Varierad kaliumgödsling i potatis
en fältstudie i Hedemora
Variation in tuber quality within a single field was one of the motives for a pilot study
in Halland, in south-western Sweden conducted during 2002. Quality problems in potatoes have been increasing due to the aggregation of several small fields with different land use history into larger farm units, which are heterogeneous in soil properties and fertility. The study in Halland indicated that both the uniformity and the mean size of tubers may increase from site-specific K fertilization, whereas total yields may be unaffected. The results from this pilot-study with site-specific fertilization showed that tubers reached a more uniform quality and gave a more uniform mean size, while the total yield wasn't affected at all.
Site-specific K-fertilization has been applied for some years in Halland with good
results. The aim of this study was to test this technique in another potato growing
area. Potatoes have a high uptake of potassium. Potassium has quality effects on
potatoes, as after cooking darkening, sogginess and decomposition. Usual fertilizing is
based on the mean need of nutrient adapted to soil content of K-AL and P-AL. Normally there are variations in soil content all over the field.
During the growing season of 2006, a field experiment was conducted close to Hedemora in central Sweden for testing the hypothesis that different rates of potassium fertilization affect tuber quality and mean size. Within the same field, three homogenous areas were selected that differed in soil properties. The whole field in Hedemora was fertilized with 850kg NPK(6.5, 7.1 and 16.2% respectively). Before the last weed treatment, potassium was site-specifically fertilized over the field. However, in the experimental areas K was applied at three fertilization doses (0, 30 and 60kg K ha-1) in a randomized block design with four replicates. Tuber yields differed significantly between two of the three locations within the field but yields did not differ significantly between the three fertilisation rates. Quality did not differ between the fertilizing rates but significant differences were found between the experimental areas. The non-significant effect of K fertilization on tuber mean size and quality was unexpected since previous field studies in Halland resulted in differences between K-application rates.