Refining of nitrogen fertilization guidelines for irrigated cotton (Gossypium hirsutum L.) in South Africa

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dc.contributor.advisorDu Preez, C. C.en_ZA
dc.contributor.authorHaumann, Eduard Johannesen_ZA
dc.date.accessioned2023-08-15T07:15:24Z
dc.date.available2023-08-15T07:15:24Z
dc.date.issued2023en_ZA
dc.description.abstractThirteen randomised block nitrogen fertilization field trials were done in five irrigated cotton producing areas of South Africa: Bela Bela, Rustenburg, Vaalharts, Rietriver and Groblersdal, with the aim to refine the existing nitrogen fertilization guideline. At Rustenburg cotton was preceded by harvested oats, harvested soybean, ploughed in soybean and babala in order to create varying soil nitrogen contents. Soil samples (0–300, 300–600 and 600–900 mm soil depths) were taken at least two weeks after irrigation for land preparation to determine total nitrogen. Leaf petiole samples were collected at two-week intervals, starting one week before first flowering for measurement of total nitrogen. After ripening, seed cotton yield was determined. The yield was subjected to analysis of variance and correlated with the nitrogen application rate to quantify an optimal nitrogen fertilization rate per site for each trial year. The estimated optimal nitrogen fertilization levels were correlated with the residual soil nitrogen content for each depth resulting in four guidelines for either maximum yield or maximum profit. Therefore, the cotton grower has eight different options for the calculation of an appropriate nitrogen application level based on the residual nitrogen content of the soil.en_ZA
dc.identifier.urihttp://hdl.handle.net/11660/12109
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA
dc.subjectThesis (Ph.D. (Soil Sciences))--University of the Free State, 2023en_ZA
dc.subjectIrrigated cottonen_ZA
dc.subjectnitrogen fertilization guidelinesen_ZA
dc.subjectresidual soil nitrogenen_ZA
dc.subjectleaf petiole nitrogenen_ZA
dc.subjectmaximum yielden_ZA
dc.subjectmaximum profiten_ZA
dc.titleRefining of nitrogen fertilization guidelines for irrigated cotton (Gossypium hirsutum L.) in South Africaen_ZA
dc.typeThesisv
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