Partners and International Organizations
(English)
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A, B, CZ, DK, FIN, F, D, H, IRL, I, NL, N, PL, P, RO, E, S, CH, GB
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Abstract
(English)
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Yield and quality of winter oilseed rape (Brassica napus) production is strongly influenced by sulfur (S) nutrition, as S-deficiency may cause severe yield reduction (10 - 50% of losses). The occurrence of S- deficiency in agricultural crops has increased over the last decade. To identify situations with risks of S-deficiency and to seek optimization of S-fertilization in oilseed rape production and other crops, different methods are available. They correspond to the different goals of our project. 1) Plant or soil analysis with corresponding critical values. Sulfate, total sulfur, and N:S ratio in the plant are the indicators of S-supply most frequently used. Critical values for those indicators vary according to the authors, method of analysis and plant development stage 2) Risks of S-deficiency can be estimated with models. Most of them are based on soil, physical and chemical properties, rainfalls and crop S-requirements, among other parameters 3) Alternative to models or plant analysis, by using winter oilseed rape as a field bio-indicator of early S-deficiency. The aim of our project (2000 to 2003) was to test the different approaches presented above. Plant or soil analysis The presented results showed that critical values for plant analysis were in the same range as published data. These informations could be useful to optimize S-nutrition of crops. However, we have in Switzerland a shortage of laboratory facilities able to run routine S-analysis. Models to estimate the risk of S-deficiency The adaptation of an existing model to our soil and climatic conditions might have the biggest impact on practices of S-fertilization in Switzerland. In fact this model is able to clearly discriminate situations with high, moderate or low risk of S-deficiency, with the possibility to consequently adapt S-fertilization. Oilseed rape as a field bio-indicator of early S-deficiency. Bio-indicator plants showed early symptoms of S-deficiency when the crop itself was under hidden deficiency (absence of visual symptoms, but detrimental effects of S-deficiency on yield). This technique needs more development in the future to be of practical use.
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