January 1, 1992Journal of Environmental Quality
The Transport of Bioavailable Phosphorus in Agricultural Runoff
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Discussion
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Implication
Field study reveals reduced total phosphorus loss but increased bioavailability in agricultural watersheds, indicating total phosphorus alone does not reflect aquatic eutrophication risk.
Key Points
- To evaluate how agricultural watershed management practices affect the transport and bioavailability of phosphorus in surface runoff.
- Monitored soluble phosphorus, particulate phosphorus, and bioavailable particulate phosphorus (via sodium hydroxide extraction) over a 5-year period.
- Sampled runoff across 20 unfertilized, fertilized, grassed, and cropped watersheds in the Southern Plains.
- Erosion-control practices reduced mean annual bioavailable phosphorus losses from 1796 g P ha⁻¹ yr⁻¹ in peanut-sorghum watersheds to 176 g P ha⁻¹ yr⁻¹ in native grass watersheds.
- Bioavailable phosphorus comprised 29% of total phosphorus loss in peanut-sorghum watersheds compared to 88% in native grass watersheds due to higher relative contributions of soluble phosphorus (69% vs. 13%) and bioavailable particulate phosphorus (69% vs. 26%).
Cite This Study
Sharpley et al. (1992) studied this question.