Kan biokol minska kväveläckaget från skånsk åkerjord?

Sammanfattning: Nitrogen leaching from modern agriculture can contribute to nitrogen enrichment in ground- and surface water, causing negative health effects or environmental issues by eutrophication. One technique to manage and reduce the nitrogen losses from arable land could be to apply biochar, a solid charred material that is produced from pyrolyzed biomass. Biochar has previously been shown by recent studies to retain nutrients, increase soil water-holding capacity, pH and the growth of mycorrhizal fungi. In this study, a two week long laboratory experiment was performed to investigate if nitrogen leaching from a fertilized soil decreased with biochar amendment. Application of 3 t ha-1 biochar derived from sewage sludge was applied to a soil collected in the southern of Sweden. Both fertilized and non-fertilized soil treatments with and without biochar were performed and leached with water, which was then tested for the concentration of leached NH4-N and NO3-N with a photometer. Additionally, pH of the leachate water and the leached water volume was measured. The result from this study did not show that addition of biochar derived from sewage sludge decreased leaching of neither NH4-N nor NO3-N from the fertilized soil treatments. The addition of biochar could not be proven to have any effect on the soil water-holding capacity and neither pH of the leachate water. The majority of the treatments had a larger total leakage of NH4-N than that of NO3-N. Further studies are needed to investigate the potential of biochar amendment to decrease the nitrogen leaching from modern agriculture.