Nutrient Cycling in Agroecosystems

, Volume 59, Issue 1, pp 29–38 | Cite as

Identifying critical sources of phosphorus export from agricultural watersheds

  • Jennifer L. Weld
  • Andrew N. Sharpley
  • Douglas B. Beegle
  • William J. Gburek


Surface runoff accounts for much of the phosphorus (P) input to and accelerated eutrophication of the fresh waters. Several states have tried to establish general threshold soil P levels above which the enrichment of surface runoff P becomes unacceptable. However, little information is available on the relationship between soil and surface runoff P, particularly for the northeastern United States. Further, threshold soil P criteria will be of limited value unless they are integrated with site potential for runoff and erosion. In response, the Natural Resource Conservation Service (NRCS) developed a P Index (PI), which ranks the vulnerability of fields as sources of P loss in runoff, based on soil P, hydrology, and land use. This study evaluated the relationship between soil and surface runoff P in a study watershed in central Pennsylvania. The relationship was then incorporated into the (PI), and its impact on the identification of critical source areas within the watershed was examined. Using simulated rainfall (6.5 cm h−1 for 30 min), the concentration of dissolved P in surface runoff (0.2–2.1 mg l−1) from soils was related (r2=0.67) to Mehlich-3 extractable soil P (30–750 mg kg−1). Using an environmentally based soil P threshold level of 450 mg kg−1 determined from the soil-runoff P relationship, the PI identified and ranked areas of the watershed vulnerable to P loss. The vulnerable areas were located along the stream channel, where areas of runoff generation and areas of high soil P coincide, and where careful management of P fertilizers and manure should be targeted.

eutrophication nonpoint source pollution risk assessment soil phosphorus surface runoff water quality 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Beegle DB (1999) Soil fertility management. In: Serotkin N and Tibbetts S (eds) The Agronomy Guide 1999–2000, pp. 19–46. Pennsylvania State University,University Park, PA: Publications Distribution CenterGoogle Scholar
  2. Burkholder JM, Noga EJ, Hobbs CW, Glasgow HB Jr and Smith SA (1992) New ‘phantom’ dinoflagellate is the causative agent of major estuarine fish kills. Nature 358: 407–410Google Scholar
  3. Carpenter SR, Caraco NF, Correll DL, Howarth RW, Sharpley AN and Smith VH (1998) Nonpoint Pollution of surface waters with phosphorus and nitrogen. Ecol Appl 8: 559–568Google Scholar
  4. Gburek WJ and Sharpley AN (1998) Hydrologic controls on phosphorus loss from upland agricultural watersheds. J Environ Qual 27: 267–277Google Scholar
  5. Gburek WJ, Sharpley AN and Folmar GJ (2000) Critical areas of phosphorus export from agricultural watersheds. In: Sharpley AN (ed), pp. 83–104. Agriculture and Phosphorus Management: The Chesapeake Bay. Boca Raton, FL: Lewis PublishersGoogle Scholar
  6. Lemunyon JL and Gilbert RG (1993) Concept and need for a phosphorus assessment tool. J Prod Agric 6: 483–486Google Scholar
  7. Matuszak DL, Sanders M, Taylor JL and Wasserman MP (1997) Toxic Pfiesteria and human health. Maryland Med J 46: 515–520Google Scholar
  8. Mehlich, A (1984) Mehlich 3 soil test extractant: a modification of Mehlich 2 extractant. Commun Soil Sci Plant Anal 15: 1409–1416Google Scholar
  9. Murphy J and Riley JP (1962) A modified single solution method for the determination of phosphate in natural waters. Anal Chim Acta 27: 31–36Google Scholar
  10. Pionke HB, Gburek WJ, Sharpley AN and Zollweg JA (1997) Hydrologic and chemical controls on phosphorus losses from catchments. In: Tunney H, Carton O, and Brookes P (eds) Phosphorus Loss to Water from Agriculture, pp. 225–242. Cambridge, UK: CAB International PressGoogle Scholar
  11. Pote DH, Daniel TC, Sharpley AN, Moore PA Jr, Edwards DR and Nichols DJ (1996) Relating extractable phosphorus in silt loam to phosphorus losses in runoff. Soil Sci Soc Am J 60: 855–859Google Scholar
  12. Pote DH, Daniel TC, Nichols DJ, Sharpley AN, Moore PA Jr, Miller DM and Edwards DR (1999) Relationship between phosphorus levels in three-Ultisols and phosphorus concentrations in runoff. J Environ Qual 28: 170–175Google Scholar
  13. Schoumans OF and Breeuwsma A (1997) The relation between accumulation and leaching of phosphorus: laboratory, field and modelling results. In: Tunney H, Carton OT, Brookes PC and Johnston AE (eds) Phosphorus loss from soil to water, pp. 361–363. Cambridge, UK: CAB International PressGoogle Scholar
  14. Sharpley AN (1995) Dependence of runoff phosphorus on soil phosphorus. J Environ Qual 24: 920–926Google Scholar
  15. Sharpley AN, Daniel TC, Sims JT and Pote DH (1996) Determining environmentally sound soil phosphorus levels. J Soil Water Conserv 51: 160–166Google Scholar
  16. Sharpley A and S Rekolainen (1997) Phosphorus in agriculture and its environmental implications. In: Tunney H (ed) Phosphorus loss to water from agriculture, pp. 1–71. Cambridge, UK: CAB International PressGoogle Scholar
  17. Sims JT (ed) (1998) Soil Testing for Phosphorus: Environmental Uses and Implications. Southern Cooperative Series Bulletin No. 389. SERA-IEG 17 Publication.Google Scholar
  18. USDA-CSREES Regional Committee: Minimizing Agricultural Phosphorus Losses for Protection of Water Resource. Newark, DE: University of DelawareGoogle Scholar
  19. US Department of Agriculture and US Environmental Protection Agency (1999) Unified national strategy for Animal Feeding Operations. March 9, 1999. ( Scholar
  20. US Environmental Protection Agency (1996) Environmental indicators of water quality in the United States. 25 pp. EPA 841-R-96-002. US EPA, Office of Water (4503F), US Govt. Washington, DC: Printing OfficeGoogle Scholar

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Jennifer L. Weld
    • 1
  • Andrew N. Sharpley
    • 2
  • Douglas B. Beegle
    • 1
  • William J. Gburek
    • 3
  1. 1.Department of AgronomyPennsylvania State UniversityUniversity ParkUSA
  2. 2.Pasture Systems and Watershed Management Research LaboratoryUSDA-ARSUniversity ParkUSA
  3. 3.Pasture Systems and Watershed Management Research LaboratoryUSDA-ARSUniversity ParkUSA

Personalised recommendations