Aggregatstabilitet, jordbearbetning och fosforförluster i ett typområde på jordbruksmark
Large amounts of phosphorus (P) are lost from the arable land due to water erosion. Both phosphorus attached to particles and dissolved phosphorus (mainly phosphate) are transported away with drainage-water and surface runoff. Good soil structure is important in minimizing these losses.
In this study, soils from 50 fields were analysed with respect to aggregate stability as measured by dispersion of clay together with the content of total phosphorus (TotP), particulate phosphorus (PP) and phosphate phosphorus (PO4P) in the water phase. All soils were clay soils with clay content varying between 21 and 54%.
The results showed that the amount of dispersed clay, as well as TotP and PP increased with decreasing soil carbon content. The dispersed clay content also had a significant positive correlation with the soil clay. For all fractions of phosphorus analysed in the water phase there was a significant correlation with the P-AL-number. The correlation was highest for PO4P with an R2?value of 0,68. Different kinds of soil management were shown to be important both for the stability of aggregates and the amount of phosphorus in the solution. Fields with pasture had significantly less dispersed clay than either ploughed fields or fields with winter wheat. There was also a significant difference between pasture and winter wheat as regards both the TotP content and PP content, with higher amounts of P in waters from the winter wheat fields.