grow acceptable quality turf in the Tucson and Phoenix areas.

Cotton (Gossypium hirsutum L.) grown under drip irrigation was evaluated over a two year period for physiological and morphological responses. Three water levels representing, 103, 93 and 87% of estimated consumptive use (63.6 ha-cm) were used in Marana, AZ. in 1983. In 1984, cotton was grown under eight drip irrigation treatments corresponding to 120, 100, 80 and 60% of the estimated consumptive use (79.5 ha-cm) in Stanfield, AZ. These volumes of water were applied as small daily amounts and larger weekly amounts for a total of eight irrigation treatments. The experimental design was a randomized complete block with four replications. Mean leaf area ratio (LAR), leaf area index (LAI), mean net assimilation rate (NAR), mean relative growth rate (RGR), mean crop growth rate (CGR), plant height and the number of mainstem nodes were determined using the growth analysis method. Transpiration, diffusive resistance, leaf and ambient temperatures were measured with a steady state porometer. Apparent photosynthesis (APS) was determined in 1983 with an infrared gas analyzer which measured CO(,2) concentrations. In 1983, the cotton plants from the 103% irrigation treatment had greater transpiration, lower diffusive resistance and lower APS than the 93% treatment plants. In 1984, no significant differences were observed between the seasonal transpiration rates from the eight irrigation treatments. Cotton plants grown under the 120% treatment showed superior diffusive resistance responses than those from the 60% treatment. Temperature differentials were higher in the 120% treatments than in the 60% treatments. No significant differences were found between LAR, NAR, RGR and CGR during 1983 and 1984. Even though there were no differences between the total number of flowers produced in the three treatments in 1983, the 93 and 87% treatment plants produced more seed cotton than the 103% treatment plants. In 1984, the seed cotton yield from the 60% daily treatment was significantly the lowest. Due to the problems related to the late initiation of treatments and excessive rainfall, the physiological and morphological responses of cotton were inconsistent across the various water levels in 1983. Regression analysis confirmed the erratic responses of cotton plants from the weekly treatments across the wide range of environmental conditions in 1984.

This dissertation explores the possible differential influence of territorial features on the performance of irrigation improvement programs in Egypt. The study was conducted in El-Mahmoudia main canal, Beheira governorate which is one of the command areas in Nile Delta where Integrated Irrigation Improvement and Management Project (IIIMP) was applied in accordance with the principles of Integrated Water Resources Management (IWRM). Three branch canals on El-Mahmoudia main canal were purposively selected to represent the current situation of improved and unimproved irrigation systems. The first is a successful improved branch canal (Kafr Nikla); the second is relatively less successful improved branch canal (Besentway), and; the third one is unimproved sub-branch canal from El-Mahmoudia canal (Ganabet Bastara & El Ziana). A simple random sample of 220 water users (25%) was drawn from the total estimated number of water users on the selected branch canals (160 from improved branch canals and 60 for unimproved ones). Mesqas' locations on branch canals, and water users' land locations on mesqas (upstream/ midstream/ downstream) were taken into account to represent the current situation of irrigation systems in these areas. Data were collected through personal interviews by using a semi-structured questionnaire designed and pretested to achieve the study objectives. Findings indicate that in improved areas, there are statistically significant and positive correlations between specific proximity dimensions (cognitive, and social) and each of IIIMP and BCWUAs' performances. Meanwhile, results point to a significant positive relationship between organizational proximity and IIIMP performance. Among the different proximity dimensions, there are significant positive relationships between: cognitive and social; cognitive and organizational, and; social and organizational proximities. Comparing the studied branch canals (Nikla and Besentway) within two different territories, there is a significant positive correlation between social proximity and mesqas' geographical location of the successful branch canal (Nikla). However, there are significant and negative relationships between Besentway's mesqas geographical locations and each of: cognitive proximity, social proximity, and IIIMPs' performance. These findings lead to an empirical evidence that cognitive, social, and organizational proximities have a strong role in supporting the implementation of IWRM.<br>Questa dissertazione esplora la possibile influenza differenziale delle caratteristiche territoriali sulla performance dei programmi di miglioramento dell'irrigazione in Egitto. Lo studio è stato condotto nel canale principale di El-Mahmoudia, nel governatorato di Beheira, una delle aree di comando del delta del Nilo, dove è stato applicato il progetto di miglioramento e gestione dell'irrigazione integrata (IIIMP) in conformità con i principi della gestione integrata delle risorse idriche (IWRM). Tre canali di diramazione sul canale principale di El-Mahmoudia sono stati scelti appositamente per rappresentare la situazione attuale di sistemi di irrigazione migliorati e non migliorati. Il primo è un canale di diramazione migliorato con successo (Kafr Nikla); il secondo è un canale di diramazione migliorato relativamente meno riuscito (Besentway), e; il terzo è un canale sub-branch non migliorato dal canale El-Mahmoudia (Ganabet Bastara e El Ziana). Un campione casuale semplice di 220 utenti di acqua (25%) è stato estratto dal numero totale stimato di utenti di acqua sui canali di diramazione selezionati (160 da canali di diramazione migliorati e 60 per canali non migliorati). Le posizioni di Mesqas sui canali delle filiali e le località terrestri degli utenti di acqua su mesqas (a monte / a valle / a valle) sono state prese in considerazione per rappresentare la situazione attuale dei sistemi di irrigazione in queste aree. I dati sono stati raccolti attraverso interviste personali utilizzando un questionario semi-strutturato progettato e pretestato per raggiungere gli obiettivi dello studio. I risultati indicano che nelle aree migliorate esistono correlazioni statisticamente significative e positive tra le dimensioni di prossimità specifiche (cognitive e sociali) e ciascuna delle prestazioni dell'IIMP e delle BCWUA. Nel frattempo, i risultati indicano una significativa relazione positiva tra prossimità organizzativa e rendimento dell'IIMP. Tra le diverse dimensioni di prossimità, vi sono relazioni positive significative tra: cognitive e sociali; cognitivo e organizzativo, e; prossimità sociale e organizzativa. Confrontando i canali delle diramazioni studiati (Nikla e Besentway) all'interno di due diversi territori, esiste una significativa correlazione positiva tra la prossimità sociale e la posizione geografica dei mesqas del canale branch di successo (Nikla). Tuttavia, vi sono relazioni significative e negative tra le località geografiche di Besentway e ognuna delle seguenti: prossimità cognitiva, prossimità sociale e prestazioni degli IIIMP. Queste scoperte portano a una prova empirica che le distanze cognitive, sociali e organizzative hanno un ruolo importante nel supportare l'attuazione dell'IWRM.

Water is Australia's most precious natural resource. The quality, quantity and availability of this resource is the single factor most limiting agricultural development and sustainability in this country. Since the development of Australia's cotton industry in the 1960's, and the expanding areas of irrigated crop, there has been an increasing demand placed on the limited water resources of the country. Consequently, the cotton industry has been the target of protest from conservation groups, residents of rural townships and others farmers engaged in competing rural sectors. Therefore, cotton farmers need to develop best practice in terms of water use efficiency. Not only does this make good ecological sense but also good economic sense. Traditional methods of irrigation scheduling have proven to be subjective and haphazard. Recently developed methods, while providing more quantitative techniques, do not give a synoptic view of a field's or region's crop moisture status. The main objective of this project was to evaluate an airborne thermal scanner (8-12 µm) as practical tool for monitoring the water requirements of an irrigated cotton crop. The thermal scanner was mounted below a light aircraft and imagery was collected over Field 86 , Togo Station, north-west NSW during the summer of 1990/91. The field was divided into nine treatments for the purpose of this project. Three irrigation regimes (early, normal and late) with three repetitions were applied to the nine treatments. A total of fourteen images were selected for analysis. These images were grouped into sets of AM images, PM images as well as diurnal groupings which were interpreted for three separate dates during the growing season. Ground based measurements of infrared crop surface and soil temperature, soil moisture deficit, leaf area index (LAI) and the Crop Water Stress Index (CWSI) were collected to calibrate the airborne imagery. Imagery was in the first instance visually interpreted to determine what information could be gained from this technique. Patterns on the imagery were related to diurnal variations in soil and crop temperatures. This investigation revealed a number of soil related phenomena inherent to the field which were influencing the airborne detected temperatures. While this technique showed variability across the field, the interpretation was somewhat subjective. Temperature values were extracted from the imagery in order to conduct an analysis of variance (ANOVA) between the airborne and ground measurements of infrared crop surface temperature. In summary, this analysis did not show a strong relationship between the airborne and ground based measurements. A number of contributing factors have been proposed as the reason for this variation in the two datasets. Pearson's correlation analysis was applied to the AM (r = 0.65) and PM (r = 0.32) groups of airborne and ground temperatures. Airborne derived calculations of the CWSI were compared to ground based measurements for the AM group of flights. These derived values were only acceptable in instances where the ANOVA results had shown them to approximate the ground based measurements. While airborne thermal imagery provides a useful tool for determining general variations in temperatures across a field, there are many additional factors, the most dominant being the thermal characteristics of the background soil, which influence the detected temperatures. This technique does not provide the precise quantitative information required to accurately determine across-field measurement of the CWSI.

Sustainable vegetable production is one of the most active areas of vegetable research and of concern to all producers. Everyone, both producers and consumers, are concerned with sustainability. Brussels sprouts and sweet basil are high value commodities, but increasing global concerns about water availability, insect-pest problems, and costly fertilizer inputs severely impact the growth and production of these crops. Low tunnels covered with spun-bonded fabric can improve production of vegetables and herbs in Virginia and the U.S. This study investigated the performance of Brussels sprouts and basil grown under low tunnels (LTs), and their relationship with water use efficiency, nitrogen use efficiency, and the level of protection against insect injury. Low tunnels increased yield, number of sprouts, and water use efficiency of Brussels sprout production. In addition, LTs decreased irrigation requirements, irrigation events, leaf feeding injury, and insect populations in comparison to open field. Similarly, LTs increased summer production of sweet basil as measured by fresh weight and biomass. In addition, plant N uptake was greater under the LTs; however, the increase in nitrogen use efficiency was inconsistent.<br>Master of Science in Life Sciences<br>Brussels sprouts and sweet basil are economically important cash crops on the East Coast. Brussels sprouts is a Cole crop and an important source of dietary fiber, vitamins (A, C & K), calcium, iron, manganese and antioxidants. Similarly, sweet basil is a member of the mint family and important high-value herb in the U.S. and the world. It is mainly grown for culinary purposes as a dried and fresh spice in the U.S. However, demand for these commodities is increasing. Low tunnels (LTs) covered with spunbonded fabric can be a practical management tool to increase yield. Results from this study indicate that LTs increase yield of Brussels sprouts and basil, water use efficiency and total nitrogen uptake, while reducing insect pest infestation. Therefore, LTs can be a useful tool to improve sustainability of Brussels sprouts and basil production.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico<br>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 &#8722;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.<br>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 &#8722;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.

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.<br>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)<br>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)<br>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<br>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.<br>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.

The PhD thesis’s aims was to investigate some theoretical and practical aspects of water irrigation used in small- and large-scale field tests. The first study analyzed the effect of the incident rainfall redistribution due to corn canopy and the effect of micro-variability of soil’s hydrological process at the row scale. Results of this study showed that the mean of throughfall and stemflow was 24% and 76% respectively, while the ratio stemflow/throughfall decreases during rainfall increases as logarithmic function. The stemflow/throughfall ratio was used to model the rainfall redistribution by Hydrus 2D/3D to simulate the crop evapotranspiration (ET) under 3 conditions: 1. sprinkler irrigation 2. precision downwards canopy application 3. hypothetical uniform application. The results of simulation by ET are hereby described. The condition 3 (hypothetical uniform application) got the best ET’s efficiency; the condition 2 (precision downwards canopy application) was more efficient compare to the condition 1 (sprinkler irrigation). The second topic concerned two field experiments to investigate the drip irrigation systems efficiency and the water distribution uniformity: the first trial was made in Verona province, on corn and the second one in Mendoza Argentina, on vineyards. The first experiment considered the effect of the uniformity distribution of two irrigation systems (drip irrigation and sprinkler irrigation) on waxy corn yield. According to DUlq and CU indexes the results showed a good water uniformity distribution in drip irrigation system and a poor uniformity using sprinkler irrigation. The water use efficiency of drip irrigation was lower than sprinkler irrigation (-42% for IWUE and -26% for WUEb), this was caused by the different management, in fact the first one was scheduled, while the second one was supplemental. No statistical correlation was found between water flow and yield for both irrigations systems, while a significant one was found between water flow and crop water use efficiency. The net profit of drip irrigation was slightly higher than sprinkler irrigation. The second experiment analyzed the effect of the distribution uniformity with drip irrigation on some vineyard yield features. Furthermore was made a comparison between surface irrigation and drip irrigation by LANDSAT satellite multispectral images. Results showed an excellent water distribution uniformity and a poor correlation between water flow and vineyard features. Vegetation indexes put into evidence a greater canopy vigor with drip irrigation compared to the surface irrigation, this highlighting that the drip irrigation is more efficient compared to surface irrigation. Finally, a study of large-scale irrigation requirements was carried on within the Piave Irrigation district, located on the north of the province of Treviso. It was designed a GIS model for water supply simulations in homogeneous areas, starting from a survey of a sample of farmers, with a questionnaire on the main features that characterized: farm irrigation, water flows, irrigation rotations, integrated with the soils map, land cover map and meteorological data. Results showed that the using water efficiency improves decreasing the monthly rotation length and increasing the rotation frequency maintaining the crop yields.<br>La tesi di dottorato si propone di studiare alcuni aspetti teorici e pratici, sia su scala di campo che su scala territoriale, relativi all’uso razionale dell’ acqua con l’irrigazione. Il primo studio riguarda la quantificazione degli effetti correlati all’intercettazione fogliare dell’acqua di pioggia e irrigua in un campo investito a mais e l’effetto di questo fenomeno, a livello della fila, sulle dinamiche dell’acqua nel suolo. I risultati delle prove evidenziano che l’intercettazione fogliare si ripartisce mediamente per il 24% in throughfall (acqua che cade dalle foglie direttamente al suolo) e per il 76 % in stemflow (acqua che arriva al suolo scorrendo lungo il culmo); si è anche riscontrato che il rapporto stemflow/throughfall diminuisce in modo logaritmico all’aumentare della pluviometria. Successivamente, utilizzando la curva che descrive la ripartizione dell’acqua al variare della pluviometria e i dati di umidità rilevati durante il periodo di prova, si è simulato in termini di evapotraspirazione del mais, con il programma Hydrus 2D/3D, l’effetto dell’intercettazione vegetale, di un’ipotetica distribuzione uniforme al suolo e di un sistema di irrigazione localizzata. Dalle simulazioni appare che l’evapotraspirazione è superiore per l’ipotetica distribuzione uniforme rispetto al sistema localizzato, entrambi però superiori rispetto al flusso ripartito dalla copertura vegetale. Il secondo argomento riguarda due sperimentazioni che sono state condotte per valutare l’efficacia dell’irrigazione a goccia nel razionalizzare l’uso dell’acqua: una in un’azienda situata nella provincia di Verona su mais ed una nella provincia di Mendoza in Argentina su vite. La prima ricerca sperimentale è stata condotta presso la Cooperativa Agricola Zootecnica “LA TORRE” di Isola della Scala (VR) e ha riguardato la valutazione dell’impatto dell’uniformità di distribuzione dei due sistemi irrigui sulla resa del mais a maturazione cerosa. I sistemi utilizzati sono stati da una parte l’irrigazione per aspersione gestita con interventi di soccorso e dall’altra l’ irrigazione a goccia gestita a calendario. È stata calcolata inoltre l’efficacia d’uso dell’acqua e la convenienza economica di entrambi i sistemi irrigui. L’uniformità di distribuzione, espressa mediante i coefficienti DUlq e CU, è risultata buona ma non ottima nel sistema microirriguo (DUlq 0,73 e CU 84,74%) a causa della lunghezza dell’appezzamento che ha portato a perdite di pressione nella parte terminale delle linee gocciolanti, mentre è stata bassa per l’aspersione (DUlq 0,33 e CU 58,94%) a causa soprattutto dell’errato posizionamento degli irrigatori che non consentiva una omogenea copertura dell’area. L’efficacia d’uso dell’acqua è stata superiore per il sistema irriguo a pioggia rispetto alla goccia, indicando che la gestione razionale dei volumi irrigui ha un’influenza maggiore rispetto all’uniformità di distribuzione. Dal bilancio economico di entrambi i sistemi irrigui è risultato che l’utile sul tal quale risulta appena superiore per il rotolone rispetto alla gestione a goccia. La seconda sperimentazione ha valutato l’effetto dell’uniformità di distribuzione dell’irrigazione a goccia su alcune caratteristiche delle piante di vite e il confronto con l’irrigazione superficiale mediante indici di vegetazione a partire da immagini satellitari Landsat. Questo lavoro sperimentale, realizzato in un’azienda viticolo frutticola nella zona est di Mendoza ha avuto tre obiettivi: 1) determinare l’impatto dell’uniformità di distribuzione sulla vite; 2) osservare l’effetto della conversione dall’irrigazione per scorrimento superficiale all’irrigazione a goccia mediante l’utilizzo di indici vegetativi a partire da immagini satellitari Landsat; 3) comparare la variabilità della resa e del diametro del tronco in viti irrigate a goccia e per scorrimento superficiale. I risultati indicano che l’uniformità di distribuzione dell’irrigazione a goccia, secondo i coefficienti DUlq, CU e CV, è stata eccellente nonostante si siano osservati un importante numero di orifizi ostruiti. Inoltre, si nota una bassa correlazione tra i parametri quantitativi e qualitativi della vite e la portata degli erogatori e la percentuale di orifizi ostruiti. Gli indici di vegetazione hanno permesso di verificare il significativo miglioramento dello stato vegetativo degli appezzamenti irrigati a goccia rispetto a quelli irrigati per scorrimento superficiale. Per ultimo, il confronto in termini di tendenza della variabilità di resa e diametro del tronco, mostra che negli appezzamenti irrigati a scorrimento superficiale appare lievemente superiore rispetto a quelli irrigati a goccia. Questo può essere attribuito alla influenza dell’irregolarità topografica del suolo. Infine, è stato effettuato uno studio sui fabbisogni idrici territoriali nell’ambito del consorzio di bonifica sinistra Piave situato sulla parte nord della provincia di Treviso. In questa ricerca è stato applicato un modello supportato da un sistema GIS per valutare l’uso dell’acqua per l’irrigazione su un’area all’interno del bacino del Piave. Il modello georefernziato è stato realizzato integrando le informazioni raccolte da un campione di agricoltori che hanno compilato un questionario mirato a caratterizzare l’uso dell’acqua irrigua dell’area, dalla mappa dei suoli, dalla mappa d’uso dei suoli, dai dati medi di evapotraspirazione e pioggia, e dalla fornitura d’acqua per l’irrigazione all’interno dell’area. Grazie all’utilizzo integrato di uno strumento GIS (Geographical Information System) e del programma Management Zone Analyst (MZA), è stata effettuata un’analisi cluster per la stima del bilancio idrico e degli eccessi di fornitura idrica. Al fine di analizzare le possibili strategie che permettono di ottenere una fornitura idrica ottimale garantendo le rese delle colture sono stati analizzati quattro diversi scenari con gestioni diverse nella frequenza e durata dei turni irrigui mensili. Dai risultati delle simulazioni si può concludere che passando da 3 a 4 turni al mese, con una riduzione però delle ore per turno tale che la quantità di acqua fornita sia inferiore a quella prevista per i tre turni, visto la maggiore efficienza irrigua, potrebbe essere una buona strategia per garantire le rese delle colture il più possibile dai cambiamenti climatici che come sembra aumentano la variabilità degli eventi piovosi. Il metodo proposto è un’applicazione semplificata che può essere usata per altri fiumi.

This PhD study examines whether water allocation becomes more productive when it is re-allocated from 'low' to 'high' efficient alternative uses in village irrigation systems (VISs) in Sri Lanka. Reservoir-based agriculture is a collective farming economic activity, which inter-sectoral allocation of water is assumed to be inefficient due to market imperfections and weak user rights. Furthermore, the available literature shows that a „head-tail syndrome. is the most common issue for intra-sectoral water management in „irrigation. agriculture. This research analyses the issue of water allocation by using primary data collected from two surveys of 460 rice farmers and 325 fish farming groups in two administrative districts in Sri Lanka. Technical efficiency estimates are undertaken for both rice farming and culture-based fisheries (CBF) production. The equi-marginal principle is applied for inter and intra-sectoral allocation of water. Welfare benefits of water re-allocation are measured through consumer surplus estimation. Based on these analyses, the overall findings of the thesis can be summarised as follows. The estimated mean technical efficiency (MTE) for rice farming is 73%. For CBF production, the estimated MTE is 33%. The technical efficiency distribution is skewed to the left for rice farming, while it skewed to the right for CBF production. The results show that technical efficiency of rice farming can be improved by formalising transferability of land ownership and, therefore, water user rights by enhancing the institutional capacity of Farmer Organisations (FOs). Other effective tools for improving technical efficiency of CBF production are strengthening group stability of CBF farmers, improving the accessibility of official consultation, and attracting independent investments. Inter-sectoral optimal allocation shows that the estimated inefficient volume of water in rice farming, which can be re-allocated for CBF production, is 32%. With the application of successive policy instruments (e.g., a community transferable quota system and promoting CBF activities), there is potential for a threefold increase in marginal value product (MVP) of total reservoir water in VISs. The existing intra-sectoral inefficient volume of water use in tail-end fields and head-end fields can potentially be removed by reducing water use by 10% and 23% respectively and re-allocating this to middle fields. This re-allocation may enable a twofold increase in MVP of water used in rice farming without reducing the existing rice output, but will require developing irrigation practices to facilitate this re-allocation. Finally, the total productivity of reservoir water can be increased by responsible village level institutions and primary level stakeholders (i.e., co-management) sharing responsibility of water management, while allowing market forces to guide the efficient re-allocation decisions. This PhD has demonstrated that instead of farmers allocating water between uses haphazardly, they can now base their decisions on efficient water use with a view to increasing water productivity. Such an approach, no doubt will enhance farmer incomes and community welfare.

Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>With the competitiveness in the increasing agricultural sector, mainly in terms of globalization of the economy, the inclusion of new technologies in the agricultural sector, especially the irrigation, is basic to become the sector each more sustainable time. The irrigation systems are projected to have a long useful life, thus being, cannot be disrespected the operational costs with the energy and the consuming of accessories that it composes the same ones, that directly they are related to its hydraulical sizing, the watershed of the cultures and to its water management. This consumption of energy has trend of increase with the consuming occurred in the equipment, or same to be extreme, which had to a deficient sizing. It is of basic importance that can have ways to evidence these events in each installation of irrigation and also to have a accompaniment of the activities executed with the equipment and that they intervene with its performance. The possible water use of inefficient form, with projected systems of irrigation with problems or necessity of maintenance, reflects the necessity of the constant evaluation in the equipment. This work evaluated some parameters that can modify the performance of systems of irrigation for center pivot. For way of this evaluation it was looked to bring to the user of the equipment of irrigation information on the modifications in the performance of the equipment, throughout its useful life, related to the three studied parameters: the time of functioning of the irrigation equipment, b) speed of the water in the aerial part of equipment and c) application or not of chemical products with the irrigation water. One concluded that: the evaluation of the operational performance of irrigation systems type "center pivot" must be effected to the long one of the useful life of the equipment, aiming at to guide adjustments and periodic corrections in the operational conditions that allow to optimize the allocation of the water and the energy. b) Is recommendable to analyze the performance of the equipment, adopting the three parameters used in this work: the Christiansen Uniformity Coefficient (CUC), the Distribution Uniformity Coefficient (CUD) and the Efficiency of Application (EA).<br>Com a competitividade no setor agrícola crescente, principalmente em termos de globalização da economia, a inclusão de novas tecnologias no setor agrícola, especialmente a irrigação, é fundamental para tornar o setor cada vez mais sustentável. Os sistemas de irrigação são projetados para terem uma longa vida útil, assim sendo, não podem-se desconsiderar os custos operacionais com a energia e o desgaste dos itens que compõe os mesmos, que estão diretamente relacionados ao seu dimensionamento hidráulico, às demandas hídricas das culturas e ao seu manejo. O consumo de energia tende a aumentar com o desgaste ocorrido no equipamento, ou mesmo ser excessivo, devido a um dimensionamento deficiente. É de fundamental importância que se tenham meios de constatar estes acontecimentos em cada instalação de irrigação e também ter o acompanhamento das atividades executadas com o equipamento e que interferem em seu desempenho. A possível utilização de água de forma ineficaz, com sistemas de irrigação dimensionados deficitariamente ou com necessidade de manutenção, reflete a necessidade da avaliação constante nos equipamentos. Este trabalho avaliou alguns parâmetros que podem modificar o desempenho de sistemas de irrigação por pivô central. Por meio dessa avaliação procurou-se trazer ao usuário do equipamento de irrigação informações sobre as modificações no desempenho dos equipamentos, ao longo de sua vida útil, relacionadas aos três parâmetros estudados: a) tempo de funcionamento do equipamento de irrigação,b) velocidade da água na parte aérea do equipamento e c) aplicação ou não de produtos químicos com a água de irrigação. Concluiu-se que: a) a avaliação do desempenho operacional de sistemas de irrigação tipo pivô central deve ser efetuada ao longo da vida útil dos equipamentos, visando orientar ajustes e correções periódicas nas condições operacionais que permitam otimizar a alocação da água e da energia. b) É recomendável analisar o desempenho dos equipamentos, adotando os três parâmetros empregados neste trabalho: o Coeficiente de Uniformidade de Christiansen (CUC), o Coeficiente de Uniformidade de Distribuição (CUD) e a Eficiência de Aplicação (EA).