Strukturkalkning av åkermark : ett sätt att minska jordbrukets bidrag till eutrofiering av vatten
Abstract: In this review article, the effect of structural liming on clay soils, which have a high leakage potential for phosphorus (P), was analyzed. The purpose was to investigate structural liming as a method to reduce the impact of agriculture on eutrophication of water sources. Second-ary aspects such as economy are concerned in order to discuss whether structural liming is a realistic technique that can be applied without financial loss. From studied material, there is a positive correlation between structural liming and reduced P leakage. The results show that the pH-enhancing effect of the structure liming changes the binding properties of the P in the soil. At an optimum pH-value between 6 and 7, P binds to calcium ions which increase both phosphorus solubility and availability for the plants. At lower and higher pH-values, phosphorus forms compounds with metal ions or carbonates, respectively, that have ions solubility and becomes inaccessible to vegetation. Structural liming also improves soil struc-ture through slow and fast-paced processes that lead to biological, chemical and physical changes. In summary, this creates a land structure with higher infiltration capacity, rein-forced aggregate structure, reduced tendency for surface run-off and internal erosion. Struc-tural changes from liming is also favorable for crop growth and crop yield. For structural liming it is important what kind of lime is used, where lime with its origin from industries as byproducts is less effective than other forms of lime, such as slaked lime. From experi-mental studies, long terms of reduced P leakage appear from structural liming. Further re-search is needed on different lime products effect on stabilizing the structure for long-term effects. Some studies have indicated that lime filter drainage, used as a measure to reduce P losses, may increase nitrogen (N) leaching. Whether or not structural liming affects the risk for N leaching should be clarified, to better understand the potential of structural liming for reducing agricultural impact on the aquatic environment and achieving the environmental goal "No Eutrophication." However, it is clear from the literature, that by structural liming, phosphorus can be retained in the soil to a higher extent, which increases the potential for plants to utilize phosphorus as nutrition. With a future change in precipitation pattern, it is likely that the interest in structural liming will increase as leaching of P then is expected to increase.
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