Thesis (M.S. - Agronomy and Plant Genetics)--University of Arizona. / Includes bibliographical references.

Thesis (M.Eng.Sc.) - University of Queensland, 2003. / Includes bibliography.

Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Many South African farmers are forced to use water from nearby rivers for crop irrigation, since it is the most affordable and sometimes only source of water available to them. During this research project, a baseline study was performed on a farm irrigating fresh produce with water obtained from the Eerste River. The baseline study was done over a five month period, at six preselected sampling points, to determine the microbial and physico-chemical parameters of the water so a baseline could be established to compare the results to when the ultraviolet (UV) apparatus was installed (February 2013). Aerobic colony count (ACC), total coliforms (TC) and Escherichia coli (E. coli) were tested for during the microbiological study, while the physico-chemical analysis comprised of temperature, pH, conductivity, chemical oxygen demand (COD), alkalinity and total soluble solids (TSS). The UV treatment study was also performed over a five month timeline, at eight different sampling points (original six sampling points, with additional sampling points before and after UV). The same microbiological tests were performed during the UV treatment study, but turbidity and percentage ultraviolet transmittance (% UVT) were performed additionally during physico-chemical analysis. During the baseline study ACC, TC and E. coli counts as high as 9 600 cfu.mL-1, 13 799 MPN.100 mL-1 and 2 098 MPN.100 mL-1 were isolated at the river (Sampling Point 1), respectively. While performing the UV treatment study ACC, TC and E. coli counts as high as 142 000 cfu.mL-1, 241 960 MPN.100 mL-1 and 6 867 MPN.100 mL-1 were isolated at the river, respectively. As a result it was concluded that the Eerste River was mostly unsuitable for irrigation of fresh produce that are consumed raw. The higher counts in the river, during the UV treatment study might be attributed to the increase in rainfall that occurred in the sampling months (March to July 2013). The counts as measured at the point of irrigation are considered of greater importance, since the counts present in the river might still decrease to below the guideline levels after passing through sand filters and the addition of hydrogen peroxide (current mode of treatment) or after passing through the UV in the UV treatment study. The ACC, TC and E. coli counts during the baseline study were as high as 8 800 cfu.mL-1, 24 196 MPN.100 mL-1 and 85 MPN.100 mL-1 at the point of irrigation (Sampling Point 6), respectively. After hydrogen peroxide addition average logreductions ranging between 0.65 and 1.13 were seen, but reduction was never constant. The counts at the point of irrigation remained more or less constant compared to the river due to contamination that occurred at the sand filters, making the water unsuitable for irrigation of fresh produce in terms of ACC and TC counts. In the UV treatment study ACC, TC and E. coli counts were as high as 35 000 cfu.mL-1, 10 462 MPN.100 mL-1 and 63 MPN.100 mL-1 at the point of irrigation (Sampling Point 8), respectively. Average log-reductions in the range of 0.90 to 1.25 were achieved, but it was inconsistent. After treatment with chlorine and re-sanding of the sand filters, no further contamination occurred and counts decreased to below guideline limits, making the water safe for irrigational use in terms of all of the microbiological parameters. Not only is UV treatment more effective in reducing microbiological counts than H2O2, it is also relatively less expensive in the long term. Hydrogen peroxide treatment of water amounts to a very high capital expense every month, whereas UV may seem expensive when starting up, but the monthly operating cost thereafter is marginally less than for H2O2. It is of great importance to farmers to find a treatment that would reduce the counts in the river water to below the guideline limits required for safe irrigation since pathogens can be carried over from water onto fresh produce, resulting in an increase in produce-associated foodborne outbreaks and loss of consumer trust. / AFRIKAANSE OPSOMMING: Menigte Suid-Afrikaners is afhanklik van nabygeleë riviere om hulle oeste te besproei aangesien dit meestal die mees bekostigbare en soms enigste bron tot hul beskikking is. Tydens hierdie projek is ‘n grondslag sowel as ‘n UV behandelingsmetode studie uitgevoer op ‘n plaas wat vars vrugte en groente besproei met water water wat hul vanuit die Eersterivier verkry. Die grondslagstudie is oor ‘n tydperk van vyf maande uitgevoer by ses voorafgekose punte. Dit is gedoen om die mikrobiologiese sowel as chemiese parameters van die water te bepaal sodat ‘n grondslag beskikbaar kon wees om met resultate te vergelyk wat met behulp van die ultravioletmasjien verkry is (in Februarie 2013 geïnstalleer). Tydens die mikrobiologiese studie is daar vir aerobiese koliform tellings (ACC), totale koliforme (TC) en Escherichia coli (E. coli) getoets. Tydens die chemiese analise is temperatuur, pH, konduktiwiteit, chemiese suurstof benodiging, alkaliniteit en totale oplosbaie vastestowwe in die water getoets. Die UV behandelingsmetode studie is ook oor ‘n tydperk van vyf maande uitgevoer, met twee addisionale toetspunte by. Presies dieselfde mikrobiologiese analises as wat tydens die grondslag studie uitgevoer is, is tydens die UV behandelingsmetode studie uitgevoer, maar vir die chemiese analise het turbiditeit en persentasie ultraviolet transmissie van die water bygekom. Gedurende die grondslag studie was ACC, TC and E. coli tellings so hoog as 9 600 cfu.mL-1, 13 799 MPN.100 mL-1 en 2 098 MPN.100 mL-1 onderskeidelik uit die rivier geïsoleer (Punt 1). Tydens die UV behandelingsmetode studie was ACC, TC en E. coli tellings so hoog as 142 000 cfu.mL-1, 241 960 MPN.100 mL-1 en 6 867 MPN.100 mL-1 onderskeidelik by die rivier geïsoleer. Gevolglik is daar afgelei dat die Eersterivier se water meestal ongeskik is om te gebruik vir die besproeiing van vars groente en vrugte wat rou geëet word sonder dat enige verdere behandeling plaasvind. Die hoër tellings wat tydens die UV behandelingsmetode in die rivier sigbaar was kan hoofsaaklik toegeskryf word aan die toename in reënval in daardie tyd (Maart tot Julie 2013). Tellings soos gemeet by die punt van besproeiing is wel van groter belang as die wat aangeteken is by die rivier; aangesien die tellings wat in die rivier aangeteken is steeds kan afneem tot onder aanvaarbare hoeveelhede soos in die standaarde uiteengesit, want die water moet steeds deur sandfilters beweeg en word ook huidiglik deur waterstofperoksied behandel tydens die die grondslagstudie of beweeg deur die UV apparaat in die UV behandelingsmetode studie. Die ACC, TC en E. coli tellings soos gemeet by die besproeiingspunt (Punt 6) was so hoog as 8 800 cfu.mL-1, 24 196 MPN.100 mL-1 en 85 MPN.100 mL-1, onderskeidelik. Na waterstofperoksied byvoeging was die gemiddelde log-reduksies sigbaar, tussen 065 en 1.13, maar afnames was nooit konstant nie. Die tellings by die punt van besproeiing het ongeveer konstant gebly in vergelyking met die tellings wat by die rivier aangeteken is; moontlik as gevolg van die hoë kontaminasie vlakke in die sandfilters. Kontaminasie van sandfilters het veroorsaak dat die water ongeskik was vir die gebruik van besproeiing van vars groente as gevolg van die hoë ACC en TC vlakke. Tydens die UV behandelingsmetode studie is ACC, TC en E. coli tellings so hoog as 35 000 cfu.mL-1, 10 462 MPN.100 mL-1 en 63 MPN.100 mL-1, onderskeidelik aangeteken (Punt 8). Gemiddelde log-reduksies tussen 0.90 tot 1.25 was verkry, maar behandeling en afnames in tellings was nie konstant nie. Nadat die sandfilters met chloor behandel is en die sand daarin vervang is, het geen verdere kontaminasie by die punt voorgekom nie. Nadat al die voorafgenoemde behandelings afgehandel is, het die tellings tot laer as die van die standaarde gedaal en dus was die water nou veilig om te gebruik vir besproeiingsdoeleindes in terme van die mikrobiologiese parameters. Die UV behandelingsmetode is nie net meer effektief in die verlaging van mikrobiologiesese tellings as waterstofperoksied nie, dis ook heelwat goedkoper in die langtermyn. Waterstofperoksied behandeling van water lei tot ‘n baie hoë kapitale onkoste per maand, terwyl UV baie duur mag voorkom in die beginfase, maar die maandelikse kostes is aansienlik laer as die van waterstofperoksied en maak sodoende op daarvoor. Dit is van uiterste belang vir boere om ‘n water behandelingsmetode te vind wat die hoë tellings in die rivier sal afbring tot laer as Suid-Afrikaanse en Kanadese riglyne; aangesien patogene oorgedra kan word van vars vrugte en groente. Laasgenoemde kan tot ‘n drastiese toename in vars voedsel geassosieerde siektes en gevolglik ‘n afname in die vertroue wat ‘n kliënt in ‘n produk plaas, lei.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This study is concerned with the development of a model for realtime water distribution management for rice crop production in the Upper Pampanga River Project (Philippines). The model utilizes a management technique which considers water distribution at the farm level on a system-wide basis under the constraints of the present users and the physical system situations. The intent of the project is to rely as much as possible on the available uncontrolled streamflows and rainfall during the wet season in order to minimize releases from the Pantabangan reservoir, and thus conserve most of the impounded water for irrigation during the dry season. A computerized model which incorporates a parameter prediction-correction technique is developed for calculating the daily water scheduling for the entire canal network of the UPRP. To determine how much water is needed, a daily water budget at each of the 2,216 rotation areas is performed in conjunction with the daily predicted uncontrolled streamflows, rainfall, varying water requirement, and water status at the farm level. Subsequent delivery correction schedules are determined based on the degree of the prediction error. Studies were conducted for the determination of the appropriate rainfall prediction scheme used in the scheduling model. Selection of the scheme was done through simulation of field operations at the farm level and by the application of the rainfall-use efficiency criterion. Time lags along the Pampanga River and the canal network were analyzed to determine the possibility of supplying the entire network from the Pantabangan Dam within 24 hours. The idealized solution of the problem of inequitable distribution of water within a rotation unit is also presented. The ability of the model to provide situation-and-user-oriented guidelines for water distribution activities is demonstrated.

The primary objective of this study was to establish a production function for alfalfa grown in the Sevier Valley using farm survey data. A secondary objective was to point out the analytical difficulties in establishing a production function for alfalfa. A multiple regression model using 12 linear, 12 nonlinear, and 7 interaction terms was employed. A coefficient of determination of .70 was obtained for the model. Intercorrelation problems associated with the model limit its usefulness for economic and predictive purposes. The predictive value of the model was greatly increased by reducing the numb er of correlated variables included in the model. The reduction in the number of variables also reduced the coefficient of determinations. Study results indicate that additional research on the correlation structure associated with multiple regression models is necessary. Study results indicate that optimum moisture days and actual consumptive use of moisture are better measures of water use than gross amounts of irrigation water applied. The use of these indicators reduces the number of problems associated with timing of water application and availability of water to plants. Their use would increase the reliability and significance of the evaluation of increments of irrigation water. The optimum use of irrigation water on alfalfa in the Sevier Valley is 40 inches per acre. At this use the net income to the farmer is $11.61 per acre.

Water is among the most abundant of all materials known to man. In all its various forms, water covers 75 percent of the earth's surface. It is estimated that the total physical quantity of water on the earth is 326,000,000 cubic miles. This apparent abundance belies the true nature of the water resource as it relates to the needs of man. At any given point in time, only a rather minute portion of this vast quantity of water is found in those forms and locations which render it useful to man. This may be attributed to the fact that utility in water is perishable and the efforts of man to amend the hydrological cycle have been successful only to a limited extent.

Thesis (Ph. D.)--University of Nebraska, 1935. / Bibliography: leaves 132-138.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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