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Effect of rainfall simulator and plot scale on overland flow and phosphorus transport
Andrew Sharpley1, Peter Kleinman
1USDA Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802-3702, USA. andrew.sharpley@ars.usda.gov
Journal of Environmental Quality
|December 17, 2003
Summary
Small plot rainfall simulations accurately predict phosphorus transport processes in overland flow, despite scale-dependent variations in concentrations and loads. This supports using rainfall simulators for soil phosphorus management research.
Area of Science:
- Environmental Science
- Soil Science
- Hydrology
Background:
- Rainfall simulation experiments are crucial for understanding erosion and contaminant transport in overland flow.
- Estimating phosphorus (P) transport at watershed scales using small plot data presents challenges due to scale effects.
Purpose of the Study:
- To compare overland flow and phosphorus transport from 2-m and 10.7-m rainfall simulation plots with watershed-scale data.
- To evaluate the consistency of phosphorus transport processes across different plot scales and land management practices.
Main Methods:
- Conducted rainfall simulation experiments (75 mm h⁻¹) on 2-m and 10.7-m plots with varying land uses (grass, no-till corn, tilled fields).
- Measured overland flow, dissolved reactive phosphorus (DRP), particulate phosphorus (PP), total phosphorus (TP), and sediment discharge.
- Analyzed relationships between soil phosphorus (Mehlich-3) and overland flow P concentrations, and P enrichment ratios with sediment discharge.
Main Results:
- Smaller 2-m plots generated more overland flow but had higher DRP concentrations compared to 10.7-m plots.
- Sediment, PP, and TP concentrations were significantly lower from 2-m plots than 10.7-m plots.
- Relationships between DRP and soil P, and P enrichment ratios and sediment discharge, were consistent across plot scales and with watershed data.
Conclusions:
- While P concentrations and loads vary with plot scale, the fundamental processes governing DRP and PP transport in overland flow are consistent.
- Small plots and rainfall simulators can be effectively used to assess soil P relationships with overland flow P, considering soil type and management.