Phosphorus dynamics in tile-drain flow during storms in the US Midwest

• Published in: Agricultural water management Vol. 98; no. 4; pp. 532 - 540
• Main Authors: Vidon, P., Cuadra, P.E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-02-2011; Amsterdam; New York: Elsevier; Elsevier
• Series: Agricultural Water Management
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Biological and medical sciences; Bulk transporters; case studies; dietary minerals; Drainage; Dynamics; eutrophication; Exports; flow; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; International trade; Macropore flow; macropores; Matrix flow; Non-point source pollution; Non-point source pollution Macropore flow Matrix flow Particulate phosphorus Soluble reactive phosphorus Rainfall events Drainage; Particulate phosphorus; Phosphorus; Precipitation; Rainfall events; Soluble reactive phosphorus; Storms; tile drainage; Transport; Indiana; United States; North America; America; USA; Drainage; Matrix flow; Particulate phosphorus; Macropore flow; Non-point source pollution; Soluble reactive phosphorus; Rainfall events; Storm; Environmental factor; Soluble form; Temperate zone; Atmospheric disturbance; Rain; Macropore; Water engineering; Chemical reactivity; Non metal; Atmospheric condition; Meteorological phenomenon; Phosphorus; Biogeochemical cycle; Physical properties; Group VA element; Diffuse source; Midwest; Pore; Nonpoint pollution; Phosphorus cycle; Pollution source; Porosity; Atmospheric precipitation; Macroporosity
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2010.09.010

▶ For large storms (>6
cm), macropore flow regulated SRP export. ▶ For small storms (<3
cm), matrix flow regulated SRP export. ▶ Macropore flow regulated TP export regardless of the storm. ▶ SRP accounted for 9–22% of TP flux in tile-drains.
Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006–0.025
mg/L for SRP and 0.057–0.176
mg/L for TP. For large storms (>6
cm bulk precipitation), for which macropore flow represented between 43 and 50% of total tile-drain flow, SRP transport to tile-drains was primarily regulated by macropore flow. For smaller tile-flow generating events (<3
cm bulk precipitation), for which macropore flow only accounted for 11–17% of total tile-drain flow, SRP transport was primarily regulated by matrix flow. Total P transport to tile-drains was primarily regulated by macropore flow regardless of the storm. Soluble reactive P (0.01–1.83
mg
m
−2/storm) and TP (0.10–8.64
mg
m
−2/storm) export rates were extremely variable and positively significantly correlated to both mean discharge and bulk precipitation. Soluble reactive P accounted for 9.9–15.5% of TP fluxes for small tile-flow generating events (<3
cm bulk precipitation) and for 16.2–22.0% of TP fluxes for large precipitation events (>6
cm bulk precipitation). Although significant variations in tile-flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of macropore flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.