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Phosphorus runoff during four years following composted manure application
Charles S Wortmann1, Daniel T Walters
1Department of Agronomy and Horticulture, 279 Plant Science, University of Nebraska, Lincoln, NE 68583-0915, USA. cwortmann2@unl.edu
Journal of Environmental Quality
|March 3, 2006
Summary
Repeated manure application impacts soil phosphorus (P) levels and runoff. Residual compost significantly reduced runoff and sediment loss, indicating its long-term benefits for P management.
Area of Science:
- Soil Science
- Environmental Chemistry
- Agronomy
Background:
- Excessive soil test phosphorus (STP) from repeated manure application increases P in runoff.
- Manure application can improve soil water infiltration and reduce runoff volume.
- Understanding residual effects of composted manure is crucial for P management.
Purpose of the Study:
- Evaluate soil P tests for predicting runoff P concentration.
- Determine residual effects of composted manure on P loss in runoff and leaching.
- Assess the long-term impact of composted manure on soil and water quality.
Main Methods:
- Field research conducted from 2001-2004 using natural runoff events on 11-m plots.
- Applied low-P and high-P composts over 3 years, totaling 750 and 1150 kg P ha(-1).
- Measured soil P (Bray-P1), runoff volume, sediment loss, and runoff P concentration.
Main Results:
- High-P compost significantly increased surface soil P (Bray-P1) from 16 to 780 mg kg(-1).
- Residual compost treatments reduced runoff and sediment losses by 69% and 120% compared to no compost.
- Runoff P concentration increased with STP, but significant P loss occurred even without compost; agronomic tests predicted mean runoff P.
Conclusions:
- Agronomic soil tests are useful for predicting long-term runoff P concentration.
- P loss risk warrants concern even at moderate soil P levels.
- Residual effects of compost application reduce sediment and runoff loss for over 3 years, impacting P indices.