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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2008

2007

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Abstract

In some parts of the world, the soil selenium (Se) content is too low to ensure the Se level recommended for human or animal consumption in the crops produced. In order to secure a desired concentration of Se in crops, Se has been applied as mineral fertilizer to agricultural fields. Since only a minor part of the inorganic Se applied is utilized by plants and small increases in Se concentrations in, e.g., drinking water, may be toxic, the method is somewhat controversial. As an alternative to Se-enriched mineral fertilizer, different seafood-processing wastes have been examined as a source for Se in crop production. Both in greenhouse pot experiments and field trials the Se in seafood waste was not plant-available during the first growing season. There was no significant difference between the Se concentration in wheat growing in soil without added Se and in soil receiving Se from seafood waste in amounts ranging from 0.9 to 9 g ha(-1). Neither was any residual effect of Se in seafood waste seen during a second year growth period. Thus, seafood-processing waste cannot be regarded as a potential source of Se in crop production. Possible mobilization of formerly applied Se, as seafood-processing waste or Se enriched mineral fertilizer due to changes in soil redox conditions were examined in a leaching experiment. The mobility of formerly applied Se was generally very low, but the results indicated that under permanently wet soil conditions leaching of Se may occur in plant dormant periods in soils with low organic matter content and high pH.

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Abstract

The objective of the present study was to investigate the influence of soil organic matter content and pH on plant availability of both inorganic and organic selenium (Se) fertilisers. Further, the risk of Se leaching after application of inorganic Se fertiliser was evaluated. A new interpretation of an older field study at different sites in Southern Norway showed that organic C was correlated with grain Se concentration in wheat, barley and oats, explaining up to 60% of the variation in Se concentration. Pot experiments with a peat soil, a loam soil and a peat/loam soil mixture were conducted for the present study at a range of pH values between pH 5 and 7. Below pH 6, Se uptake from added Se fertiliser was higher in the soil types with high organic matter content than in the loam. The opposite occurred at a soil pH above 6, where Se uptake was higher in the loam than in the peat soil. A simple leaching experiment after one growing season confirmed the findings of the pot experiments that Se availability in the loam soil with a relatively low organic matter content increased with increasing pH, whereas it decreased in the peat soil. Neither Se yeast, nor pure Se methionine, used as organic Se fertiliser, resulted in any significant uptake of Se when added at concentrations similar to the inorganic Se applications.

Abstract

In parts of the world, Se availability in the soil is so low that Se contents in the crops produced there are well below recommended values. Since the difference between Se essentiality and toxicity is very small, the addition of Se via fertiliser is controversial. Therefore, it is important to utilise the Se added in the best possible way. The objective of the present study was to investigate the influence of soil organic matter on the one hand, and addition of organic material (slurry) on the other hand on plant availability of selenium (Se) in soil. Pot experiments with the Se addition in the form of selenate were conducted with a peat, a loam and a peat/loam mixture at a range of pH values between 5 and 6.8. Se uptake from added Se fertiliser was higher in the soil types with high organic matter content than in the loam at pH 6 and below. The opposite occurred at a soil pH above 6.4, where Se uptake was higher in the loam than in the peat. In a pot experiment using only peat and loam at two pH levels, cattle slurry added together with selenate was found to increase the Se concentration in grain at the higher pH. At the lower pH there was no significant effect of slurry on Se concentration in grain. Application of slurry also increased the residual effect of Se that had been applied to the loam in the preceding growing season. In the peat, no residual effect of Se was found either with or without the addition of slurry.