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Doctoral thesis, 2014

Risk assessment of erosion and losses of particulate phosphorus

Villa Solís, Ana


Phosphorus (P) losses from agricultural land are considered a major contributor to eutrophication in many aquatic ecosystems. Areas more vulnerable to losses of P need to be identified in order to effectively apply mitigation measures aimed at reducing total loads of P. This thesis focuses on the identification of soils and fields vulnerable to losses of particulate P (PP) due to erosion. Two simple soil dispersion tests to estimate the initial risk of soil and P mobilization (DESPRAL and SST) were tested and compared in the laboratory. The outcome was combined with data relative to source (soil P content) and transport (unit stream power length-slope topographic factor calculated from a high resolution digital elevation model) risks to establish probable causes of P losses at field scale and to target critical source areas at catchment scale. DESPRAL showed higher precision and shorter execution time than SST, in addition to its already proven validation and reproducibility. Also, compared with other methods, the test returned a wider range of values for each textural class, allowing the differentiation of soils within these classes. This is especially important for finetextured soils, which are the most sensitive to the mobilization of particles. The study of long-term P and sediment losses from five fields confirmed the relevance of adequately identifying the source and transport conditions within fields when assigning appropriate countermeasures. Finally, the assessment of long-term losses from two contrasting catchments highlighted how transport and mobilization risks have a greater effect on P losses due to erosion than P accumulation in soil. When ranking the fields within both catchments according to this prioritization of factors, a greater number of high-risk fields were found in the catchment with more pronounced transport pathways. The outcome of this thesis is the proposal of methodology whereby easily obtainable data can be used in risk assessments to identify fields and catchments vulnerable to PP losses. The knowledge gained provides a good starting point to improve these assessments by incorporating means for prioritizing different mitigation measures currently not performed in Sweden.


erodibility; erosion; critical source areas; mobilization risk; phosphorus; particulate phosphorus; soil dispersion; transport risk

Published in

Acta Universitatis Agriculturae Sueciae
2014, number: 2014:64
ISBN: 978-91-576-8076-1, eISBN: 978-91-576-8077-8
Publisher: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences

Authors' information

Villa Solís, Ana (Villa Solís, Ana)
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment

UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Soil Science

URI (permanent link to this page)