Threshold values for sulphur in soils of the main maize-producing areas of South Africa
| Autor: | D.S. Fouche, A.D.P. Botha, J. J. van Biljon |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | South African Journal of Plant and Soil. 21:152-156 |
| ISSN: | 2167-034X 0257-1862 |
| Popis: | Fertilizers introduced to South Africa after World War 2 contained sufficient sulphur (S) to satisfy the demands of all crops. However, dramatic shifts to high-analysis NPK fertilizers containing little or no S and restriction on sulphur dioxide emissions by industries lowered the coincidental input of S. At the same time continuous crop- ping and higher-yielding cultivars removed more S which led to low S levels in cultivated soils. The aim of this study was to determine the threshold value for S and to evaluate the S-levels in soils of the main maize-growing areas of South Africa. In order to determine the critical sulphur content in these soils, field trials were carried out at ten localities during four consecutive seasons. The treatments were full fertilization as reference, with the comparative treatment being where S was omitted. Relative yields were calculated as the yield of the (-S) plot expressed as a percentage of the yield of the plot (in the same replicate) which received all the nutrients i... |
| Databáze: | OpenAIRE |
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