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Soil variables for predicting potential phosphorus release in Swedish noncalcareous soils
Katarina Börling1, Erasmus Otabbong, Elisabetta Barberis
1Department of Soil Sciences, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden. Katarina.Borling@mv.slu.se
Journal of Environmental Quality
|February 18, 2004
Summary
Excess soil phosphorus (P) risks water pollution. This study identified key soil variables, like phosphorus saturation degree (DPS), to predict potential P release from agricultural soils, improving risk assessments for P loss.
Area of Science:
- Agricultural Science
- Soil Science
- Environmental Chemistry
Background:
- Phosphorus (P) accumulation in agricultural soils from fertilization poses a risk of P loss to surface waters.
- Effective risk assessment systems for P loss require understanding both P release from soil and transport mechanisms.
Purpose of the Study:
- To identify soil variables that can accurately predict the potential for P release from soil into solution.
- To improve phosphorus risk assessment models for agricultural runoff.
Main Methods:
- Utilized soils from nine sites within the Swedish long-term fertility experiment, each with four distinct soil P levels.
- Measured CaCl2-extractable phosphorus (P) as an indicator of potential P release.
- Calculated Degree of Phosphorus Saturation (DPS) using Olsen P or P-AL relative to Phosphorus Sorption Capacity (PSC).
Main Results:
- Standard soil tests like Olsen P or P-AL alone were insufficient for predicting P release due to varying Phosphorus Sorption Capacity (PSC).
- CaCl2-extractable total phosphorus (CaCl2-TP) showed strong exponential relationships with DPS values (r2 ≥ 0.79).
- Ratios of Olsen P or P-AL to a single-point Phosphorus Sorption Index (PSI) provided strong linear correlations with CaCl2-TP (r2 ≥ 0.86) and are easily determined.
Conclusions:
- Degree of Phosphorus Saturation (DPS) and easily determined ratios involving Phosphorus Sorption Index (PSI) are effective predictors of potential P release from soils.
- These improved predictors are valuable for developing robust risk assessment systems to mitigate P loss from agricultural fields.