Drought has an increasing importance in the Czech republic. It is necessary to look for potential irrigation water sources, which are important for agriculture. Treated wastewater can be one of them. It has potentially negative impact on soil physico-chemical properties, which is well-known from many researches in arid regions. The aim of this diploma thesis was to investigate, if the drip irrigation with treated wastewater (from constructed wetland) also has a potentially negative impact on two soils in the Czech republic. In one year experiment drip irrigation with treated wastewater was carried out in the greenhouse. Four treatments of irrigation was used for both soils - irrigation with treated wastewater, irrigation with groundwater, irrigation with treated wastewater + rainwater, irrigation with groundwater + rainwater. An amount of rainwater correspond with total precipitation of two locations, where the soils were brought from (Kostelec nad Ohří - Ústí nad Labem region and Hostětín - Zlín region). pH and electrical conductivity of soil leachate, total concentration of Na, K, Ca, Mg a P, bulk density, particle density and porosity was measured in both soils in 5 and 10 centimeters from source of irrigation. Values of pH of soil leachate fluctuated in every treatment in both soils during the...

Thesis (M. Agricultural Management (Plant Production)) -- University of Limpopo, 2020 / Tomato is a major vegetable crop produced in Limpopo province by subsistence and commercial farmers. Biotic and abiotic factors such as diseases and drought affect its productivity and yield negatively. The most economically important tomato disease in Limpopo is early blight, caused by Alternaria solani. Early blight affects tomato growing under stressful conditions such as drought. The main aim of this study was to evaluate water management in tomato production and its effect on tomato yield, early blight occurrence and severity under smallholder farming systems in Giyani. A survey study and field experiments on early blight occurrence and severity were conducted in the Greater Giyani municipality in Limpopo province. Firstly, a survey of early blight was conducted in tomato fields selected from three service centres namely Guwela, Hlaneki and Mhlava Willem. Twenty five potential tomato grower’s farms were randomly selected for survey based on the location and production management strategies. A second study was carried out by establishing field experiments at two farms in the same area, namely: A hi tirheni Mqekwa and Duvadzi farms. The experiments were laid out in a randomized complete block design (RCBD) in a split plot arrangement, with irrigation as the main plot treatment and tomato variety as the subplot treatment. Each treatment was replicated four times. The irrigation treatments consisted of full irrigation up to field capacity and deficit irrigation. The tomato varieties planted were HTX14, Rodade, STAR9006 and Commander, and were irrigated with a drip irrigation system. The overall survey results showed that Guwela s/c had high disease incidence and the lowest disease severity as compared to the other two service centers. The lowest disease incidence was observed at Hlaneki s/c whilst Mhlava willem s/c had the highest disease severity. The two water treatments (full and deficit irrigation) in both farms have shown no significant pairwise differences among xx the volumetric water content means. There was no significant difference (P≥0.05) in early blight disease severity in both farms. Results shows that, all tomato varieties did not differ significantly (P≥0.05) in yield observed between treatments at Duvadzi and A hi tirheni Mqekwa Farm. Deficit irrigation can be used effectively to produce high yields in tomato production provided the cropping season window does not coincide with the hottest time of the year. Full and deficit irrigation did not have influence on the early blight disease incidence on tomato plants. Key words: Alternaria solani; disease incidence; disease severity and drip irrigation

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<p dir="ltr"><a href="" target="_blank">Watermelon [<i>Citrullus lanatus </i>(Thunb.) Matsum. & Nakai] is one of the world's top three most consumed fruits.</a> Indiana cultivates approximately 7,000 acres of watermelons every year, ranking 6^th in the nation. More than 70% of this production is concentrated in and around Knox County, making Southern Indiana a key region for watermelon production in the States. Despite its significance, watermelon production faces many challenges, including erratic rainfall patterns exacerbated by climate change. Enhanced irrigation management has emerged as a critical strategy in mitigating negative environmental effects and in optimizing fertilizer applications.</p><p dir="ltr">Currently, Southern Indiana farmers have incorporated different irrigation and fertilization practices into watermelon production, yet the effects on production outcomes remain poorly understood. To bridge this gap in knowledge, this study aims to explore the effects of existing practices on watermelon yield and develop irrigation guidelines for optimal production in the region. The experiment was conducted at Southwest Purdue Agricultural Center, Vincennes, Indiana, in 2022 and 2023. Four treatments were applied: High Irrigation, Low Irrigation, No Irrigation, and Fertigation. Fertigation treatment received the same water application as the High Irrigation treatment. Fertilizers were applied pre-plant in the High, Low, and No irrigation treatments, while frequent fertigation was applied to the Fertigation Treatment. Soil moisture sensors measuring volumetric water content were used for irrigation decisions. In 2022, the irrigation thresholds were set at 15% water depletion at 1-ft depth for High Irrigation and Fertigation treatment, and 2-ft depth for Low Irrigation. In 2023, the irrigation threshold for Low Irrigation was adjusted to 40% water depletion at 1-ft depth.</p><p dir="ltr">While soil moisture levels in the bed at the different depths varied notably among treatments, no significant differences in yield by weight were observed. The minimal impact of irrigation on watermelon yield suggests that rainfall provides sufficient water, preventing yield-reducing stress. However, the Fertigation and High Irrigation treatments yielded more fruit than the Low Irrigation and No Irrigation treatments. The dry periods in both years coincided with the watermelon fruit setting stages that may have contributed to the lower fruit set in the Low Irrigation and No Irrigation treatments. Fertigation showed a higher early yield than the other treatments in 2022. Analysis of soil and tissue nitrogen levels indicated that sole nitrogen application before planting could result in excessive soil nitrogen levels during vegetative growth. This excess nitrogen might delay flowering and harvest. This project offers insights into enhancing irrigation and fertilization practices for watermelon production in southern Indiana.</p>

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Shiraz/110R grapevines, growing in a fine sandy loam soil in the Breede River Valley, were subjected to ten different drip irrigation strategies during the 2006/07, 2007/08 and 2008/09 seasons. Grapevines of the control treatment (T1) were irrigated at 30% to 40% plant available water (PAW) depletion throughout the growing season. Grapevines of three treatments were irrigated at 70% to 80% PAW depletion from bud break until véraison (i.e. when ca. 95% of grape berries have changed colour), followed by either irrigation at 30% to 40% PAW depletion (T2) or a continuous deficit irrigation (CDI) strategy (T3) or irrigation at 70% to 80% PAW depletion (T4) during ripening. The CDI strategy was obtained by applying ca. half the volume of water that was applied to the control. This allowed the soil to dry out gradually between physiological stages (i.e. bud break and véraison or véraison and harvest). Grapevines of three further treatments were irrigated at ca. 90% PAW depletion from bud break until véraison, followed by irrigation at 30% to 40% PAW depletion (T5) or a CDI strategy (T6) or irrigation at ca. 90% PAW depletion (T7) during ripening. Grapevines of two treatments were irrigated by means of a CDI strategy from bud break until véraison. For both treatments, the soil water content (SWC) was allowed to dry out gradually until ca. 90% PAW depletion was reached. After véraison, the SWC of the one treatment was maintained at ca. 90% PAW depletion by applying only four small irrigations of three hours each during ripening (T8). The soil of the other treatment, received an irrigation at véraison to refill the SWC to field capacity (T9) followed by the CDI strategy during ripening. Grapevines of the tenth treatment were irrigated at ca. 90% PAW depletion between bud break and véraison followed by a partial profile refill (PPR) strategy during ripening (T10). In order to obtain the PPR strategy, SWC was only maintained between 40% and 60% PAW depletion. Evapotranspiration varied between 3.5 mm/day and 0.1 mm/day for driest and wettest treatments, respectively, during the period between December and February. This was substantially less than the volumes required for full surface irrigation. For irrigations applied at 30% to 40% PAW depletion (T1), 70% to 80% PAW depletion (T4) and ca. 90% PAW depletion (T7) levels throughout the season, crop coefficients for the Penman-Monteith reference evapotranspiration (ETo) were 0.4, 0.2 and 0.1, respectively. Under the given conditions, the different irrigation strategies did not have any effect on root distribution and density. Shoot growth of grapevines exposed to high to severe water deficits in the pre-véraison period stopped before mid December. Shoots of grapevines that were exposed to high or severe water deficits before véraison followed by more frequent irrigation during ripening showed active re-growth. These trends occurred during all the seasons. The level of PAW depletion reflected strongly in the plant water potential in the grapevines. Leaf water potential was influenced by the prevailing atmospheric conditions, whereas stem water potential was less sensitive to atmospheric conditions, but responded more directly to soil water availability. Due to the good relationships between pre-dawn leaf, mid-day leaf, mid-day stem and total diurnal water potential, it was possible to re-classify the water status in terms of previous classifications for these water potentials based on pre-dawn measurements. Water constraints in T1, T2 and T5 grapevines were classed as experiencing no stress, whereas the T7 and T8 ones experienced strong to severe water constraints before harvest. High frequency irrigation strategies during ripening delayed sugar accumulation due to dilution of sugar in the larger berries. Except for the wettest strategy, and where grapevines were subjected to the CDI strategy throughout the season, berry mass increased during ripening, i.e. from véraison to harvest. Water deficits had a negative effect on berry mass, bunch size and yield. Where higher soil water depletion levels were allowed, irrigation strategies had a positive effect on the irrigation water productivity of grapevines compared to the frequently irrigated or CDI strategies. Higher water constraints in grapevines, particularly during ripening, improved sensorial wine colour and enhanced some of the more prominent wine aromas, e.g. spicy and berry. Grapevines that were irrigated at a high frequency during ripening produced wines with diluted character flavours and aromas and inferior overall quality. Under the given conditions, sensorial wine colour and spicy character were the dominant factors in determining overall sensorial wine quality. / AFRIKAANSE OPSOMMING: Shiraz/110R wingerdstokke in ‘n fyn sandleem grond in die Breede Rivier vallei is gedurende die 2006/07, 2007/08 en 2008/09 seisoene met tien verskillende drupbesproeiingstrategieë besproei. Wingerdstokke van die kontrole (B1) is deur die seisoen by 30% to 40% plant beskikbare water (PBW) onttrekking besproei. Drie behandelings is tussen bot en deurslaan (wanneer ca. 95% van die korrels verkleur het) by 70% tot 80% PBW onttrekking besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B2), ‘n deurlopende tekort besproeiing (DTB) strategie (B3) of besproeiing by 70% tot 80% PBW onttrekking (B4) gedurende rypwording. In die geval van die DTB strategie is ongeveer die helfte van die volume water toegedien wat by die kontrole toegedien is. Laasgenoemde strategie het die grond toegelaat om geleidelik tussen fisiologiese fases (i.e. tussen bot en deurslaan of tussen deurslaan en oes) uit te droog. Drie ander behandelings is by ca. 90% PBW onttrekking tussen bot en deurslaan besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B5) of ‘n DTB strategie (B6) of besproeiing by ca. 90% PBW onttrekking (B7) gedurende rypwording. Wingerdstokke van twee ander behandelings is d.m.v. ‘n DTB strategie vanaf bot tot deurslaan besproei. Beide behandelings se grondwaterinhoud (GWI) was toegelaat om geleidelik uit te droog tot ca. 90% PBW onttrekking bereik was. Na deurslaan was die GWI van die een behandeling naby ca. 90% PBW onttrekking gehandhaaf deur slegs vier klein besproeiings van drie uur elk gedurende rypwording toe te pas (B8). Die grond van die ander behandeling het tydens deurslaan ‘n besproeiing ontvang om die GWI tot by veldkapasiteit te hervul (B9) en is tydens rypwording weer d.m.v. ‘n DTB strategie besproei. Stokke van die tiende behandeling is tussen bot en deurslaan by ca. 90% PBW onttrekking besproei, gevolg deur besproeiing d.m.v. ‘n gedeeltelike profiel hervul (GPH) strategie tydens rypwording (B10). Om ‘n GPH strategie toe te kon pas, is tussen 40% en 60% PBW ontrekking gehandhaaf. Evapotranspirasie het tussen 3.5 mm/dag en 0.1 mm/dag vir onderskeidelik die natste en droogste behandelings tussen Desember en Februarie gevarieer. Dit was aansienlik laer as volumes wat vir voloppervlak besproeide wingerde benodig word. In die geval van besproeiing by 30% tot 40% PBW onttrekking (B1), 70% tot 80% PBW onttrekking (B4) en ca. 90% PBW onttrekking (B7) deur die loop van die seisoen was die gewasfaktore vir die verwysingverdamping (ETo) 0.4, 0.2 en 0.1 onderskeidelik. Onder die gegewe toestande het die verskillende besproeiingstrategië geen effek op die worteldigtheid en –verspreiding gehad nie. Lootgroei van wingerdstokke wat aan hoë tot baie hoë watertekorte blootgestel was voor deurslaan, het voor middel Desember gestop. Lote van wingerdstokke wat aan hoë tot baie hoë watertekorte voor deurslaan blootgestel is, gevolg deur besproeiing teen ’n hoë frekwensie tydens rypwording, het aktiewe hergroei getoon. Die PBW ontrekkingspeil het sterk in die plantwaterpotensiale van wingerdstokke weerspieël. Blaarwaterpotensiaal is deur heersende klimaatstoestande beïnvloed, terwyl stamwaterpotensiaal minder sensitief teenoor die klimaat was, maar meer direk deur die beskikbaarheid van grondwater beïnvloed is. Vanweë die goeie verband tussen voordagbreek blaar-, mid-dag blaar-, mid-dag stam- en totale daaglikse waterpotensiaal, was dit moontlik om water status van die stokke te her-klassifiseer in terme van vorige vir waterpotensiaalklassifikasies wat op voordagbreek waardes gebasseer is. Waterspanning in B1, B2 en B5 stokke is as geen spanning geklassifiseer, terwyl dié van B7 en B8 voor oes in die hoë tot baie hoë klasse geval het. Hoë frekwensie besproeiing strategieë gedurende rypwording kan suikertoename a.g.v. die groter korrels vertraag. Met die uitsondering van die natste strategie, asook waar stokke volgens die DTB strategie deur die seisoen besproei is, het korrelmassa gedurende rypwording toegeneem. Watertekorte het ’n negatiewe effek op korrelmassa, trosgrootte en produksie gehad. Besproeiingstrategieë waar ’n hoë mate van grondwateronttrekking voor besproeiings toegelaat is, het ’n positiewe effek op die besproeiingwaterproduktiwiteit van wingerd in vergelyking met gereelde besproeiings of ‘n DTB strategie gehad. Watertekorte, veral gedurende rypwording, het ’n verbetering in sensoriese wynkleur en meer prominente wyn aromas, tot gevolg gehad. Besproeiing teen hoë frekwensies gedurende rypwording, het wyne met ’n afgewaterde smaak en aroma karakters asook ’n swak algehele gehalte produseer. Sensoriese wynkleur en spesery karakter die dominante faktore in die bepaling van algehele kwaliteit.

4 pp. / Converting from Gallons -- to Inches -- to Runtime Hours for Row Crop Drip Irrigation Systems / Many growers in Arizona are switching from surface to drip irrigation. This change requires many changes in water management. One of the changes that growers are having the most difficulty with is the concept of applying gallons of water instead of inches. This paper helps growers make this conversion from inches to gallons and then back again. An accompanying EXCEL program, available on the web, will help growers determine run times and application amounts.

4 pp. / Many growers in Arizona are switching from surface to drip irrigation. This change requires many changes in water management. One of the changes that growers are having the most difficulty with is the concept of applying gallons of water instead of inches. This paper helps growers make this conversion from inches to gallons and then back again. An accompanying EXCEL program, available on the web, will help growers determine run times and application amounts.

Revised; Originally Published: 2007 / 4 pp.

Dans le cadre du présent travail, nous nous intéressons à l'étude de l'impact des conditions hydrodynamiques et des matériaux utilisés sur le développement de biofilm au niveau des conduites des systèmes de micro-irrigation. Cette étude contribue à l'amélioration de la compréhension de l'impact de ces paramètres dans la mise en place et la croissance du biofilm. Pour ceci, un montage expérimental aux conditions d'écoulement maîtrisées a été mis en place au laboratoire avec une eau usée modèle de forte concentration en DCO (200 mg.L-1). Le suivi des paramètres de qualité d'eau (COT et oxygène dissous) ont été réalisés au cours des expérimentations. La masse du biofilm récupéré dans les conduites a été mesurée après un séchage à l'étuve à 105°C pendant 24 heures. Les résultats montrent une cinétique de développement du biofilm dans les conduites et confirment l'influence de l'hydrodynamique sur le développement de biofilm. Trois vitesses d'écoulement ont été testées (0,4, 0,8 et 1,2 m. s-1), le biofilm a tendance à se développer dans les conduites à plus faible vitesse. Une valeur seuil, à partir de laquelle la croissance du biofilm est observée tardivement, a été également identifiée. Les résultats obtenus ont été utilisés pour paramétrer un modèle cinétique simple qui permet de décrire le développement de biofilm en fonction des conditions hydrodynamiques. D'autres expérimentations ont été réalisées en parallèle pour étudier l'impact des matériaux plastiques (PE et PVC) et la configuration des conduites du montage expérimental sur le développement de biofilm. / This work aims to improve our understanding on how these parameters impact biofilm establishment and growth. For this purpose, we carried out an experiment in controlled hydrodynamic conditions using a synthetic effluent (200 mg.L-1 of COD concentration). Some water quality parameters (TOC and dissolved oxygen) were monitored . Moreover, biofilm was removed from pipes and then weighed after drying at 105°C for 24 hours. The obtained results confirmed the influence of hydrodynamic on biofilm development. Three flow rates were tested (0,4 ; 0,8 and 1,2 m.s-1) and it was observed that biofilm tends to develop in pipes at lower velocities. A threshold velocity value, from which biofilm growth was observed later, was also identified. The experimental results were used to build a simple model to describe biofilm development as a function of hydrodynamic conditions. Additionnal experiments were performed to study the impact of plastic materials (PE and PVC) and pipes configuration on biofilm growth