Dissertations / Theses on the topic 'Volumetric water content'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 26 dissertations / theses for your research on the topic 'Volumetric water content.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Rasam, Setty Harish Raghav. "Assessment of Volumetric Water Content Using Radio Waves." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textBagour, Mohammed H., and Donald F. Post. "Predicting the Volumetric Water Content of Irrigated Arizona Soils at Different Soil Water Potentials." Arizona-Nevada Academy of Science, 2001. http://hdl.handle.net/10150/296584.
Full textPreko, Kwasi. "Determination of Volumetric Soil Water Content Using Ground Penetrating Radar Bestimmung des volumetrischen Bodenwassergehaltes mit dem Bodenradar /." [S.l. : s.n.], 2007. http://digbib.ubka.uni-karlsruhe.de/volltexte/1000007396.
Full textAli, Mohamad Idaly Bin. "Development and implementation of a low-cost data acquisition system using single-board computers to measure volumetric water content." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119312.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (page 73).
The work described in this thesis is aimed at exploring the use of single-board computers, specifically the Raspberry Pi platform, to measure volumetric water content of soils or other porous media. We first investigated the different methods to condition and measure signal frequencies. Subsequently, we designed and fabricated a Hardware Attached on Top frequency counter add-on board for the Raspberry Pi based on the reciprocal frequency counting method, and found that this accurately and precisely measures frequency signals from water content reflectometers. We then built a dormant deploy-and-forget sensor system around this hardware. The system will be used at our research field site in Brunei Darussalam to measure volumetric water content of peat. Further work focuses on improvements to the encapsulation of the electronic hardware, and designing a multiplexer-controlled relay board to acquire signals from multiple reflectometers simultaneously.
by Mohamad Idaly Bin Ali.
M. Eng.
Cangialosi, Michael Vincent. "The Effect of Clay Content and Iron Oxyhydroxide Coatings on the Dielectric Properties of Quartz Sand." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/42579.
Full textMaster of Science
Masbruch, Karen, and Karen Masbruch. "A time domain transmission method for determining the dependence of the dielectric permittivity on volumetric water content: applications to municipal landfills." Thesis, The University of Arizona, 2002. http://hdl.handle.net/10150/626872.
Full textBergsten, Steven J. "Certain Agave Species Exhibit the Capability to be Moderately Productive Under Conditions of High Salt and Drought Stress." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3818.
Full textRoberson, Travis Leon. "Improving Soil Moisture Assessment of Turfgrass Systems Utilizing Field Radiometry." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87391.
Full textMaster of Science in Life Sciences
Managed turfgrasses provide several benefits including filtering pollutants, cooling their surroundings, generating oxygen, preventing erosion, serving as recreational surfaces, and increasing landscape aesthetics. Intensively managed turfgrass systems, such as on golf courses and sports fields, require more inputs to maintain acceptable conditions. Freshwater use is often excessive on intensively managed turfgrasses to maintain proper plant growth. Drought conditions often limit water availability, especially in regions with limited rainfall. Turf managers tend to over-apply water across large acreage when few localized areas begin to show symptoms of drought. Additionally, turf managers sometimes wrongly identify stressed areas from other factors as ones being moisture-deprived. Advancements such as the use of soil moisture meters have simplified irrigation decisions as an aid to visual inspections for drought stress. While this method enhances detection accuracy, it still provides no solution to increase efficiency. Expanding our current knowledge of turfgrass canopy light reflectance for rapid moisture stress identification can potentially save both time and water resources. The objective of this research was to enhance our ability to identify and predict moisture stress of creeping bentgrass (CBG) and hybrid bermudagrass (HBG) canopies integrated into varying soil textures (USGA 90:10 sand (S), sand loam (SL) and Clay (C)) using light reflectance measurements. Dry-down cycles were conducted under greenhouses conditions collecting soil moisture and light reflectance data every hour from 7 am to 7 pm after saturating and withholding water from established plugs. Moisture stress was most accurately estimated over time using two vegetation indices, the water band index (WBI) and green-to-red ratio index (GRI), with approximately ninety percent accuracy to visible wilt stress. The WBI and GRI predicted moisture stress of CBG in all soil types and HBG in SL and C approximately 14 hours before the grasses reached 50% wilt. While light reflectance varies on exposed soils, our research shows that underlying soils do not interfere with measurements across typical turfgrass stands. This research provides a foundation for future research implementing rapid, aerial measurements of moisture stressed turfgrasses on a broad application of CBG and HBG on constructed or native soils.
Vismara, Edgar de Souza. "Mensuração da biomassa e construção de modelos para construção de equações de biomassa." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-18052009-155116/.
Full textForest biomass measurement implies a destructive procedure, thus forest inventories and biomass surveys apply indirect procedure for the determination of biomass of the different components of the forest (wood, branches, leaves, roots, etc.). The usual approch consists in taking a destructive sample for the measurment of trees attributes and an empirical relationship is established between the biomass and other attributes that can be directly measured on standing trees, e.g., stem diameter and tree height. The biomass determination of felled trees can be achived by two techniques: the gravimetric technique, that weights the components in the field and take a sample for the determination of water content in the laboratory; and the volumetric technique, that determines the volume of the component in the field and take a sample for the determination of the wood specific gravity (wood basic density) in the laboratory. The gravimetric technique applies to all components of the trees, while the volumetric technique is usually restricted to the stem and large branches. In this study, these two techniques are studied in a sample fo 200 trees of 10 different species from the region of Linhares, ES. In each tree, 5 cross-sections of the stem were taken to investigate the best procedure for the determination of water content in gravimetric technique and for determination of the wood specific gravity in the volumetric technique. Also, Akaike Information Criterion (AIC) was used to compare different statistical models for the prediction o tree biomass. For the stem water content determination, the best procedure as the aritmetic mean of the water content from the cross-sections in the base, middle and top of the stem. In the determination of wood specific gravity, the best procedure was the aritmetic mean of all five cross-sections discs of the stem, however, for the determination of the biomass, i.e., the product of stem volume and wood specific gravity, the best procedure was the use of the middle stem cross-section disc wood specific gravity. The use of an average wood specific gravity by species showed worse results than any procedure that used information of wood specific gravity at individual tree level. Seven models, as variations of Spurr and Schumacher-Hall volume equation models, were tested for the different tree components: wood (stem and large branches), little branches, leaves and total biomass. In general, Schumacher-Hall models were better than Spurr based models, and models that included only diameter (DBH) information performed better than models with diameter and height measurements. When a measure of penetration in the wood, as a surrogate of wood density, was added to the models, the models with the three variables: diameter, height and penetration, became the best models.
Vláčilíková, Michaela. "Měření infiltrace v terénu pomocí MiniDiskového infiltrometru." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409739.
Full textJiang, Shuang. "Bacterial leaching from dairy shed effluent applied to a fine sandy loam under flood and spray irrigations." Lincoln University, 2008. http://hdl.handle.net/10182/668.
Full textFouché, Julien. "Effet du réchauffement climatique sur le fonctionnement biogéochimique de deux cryosols arctiques dans la région de Salluit, Nunavik, Canada." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4306.
Full textIncreased organic mater decomposition rate in Arctic Cryosols due to warming and to permafrost thawing can lead to the release of greenhouse gases, thus potentially creating a positive feedback on climate change. We studied the biogeochemical functioning of two different permafrost-affected soils (i.e. Cryosols): a Histic Cryosol (H) and a Turbic Cryosol (T), both in natural conditions and under an experimental warming. Profiles were instrumented in Salluit (Nunavik, Canada) and monitored during summers 2010 and 2011. The induced warming increased CO2 fluxes in both soils; this impact was however more striking at H even if ER was lower than at T. Temperature sensitivity of ER (Q10) was higher at T than at H and decreased both with warming. We highlighted that diurnal ER cycles as a function of temperature showed hysteretic loops. Linear models performed to explain ER variance were improved adding daily minimum temperature and thaw front depth at H. In contrast at T, adding wind speed and solar radiation in models improved the ER variance explanation. We showed three specific CO2 flux dynamics related to northern ecosystems: 1) the large difference of ER depending on soil properties and soil solution composition; 2) environmental variables strongly alter CO2 fluxes and 3) the diurnal Q10 variations and the inter annual variability of basal respiration. Our results support the assumption that organic matter decomposition might be the major source of CO2 at H while plant-derived processes dominated ER at T. Our results contribute to understand and extrapolate the numerous punctual measurements of CO2 fluxes from tundra ecosystems improving carbon cycle modeling in Cryosols
Mayeli, Nader. "An experimental study of the unrestrained shrinkage of isotropic paper sheets." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/an-experimental-study-of-the-unrestrained-shrinkage-of-isotropicpaper-sheets(6f0e3356-2e17-4433-8303-723a863c11f0).html.
Full textSuchá, Kateřina. "Hodnocení kvality/zdraví půdy v blízkosti obce Bohaté Málkovice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392022.
Full textWu, Yu-Zhang, and 吳郁璋. "Estimating The Moving Routes Of Earthworm By Volumetric Water Content." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/79112538782028198526.
Full text國立臺灣大學
生物環境系統工程學研究所
96
The purpose of this study is to discuss the influences of the soil water content on earthworm movements. Three situations including earthworm movement in the soil with dry surface, and the movement of either healthy or sick earthworms in the soil during rainfall via numerical simulations were studied. This study was based upon two assumptions. First, the earthworms inhabit in the homogenous soil. Second, The earthworms go towards the soil with higher growth curve. Here, an 1-D earthworm movement-water content governing equation (EWE) was proposed to describe the relationship between earthworm movement and soil water content. The relationship between displacement of the earthworms and time, thus, was derived by integrating EWE with time. The simulation of the earthworm movement required with some experimental parameters, such as hydraulic conductivities, the theory maximum drilling velocity (TMDV) of the earthworm, etc. The simulation of earthworm movement was terminated once the earthworms reached the ground surface, since ultraviolet radiation can cause earthworms paralysis based upon the previous studies. The numerical simulation results match with the previous studies and show that (1) earthworms manage to move downwards to the soil as ground surface is drying, (2) earthworms tend to move to the surface under greater rainfall intensity, and (3) earthworms are more likely to move to the surface at rainfall while they are sick. All of the three conclusion match with the with former observations.
Chiang, Chia-Chen, and 蔣佳真. "Optimal Layout for Volumetric Water Content Measurements of Unsaturated Soil Slope." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/14801496342724855100.
Full text國立雲林科技大學
營建工程系
104
Recently, climate change in Taiwan has caused extreme weather conditions and resulted in many rainfall-induced slope failures. To predict the transient volumetric water content (VWC) in an unsaturated slope during rainfall, an optimization analysis method based on two dimensional finite element method and Levenberg-Marquart method was proposed. The proposed methodology was verified and proven to be applicable to simulate the transient VWC distributions. A series of inverse analyses on the measured transient volumetric water content of model slopes was performed. These analyses were specially focused on the effect of layout of volumetric measurements, the number of monitoring points, and the duration of monitoring time on the optimized soil parameters. Numerical results shows that for the case of using single monitoring point at shallow depth of slope, especially at the toe of slope, its optimized parameters were not as good as those of the cases using a deeper point. Besides, it was found that using multiple monitoring points with sufficient monitoring time can enhance the precision of inverse analysis.
Mohamed, Mostafa H. A., and Kirill V. Horoshenkov. "Airborne acoustic method to determine the volumetric water content of unsaturated sands." 2009. http://hdl.handle.net/10454/6099.
Full textChen, Chia-Yang, and 陳佳暘. "The Back Analysis on the Volumetric Water Content of Unsaturated Soil Model Slopes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16853531751160211743.
Full text國立雲林科技大學
營建工程系碩士班
99
Recently, climate change in Taiwan has caused more extreme weather conditions and resulted in many rainfall-induced slope failures. To predict the transient volumetric water content (VWC) in an unsaturated slope during rainfall, an optimization analysis method based on two dimensional finite element method and Levenberg-Marquart method was proposed. The proposed methodology was verified and proven to be applicable to simulate the transient VWC distributions. A series of inverse analyses on the measured transient volumetric water content of two model slopes was performed. The effects of monitoring point location, the number of monitoring point, and the duration of monitoring time on the optimized soil parameters were presented. Among them, the location of monitoring point is the most crucial factor that may influence the results of inverse analyses. It is suggested that using the monitoring data from a sensor embedded in a shallow location can enhance the precision of inverse analysis.
YANG, SHIH-TING, and 楊士霆. "Stability Analysis of Rainfall Infiltrated Unsaturated Soil Slope and its Critical Volumetric Water Content." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4cm5cr.
Full text國立臺北科技大學
土木工程系土木與防災碩士班
107
Taiwan has many hillsides and many slopes with steep slopes. When these unsaturated slopes are affected by rainfall, the infiltration of water leads to loss of matric suction, which causes the shear strength to decrease and, in turn, leads to the subsequent slope instability. In this study, numerical analysis is used to investigate the infiltration and the instability mechanism of unsaturated slopes affected by rainfall, Through the coupling of solid mechanics equation and the seepage governing equation together with the soil characteristics of the unsaturated soil and the hydrological characteristics of rainfall, stability of unsaturated soil slope is modeled. The safety factor is obtained by shear strength reduction method. The effects of different slope height, slope angle, groundwater level and elastic modulus on slope stability are also discussed. Finally, the critical volumetric water content and the potential sliding surface are obtained to inspect their possible correlation.
Tang, Yucao. "Calibration of water content reflectometer in Rocky Mountain arsenal soil." Thesis, 2009. http://hdl.handle.net/2152/ETD-UT-2009-08-311.
Full texttext
Chen, Jung-Hua, and 陳容花. "Influence of Rainfall Infiltration on Unsaturated Soil Slope and Critical Volumetric Water Content under Different Rainfall Scenarios." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/38957571487701006706.
Full text國立臺灣科技大學
營建工程系
103
ABSTRACT The majority of Taiwan’s hillsides belong to unsaturated soil slope. Seepage in these unsaturated slopes situated above groundwater level would easily lead to changes of hydrological characteristics (such as matric suction, etc.) when encountered rainfall, and then trigger subsequent slope stability problems. This study adopted a field case and used numerical analysis program SEEP/W and SLOPE/W module to conduct seepage simulation and stability analysis on unsaturated soil slopes under different rainfall scenarios. In addition to simulation and exploration of original alert modes (rainfall, groundwater level), this study also investigates changes of hydrological characteristics and stability in unsaturated soil slopes caused by rainfall infiltration, and then identify more accurate landslide disaster occurrence indicators also having a mechanical basis for potential application by related agencies in implementing disaster prevention and early warning measures. This study found that the slope stability analysis results of unsaturated soil slope would vary under same cumulative rainfall but different durations. Therefore, only cumulative rainfall was used as indicator parameter of whether landslide will occur or not, in terms of this case study, its accuracy still has room for improvement. And under different rainfall scenarios the changes of water level in slopes with thick colluvium or deep groundwater are not significant. The majority of damage types of unsaturated soil slope belong to shallow landslide, and slope failures mostly occur along the wetting front, while the generation of wetting front represents the dissipation of matric suction, as a result the shear strength of soil will also drop, and this is one of the important factors causing slope instability. The analytical results exhibit critical value characteristic of volumetric water content prior to slope failure induced by rainfall infiltration. In addition, this critical volumetric water content would not be influenced by rainfall conditions and positions in the slope. Therefore, using critical volumetric water content as a landslide disaster occurrence indicator should be a feasible direction and warrants further study.
Hsu, Kan-Sheng, and 許堪昇. "Soil Temperature and Volumetric Water Content Prediction in Greenhouse by Using Hydrus-1D, ICON and Random Forest Method." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/p6tjuv.
Full text國立臺灣大學
生物環境系統工程學研究所
107
Due to the impact of climate change and the rising frequency of extreme weather have caused the problem of food security and water resources. Precision agriculture in greenhouses is gradually becoming a trend because it is less affected by external environmental factors and easier to manage. In order to effectively improve the utilization of water resources and reduce wasting water, this study planted cherry tomatoes in the greenhouse and installed monitoring instruments to collect data. The soil temperature and volumetric water content during tomato growth can be predicted effectively by combining the weather forecast. The Hydrus-1D, random forest method and ICON were used to simulate the change of soil temperature and volumetric water content in the greenhouse. The results of the simulation show good performances among the three models. Further combined with weather forecast data, three models were applied to predict soil temperatures and volumetric moisture contents. Both of predicted soil temperature and volumetric water content by Hydrus-1D followed the trend of real measured data, but Hydrus-1D can’t predict the watering situation. The predicted performance of soil temperature by ICON was low. Nevertheless, both predictions by random forest method were better than others. This study simulated and predicted the soil temperatures and volumetric water contents by applying Hydrus-1D, random forest method and ICON to improve greenhouse management and increase water-use efficiency.
Adhikari, Bishwodeep. "The Contributions of Soil Moisture and Groundwater to Non-Rainfall Water Formation in the Namib Desert." Thesis, 2019. http://hdl.handle.net/1805/20533.
Full textNon-rainfall waters such as fog and dew are considered as important source of water in drylands, and the knowledge of possible sources of its formation is very important to make future predictions. Prior studies have suggested the presence of radiation fog in drylands; however, its formation mechanism still remains unclear. There have been earlier studies on the effects of fog on soil moisture dynamics and groundwater recharge. On the contrary, no research has yet been conducted to understand the contribution of soil moisture and groundwater to fog formation. This study, therefore, for the first time intends to examine such possibility in a fog-dominated dryland ecosystem, the Namib Desert. The study was conducted at three sites representing two different land forms (sand dunes and gravel plains) in the Namib Desert. This thesis is divided into two parts: the first part examines evidences of fog formation through water vapor movement using field observations, and the second part simulates water vapor transport using HYDRUS-1D model. In the first part of the study, soil moisture, soil temperature and air temperature data were analyzed, and the relationships between these variables were taken as one of the key indicators for the linkage between soil water and fog formation. The analysis showed that increase in soil moisture generally corresponds to similar increase in air or soil temperature near the soil surface, which implied that variation in soil moisture might be the result of water vapor movement (evaporated soil moisture or groundwater) from lower depths to the soil surface. In the second part of the study, surface fluxes of water vapor were simulated using the HYDRUS-1D model to explore whether the available surface flux was sufficient to support fog formation. The actual surface flux and cumulative evaporation obtained from the model showed positive surface fluxes of water vapor. Based on the field observations and the HYDRUS-1D model results, it can be concluded that water vapor from soil layers and groundwater is transported through the vadose zone to the surface and this water vapor likely contributes to the formation of non-rainfall waters in fog-dominated drylands, like the Namib Desert.
Preko, Kwasi [Verfasser]. "Determination of volumetric soil water content using ground penetrating radar = Bestimmung des volumetrischen Bodenwassergehaltes mit dem Bodenradar / vorgelegt von Kwasi Preko." 2008. http://d-nb.info/987794604/34.
Full textAbdelkhalik, Abdelsattar Gamal Abdelsattar. "Effect of continued and regulated deficit irrigation on the productivity of four vegetable crops in open-field conditions in the Mediterranean area." Doctoral thesis, 2020. http://hdl.handle.net/10251/129868.
Full text[CAT] Resum L'escassesa d'aigua s'està convertint en un problema en zones àrides i semiàrides del món, on es localitza part de la producció dels principals cultius hortícoles, com és el cas de l'àrea mediterrània. La sequera és un dels principals factors limitants en l'agricultura i està afectant greument a la producció de cultius hortícoles. La millora de la productivitat de l'aigua en l'agricultura en general, i en l'horticultura en particular, es pot aconseguir mitjançant la utilització de determinades estratègies. El reg deficitari consisteix en l'aportació d'aigua per sota de les necessitats de reg (NR) dels cultius, de manera que es produeix una reducció de l'evapotranspiració. Es pot fer de manera contínua o sostinguda (RDS) o controlada (RDC). Amb el reg deficitari es pot millorar l'eficiència de l'ús de l'aigua de reg, mantenint el rendiment, i fins i tot de vegades, podria conduir a una millora de la qualitat de la collita. En aquest estudi, realitzat al Centre Experimental Cajamar de Paiporta (València, Espanya) s'avalua l'efecte del reg deficitari en quatre dels principals cultius hortícoles conreats a l'aire lliure, a l'àrea mediterrània: dos de cultiu de tardor-hivern (coliflor i ceba) i dues de cultiu primaveral-estival (pimentó i meló d'Alger). En l'avaluació s'han analitzat els següents paràmetres: creixement i estat hídric de les plantes, rendiment, eficiència de l'ús de l'aigua de reg, qualitat de la producció i rendibilitat dels cultius. A la primera campanya es va assajar el RDS, el que va permetre establir les diferents etapes de creixement de cada cultiu, que es van utilitzar en les següents campanyes en el RDC. En els quatre cultius, les plantes control (100% NR) han mostrat un adequat estat hídric, tant en el contingut relatiu d'aigua com en l'índex d'estabilitat de la membrana, mentre que les sotmeses a un RDS sever, han mostrat els menors valors d'ambdós índexs. L'efecte negatiu del reg deficitari sobre el rendiment ha resultat menys important en els cultius de tardor-hivern que en els cultius de primavera-estiu, especialment en la coliflor. El RDS del 50% NR ha reduït dràsticament el rendiment comercial i, conseqüentment, els ingressos bruts, encara que hagi suposat una millora en l'eficiència de l'ús de l'aigua de reg per als cultius de tardor-hivern. De l'anàlisi individual dels cultius es dedueix que el rendiment de coliflors obtingudes amb RDS al 75% NR o RDC al 50% NR durant la fase juvenil, s'ha mantingut en nivells similars al control, millorant l'eficiència de l'ús de l'aigua de reg. En ceba, en cas de restricció hídrica severa, seria aconsellable aplicar RDS amb el 75% NR o RDC al 50% NR durant la maduració del bulb, ja que aquestes estratègies han disminuït lleugerament el rendiment, millorant l'eficiència de l'ús de l'aigua de reg . En condicions menys restrictives, RDC al 75% NR durant la maduració del bulb ha donat lloc a un rendiment satisfactori, amb un augment de l'eficiència de l'ús de l'aigua de reg. En pimentó dolç italià, l'aplicació de RDC al 75% NR durant la recol·lecció ha donat lloc a una reducció considerable del rendiment, i per tant, dels ingressos bruts, encara que amb importants estalvis d'aigua i amb un increment en el contingut de sòlids solubles i de compostos fenòlics dels fruits. Retallant el cicle de cultiu fins a principis de setembre, quan ja s'ha collit la major part del rendiment comercial, s'aconseguiria un important estalvi d'aigua i permetria utilitzar la parcel·la en altres cultius. El RDS al 75% i al 50% NR, o RDC al 50% NR durant la collita han donat lloc a una alta incidència de fruits afectats per blossom-end rot. En meló d'Alger es pot recomanar l'aplicació de RDC, tant al 75% com al 50% NR durant la maduració del fruit, ja que ha conduït a rendiments comercials acceptables. De manera general es pot afirmar que l'aplicació de RDS i de RDC en els quatre cultius, no ha afectat de maner
[EN] Water scarcity is becoming a critical problem in arid and semi-arid areas of the world, where part of the production of the main horticultural crops is located, as is the case of the Mediterranean area. Drought is one of the main limiting factors in agriculture and it is seriously affecting the production of horticultural crops. The improvement of water productivity in agriculture in general, and in horticulture in particular, can be achieved through the use of certain strategies. Deficit irrigation consists of the supply of water below the irrigation water requirements (IWR), so that there is a reduction in evapotranspiration. It can be done continuously (CDI) or regulated (RDI). With deficit irrigation, the irrigation water use efficiency can be improved, maintaining yield, and it could even lead to an improvement in the quality of the harvest. This study, carried out at the Cajamar in Paiporta Experimental Center (Valencia, Spain), analyzes the effect of deficit irrigation on four of the main cultivated horticultural crops, open field cultivated in the Mediterranean area: two of autumnal-winter crops (cauliflower and onion) and two spring-summer crops (pepper and watermelon). In the evaluation, the following parameters have been analyzed: plant growth and water status, yield, irrigation water use efficiency, quality of production and crop profitability. In the first season the CDI was tested, which allowed to establish the different growth stages for each crop, which were used in the following season for the RDI. In the four crops, the control plants (100% IWR) have shown an adequate water status, in terms of both relative water content and membrane stability index, while those subjected to a severe CDI, have shown the lowest values of both indexes. The negative effect of deficit irrigation on yield has been less important in autumn-winter crops than in spring-summer crops, especially in cauliflower. The CDI at 50% IWR has drastically reduced the marketable yield and, consequently, the gross revenue, although it has supposed an improvement in the irrigation water use efficiency for the autumn-winter crops. From the individual analysis of the crops, it can be stated that cauliflower yield obtained with CDI at 75% IWR or RDI at 50% IWR during the juvenile phase, has remained at levels similar to the control, improving the irrigation water use efficiency. In relation to onion, in case of severe water restriction, it would be advisable to apply CDI with 75% IWR or RDI at 50% IWR during bulb ripening, since these strategies have slightly decreased yield, improving the irrigation water use efficiency. In less restrictive conditions, RDI at 75% IWR during the bulb maturation has led to a satisfactory yield, with an increase in the irrigation water use efficiency. In Italian sweet pepper, the application of RDI to 75% IWR during the harvesting has resulted in a considerable reduction of the yield, and therefore, of the gross income, although with important water savings and increasing the fruit soluble solids and phenolic compounds content. By shortening the cultivation cycle until the beginning of September, when most of the marketable yield has already been harvested, significant water savings would be achieved, and the land could be used in other crops. CDI at 75% IWR and 50% IWR, or RDI at 50% IWR at harvesting have resulted in a high incidence of fruit affected by blossom-end rot. In watermelon the RDI application can be recommended, both 75% and 50% IWR, during the fruit ripening, since it has led to acceptable marketable yields. In general terms, it can be affirmed that the application of CDI and RDI in the four crops has not significantly affected the product quality, in terms of the analyzed parameters.
My grateful thanks to the Cultural Affairs and Mission Sector, Egyptian Ministry of Higher Education for supporting me with a scholarship.
Abdelkhalik, AGA. (2019). Effect of continued and regulated deficit irrigation on the productivity of four vegetable crops in open-field conditions in the Mediterranean area [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/129868
TESIS
Slavík, Martin. "Vlhkostní charakteristiky přirozených pískovcových výchozů." Doctoral thesis, 2019. http://www.nusl.cz/ntk/nusl-398168.
Full text